ray tracing for dispersive tsunamis and source amplitude estimation based on green s law application to the 2015 volcanic tsunami earthquake near torishima south of japan ray tracing which has been widely used for seismic waves was also applied to tsunamis to examine the bathymetry effects during propagation but it was limited to linear shallow water waves green s law which is based on the conservation of energy flux has been used to estimate tsunami amplitude on ray paths in this study we first propose a new ray tracing method extended to dispersive tsunamis by using an iterative algorithm to map two dimensional tsunami velocity fields at different frequencies ray paths at each frequency can be traced we then show that green s law is valid only outside the source region and that extension of green s law is needed for source amplitude estimation as an application example we analyzed tsunami waves generated by an earthquake that occurred at a submarine volcano smith caldera near torishima japan in 2015 the ray tracing results reveal that the ray paths are very dependent on its frequency particularly at deep oceans the validity of our frequency dependent ray tracing is confirmed by the comparison of arrival angles and travel times with those of observed tsunami waveforms at an array of ocean bottom pressure gauges the tsunami amplitude at the source is nearly twice or more of that just outside the source estimated from the array tsunami data by green s law

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

tsunami hazard assessment of coastal south africa based on mega earthquakes of remote subduction zones the nuclear structural engineering pty and the national research foundation through the technology and human resources for industry programme project thrip tp2011061400009

airburst generated tsunamis this paper examines the questions of whether smaller asteroids that burst in the air over water can generate tsunamis that could pose a threat to distant locations such airburst generated tsunamis are qualitatively different than the more frequently studied earthquake generated tsunamis and differ as well from tsunamis generated by asteroids that strike the ocean numerical simulations are presented using the shallow water equations in several settings demonstrating very little tsunami threat from this scenario a model problem with an explicit solution that demonstrates and explains the same phenomena found in the computations is analyzed we discuss the question of whether compressibility and dispersion are important effects that should be included and show results from a more sophisticated model problem using the linearized euler equations that begins to addresses this

time frequency characteristics of tsunami magnetic signals from four pacific ocean events the recent deployment of highly sensitive seafloor magnetometers coinciding with the deep solar minimum has provided excellent opportunities for observing tsunami electromagnetic signals these fluctuating signals periods ranging from 10 20 min are generally found to be within pm sim 1 nt and coincide with the arrival of the tsunami waves previous studies focused on tsunami electromagnetic characteristics as well as modeling the signal for individual events this study instead aims to provide the time frequency characteristics for a range of tsunami signals and a method to separate the data s noise using additional data from a remote observatory we focus on four pacific ocean events of varying tsunami signal amplitude 1 the 2011 tohoku japan event m9 0 2 the 2010 chile event m8 8 3 the 2009 samoa event m8 0 and 4 the 2007 kuril islands event m8 1 we find possible tsunami signals in high pass filtered data and successfully isolate the signals from noise using a cross wavelet analysis the cross wavelet analysis reveals that the longer period signals precede the stronger shorter period signals our results are very encouraging for using tsunami magnetic signals in warning systems

impact of hellenic arc tsunamis on corsica france in the historical period the eastern mediterranean has been devastated by several tsunamis the two most damaging were those of ad 365 and ad 1303 generated by great earthquakes of magnitude 8 at the hellenic plate boundary recently events of 6 7 magnitude have occurred in this region as the french tsunami warning center has to ensure the warning for the french coastlines the question has raised the possibility for a major tsunami triggered along the hellenic arc to impact the french coasts the focus is on the corsica coasts especially to estimate what would be the expected wave heights and from which threshold of magnitude it would be necessary to put the population under cover this study shows that a magnitude 8 0 earthquake nucleated along the hellenic arc could induce in some cases a tsunami that would be observed along the corsica coasts and for events of 8 5 magnitude amplitudes exceeding 50 cm can be expected which would be dangerous in harbors and beach areas especially the main contribution of these results is the establishment of specific thresholds of magnitude for the tsunami warning along the french coasts 7 8 for the advisory level coastal marine threat with harbors and beaches evacuation and 8 3 for the watch level inland inundation threat for tsunamis generated along the hellenic arc

spectral analysis of water level and velocity data from crescent city harbor during the april 1 2014 chilean tsunami crescent city california typically records some of the largest waveheights along the us west coast for far field tsunami sources and has suffered more loss than any north american site over the past century we installed a nortek acoustic doppler profiler adp in crescent city harbor in 2014 to better understand variations in water level and currents caused by forcing such as tsunamis tides and weather events a small tsunami was first detected in the harbor on april 2 2014 and had a maximum peak to trough waveheight of 0 37 m this event was near the adp limit of detectability with a peak observed tsunami current on the order of 0 16 m s spectral analysis of water level and velocities before during and after the tsunami shows well defined spectral peaks with periods corresponding to roughly 20 and 5 6 min in both water level and velocity elevated spectral levels also appear around 10 min although a consistent peak location was less well defined an additional peak appeared at around 2 5 min in water level but was not consistently observed in velocity during the tsunami spectral levels increased by roughly an order of magnitude around the 20 min peak averaged over 24 h with reduced levels at shorter periods motions around the 20 min period were aligned roughly ne sw approximately along the channel leading into the inner boat basin at 5 6 min periods the motion was roughly nw se suggesting a higher frequency modal response of the harbor

method to determine appropriate source models of large earthquakes including tsunami earthquakes for tsunami early warning in central america large earthquakes such as the mw 7 7 1992 nicaragua earthquake have occurred off the pacific coasts of el salvador and nicaragua in central america and have generated distractive tsunamis along these coasts it is necessary to determine appropriate fault models before large tsunamis hit the coast in this study first fault parameters were estimated from the w phase inversion and then an appropriate fault model was determined from the fault parameters and scaling relationships with a depth dependent rigidity the method was tested for four large earthquakes the 1992 nicaragua tsunami earthquake mw7 7 the 2001 el salvador earthquake mw7 7 the 2004 el astillero earthquake mw7 0 and the 2012 el salvador nicaragua earthquake mw7 3 which occurred off el salvador and nicaragua in central america the tsunami numerical simulations were carried out from the determined fault models we found that the observed tsunami heights run up heights and inundation areas were reasonably well explained by the computed ones therefore our method for tsunami early warning purpose should work to estimate a fault model which reproduces tsunami heights near the coast of el salvador and nicaragua due to large earthquakes in the subduction zone

