an alternative interpretation of the cayman trough evolution from a reidentification of magnetic anomalies magnetic data were collected during the wilkes 1973 and seacarib ii 1987 cruises to the cayman trough a new interpretation of magnetic data is carried out an isochron pattern is drawn up from our anomaly identifications an early eocene age 49 ma ypresian for cayman trough opening is proposed instead of the late oligocene or middle eocene ages suggested by previous studies our plate tectonic reconstruction is simpler and fits the on land geology jamaica and cuba and the tectonics our reconstruction shows a southward propagation of the spreading centre between magnetic anomalies 8 and 6 26 and 20 ma the trough width increases by 30 km in this period the southward propagation of the cayman spreading centre from the middle oligocene to the early miocene induced the development of the restraining bend of the swan islands the formation of a 1 km high scarp on the eastern trace of the cayman trough transform fault walton fault and the formation of a pull apart basin hendrix pull apart magnetic anomalies and magnetization maps give information about the deformation and the rocks the proposed evolutionary model of the cayman trough from the inception of seafloor spreading to the present configuration is presented in relation to the tectonic escape of the northern boundary of the caribbean plate from the maastrichtian to the present

probabilistic forecasting of earthquakes we present long term and short term forecasts for magnitude 5 8 and larger earthquakes we discuss a method for optimizing both procedures and testing their forecasting effectiveness using the likelihood function our forecasts are expressed as the rate density that is the probability per unit area and time anywhere on the earth our forecasts are for scientific testing only they are not to be construed as earthquake predictions or warnings and they carry no official endorsement for our long term forecast we assume that the rate density is proportional to a smoothed version of past seismicity using the harvard cmt catalogue this is in some ways antithetical to the seismic gap model which assumes that recent earthquakes deter future ones the estimated rate density depends linearly on the magnitude of past earthquakes and approximately on a negative power of the epicentral distance out to a few hundred kilometres we assume no explicit time dependence although the estimated rate density will vary slightly from day to day as earthquakes enter the catalogue the forecast applies to the ensemble of earthquakes during the test period it is not meant to predict any single earthquake and no single earthquake or lack of one is adequate to evaluate such a hypothesis we assume that 1 per cent of all earthquakes are surprises assumed uniformly likely to occur in those areas with no earthquakes since 1977 we have made specific forecasts for the calendar year 1999 for the northwest pacific and southwest pacific regions and we plan to expand the forecast to the whole earth we test the forecast against the earthquake catalogue using a likelihood test and present the results our short term forecast updated daily makes explicit use of statistical models describing earthquake clustering like the long term forecast the short term version is expressed as a rate density in location magnitude and time however the short term forecasts will change significantly from day to day in response to recent earthquakes the forecast applies to main shocks aftershocks aftershocks of aftershocks and main shocks preceded by foreshocks however there is no need to label each event and the method is completely automatic according to the model nearly 10 per cent of moderately sized earthquakes will be followed by larger ones within a few weeks

seismic moment distribution revisited i statistical results summary an accumulation of seismic moment data gathered over the previous decade justifies a new attempt at a comprehensive statistical analysis of these data herein more rigourous statistical techniques are introduced their properties investigated and these methods are employed for analysis of large modern data sets several theoretical distributions of earthquake size seismic moment frequency relations are described and compared we discuss the requirements for such distributions and introduce an upper bound or a corner moment for a distribution to have a finite energy or moment flux we derive expressions for probability density functions and statistical moments of the distributions we also describe parameter evaluation in particular how to estimate the seismic moment distribution for the largest earthquakes simulating earthquake size distributions allows for a more rigourous evaluation of distribution parameters and points to the limitations of the classical statistical analysis of earthquake data simulations suggest that several earthquakes approaching or exceeding the corner magnitude mc limit need to be registered to evaluate mc with reasonable accuracy using the harvard catalogue data we compare moment distribution parameters for various temporal spans of the catalogue for different tectonic provinces and depth ranges and for earthquakes with various focal mechanisms the statistical analysis suggests that the exponent b is universal b 0 60 0 65 for all moderate earthquakes the corner moment mc value determined by the maximum likelihood method both in subduction zones and globally is about 10 21 n m corresponding to the corner moment magnitude mc 8 0 for midoceanic earthquakes mc is apparently smaller for spreading ridges it is about 5 8 and for strike slip earthquakes on transform faults it decreases from 7 2 to 6 5 as the relative slip velocity of faults increases we investigate the seismic moment errors both random and systematic and their dependence on earthquake size the relative errors seem to decrease for larger events the influence of moment uncertainties on the parameter estimates is studied whereas the b values do not appear to be significantly influenced by the errors for the corner moment large errors can lead to substantially biased estimates we compare the harvard catalogue results with the earthquake data from instrumental catalogues in the first three quarters of the 20th century several very large earthquakes mi9 occurred around the middle of the century their magnitude values cannot be fitted by a modified gutenberg richter law with mc 8 0 8 5 among other factors this discrepancy can be explained by either substantially higher errors in the earlier magnitude values or by mc being higher for some subduction zones it is unlikely that data available presently or soon will be sufficient to determine the corner magnitude of 9 and above with reasonable precision using purely statistical methods