odessa tsunami of 27 june 2014 observations and numerical modelling on 27 june a 1 2 m high wave struck the beaches of odessa the third largest ukrainian city and the neighbouring port town illichevsk northwestern black sea throughout the day prominent seiche oscillations were observed in several other ports of the black sea tsunamigenic synoptic conditions were found over the black sea stretching from romania in the west to the crimean peninsula in the east intense air pressure disturbances and convective thunderstorm clouds were associated with these conditions right at the time of the event a 1 5 hpa air pressure jump was recorded at odessa and a few hours earlier in romania we have utilized a barotropic ocean numerical model to test two hypotheses 1 a tsunami like wave was generated by an air pressure disturbance propagating directly over odessa experiment 1 2 a tsunami like wave was generated by an air pressure disturbance propagating offshore approximately 200 km to the south of odessa and along the shelf break experiment 2 both experiments decisively confirm the meteorological origin of the tsunami like waves on the coast of odessa and imply that intensified long ocean waves in this region were generated via the proudman resonance mechanism while propagating over the northwestern black sea shelf the odessa tsunami of 27 june 2014 was identified as a beach meteotsunami similar to events regularly observed on the beaches of florida usa but different from the harbour meteotsunamis which occurred 1 3 days earlier in ciutadella baleares spain mazara del vallo sicily italy and vela luka croatia in the mediterranean sea despite that they were associated with the same atmospheric system moving over the mediterranean black sea region on 23 27 june 2014

source inversion of w phase speeding up seismic tsunami warning w phase is a long period phase arriving before s wave it can be interpreted as superposition of the fundamental first second and third overtones of spheroidal modes or rayleigh waves and has a group velocity from 4 5 to 9 km s 1 over a period range of 100 1000 s the amplitude of long period waves better represents the tsunami potential of an earthquake because of the fast group velocity of w phase most of w phase energy is contained within a short time window after the arrival of the p wave at a distance of 50 w phase energy is contained within 23 min after the origin time which is the distinct advantage of using w phase for rapid tsunami warning purposes we use a time domain deconvolution method to extract w phases from the broad band records of global seismic networks the bandwidth of w phase is approximately from 0 001 to 0 01 hz and we bandpass filter the data from 0 001 to 0 005 hz in most cases having extracted w phase from the vertical component records we perform a linear inversion using a point source to determine mw and the source mechanism for several large earthquakes including the 2004 sumatra andaman earthquake the 2005 nias earthquake the 2006 kuril is earthquake and the 2007 sumatra earthquake w phase inversion yields reliable solutions and holds promise of the use of w phase for rapid assessment of tsunami potential

tsunami bores in kitakami river the 2011 tohoku tsunami entered the kitakami river and propagated there as a train of shock waves recorded with a 1 min interval at water level stations at fukuchi iino and the weir 17 2 km from the mouth where the bulk of the wave was reflected back the records showed that each bore kept its shape and identity as it traveled a 10 9 km path fukuchi iino weir iino shock handling based on the cross river integrated classical shock conditions was applied to reconstruct the flow velocity time histories at the measurement sites to estimate inflow into the river at each site to evaluate the wave heights of incident and reflected tsunami bores near the weir and to estimate propagation speed of the individual bores theoretical predictions are verified against the measurements we discuss experiences of exercising the shock conditions with actual tsunami measurements in the kitakami river and test applicability of the shallow water approximation for describing tsunami bores with heights ranging from 0 3 to 4 m in a river segment with a depth of 3 4 m

source characterization and tsunami modeling of submarine landslides along the yucatan shelf campeche escarpment southern gulf of mexico submarine landslides occurring along the margins of the gulf of mexico gom represent a low likelihood but potentially damaging source of tsunamis new multibeam bathymetry coverage reveals that mass wasting is pervasive along the yucatan shelf edge with several large composite landslides possibly removing as much as 70 km3 of the cenozoic sedimentary section in a single event using gis based analysis the dimensions of six landslides from the central and northern sections of the yucatan shelf campeche escarpment were determined and used as input for preliminary tsunami generation and propagation models tsunami modeling is performed to compare the propagation characteristics and distribution of maximum amplitudes throughout the gom among the different landslide scenarios various factors such as landslide geometry location along the yucatan shelf campeche escarpment and refraction during propagation result in significant variations in the affected part of the mexican and us gulf coasts in all cases however tsunami amplitudes are greatest along the northern yucatan peninsula

rupture process of the 1969 and 1975 kurile earthquakes estimated from tsunami waveform analyses the 1969 and 1975 great kurile earthquakes occurred along the kurile trench tsunamis generated by these earthquakes were observed at tide gauge stations around the coasts of the okhotsk sea and pacific ocean to understand rupture process of the 1969 and 1975 earthquakes slip distributions of the 1969 and 1975 events were estimated using tsunami waveform inversion technique seismic moments estimated from slip distributions of the 1969 and 1975 earthquakes were 1 1 1021 nm mw 8 0 and 0 6 1021 nm mw 7 8 respectively the 1973 nemuro oki earthquake occurred at the plate interface adjacent to that ruptured by the 1969 kurile earthquake the 1975 shikotan earthquake occurred in a shallow region of the plate interface where was not ruptured by the 1969 kurile earthquake further like a sequence of the 1969 and 1975 earthquakes it is possible that a great earthquake may occur in a shallow part of the plate interface a few years after a great earthquake that occurs in a deeper part of the same region along the trench

meteotsunamis occurring along the southwest coast of south america during an intense storm in this paper we report meteotsunamis occurring along the chilean and peruvian coasts these atmospherically induced tsunami like oscillations were instrumentally recorded during an intense storm that affected central chile on august 8th 2015 the storm was characterized by strong winds a locally unprecedented atmospheric low pressure and intense sea level oscillations which caused six casualties and severe damage to infrastructure along 500 km of coastline the meteotsunamis are analyzed on both regional and local scales on the regional scale the temporal behavior and spatial behavior were discussed from the analysis of various tide gauges covering roughly 3000 km of the southwest coast of south america between callao in central peru and lebu in southern chile surprisingly the phenomenon was recorded in the majority of the tide gauges in this vast region on the area constrained by the storm region a more detailed analysis is performed we confirm the atmospheric origin of these intense sea level oscillations by further analyzing meteorological records of air pressure and wind an attempt to explain local shelf and harbor resonant mechanisms is achieved by means of wavelet analysis while greenspan and proudman resonance mechanisms are superficially analyzed our results indicate that large meteotsunamis can occur along the west coast of south america and when combined with other meteooceanographic conditions may cause damage levels comparable to those resulting from mw 8 earthquake generated tsunamis

a response function approach for rapid far field tsunami forecasting predicting tsunami impacts at remote coasts largely relies on tsunami en route measurements in an open ocean in this work these measurements are used to generate instant tsunami predictions in deep water and near the coast the predictions are generated as a response or a combination of responses to one or more tsunameters with each response obtained as a convolution of real time tsunameter measurements and a pre computed pulse response function prf practical implementation of this method requires tables of prfs in a 3d parameter space earthquake location tsunameter forecasted site examples of hindcasting the 2010 chilean and the 2011 tohoku oki tsunamis along the us west coast and beyond demonstrated high accuracy of the suggested technology in application to trans pacific seismically generated tsunamis

numerical procedure to forecast the tsunami parameters from a database of pre simulated seismic unit sources we have implemented a numerical procedure to forecast the parameters of a tsunami such as the arrival time of the front of the first wave and the maximum wave height in real and virtual tidal stations along the peruvian coast with this purpose a database of pre computed synthetic tsunami waveforms or green functions was obtained from numerical simulation of seismic unit sources dimension 50 50 km2 for subduction zones from southern chile to northern mexico a bathymetry resolution of 30 arc sec approximately 927 m was used the resulting tsunami waveform is obtained from the superposition of synthetic waveforms corresponding to several seismic unit sources contained within the tsunami source geometry the numerical procedure was applied to the chilean tsunami of april 1 2014 the results show a very good correlation for stations with wave amplitude greater than 1 m in the case of the arica tide station an error from the maximum height of the observed and simulated waveform of 3 5 was obtained for callao station the error was 12 and the largest error was in chimbote with 53 5 however due to the low amplitude of the chimbote wave 1 m the overestimated error in this case is not important for evacuation purposes the aim of the present research is tsunami early warning where speed is required rather than accuracy so the results should be taken as preliminary

reconstruction of far field tsunami amplitude distributions from earthquake sources the probability distribution of far field tsunami amplitudes is explained in relation to the distribution of seismic moment at subduction zones tsunami amplitude distributions at tide gauge stations follow a similar functional form well described by a tapered pareto distribution that is parameterized by a power law exponent and a corner amplitude distribution parameters are first established for eight tide gauge stations in the pacific using maximum likelihood estimation a procedure is then developed to reconstruct the tsunami amplitude distribution that consists of four steps 1 define the distribution of seismic moment at subduction zones 2 establish a source station scaling relation from regression analysis 3 transform the seismic moment distribution to a tsunami amplitude distribution for each subduction zone and 4 mix the transformed distribution for all subduction zones to an aggregate tsunami amplitude distribution specific to the tide gauge station the tsunami amplitude distribution is adequately reconstructed for four tide gauge stations using globally constant seismic moment distribution parameters established in previous studies in comparisons to empirical tsunami amplitude distributions from maximum likelihood estimation the reconstructed distributions consistently exhibit higher corner amplitude values implying that in most cases the empirical catalogs are too short to include the largest amplitudes because the reconstructed distribution is based on a catalog of earthquakes that is much larger than the tsunami catalog it is less susceptible to the effects of record breaking events and more indicative of the actual distribution of tsunami amplitudes

introduction to historical and recent catastrophic tsunamis in the world volume ii tsunamis from 1755 to 2010 eighteen papers on past and recent destructive tsunamis are included in volume ii of the pageoph topical issue historical and recent catastrophic tsunamis in the world three papers discuss deep sea dart and coastal tsunami observations warning systems and risk management in the pacific ocean four papers examine the 1755 lisbon 1964 alaska 2003 algeria and 2011 haiti tsunamis four more papers as well as some papers in volume i report on various aspects of the 2010 chile tsunami two papers present some results of field survey and modelling investigation of the 2010 mentawai indonesia tsunami three papers report on modelling efforts of tsunami generation by earthquake and landslide and of tsunami propagation finally two papers discuss hazard assessment using a probabilistic approach

relict landscape resistance to dissection by upstream migrating knickpoints expanses of subdued topographies are common at high elevation in mountain ranges they are often interpreted as relict landscapes and are expected to be replaced by steeper topography as erosion proceeds preservation of such relict fragments can merely reflect the fact that it takes time to remove any preexisting topography however relict fragments could also possess intrinsic characteristics that make them resilient to dissection we document here the propagation of a wave of dissection across an uplifted relict landscape in puerto rico using 10be 26al burial dating on cave sediments we show that uplift started 4 ma and that river knickpoints have since migrated very slowly across the landscape modern detrital 10be erosion rates are consistent with these long term rates of knickpoint retreat analysis of knickpoint distribution combined with visual observations along the streambeds indicates that incision by abrasion and plucking is so slow that bedrock weathering becomes a competing process of knickpoint retreat the studied rivers flow over a massive stock of quartz diorite surrounded by an aureole of metavolcanic rocks earlier studies have shown that vegetation over the relict topography efficiently limits erosion allowing for the formation of a thick saprolite underneath such slow erosion reduces streambed load fluxes delivered to the knickpoints as well as bed load grain size both processes limit abrasion compounding the effect of slow abrasion wide joint spacing in the bedrock makes plucking infrequent thus the characteristics of the relict upstream landscape have a direct effect on stream incision farther downstream reducing the celerity at which the relict subdued landscape is dissected we conclude that similar top down controls on river incision rate may help many relict landscapes to persist amidst highly dissected topographies

the effects on tsunami hazard assessment in chile of assuming earthquake scenarios with spatially uniform slip we investigated the effect that along dip slip distribution has on the near shore tsunami amplitudes and on coastal land level changes in the region of central chile 29 37 s here and all along the chilean megathrust the seismogenic zone extends beneath dry land and thus tsunami generation and propagation is limited to its seaward portion where the sensitivity of the initial tsunami waveform to dislocation model inputs such as slip distribution is greater we considered four distributions of earthquake slip in the dip direction including a spatially uniform slip source and three others with typical bell shaped slip patterns that differ in the depth range of slip concentration we found that a uniform slip scenario predicts much lower tsunami amplitudes and generally less coastal subsidence than scenarios that assume bell shaped distributions of slip although the finding that uniform slip scenarios underestimate tsunami amplitudes is not new it has been largely ignored for tsunami hazard assessment in chile our simulations results also suggest that uniform slip scenarios tend to predict later arrival times of the leading wave than bell shaped sources the time occurrence of the largest wave at a specific site is also dependent on how the slip is distributed in the dip direction however other factors such as local bathymetric configurations and standing edge waves are also expected to play a role arrival time differences are especially critical in chile where tsunamis arrive earlier than elsewhere we believe that the results of this study will be useful to both public and private organizations for mapping tsunami hazard in coastal areas along the chilean coast and therefore help reduce the risk of loss and damage caused by future tsunamis