quantification of interplate coupling in subduction zones and forearc topography the effect of long term coupling in subduction zones on forearc topography is studied using a 2 dimensional finite element model a curved fault representing the interface between subducting slab and overriding plate has been incorporated into a model with an elastic crustal layer a viscoelastic upper mantle an initial topography and an effective coefficient of friction on the fault we assume that traction arising from friction is one of the stresses acting on topography for various friction coefficients the change of topography after some equilibration time is computed with specific geometry and kinematic boundary conditions for three subduction zones northern chile northern japan and tonga while the intrinsic coefficient of friction for small rock samples is high 0 6 0 8 the observed topography of forearc regions are inconsistent with an effective friction coefficient larger than 0 2

the dependency of probabilistic tsunami hazard assessment on magnitude limits of seismic sources in the south china sea and adjoining basins the south china sea scs and its adjacent small basins including sulu sea and celebes sea are commonly identified as tsunami prone region by its historical records on seismicity and tsunamis however quantification of tsunami hazard in the scs region remained an intractable issue due to highly complex tectonic setting and multiple seismic sources within and surrounding this area probabilistic tsunami hazard assessment ptha is performed in the present study to evaluate tsunami hazard in the scs region based on a brief review on seismological and tsunami records 5 regional and local potential tsunami sources are tentatively identified and earthquake catalogs are generated using monte carlo simulation following the tapered gutenberg richter relationship for each zone considering a lack of consensus on magnitude upper bound on each seismic source as well as its critical role in ptha the major concern of the present study is to define the upper and lower limits of tsunami hazard in the scs region comprehensively by adopting different corner magnitudes that could be derived by multiple principles and approaches including tgr regression of historical catalog fault length scaling tectonic and seismic moment balance and repetition of historical largest event the results show that tsunami hazard in the scs and adjoining basins is subject to large variations when adopting different corner magnitudes with the upper bounds 2 6 times of the lower the probabilistic tsunami hazard maps for specified return periods reveal much higher threat from cotabato trench and sulawesi trench in the celebes sea whereas tsunami hazard received by the coasts of the scs and sulu sea is relatively moderate yet non negligible by combining empirical method with numerical study of historical tsunami events the present ptha results are tentatively validated the correspondence lends confidence to our study considering the proximity of major sources to population laden cities around the scs region the tsunami hazard and risk should be further highlighted in the future

temporal variation in the shear wave anisotropy detected using the accurately controlled routinely operated signal system across 1 temporal variation in shear wave anisotropy was detected in a monitoring experiment using an accurately controlled routinely operated signal system accurately controlled routinely operated signal system across we conducted an experiment that lasted for 15 months between january 2000 and april 2001 at a site near the nojima fault which ruptured during the 1995 kobe earthquake mw 7 2 yamaoka et al 2001 ikuta et al 2002 two vibration sources that generated 2 105 n with centrifugal force which were firmly fixed on the ground were used to emit elastic waves seismometers deployed at the bottom of 800 m and 1700 m deep boreholes near the across sources were used to receive the signal we extracted small temporal changes in the travel time of the p and s wave by calculating cross spectral density among the records every hour during the experiment sudden delays in travel times for the s wave were observed when the 2000 western tottori earthquake mw 6 6 and the 2001 geiyo earthquake mw 6 4 occurred their epicenters were 165 and 215 km away from the site respectively the travel times of the s waves between the surface and the bottom of 800 m deep borehole abruptly slowed down and gradually speeded up with each earthquake the delay in s was about 0 4 and 0 1 of the absolute travel time for the western tottori earthquake and the geiyo earthquake respectively the delays were polarized in a direction perpendicular to the nojima fault in both cases this indicates that the density of the cracks parallel to the fault increased in association with the earthquakes these cracks can be regarded as opened by the increase in pore pressure the small changes in p wave velocities support this interpretation an additional experiment to determine the static anisotropy revealed that there was a preferred orientation of the cracks that was enhanced with the strong shaking of earthquakes in the middle distance

bonaire s boulder fields revisited evidence for holocene tsunami impact on the leeward antilles abstract supralittoral boulders and blocks are prominent sedimentary features along rocky shorelines worldwide in most cases their deposition is attributed to high energy wave events tsunamis severe storms even though tsunami waves are expected to have higher transport capacities compared to storm waves megaclasts of up to 100 t were observed to have been moved laterally by the latter waveform the deduction of certain extreme wave events tsunamis severe storms from the boulder record thus remains a major challenge in palaeo event research the debate on their differentiation is ongoing at the eastern coast of bonaire leeward antilles in the southern caribbean numerous limestone blocks and boulders up to c 130 t are distributed on top of a 3 6 m a s l above mean sea level palaeo reef platform disagreement exists among a number of authors concerning the transport processes involved in the formation of the boulder fields in this paper state of the art modelling approaches of coastal boulder entrainment and transport were applied in order to provide new and more reliable data to support challenge the working hypothesis of tsunami deposition to improve the reliability of the boulder transport model more realistic input parameters were provided by new dgps measurements of the boulder dimensions and the calculation of bulk densities by taking into account the heterogeneity of the reef rock boulders existing hydrodynamic equations were modified to allow for the irregular shape and real dimensions of the boulders the results indicate that i boulder weight and dimension and thus ii calculated wave energy and wave heights were overestimated in most of the previous studies where calculations of boulder volume were based on multiplication of the main axes the results of this study and wave heights observed during recent severe tropical cyclones seem to rule out storm generated waves for the dislocation of the largest blocks however the majority of coarse clast deposits may have been generated by periodic hurricane swells the results underline the significance of more realistic field data in modelling boulder transports by waves

slab dip vs lithosphere age no direct function one paradigm of subduction relates the dip of the slab to the buoyancy of the downgoing lithosphere along subduction zones with the negative buoyancy proportional to the age of the oceanic lithosphere we measured the dip of the slab down to depths of 250 km along 164 sections crossing 13 subduction zones and compared it with the age of the subducting oceanic lithosphere both at the trench and at depth we show here that this relationship is far more irregular than previously suggested and that it is not possible to simply correlate the increase of the slab dip to the increasing age of the downgoing cooler lithosphere younger oceanic lithosphere may show steeper dip than older segments of slabs e g central america vs south america in contrast with predictions of models considering only slab pull the combination of slab age and subduction rate better accounts for slab dip however the correlation is not satisfactory correlation coefficient equal to 0 450 these results suggest that supplemental forces or constraints have to be accounted for such as thickness and shape of the hangingwall plate absolute plate velocity presence of lateral density variations in the hosting upper mantle effects of accretion erosion subduction of oceanic plateaus and slab deformation due to the motion of the mantle relative to the subducting plate d 2005 elsevier b v all rights reserved

twin tsunamis triggered by the 12 january 2010 haiti earthquake on 12 january 2010 a magnitude m w 7 0 earthquake occurred 25 km west southwest of haiti s capital port au prince causing an estimated 316 000 fatalities thereby exceeding any previous loss of life from a similar size earthquake in addition tsunami waves triggered by the earthquake caused at least three fatalities at petit paradis due to a complete lack of tsunami awareness the international tsunami survey team itst was deployed within weeks of the event and covered the greater bay of port au prince and more than 100 km of hispaniola s southern coastline the collected survey data include more than 21 tsunami heights along with observations of coastal land level change maximum tsunami heights of 3 m have been measured for two independently triggered tsunamis

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

spatio temporal changes in seismic velocity associated with the 2000 activity of miyakejima volcano as inferred from cross correlation analyses of ambient noise abstract miyakejima volcano japan showed strong and interesting volcanic activities in 2000 with the occurrence of dike intrusions caldera formation and a large amount of gas emission to understand temporal changes of the volcanic structure associated with this activity we apply ambient noise correlation analyses to the seismic records of five seismic stations at miyakejima volcano from july 1999 to december 2002 we calculate cross correlation functions ccfs for eight available station pairs at frequency bands of 0 4 0 8 hz and 0 8 1 6 hz and retrieve the rayleigh waves propagating with a group velocity of about 1 0 km s comparing ccfs obtained for each day with the reference ccfs that are calculated from a few months of data we estimate seismic velocity changes before and after the 2000 activity results at the two frequency bands show seismic velocity increase and decrease shallow structure at the volcanic edifice on the flanks experienced a seismic velocity increase up to 3 3 on the other hand the regions located close to the collapsed caldera show a seismic velocity decrease down to 2 3 to understand the mechanisms that may introduce these seismic velocity increase and decrease we examine several possible mechanisms of the velocity changes stress changes due to volcanic pressure sources and caldera formation and topographic changes by using the deflation sources previously determined from gps data we calculate the stresses at depths of 0 km and 1 km at the volcano the results suggest that the seismic velocity increases observed at seismic paths on the volcanic flank are explained by the compression caused by the deflation sources associated with magma activity in 2000 stress sensitivities of the seismic velocity changes are estimated to be 1 5 10 2 to 2 2 10 2 mpa 1 and 4 6 10 3 to 2 4 10 2 mpa 1 at frequency bands of 0 4 0 8 hz and 0 8 1 6 hz respectively which are in the range of the previously reported results our three dimensional numerical calculations on seismic wave propagation show that the seismic velocity decreases observed at seismic paths crossing the collapsed caldera can be explained by topographic changes introduced by a caldera we further suggest that the seismic velocity decreases detected around the regions close to the caldera may originate from the dilated regions cause by formation of the caldera

linear and nonlinear computations of the 1992 nicaragua earthquake tsunami numerical computations of tsunamis are made for the 1992 nicaragua earthquake using different governing equations bottom frictional values and bathymetry data the results are compared with each other as well as with the observations both tide gauge records and runup heights comparison of the observed and computed tsunami waveforms indicates that the use of detailed bathymetry data with a small grid size is more effective than to include nonlinear terms in tsunami computation linear computation overestimates the amplitude for the later phase than the first arrival particularly when the amplitude becomes large the computed amplitudes along the coast from nonlinear computation are much smaller than the observed tsunami runup heights the average ratio or the amplification factor is estimated to be 3 in the present case when the grid size of 1 minute is used the factor however may depend on the grid size for the computation

a subsurface structure change associated with the eruptive activity at sakurajima volcano japan inferred from an accurately controlled source temporal variations of green functions associated with the eruptive activity at sakurajima volcano japan were estimated using an accurately controlled routinely operated signal system across we deconvolved 400 s waveforms of the across signal at nearby stations by a known source time function and stacked the results based on the time relative to individual eruptions and the eruption intervals the quantities obtained by this procedure are green functions corresponding to various stages of the eruptive activity we found an energy decrease in the later phase of the green functions in active eruptive periods this energy decrease localized in the 2 6 s window of the green functions is difficult to explain by contamination from volcanic earthquakes and tremors the decrease could be more reasonably attributed to a subsurface structure change caused by the volcanic activity