tsunami simulation by tuned seismic source inversion for the great 2011 tohoku earthquake seismic and tsunami waves were the most destructive phenomena during the 2011 tohoku earthquake here we ask whether the same source model can be used to obtain equally good simulations of the observed strong ground motions and the tsunami waves if so we could use the same source modeling technique for predictions of both tsunami waves and strong ground motions long period 20 200 s strong ground motion data were inverted to determine the rupture process of the 2011 tohoku earthquake the inverted slip distribution shows that large slip area was extended around 150 km to north and 120 km to south from hypocenter and stretched between hypocenter and the trench we estimated two slip models without and with additional constraints the first relatively rough slip model reproduced short period tsunami wave 4 5 min due to better constraint by data of other kind and being relatively smooth the second model reproduces long period tsunami wave 15 25 min as well as keeps good fit of the short period tsunami although short period tsunami becomes underestimated we used a fully nonlinear boussinesq water wave model to model tsunami propagation and used the results to tune the slip model finally we developed a tuned slip model that combines the features of both the first and the second slip models and reproduced both the short and long period tsunami waves while maintaining good fit of the seismic waveforms

possible worst case tsunami scenarios around the marmara sea from combined earthquake and landslide sources this study evaluates tsunami hazards in the marmara sea from possible worst case tsunami scenarios that are from submarine earthquakes and landslides in terms of fault generated tsunamis seismic ruptures can propagate along the north anatolian fault naf which has produced historical tsunamis in the marmara sea based on the past studies which consider fault generated tsunamis and landslide generated tsunamis individually future scenarios are expected to generate tsunamis and submarine landslides could be triggered by seismic motion in addition to these past studies numerical modeling has been applied to tsunami generation and propagation from combined earthquake and landslide sources in this study tsunami hazards are evaluated from both individual and combined cases of submarine earthquakes and landslides through numerical tsunami simulations with a grid size of 90 m for bathymetry and topography data for the entire marmara sea region and validated with historical observations from the 1509 and 1894 earthquakes this study implements tunami model with a two layer model to conduct numerical tsunami simulations and the numerical results show that the maximum tsunami height could reach 4 0 m along istanbul shores for a full submarine rupture of the naf with a fault slip of 5 0 m in the eastern and western basins of the marmara sea the maximum tsunami height for landslide generated tsunamis from small medium and large of initial landslide volumes 0 15 0 6 and 1 5 km3 respectively could reach 3 5 6 0 and 8 0 m respectively along istanbul shores possible tsunamis from submarine landslides could be significantly higher than those from earthquakes depending on the landslide volume significantly these combined earthquake and landslide sources only result in higher tsunami amplitudes for small volumes significantly because of amplification within the same tsunami amplitude scale 3 0 4 0 m waveforms from all the coasts around the marmara sea indicate that other residential areas might have had a high risk of tsunami hazards from submarine landslides which can generate higher tsunami amplitudes and shorter arrival times compared to istanbul

tsunami hazard assessment in the hudson river estuary based on dynamic tsunami tide simulations this work is part of a tsunami inundation mapping activity carried out along the us east coast since 2010 under the auspice of the national tsunami hazard mitigation program nthmp the us east coast features two main estuaries with significant tidal forcing which are bordered by numerous critical facilities power plants major harbors as well as densely built low level areas chesapeake bay and the hudson river estuary hre hre is the object of this work with specific focus on assessing tsunami hazard in manhattan the hudson and east river areas in the nthmp work inundation maps are computed as envelopes of maximum surface elevation along the coast and inland by simulating the impact of selected probable maximum tsunamis pmt in the atlantic ocean margin and basin at present such simulations assume a static reference level near shore equal to the local mean high water mhw level here instead we simulate maximum inundation in the hre resulting from dynamic interactions between the incident pmts and a tide which is calibrated to achieve mhw at its maximum level to identify conditions leading to maximum tsunami inundation each pmt is simulated for four different phases of the tide and results are compared to those obtained for a static reference level we first separately simulate the tide and the three pmts that were found to be most significant for the hre these are caused by 1 a flank collapse of the cumbre vieja volcano cvv in the canary islands with a 80 km3 volume representing the most likely extreme scenario 2 an m9 coseismic source in the puerto rico trench prt and 3 a large submarine mass failure smf in the hudson river canyon of parameters similar to the 165 km3 historical currituck slide which is used as a local proxy for the maximum possible smf simulations are performed with the nonlinear and dispersive long wave model funwave tvd in a series of nested grids of increasing resolution towards the coast by one way coupling four levels of nested grids are used from a 1 arc min spherical coordinate grid in the deep ocean down to a 39 m cartesian grid in the hre bottom friction coefficients in the finer grids are calibrated for the tide to achieve the local spatially averaged mhw level at high tide in the hre combined tsunami tide simulations are then performed for four phases of the tide corresponding to each tsunami arriving at sandy hook nj 1 5 h ahead concurrent with 1 5 h after and 3 h after the local high tide these simulations are forced along the offshore boundary of the third level grid by linearly superposing time series of surface elevation and horizontal currents of the calibrated tide and each tsunami wave train this is done in deep enough water for a linear superposition to be accurate combined tsunami tide simulations are then performed with funwave tvd in this and the finest nested grids results show that for the 3 pmts depending on the tide phase the dynamic simulations lead to no or to a slightly increased inundation in the hre by up to 0 15 m depending on location and to larger currents than for the simulations over a static level the crt smf proxy tsunami is the pmt leading to maximum inundation in the hre for all tide phases nonlinear interactions between tide and tsunami currents modify the elevation current and celerity of tsunami wave trains mostly in the shallower water areas of the hre where bottom friction dominates as compared to a linear superposition of wave elevations and currents we note that while dynamic simulations predict a slight increase in inundation this increase may be on the same order as or even less than sources of uncertainty in the modeling of tsunami sources such as their initial water elevation and in bottom friction and bathymetry used in tsunami grids nevertheless results in this paper provide insight into the magnitude and spatial variability of tsunami propagation and impact in the complex inland waterways surrounding new york city and of their modification by dynamic tidal effects we conclude that changes in inundation resulting from the inclusion of a dynamic tide in the specific case of the hre although of scientific interest are not significant for tsunami hazard assessment and that the standard approach of specifying a static reference level equal to mhw is conservative however in other estuaries with similarly complex bathymetry topography and stronger tidal currents a simplified static approach might not be appropriate

consistent estimates of tsunami energy show promise for improved early warning early tsunami warning critically hinges on rapid determination of the tsunami hazard potential in real time before waves inundate critical coastlines tsunami energy can quickly characterize the destructive potential of generated waves traditional seismic analysis is inadequate to accurately predict a tsunami s energy recently two independent approaches have been proposed to determine tsunami source energy one inverted from the deep ocean assessment and reporting of tsunamis dart data during the tsunami propagation and the other derived from the land based coastal global positioning system gps during tsunami generation here we focus on assessing these two approaches with data from the march 11 2011 japanese tsunami while the gps approach takes into consideration the dynamic earthquake process the dart inversion approach provides the actual tsunami energy estimation of the propagating tsunami waves both approaches lead to consistent energy scales for previously studied tsunamis encouraged by these promising results we examined a real time approach to determine tsunami source energy by combining these two methods first determine the tsunami source from the globally expanding gps network immediately after an earthquake for near field early warnings and then to refine the tsunami energy estimate from nearby dart measurements for improving forecast accuracy and early cancelations the combination of these two real time networks may offer an appealing opportunity for early determination of the tsunami threat for the purpose of saving more lives and early cancelation of tsunami warnings to avoid unnecessary false alarms