relative motion between the caribbean and north american plates and related boundary zone deformation from a decade of gps observations global positioning system gps measurements in 1986 1994 and 1995 at sites in dominican republic puerto rico cuba and grand turk define the velocity of the caribbean plate relative to north america the data show eastward motion of the caribbean plate at a rate of 21 1 mm yr 1 standard error in the vicinity of southern dominican republic a factor of 2 higher than the nuvel 1a plate motion model prediction of 11 3 mm yr independent measurements on san andres island and an euler vector derived from these data also suggest a rate that is much higher than the nuvel 1a model available data combined with simple elastic strain models give the following slip rate estimates for major left lateral faults in hispaniola 1 the north hispaniola fault offshore the north coast of hispaniola 4 3 mm yr 2 the septentrional fault in northern dominican republic 8 3 mm yr and 3 the enriquillo fault in southern dominican republic and haiti 8 4 mm yr the relatively high plate motion rate and fault slip rates suggested by our study combined with evidence for strain accumulation and historical seismicity imply that seismic risk in the region may be higher than previous estimates based on low plate rate low fault slip rate models and the relatively low rate of seismicity over the last century

seismic moment distribution revisited ii moment conservation principle summary we compare the tectonic rate with earthquake data using several theoretical distributions to approximate the seismic moment frequency relation we derive formulae to estimate parameters of the seismic moment distributions by comparing the earthquake occurrence rate with tectonic strain we analyse the tectonic moment rate and the earthquake moment distribution for several types of tectonic environments including subduction zones plate bounding transform faults and deforming continental regions in this analysis we use finer subdivisions of tectonic regions to infer whether earthquake size distribution properties established previously for large provinces flinn engdahl seismic regions could be applied to smaller zones extending over a few hundred kilometres although the shortness of the available earthquake catalogues makes our results less reliable several conclusions can be drawn from the analysis the universality of the parameter the slope of the moment frequency relation is reasonably well confirmed for all of these tectonic regions and their subdivisions in each region we estimate the strain rate or relative plate motion from a plate tectonic model active fault data or geodetic data according to the moment frequency relation the ratio of the tectonic moment rate to the earthquake rate depends on the value the corner magnitude mc and the effective seismogenic thickness we find that this ratio does not vary systematically with the relative plate velocity the ratio of parallel to perpendicular plate motion time since the last major earthquake and the length of fault zone segments established by previous earthquake history we obtain similar results for the western united states and southeast asia the corner magnitude is approximately equal to that for the circum pacific rim and there is no systematic dependence of the mc parameter on a geographic region or strain rate assuming the commonly accepted values for seismogenic thickness elastic modulus and 100 per cent seismic coupling the corner magnitude values for plate boundary zones and continental areas are 8 3 8 8 i e similar to those values obtained by statistical analysis

temporal change of phase velocity beneath mt asama japan inferred from coda wave interferometry 1 we estimated the temporal changes of phase velocity of rayleigh waves extracted from cross correlations of s coda waves recorded at 12 stations around mt asama japan first we extracted a rayleigh wave by taking cross correlations of s coda waves for 315 regional earthquakes between october 2005 and february 2009 the dispersion curve of the rayleigh wave was measured and compared with the one extracted from 18 days of ambient seismic noise we found that both dispersion curves are consistent with each other demonstrating the dominance of the fundamental rayleigh waves we then divided the entire time period into sub periods each of which consists of 80 earthquakes to measure the temporal changes at frequencies between 0 3 and 0 6 hz the result shows the reduction of phase velocity by 1 5 and the subsequent recovery before the eruption of mt asama in 2008

assessment of source probabilities for potential tsunamis affecting the u s atlantic coast abstract estimating the likelihood of tsunamis occurring along the u s atlantic coast critically depends on knowledge of tsunami source probability we review available information on both earthquake and landslide probabilities from potential sources that could generate local and transoceanic tsunamis estimating source probability includes defining both size and recurrence distributions for earthquakes and landslides for the former distribution source sizes are often distributed according to a truncated or tapered power law relationship for the latter distribution sources are often assumed to occur in time according to a poisson process simplifying the way tsunami probabilities from individual sources can be aggregated for the u s atlantic coast earthquake tsunami sources primarily occur at transoceanic distances along plate boundary faults probabilities for these sources are constrained from previous statistical studies of global seismicity for similar plate boundary types in contrast there is presently little information constraining landslide probabilities that may generate local tsunamis though there is significant uncertainty in tsunami source probabilities for the atlantic results from this study yield a comparative analysis of tsunami source recurrence rates that can form the basis for future probabilistic analyses

numerical simulations of the 1991 limon tsunami costa rica caribbean coast the second largest recorded tsunami along the caribbean margin of central america occurred 25 years ago on april 22nd 1991 an earthquake with magnitude mw 7 6 ruptured along the thrust faults that form the north panama deformed belt npdb the earthquake triggered a tsunami that affected the caribbean coast of costa rica and panama within few minutes generating two casualties these are the only deaths caused by a tsunami in costa rica coseismic uplift up to 1 6 m and runup values larger than 2 m were measured along some coastal sites here we consider three solutions for the seismic source as initial conditions to model the tsunami each considering a single rupture plane we performed numerical modeling of the tsunami propagation and runup using neowave numerical model yamazaki et al in int j numer methods fluids 67 2081 2107 2010 doi 10 1002 fld 2485 on a system of nested grids from the entire caribbean sea to limon city the modeled surface deformation and tsunami runup agreed with the measured data along most of the coastal sites with one preferred model that fits the field data the model results are useful to determine how the 1991 tsunami could have affected regions where tsunami records were not preserved and to simulate the effects of the coastal surface deformations as buffer to tsunami we also performed tsunami modeling to simulate the consequences if a similar event with larger magnitude mw 7 9 occurs offshore the southern costa rican caribbean coast such event would generate maximum wave heights of more than 5 m showing that limon and northwestern panama coastal areas are exposed to moderate to large tsunamis these simulations considering historical events and maximum credible scenarios can be useful for hazard assessment and also as part of studies leading to tsunami evacuation maps and mitigation plans even when that is not the scope of this paper

structure of the merida andes venezuela relations with the south america caribbean geodynamic interaction for over 50 years several models based on diverse geologic concepts and variable quality of data have been proposed to explain the major structure and history of the merida andes ma in western venezuela lately this chain growth and associated flexural basins deepening have been related to incipient type a subductions of either polarity accounting for the across chain asymmetry however these recent models have not well integrated the present tectonically active setting driven by neighboring major plate interactions at present this chain exhibits ongoing strain partitioning where cumulative right lateral slip along chain axis is as much as half of or about the same as the transverse shortening since late miocene thus implying that the nne directed maracaibo block extrusion with respect to the south america sa plate is not a secondary feature consequently this paper discusses some limitations exhibited by the se directed continental subduction models maracaibo crust underthrusting the merida andes in the light of available geological and geophysical data besides it is herein proposed that the merida andes structuration is related to a nw directed gently dipping incipient type a subduction where chain growth and evolution are similar to those of a sedimentary accretionary wedge i e barbados but at crustal scale and with ongoing strain partitioning this continental subduction is the se portion of a major orogenic float that also comprises the perija range and the santa marta block d 2002 elsevier science b v all rights reserved

sensitivity of probabilistic tsunami hazard assessment to far field earthquake slip complexity and rigidity depth dependence case study of australia probabilistic tsunami hazard assessment ptha often proceeds by constructing a suite of hypothetical earthquake scenarios and modelling their tsunamis and occurrence rates both tsunami and occurrence rate models are affected by the representation of earthquake slip and rigidity but the overall importance of these factors for far field ptha is unclear we study the sensitivity of an australia wide ptha to six different far field earthquake scenario representations including two rigidity models constant and depth varying combined with three slip models fixed area uniform slip with rupture area deterministically related to magnitude variable area uniform slip and spatially heterogeneous slip earthquake tsunami scenarios are tested by comparison with dart buoy tsunami observations demonstrating biases in some slip models scenario occurrence rates are modelled using bayesian techniques to account for uncertainties in seismic coupling maximum magnitudes and gutenberg richter b values the approach maintains reasonable consistency with the historical earthquake record and spatially variable plate convergence rates for all slip rigidity model combinations and facilitates partial correction of model specific biases identified via dart buoy testing the modelled magnitude exceedance rates are tested by comparison with rates derived from long term historical and paleoseismic data and alternative moment conservation techniques demonstrating the robustness of our approach the tsunami hazard offshore of australia is found to be insensitive to the choice of rigidity model but significantly affected by the choice of slip model the fixed area uniform slip model produces lower hazard than the other slip models bias adjustment of the variable area uniform slip model produces a strong preference for compact scenarios which compensates for a lack of slip heterogeneity thus both heterogeneous slip and variable area uniform slip models induce similar far field tsunami hazard

distribution of tsunami interevent times 1 the distribution of tsunami interevent times is analyzed using global and site specific hilo hawaii tsunami catalogs an empirical probability density distribution is determined by binning the observed interevent times during a period in which the observation rate is approximately constant the empirical distributions for both catalogs exhibit non poissonian behavior in which there is an abundance of short interevent times compared to an exponential distribution two types of statistical distributions are used to model this clustering behavior 1 long term clustering described by a universal scaling law and 2 omori law decay of aftershocks and triggered sources the empirical and theoretical distributions all imply an increased hazard rate after a tsunami followed by a gradual decrease with time approaching a constant hazard rate examination of tsunami sources suggests that many of the short interevent times are caused by triggered earthquakes though the triggered events are not necessarily on the same fault

dependence of earthquake size distributions on convergence rates at subduction zones the correlation of numbers of thrust earthquakes of moment magnitude 7 or greater in this century at subduction zones with convergence rate results from a combination of lower recurrence intervals for earthquakes of a given size where slip rates are high and a peak in the global distribution of subduction zone convergence rates at high values 55 to 90 mm yr hence physical mechanisms related to convergence rate such as plate interface force slab pull or thermal effects are not required to explain the distribution of large earthquakes with convergence rate the seismic coupling coefficient ranges from 10 to 100 at subduction zone segments where convergence is faster than 45 mm yr but does not correlate with rate the coefficient is generally orders of magnitude lower at rates below 40 mm yr which may be due to long recurrence intervals and a short sampling period 94 years

poleward ocean heat transports sea ice processes and arctic sea ice variability in noresm1 m simulations results from the noresm1 m coupled climate model were used to examine relationships between arctic sea ice area and ocean heat transports through the primary arctic gateways comparisons were made with two other models cnrm cm5 and mri cgm3 that are part of the cmip5 archive which have the required outputs for calculating ocean heat transports based on an evaluation noresm1 m was found to be best suited to study the effects of heat transports on sea ice area and conclusions are based on results from this model the arctic ocean was divided into two regions the barents sea and the central arctic ocean the sea ice area variability was further analyzed in terms of frazil and congelation growth top and bottom melting and heat transports in the barents sea opening bso and the fram strait fs in the barents sea increased heat transport in the bso has a strong influence on sea ice area in terms of reduced congelation growth while bottom melting is important for the variability in the central arctic ocean the negative trend in sea ice area is considerably greater in the barents sea than in the central arctic ocean despite the central arctic ocean area being much larger and reflects the major trend in the bso heat transport the model results in this study suggest that the ocean has stronger direct impact on changes in sea ice mass in terms of freezing and melting than the atmosphere both in the mean and with respect to variability