a comparative analysis of coastal and open ocean records of the great chilean tsunamis of 2010 2014 and 2015 off the coast of mexico the three great earthquakes off the coast of chile on 27 february 2010 maule mw 8 8 1 april 2014 iquique mw 8 2 and 16 september 2015 illapel mw 8 3 generated major transoceanic tsunamis that spread throughout the pacific ocean and were measured by numerous coastal tide gauges and open ocean dart stations statistical and spectral analyses of the tsunami waves from the events recorded on the pacific coast of mexico enabled us to estimate parameters of the waves along the coast and to compare statistical features of the events we also identified three coastal hot spots sites having maximum tsunami risk puerto angel puerto madero and manzanillo based on the joint spectral analyses of the tsunamis and background noise we have developed a method for using coastal observations to determine the underlying spectrum of tsunami waves in the deep ocean the reconstructed open ocean tsunami spectra are in close agreement with the actual tsunami spectra evaluated from direct analysis of the dart records offshore of mexico we have further used the spectral estimates to parameterize the energy of the three chilean tsunamis based on the total open ocean tsunami energy and frequency content of the individual events

introduction to global tsunami science past and future volume ii twenty two papers on the study of tsunamis are included in volume ii of the pageoph topical issue global tsunami science past and future volume i of this topical issue was published as pageoph vol 173 no 12 2016 eds e l geist h m fritz a b rabinovich and y tanioka three papers in volume ii focus on details of the 2011 and 2016 tsunami generating earthquakes offshore of tohoku japan the next six papers describe important case studies and observations of recent and historical events four papers related to tsunami hazard assessment are followed by three papers on tsunami hydrodynamics and numerical modelling three papers discuss problems of tsunami warning and real time forecasting the final set of three papers importantly investigates tsunamis generated by non seismic sources volcanic explosions landslides and meteorological disturbances collectively this volume highlights contemporary trends in global tsunami research both fundamental and applied toward hazard assessment and mitigation

comparison and computational performance of tsunami hysea and most models for lantex 2013 scenario impact assessment on puerto rico coasts tsunami hysea model is used to simulate the caribbean lantex 2013 scenario lantex is the acronym for large atlantic tsunami exercise which is carried out annually the numerical simulation of the propagation and inundation phases is performed with a single integrated model but using different mesh resolutions and nested meshes special emphasis is placed on assessing the most exposed coastal areas at puerto rico affected by this event some comparisons with the most tsunami model available at the university of puerto rico upr are made both models compare well for propagating tsunami waves in open sea producing very similar results in near shore shallow waters tsunami hysea should be compared with the inundation version of most since the propagation version is limited to deeper waters for inundation larger differences between model results are observed nevertheless the most striking difference resides in computational time tsunami hysea is coded using the advantages of gpu architecture and can produce a 4 h simulation in a 60 arc sec resolution grid for the whole caribbean sea in less than 4 min with a single gpu and as fast as 11 s with 32 gpus when details about the inundation must be simulated a 1 arc sec approximately 30 m inundation resolution mesh covering all of puerto rico an island with dimensions of 160 km east west and 56 km north south is used and a three level nested meshes technique implemented in this case approximately 8 h of wall clock time is needed for a 2 h simulation in a single gpu versus more than 2 days for the most inundation running three different parts of the island west center east at the same time due to memory limitations in most when domain decomposition techniques are finally implemented by breaking up the computational domain into sub domains and assigning a gpu to each sub domain multi gpu tsunami hysea version we show that the wall clock time significantly decreases allowing high resolution inundation modeling in very short computational times reducing for example if eight gpus are used the wall clock time to around 1 h besides these computational times are obtained at a modest hardware cost compared with present tsunami models

introduction to tsunami science ten years after the 2004 indian ocean tsunami volume i twenty papers on the study of tsunamis and respective tsunamigenic earthquakes are included in volume ii of the pageoph topical issue tsunami science ten years after the 2004 indian ocean tsunami the papers presented in this second of two special volumes of pure and applied geophysics reflect the state of tsunami science during this time including five papers devoted to new findings specifically in the indian ocean two papers compile results from global observations and eight papers cover pacific ocean studies focusing mainly on the 2011 tohoku earthquake and tsunami remaining papers in this volume describe studies in the atlantic ocean and mediterranean sea and tsunami source studies overall the volume not only addresses the pivotal 2004 indian ocean and 2011 tohoku tsunamis but also examines the tsunami hazard posed to other critical coasts in the world

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

tsunami detection by high frequency radar beyond the continental shelf ii extension of time correlation algorithm and validation on realistic case studies in past work tsunami detection algorithms tdas have been proposed and successfully applied to offline tsunami detection based on analyzing tsunami currents inverted from high frequency hf radar doppler spectra with this method however the detection of small and short lived tsunami currents in the most distant radar ranges is challenging due to conflicting requirements on the doppler spectra integration time and resolution to circumvent this issue in part i of this work we proposed an alternative tda referred to as time correlation tc tda that does not require inverting currents but instead detects changes in patterns of correlations of radar signal time series measured in pairs of cells located along the main directions of tsunami propagation predicted by geometric optics theory such correlations can be maximized when one signal is time shifted by the pre computed long wave propagation time we initially validated the tc tda based on numerical simulations of idealized tsunamis in a simplified geometry here we further develop extend and apply the tc algorithm to more realistic tsunami case studies these are performed in the area west of vancouver island bc where ocean networks canada recently deployed a hf radar in tofino bc to detect tsunamis from far and near field sources up to a 110 km range two case studies are considered both simulated using long wave models 1 a far field seismic and 2 a near field landslide tsunami pending the availability of radar data a radar signal simulator is parameterized for the tofino hf radar characteristics in particular its signal to noise ratio with range and combined with the simulated tsunami currents to produce realistic time series of backscattered radar signal from a dense grid of cells numerical experiments show that the arrival of a tsunami causes a clear change in radar signal correlation patterns even at the most distant ranges beyond the continental shelf thus making an early tsunami detection possible with the tc tda based on these results we discuss how the new algorithm could be combined with standard methods proposed earlier based on a doppler analysis to develop a new tsunami detection system based on hf radar data that could increase warning time this will be the object of future work which will be based on actual rather than simulated radar data