quantification of source uncertainties in seismic probabilistic tsunami hazard analysis sptha this article has been accepted for publication in geophysical journal internationa 2016 published by oxford university press on behalf of the royal astronomical society all rights reserved

tsunami probability in the caribbean region we calculated tsunami runup probability in excess of 0 5 m at coastal sites throughout the caribbean region we applied a poissonian probability model because of the variety of uncorrelated tsunami sources in the region coastlines were discretized into 20 km by 20 km cells and the mean tsunami runup rate was determined for each cell the remarkable 500 year empirical record compiled by o loughlin and lander 2003 was used to calculate an empirical tsunami probability map the first of three constructed for this study however it is unclear whether the 500 year record is complete so we conducted a seismic moment balance exercise using a finite element model of the caribbean north american plate boundaries and the earthquake catalog and found that moment could be balanced if the seismic coupling coefficient is c 0 32 modeled moment release was therefore used to generate synthetic earthquake sequences to calculate 50 tsunami runup scenarios for 500 year periods we made a second probability map from numerically calculated runup rates in each cell differences between the first two probability maps based on empirical and numerical modeled rates suggest that each captured different aspects of tsunami generation the empirical model may be deficient in primary plate boundary events whereas numerical model rates lack backarc fault and landslide sources we thus prepared a third probability map using bayesian likelihood functions derived from the empirical and numerical rate models and their attendant uncertainty to weight a range of rates at each 20 km by 20 km coastal cell our best estimate map gives a range of 30 year runup probability from 0 30 regionally

extreme inundation flows during the hokkaido nansei oki tsunami the tsunami generated by the july 12 1993 hokkaido nansei oki mw 7 8 earthquake produced in japan the worst local tsunami related death toll in fifty years with estimated 10 18m sec overland flow velocities and 30m runup these extreme values are the largest recorded in japan this century and are among the highest ever documented for non landslide generated tsunamis we model this event to confirm the estimated overland flow velocities and we find that given reasonable ground deformation data current state of the art shallow water wave models can predict tsunami inundation correctly including extreme runup current velocities and overland flow we find that even small local topographic structures affect the runup to first order and that the resolution of the bathymetric data is more important than the grid resolution our results qualitatively suggest that for this event coastal inundation is more correlated with inundation velocities than with inundation heights explaining also why threshold type modeling has substantially underpredicted coastal inundation for this and other recent events

potential and limits of combining studies of coarse and fine grained sediments for the coastal event history of a caribbean carbonate environment the coastal deposits of bonaire leeward antilles are among the most studied archives for extreme wave events ewes in the caribbean here we present more than 400 electron spin resonance esr and radiocarbon data on coarse clast deposits from bonaire s eastern and western coasts the chronological data are compared to the occurrence and age of fine grained extremewave deposits detected in lagoons and floodplains both approaches are aimed at the identification of ewes the differentiation between extraordinary storms and tsunamis improving reconstructions of the coastal evolution and establishing a geochronological framework for the events although the combination of different methods and archives contributes to a better understanding of the interplay of coastal and archive related processes insufficient separation superimposition or burying of coarse clast deposits and restricted dating accuracy limit the use of both fine grained and coarse clast geoarchives to unravel decadal to centennial scale events at several locations distinct landforms are attributed to different coastal flooding events interpreted to be of tsunamigenic origin coastal landforms on the western coast have significantly been influenced by sub recent hurricanes indicating that formation of the coarse clast deposits on the eastern coast is likely to be related to past events of higher energy

friction experiments on saturated sediments and their implications for the stress state of the nankai and barbados subduction thrusts the nankai and barbados forearcs have low stress subduction thrusts the sediments entering the subduction zone and namely the material in the decollement zones have been well characterized by numerous deep sea drilling legs and studies of the recovered cores nankai has high heat flow and significant amounts of illite while barbados is a smectite dominated system based on results from ring shear 2 mpa normal stress and direct shear 30 mpa tests on marine sediments and mineral standards this translates into a residual frictional resistance of r 0 25 and r 0 11 in clay horizons respectively such values agree with theoretical estimates from critical wedge theory nankai b 0 16 0 26 and barbados b 0 06 0 09 and fault spacing geometries from seismic profiles nankai b 0 12 0 23 and barbados b 0 11 0 19 maximum pore pressure ratios of 0 85 and 0 73 for nankai and barbados respectively allow us to estimate effective shear stresses as a function of friction coefficient and density of the sediment gouge to reach only 10 mpa or less in the frontal 50 km of the decollement zone respectively our data support the contention that fluid pressure transients and sediment composition contribute equally to the weakness along plate boundary faults down to the seismogenic zone with the first probably dominating the shallow decollement shear velocity stepping tests show that the clay dominated gouges strengthen velocity irrespective of the clay mineralogy and hence suggest that clay transformation does not affect the onset of seismogenesis