a possible source mechanism of the 1946 unimak alaska far field tsunami uplift of the mid slope terrace above a splay fault zone in 1946 megathrust seismicity along the unimak segment of the alaska subduction zone generated the largest ever recorded alaska aleutian tsunami the tsunami severely damaged pacific islands and coastal areas from alaska to antarctica it is the charter member of tsunami earthquakes that produce outsized far field tsunamis for the recorded magnitude its source mechanisms were unconstrained by observations because geophysical data for the unimak segment were sparse and of low resolution reprocessing of legacy geophysical data reveals a deep water high angle reverse or splay thrust fault zone that leads megathrust slip upward to the mid slope terrace seafloor rather than along the plate boundary toward the trench axis splay fault uplift elevates the outer mid slope terrace and its inner area subsides multibeam bathymetry along the splay fault zone shows recent but undated seafloor disruption the structural configuration of the nearby semidi segment is similar to that of the unimak segment portending generation of a future large tsunami directed toward the us west coast

the 1979 submarine landslide generated tsunami in mururoa french polynesia this paper aims at best describing the submarine landslide which induced partial submersion of the atolls of mururoa and fangataufa in 1979 more precisely waves propagated along the south coast of mururoa atoll and penetrated into its lagoon some minutes after the landslide triggering t 0 s whereas a train of eight water waves reached the runway located on the north east coast of fangataufa 40 km south of mururoa between t 7 min 30 s and t 20 min a numerical model based on shallow water equations is used to simulate the landslide as well as the associated tsunami saint venant equations are used to propagate the tsunami in coastal areas whereas the offshore propagation is simulated by solving weakly nonlinear boussinesq equations low and high resolution nested grids are used to simulate the tsunami propagation in deep sea and in shallow waters respectively several scenarios have been tested to reproduce the observed water and run up heights in the near and far fields the best scenarios correspond to a landslide with a volume in the range 75 90 mm3 for a basal friction angle of 35 and with a basal friction angle in the range 30 40 for a volume of 80 mm3 these results have been completed by a parametric study on the slide parameters

generating random earthquake events for probabilistic tsunami hazard assessment to perform probabilistic tsunami hazard assessment for subduction zone earthquakes it is necessary to start with a catalog of possible future events along with the annual probability of occurrence or a probability distribution of such events that can be easily sampled for near field events the distribution of slip on the fault can have a significant effect on the resulting tsunami we present an approach to defining a probability distribution based on subdividing the fault geometry into many subfaults and prescribing a desired covariance matrix relating slip on one subfault to slip on any other subfault the eigenvalues and eigenvectors of this matrix are then used to define a karhunen loeve expansion for random slip patterns this is similar to a spectral representation of random slip based on fourier series but conforms to a general fault geometry we show that only a few terms in this series are needed to represent the features of the slip distribution that are most important in tsunami generation first with a simple one dimensional example where slip varies only in the down dip direction and then on a portion of the cascadia subduction zone

pre computed tsunami inundation database and forecast simulation in pelabuhan ratu indonesia we built a pre computed tsunami inundation database in pelabuhan ratu one of tsunami prone areas on the southern coast of java indonesia which can be employed for a rapid estimation of tsunami inundation during an event the pre computed tsunami waveforms and inundations are from a total of 340 scenarios ranging from 7 5 to 9 2 in moment magnitude scale mw including simple fault models of 208 thrust faults and 44 tsunami earthquakes on the plate interface as well as 44 normal faults and 44 reverse faults in the outer rise region using our tsunami inundation forecasting algorithm neartif we could rapidly estimate the tsunami inundation in pelabuhan ratu for three different hypothetical earthquakes the first hypothetical earthquake is a megathrust earthquake type mw 9 0 offshore sumatra which is about 600 km from pelabuhan ratu to represent a worst case event in the far field the second hypothetical earthquake mw 8 5 is based on a slip deficit rate estimation from geodetic measurements and represents a most likely large event the third hypothetical earthquake is a tsunami earthquake type mw 8 1 which often occurs south of java we compared the tsunami inundation maps produced by the neartif algorithm with results of direct forward inundation modeling for the hypothetical earthquakes the tsunami inundation maps produced from both methods are similar for the three cases however the tsunami inundation map from the inundation database can be obtained in much shorter time 1 min than the one from a forward inundation modeling 40 min these indicate that the neartif algorithm based on pre computed inundation database is reliable and useful for tsunami warning purposes this study also demonstrates that the neartif algorithm can work well though the earthquake source is located outside the area of fault model database because it uses a time shifting procedure for the best fit scenario searching

estimating the topography before volcanic sector collapses using tsunami survey data and numerical simulations large sector collapses and landslides have the potential to cause significant disasters estimating the topography and conditions such as volume before the collapse is thus important for analyzing the behavior of moving collapsed material and hazard risks this study considers three historical volcanic sector collapses in japan that caused tsunamis the collapses of the komagatake volcano in 1640 oshima oshima island in 1741 and unzen mayuyama volcano in 1792 numerical simulations of the tsunamis generated by each event were first carried out based on assumed collapse scenarios the primary objective of this study is to present conditions related to the topography before the events based on inverse models of the topography from those results and tsunami survey data the oshima oshima tsunami which is the subject of many previous studies was first simulated to validate the model accuracy and evaluate how run up heights changed during the simulation as the topographic conditions changed the run up height was especially sensitive to the collapsed volume and frictional acceleration affecting the collapsed material however the observed run up heights could be reproduced with high accuracy using proper conditions of frictional acceleration for the scenarios even if they were not exact a minimum requirement for the collapsed volume to generate the observed run up height was introduced and quantitatively evaluated using the results of numerical tsunami simulations the minimum volumes of the collapses of the komagatake and unzen mayuyama volcanoes were estimated to be approximately 1 2 and 0 3 km3 respectively

ice cores as an index of global volcanism from 1850 to the present to evaluate an important cause of past climate change climate researchers need reliable estimates of volcanic aerosol loading in the atmosphere previous indices the dust veil index volcanic explosivity index and those by mitchell 1970 sato et al 1993 and khmelevtsov et al unpublished manuscript 1993 all have drawbacks ice core acidity and sulfate records because they contain physical evidence of atmospheric loading are a promising source of information on past volcanic aerosols but these records contain large nonvolcanic signals as well we have compared northern hemisphere nh and southern hemisphere sh annual average versions of five indices with eight nh and six sh ice core records for the period 1850 to the present in an attempt to identify the volcanic signal common to all records the indices are all highly correlated with each other for the nh although the individual ice core records are in general not well correlated with each other or with any of the indices a composite derived from averaging the cores the ice core volcano index ivi shows promise as a new index of volcanic aerosol loading this new index correlates well with the existing non ice core volcanic indices and with high frequency temperature records for the sh the individual ice cores and indices are better correlated the shivi is again highly correlated with all indices and individual ice cores but not with high frequency temperature records for both hemispheres the southern oscillation index shows no significant correlation with the volcanic indices ice cores or the ivi thus providing no evidence for the impact of volcanic eruptions on el nino southern oscillation events

coastal amplification laws for the french tsunami warning center numerical modeling and fast estimate of tsunami wave heights along the french riviera tsunami modeling tools in the french tsunami warning center operational context provide rapidly derived warning levels with a dimensionless variable at basin scale a new forecast method based on coastal amplification laws has been tested to estimate the tsunami onshore height with a focus on the french riviera test site nice area this fast prediction tool provides a coastal tsunami height distribution calculated from the numerical simulation of the deep ocean tsunami amplitude and using a transfer function derived from the green s law due to a lack of tsunami observations in the western mediterranean basin coastal amplification parameters are here defined regarding high resolution nested grids simulations the preliminary results for the nice test site on the basis of nine historical and synthetic sources show a good agreement with the time consuming high resolution modeling the linear approximation is obtained within 1 min in general and provides estimates within a factor of two in amplitude although the resonance effects in harbors and bays are not reproduced in nice harbor especially variation in tsunami amplitude is something that cannot be really assessed because of the magnitude range and maximum energy azimuth of possible events to account for however this method is well suited for a fast first estimate of the coastal tsunami threat forecast

tsunami hazard in la reunion island sw indian ocean scenario based numerical modelling on vulnerable coastal sites several major tsunamis have affected the southwest indian ocean area since the 2004 sumatra event and some of them 2005 2006 2007 and 2010 have hit la reunion island in the southwest indian ocean however tsunami hazard is not well defined for la reunion island where vulnerable coastlines can be exposed this study offers a first tsunami hazard assesment for la reunion island we first review the historical tsunami observations made on the coastlines where high tsunami waves 2 3 m have been reported on the western coast especially during the 2004 indian ocean tsunami numerical models of historical scenarios yield results consistent with available observations on the coastal sites the harbours of la pointe des galets and saint paul the 1833 pagai earthquake and tsunami can be considered as the worst case historical scenario for this area in a second step we assess the tsunami exposure by covering the major subduction zones with syntethic events of constant magnitude 8 7 9 0 and 9 3 the aggregation of magnitude 8 7 scenarios all generate strong currents in the harbours 3 7 m s 1 and about 2 m of tsunami maximum height without significant inundation the analysis of the magnitude 9 0 events confirms that the main commercial harbour port est is more vulnerable than port ouest and that flooding in saint paul is limited to the beach area and the river mouth finally the magnitude 9 3 scenarios show limited inundations close to the beach and in the riverbed in saint paul more generally the results confirm that for la runion the sumatra subduction zone is the most threatening non local source area for tsunami generation this study also shows that far field coastal sites should be prepared for tsunami hazard and that further work is needed to improve operational warning procedures forecast methods should be developed to provide tools to enable the authorities to anticipate the local effects of tsunamis and to evacuate the harbours in sufficient time when such an earthquake occurs

multi meteotsunami event in the adriatic sea generated by atmospheric disturbances of 25 26 june 2014 a series of meteotsunamis hit a few locations in the mediterranean and black seas during 22 27 june 2014 meteotsunamis were particularly numerous on 25 and 26 june in the adriatic sea where at least six harbours and bays were stricken by powerful waves strongest events occurred in vela luka korcula island a known meteotsunami hot spot where waves reached height of 3 m and in rijeka dubrovacka bay where strong 5 m s currents accompanied 2 5 m high waves intensification of high frequency sea level activity was observed at both the eastern and western adriatic tide gauge stations with maximum recorded wave heights reaching 68 cm ortona italy a series of individual air pressure disturbances characterized by pronounced rates of air pressure change up to 2 4 hpa 5 min limited spatial extent 50 km and high temporal variability propagated over the adriatic on 2 days in question numerical hydrodynamic model schism forced by measured and idealised air pressure disturbances was utilised to reproduce the observed adriatic sea level response several important conclusions were reached 1 meteotsunamis occurring at various parts of the coast were generated by different atmospheric air pressure disturbances 2 topographic influence can be removed from sea level spectra by computing spectral signal to background ratios the result being related to the external forcing resembles atmospheric pressure spectra 3 sea response is strongly dependant on details of atmospheric forcing and 4 over complex bathymetries like the middle and south adriatic ones numerous effects including proudman resonance edge waves strong topographical enhancement and refractions on the islands placed on the pathway of atmospheric disturbances should be taken into account to fully understand meteotsunami generation and dynamics an in depth numerical study is planned to supplement the latter conclusion and to quantify contribution of each process

very fast characterization of focal mechanism parameters through w phase centroid inversion in the context of tsunami warning most of the tsunami potential seismic sources in the neam region are in a magnitude range of 6 5 le m w le 7 5 e g the tsunami triggered by the boumerdes earthquake of 2003 with m w 6 9 the centre d alerte aux tsunamis cenalt in operation since 2012 as the french national tsunami warning centre ntwc and candidate tsunami service provider ctsp has to issue warning messages within 15 min of earthquake origin time these warnings are based on the seismic source parameters m w magnitude focal depth and type of fault which are computed by focal mechanisms and centroid inversion methods the w phase method developed by kanamori and rivera allows quick computation of seismic source parameters due to the early arrival time between p waves and surface waves and is therefore particularly useful for monitoring we assess the w phase method with 29 events of magnitude m w ge 5 8 for the period 2010 2015 in the neam region results with 10 min of signal length are in good agreement compared to the global centroid moment tensor gcmt catalog

the 2011 tohoku tsunami on the coast of mexico a case study the tohoku east japan earthquake of 11 march 2011 m w 9 0 generated a great trans oceanic tsunami that spread throughout the pacific ocean where it was measured by numerous coastal tide gauges and open ocean dart deep ocean assessment and reporting of tsunamis stations statistical and spectral analyses of the tsunami waves recorded along the pacific coast of mexico have enabled us to estimate the principal parameters of the waves along the coast and to compare statistical features of the tsunami with other tsunamis recorded on this coast we identify coastal hot spots manzanillo zihuatanejo acapulco and ensenada corresponding to sites having highest tsunami hazard potential where wave heights during the 2011 event exceeded 1 5 2 m and tsunami induced currents were strong enough to close port operations based on a joint spectral analysis of the tsunamis and background noise we reconstructed the spectra of tsunami waves in the deep ocean and found that with the exception of the high frequency spectral band 5 cph the spectra are in close agreement with the true tsunami spectra determined from dart bottom pressure records the departure of the high frequency spectra in the coastal region from the deep sea spectra is shown to be related to background infragravity waves generated in the coastal zone the total energy and frequency content of the tohoku tsunami is compared with the corresponding results for the 2010 chilean tsunami our findings show that the integral open ocean tsunami energy i 0 was 2 30 cm2 or approximately 1 7 times larger than for the 2010 event comparison of this parameter with the mean coastal tsunami variance 451 cm2 indicates that tsunami waves propagating onshore from the open ocean amplified by 14 times the same was observed for the 2010 tsunami the tsunami colour frequency content for the 2011 tohoku tsunami was red with about 65 of the total energy associated with low frequency waves at frequencies 35 min the red colour i e the prevalence of low frequency waves in the 2011 tohoku as well as in the 2010 chile tsunamis is explained by the large extension of the source areas in contrast the 2014 and 2015 chilean earthquakes had much smaller source areas and consequently induced bluish high frequency tsunamis