seismogram envelope inversion for the spatial distribution of high frequency energy radiation from the earthquake fault application to the 1994 far east off sanriku earthquake japan incoherency of high frequency seismic waves leads to the idea to analyze seismogram envelopes disregarding phase information for the source study we develop an inversion method for estimating high frequency above 1 hz energy radiation from the earthquake fault and site amplification factors from observed mean square s wave seismogram envelopes the inversion is executed by using the s wave envelope green function from the onset to coda for a point shear dislocation source in a scattering medium which is formulated based on an extended version of the radiative transfer theory the use of the envelope green function enables us to estimate the spatial distribution of high frequency energy radiation on a fault plane this has been difficult by conventional waveform inversion methods the rupture velocity and the duration time of energy radiation on each subfault are also estimated by grid search method we apply this new method to the 1994 far east off sanriku northeastern japan earthquake mw 7 7 which ruptured a 90 km segment of the plate boundary along the japan trench inverting observed seismogram envelopes at 10 strong motion stations in japan it is concluded that above 90 of the high frequency energy was radiated from the western half of the fault with the largest energy radiation near the deep side edge the rupture velocity is estimated to be 2 7 km s the estimated site amplification factors ranging between 0 3 and 15 are consistent with those independently estimated by the coda normalization method

the effect of bathymetry on tsunami characteristics at sisano lagoon papua new guinea the 1998 papua new guinea tsunami was greater than expected from its earthquake magnitude the area of significant impact was small approximately a 30 km stretch near the mouth of sissano lagoon papua new guinea to explain the localized nature of the event a submarine landslide has been conjectured to be responsible our study indicates that offshore bathymetry is critical to predicting tsunami coastal behavior model runs with newly obtained bathymetric data indicate that an earthquake fault source combined with the existing seafloor geometry may also explain the concentrated tsunami although the definitive cause of the papua new guinea tsunami remains uncertain local bathymetry had a notable effect on the wave behavior

probabilistic tsunami hazard assessment at seaside oregon for near and far field seismic sources 1 the first probabilistic tsunami flooding maps have been developed the methodology called probabilistic tsunami hazard assessment ptha integrates tsunami inundation modeling with methods of probabilistic seismic hazard assessment psha application of the methodology to seaside oregon has yielded estimates of the spatial distribution of 100 and 500 year maximum tsunami amplitudes i e amplitudes with 1 and 0 2 annual probability of exceedance the 100 year tsunami is generated most frequently by far field sources in the alaska aleutian subduction zone and is characterized by maximum amplitudes that do not exceed 4 m with an inland extent of less than 500 m in contrast the 500 year tsunami is dominated by local sources in the cascadia subduction zone and is characterized by maximum amplitudes in excess of 10 m and an inland extent of more than 1 km the primary sources of uncertainty in these results include those associated with interevent time estimates modeling of background sea level and accounting for temporal changes in bathymetry and topography nonetheless ptha represents an important contribution to tsunami hazard assessment techniques viewed in the broader context of risk analysis ptha provides a method for quantifying estimates of the likelihood and severity of the tsunami hazard which can then be combined with vulnerability and exposure to yield estimates of tsunami risk

imaging and monitoring of the shallow subsurface using spatially windowed surface wave analysis with a single permanent seismic source abstractdevelopment of shallow subsurface monitoring systems is important for monitoring the ground stability of shallow formation and also for conventional deep seismic monitoring because with cu

plate tectonic analysis of shallow seismicity apparent boundary width beta corner magnitude coupled lithosphere thickness and coupling in seven tectonic settings a new plate model is used to analyze the mean seismicities of seven types of plate boundary crb continental rift boundary ctf continental transform fault ccb continental convergent boundary osr oceanic spreading ridge otf oceanic transform fault ocb oceanic convergent boundary sub subduction zone we compare the platelike nonorogen regions of model pb2002 bird 2003 with the centroid moment tensor cmt catalog to select apparent boundary half widths and then assign 95 of shallow earthquakes to one of these settings a tapered gutenberg richter model of the frequency moment relation is fit to the subcatalog for each setting by maximum likelihood best fitting values range from 0 53 to 0 92 but all 95 confidence ranges are consistent with a common value of 0 61 0 66 to better determine some corner magnitudes we expand the subcatalogs by 1 inclusion of orogens and 2 inclusion of years 1900 1975 from the catalog of pacheco and sykes 1992 combining both earthquake statistics and the plate tectonic constraint on moment rate corner magnitudes include the following crb graphic 1 ctf graphic 2 ccb graphic 3 ocb graphic 4 and sub graphic 5 coupled lithosphere thicknesses are found to be the following crb graphic 6 ctf graphic 7 ccb graphic 8 osr graphic 9 for normal faulting and graphic 10 for strike slip otf graphic 11 and graphic 12 at low medium and high velocities ocb graphic 13 and sub graphic 14 in general high coupling of subduction and continental plate boundaries suggests that here all seismic gaps are dangerous unless proven to be creeping in general low coupling within oceanic lithosphere suggests a different model of isolated seismic fault patches surrounded by large seismic gaps that may be permanent online material global seismic subcatalogs of shallow earthquakes 1 embed inline graphic 1 gif 2 embed inline graphic 2 gif 3 embed inline graphic 3 gif 4 embed inline graphic 4 gif 5 embed inline graphic 5 gif 6 embed inline graphic 6 gif 7 embed inline graphic 7 gif 8 embed inline graphic 8 gif 9 embed inline graphic 9 gif 10 embed inline graphic 10 gif 11 embed inline graphic 11 gif 12 embed inline graphic 12 gif 13 embed inline graphic 13 gif 14 embed inline graphic 14 gif

a probabilistic tsunami hazard study of the auckland region part ii inundation modelling and hazard assessment regional source tsunamis pose a potentially devastating hazard to communities and infrastructure on the new zealand coast but major events are very uncommon this dichotomy of infrequent but potentially devastating hazards makes realistic assessment of the risk challenging here we describe a method to determine a probabilistic assessment of the tsunami hazard by regional source tsunamis with an average recurrence interval of 2 500 years the method is applied to the east auckland region of new zealand from an assessment of potential regional tsunamigenic events over 100 000 years the inundation of the auckland region from the worst 100 events is modelled using a hydrodynamic model and probabilistic inundation depths on a 2 500 year time scale were determined tidal effects on the potential inundation were included by coupling the predicted wave heights with the probability density function of tidal heights at the inundation site results show that the more exposed northern section of the east coast and outer islands in the hauraki gulf face the greatest hazard from regional tsunamis in the auckland region incorporating tidal effects into predictions of inundation reduced the predicted hazard compared to modelling all the tsunamis arriving at high tide giving a more accurate hazard assessment on the specified time scale this study presents the first probabilistic analysis of dynamic modelling of tsunami inundation for the new zealand coast and as such provides the most comprehensive assessment of tsunami inundation of the auckland region from regional source tsunamis available to date

complex earthquake rupture and local tsunamis 1 in contrast to far field tsunami amplitudes that are fairly well predicted by the seismic moment of subduction zone earthquakes there exists significant variation in the scaling of local tsunami amplitude with respect to seismic moment from a global catalog of tsunami runup observations this variability is greatest for the most frequently occurring tsunamigenic subduction zone earthquakes in the magnitude range of 7 mw 8 5 variability in local tsunami runup scaling can be ascribed to tsunami source parameters that are independent of seismic moment variations in the water depth in the source region the combination of higher slip and lower shear modulus at shallow depth and rupture complexity in the form of heterogeneous slip distribution patterns the focus of this study is on the effect that rupture complexity has on the local tsunami wave field a wide range of slip distribution patterns are generated using a stochastic self affine source model that is consistent with the falloff of far field seismic displacement spectra at high frequencies the synthetic slip distributions generated by the stochastic source model are discretized and the vertical displacement fields from point source elastic dislocation expressions are superimposed to compute the coseismic vertical displacement field for shallow subduction zone earthquakes it is demonstrated that self affine irregularities of the slip distribution result in significant variations in local tsunami amplitude the effects of rupture complexity are less pronounced for earthquakes at greater depth or along faults with steep dip angles for a test region along the pacific coast of central mexico peak nearshore tsunami amplitude is calculated for a large number n 100 of synthetic slip distribution patterns all with identical seismic moment mw 8 1 analysis of the results indicates that for earthquakes of a fixed location geometry and seismic moment peak nearshore tsunami amplitude can vary by a factor of 3 or more these results indicate that there is substantially more variation in the local tsunami wave field derived from the inherent complexity subduction zone earthquakes than predicted by a simple elastic dislocation model probabilistic methods that take into account variability in earthquake rupture processes are likely to yield more accurate assessments of tsunami hazards

tsunami generation by horizontal displacement of ocean bottom tsunami generation by an earthquake is generally modeled by water surface displacement identical to the vertical deformation of ocean bottom due to faulting the effect of horizontal deformation is usually neglected however when the tsunami source is on a steep slope and the horizontal displacement is large relative to the vertical displacement the effect becomes significant we show this for two recent earthquakes which generated much larger tsunamis than expected from seismic waves in the case of the 1994 june 2 java indonesia earthquake the focal mechanism was a very shallow dipping thrust and the source was near a very steep trench slope in the case of the 1994 nov 14 mindoro philippines earthquake strike slip faulting extended from ocean to land perpendicular to the coast line in both cases we found that the horizontal motion of slope had an important contribution to the tsunami generation

stress interaction between subduction earthquakes and forearc strike slip faults modeling and application to the northern caribbean plate boundary 1 strike slip faults in the forearc region of a subduction zone often present significant seismic hazard because of their proximity to population centers we explore the interaction between thrust events on the subduction interface and strike slip faults within the forearc region using three dimensional models of static coulomb stress change model results reveal that subduction earthquakes with slip vectors subparallel to the trench axis enhance the coulomb stress on strike slip faults adjacent to the trench but reduce the stress on faults farther back in the forearc region in contrast subduction events with slip vectors perpendicular to the trench axis enhance the coulomb stress on strike slip faults farther back in the forearc while reducing the stress adjacent to the trench a significant contribution to coulomb stress increase on strike slip faults in the back region of the forearc comes from unclamping of the fault i e reduction in normal stress due to thrust motion on the subduction interface we argue that although coulomb stress changes from individual subduction earthquakes are ephemeral their cumulative effects on the pattern of lithosphere deformation in the forearc region are significant we use the coulomb stress models to explain the contrasting deformation pattern between two adjacent segments of the caribbean subduction zone subduction earthquakes with slip vectors nearly perpendicular to the caribbean trench axis is dominant in the hispaniola segment where the strike slip faults are more than 60 km inland from the trench in contrast subduction slip motion is nearly parallel to the caribbean trench axis along the puerto rico segment where the strike slip fault is less than 15 km from the trench this observed jump from a strike slip fault close to the trench axis in the puerto rico segment to the inland faults in hispaniola is explained by different distributions of coulomb stress in the forearc region of the two segments as a result of the change from the nearly trench parallel slip on the puerto rico subduction interface to the more perpendicular subduction slip beneath hispaniola the observations and modeling suggest that subduction induced strike slip seismic hazard to puerto rico may be smaller than previously assumed but the hazard to hispaniola remains high