challenges in defining tsunami wave heights the national oceanic and atmospheric administration noaa national centers for environmental information ncei and co located world data service for geophysics maintain the global tsunami archive consisting of the historical tsunami database imagery and raw and processed water level data the historical tsunami database incorporates where available maximum wave heights for each coastal tide gauge and deep ocean buoy that recorded a tsunami signal these data are important because they are used for tsunami hazard assessment model calibration validation and forecast and warning there have been ongoing discussions in the tsunami community about the correct way to measure and report these wave heights it is important to understand how these measurements might vary depending on how the data were processed and the definition of maximum wave height on september 16 2015 an 8 3 m w earthquake located 48 km west of illapel chile generated a tsunami that was observed all over the pacific region we processed the time series water level data for 57 coastal tide gauges that recorded this tsunami and compared the maximum wave heights determined from different definitions we also compared the maximum wave heights from the ncei processed data with the heights reported by the noaa tsunami warning centers we found that in the near field different methods of determining the maximum tsunami wave heights could result in large differences due to possible instrumental clipping we also found that the maximum peak is usually larger than the maximum amplitude peak to trough but the differences for the majority of the stations were 20 cm for this event the maximum tsunami wave heights determined by either definition maximum peak or amplitude would have validated the forecasts issued by the noaa tsunami warning centers since there is currently only one field in the ncei historical tsunami database to store the maximum tsunami wave height for each tide gauge and deep ocean buoy ncei will consider adding an additional field for the maximum peak measurement

probabilistic hazard of tsunamis generated by submarine landslides in the cook strait canyon new zealand cook strait canyon is a submarine canyon that lies within ten kilometres of wellington the capital city of new zealand the canyon walls are covered with scars from previous landslides which could have caused local tsunamis palaeotsunami evidence also points to past tsunamis in the wellington region furthermore the canyon s location in cook strait means that there is inhabited land in the path of both forward and backward propagating waves tsunamis induced by these submarine landslides pose hazard to coastal communities and infrastructure but major events are very uncommon and the historical record is not extensive enough to quantify this hazard the combination of infrequent but potentially very consequential events makes realistic assessment of the hazard challenging however information on both magnitude and frequency is very important for land use planning and civil defence purposes we use a multidisciplinary approach bringing together geological information with modelling to construct a probabilistic tsunami hazard assessment of submarine landslide generated tsunami although there are many simplifying assumptions used in this assessment it suggests that the cook strait open coast is exposed to considerable hazard due to submarine landslide generated tsunamis we emphasise the uncertainties involved and present opportunities for future research

tsunami wave run up on a vertical wall in tidal environment we solve analytically a nonlinear problem of shallow water theory for the tsunami wave run up on a vertical wall in tidal environment shown that the tide can be considered static in the process of tsunami wave run up in this approximation it is possible to obtain the exact solution for the run up height as a function of the incident wave height this allows us to investigate the tide influence on the run up characteristics

fault slip distribution of the 2016 fukushima earthquake estimated from tsunami waveforms the 2016 fukushima normal faulting earthquake mjma 7 4 occurred 40 km off the coast of fukushima within the upper crust the earthquake generated a moderate tsunami which was recorded by coastal tide gauges and offshore pressure gauges first the sensitivity of tsunami waveforms to fault dimensions and depths was examined and the best size and depth were determined tsunami waveforms computed based on four available focal mechanisms showed that a simple fault striking northeast southwest and dipping southeast strike 45 dip 41 rake 95 yielded the best fit to the observed waveforms this fault geometry was then used in a tsunami waveform inversion to estimate the fault slip distribution a large slip of 3 5 m was located near the surface and the major slip region covered an area of 20 km 20 km the seismic moment calculated assuming a rigidity of 2 7 1010 n m2 was 3 70 1019 nm equivalent to mw 7 0 this is slightly larger than the moments from the moment tensor solutions mw 6 9 large secondary tsunami peaks arrived approximately an hour after clear initial peaks were recorded by the offshore pressure gauges and the sendai and ofunato tide gauges our tsunami propagation model suggests that the large secondary tsunami signals were from tsunami waves reflected off the fukushima coast a rather large tsunami amplitude of 75 cm at kuji about 300 km north of the source was comparable to those recorded at stations located much closer to the epicenter such as soma and onahama tsunami simulations and ray tracing for both real and artificial bathymetry indicate that a significant portion of the tsunami wave was refracted to the coast located around kuji and miyako due to bathymetry effects

linking oceanic tsunamis and geodetic gravity changes of large earthquakes large earthquakes at subduction zones usually generate tsunamis and coseismic gravity changes these two independent oceanic and geodetic signatures of earthquakes can be observed individually by modern geophysical observational networks the gravity recovery and climate experiment twin satellites can detect gravity changes induced by large earthquakes while altimetry satellites and deep ocean assessment and reporting of tsunamis buoys can observe resultant tsunamis in this study we introduce a method to connect the oceanic tsunami measurements with the geodetic gravity observations and apply it to the 2004 sumatra mw 9 2 earthquake the 2010 maule mw 8 8 earthquake and the 2011 tohoku mw 9 0 earthquake our results indicate consistent agreement between these two independent measurements since seafloor displacement is still the largest puzzle in assessing tsunami hazards and its formation mechanism our study demonstrates a new approach to utilizing these two kinds of measurements for better understanding of large earthquakes and tsunamis

benchmarking an unstructured grid model for tsunami current modeling we present model results derived from a tsunami current benchmarking workshop held by the nthmp national tsunami hazard mitigation program in february 2015 modeling was undertaken using our own 3d unstructured grid model that has been previously certified by the nthmp for tsunami inundation results for two benchmark tests are described here including 1 vortex structure in the wake of a submerged shoal and 2 impact of tsunami waves on hilo harbor in the 2011 tohoku event the modeled current velocities are compared with available lab and field data we demonstrate that the model is able to accurately capture the velocity field in the two benchmark tests in particular the 3d model gives a much more accurate wake structure than the 2d model for the first test with the root mean square error and mean bias no more than 2 cm s 1 and 8 mm s 1 respectively for the modeled velocity