evaluation of velocity related approximations in the nonlinear shallow water equations for the kuril islands 2006 tsunami event at honolulu hawaii 1 the nonlinear shallow water equations nswe provide a model for long wave behavior commonly used in tsunami modeling problems in which the scale associated with the surface wavelength is much greater than the ocean depth this approximation allows for the derivation of the nswe under the assumptions that the pressure is hydrostatic and the horizontal velocity components uniform along the water column the present study uses current velocity data acquired by the kilo nalu near shore reef observatory acoustic doppler current profiler adcp on the south shore of oahu 21 288 n 157 865 w in the aftermath of the 2006 kuril tsunami to assess the validity of the nswe assumptions on the velocity components adcp measurements provide information on all three velocity components along the water column allowing the calculation of terms discarded in the nswe approximation containing temporal or vertical derivatives comparison of the relative magnitude of terms retained and neglected in the nswe reveals that in shallow waters 10 m the size of discarded terms remains smaller but approaches the order of magnitude of retained terms in the momentum equations not all terms present in the equations can be evaluated from the available data so verification of the assumptions investigated here represents a necessary but not sufficient condition for the validity of the nswe approximation to model tsunami waves in shallow coastal waters

field survey of the 1993 hokkaido nansei oki earthquake tsunami runup data in hokkaido and in three prefectures in the tohoku district are described with a few witnessed arrival times and with comments of tide records the highest runup of 31 7 m was found at the bottom of a narrow valley on the west coast of okushiri island in order to explain high runups of 20 m at hamatsumae in the sheltered area roles of edge waves refraction of the okushiri spur and tsunami generation by causes other than the major fault motion should be understood an early arrival of the tsunami on the west coast of hokkaido suggests another tsunami generation mechanism in addition to the major fault motion

tsunami generation of the 1993 hokkaido nansei oki earthquake heterogeneous fault motion of the 1993 hokkaido nansei oki earthquake is studied by using seismic geodetic and tsunami data and the tsunami generation from the fault model is examined seismological analyses indicate that the focal mechanism of the first 10 s when about a third of the total moment was released is different from the overall focal mechanism a joint inversion of geodetic data on okushiri island and the tide gauge records in japan and korea indicates that the largest slip about 6 m occurred in a small area just south of the epicenter this corresponds to the initial rupture on a fault plane dipping shallowly to the west the slip on the northernmost subfault which is dipping to the east is about 2 m while the slips on the southern subfaults which are steeply dipping to the west are more than 3 m tsunami heights around okushiri island are calculated from the heterogeneous fault model using different grid sizes computation on the smaller grids produces larger tsunami heights that are closer to the observed tsunami runup heights tsunami propagation in the nearly closed japan sea is examined as the free oscillation of the japan sea the excitation of the free oscillation by this earthquake is smaller than that by the 1964 niigata or 1983 japan sea earthquake

stratigraphic record of pliocene pleistocene basin evolution and deformation within the southern san andreas fault zone mecca hills california abstract a thick section of pliocene pleistocene nonmarine sedimentary rocks exposed in the mecca hills california provides a record of fault zone evolution along the coachella valley segment of the san andreas fault saf geologic mapping measured sections detailed sedimentology and paleomagnetic data document a 3 5 myr history of deformation and sedimentation in this area sw side down offset on the painted canyon fault pcf starting 3 7 ma resulted in deposition of the mecca conglomerate southwest of the fault the lower member of the palm spring formation accumulated across the pcf from 3 0 to 2 6 ma during regional subsidence sw side up slip on the pcf and related transpressive deformation from 2 6 to 2 3 ma created a time transgressive angular unconformity between the lower and upper members of the palm spring formation the upper member accumulated in discrete fault bounded depocenters until initiation of modern deformation uplift and basin inversion starting at 0 7 ma some spatially restricted deposits can be attributed to the evolution of fault zone geometric complexities however the deformation events at ca 2 6 ma and 0 7 ma are recorded regionally along 80 km of the saf through coachella valley covering an area much larger than mapped fault zone irregularities and thus require regional explanations we therefore conclude that late cenozoic deformation and sedimentation along the saf in coachella valley has been controlled by a combination of regional tectonic drivers and local deformation due to dextral slip through fault zone complexities we further propose a kinematic link between the 2 6 2 3 ma angular unconformity and a previously documented but poorly dated reorganization of plate boundary faults in the northern gulf of california at 3 3 2 0 ma this analysis highlights the potential for high precision chronologies in deformed terrestrial deposits to provide improved understanding of local to regional scale structural controls on basin formation and deformation along an active transform margin

field survey report on tsunami disasters caused by the 1993 southwest hokkaido earthquake detailed field work at okushiri island and along the southwest coast of hokkaido has revealed quantitatively 1 the advancing direction of tsunami on land 2 the true tsunami height i e height of tsunami excluding its splashes as measured from the ground and 3 the flow velocity of tsunami on land in heavily damaged areas when a japanese wooden house is swept away by tsunami bolts that tie the house to its concrete foundation resist until the last moment and become bent towards the direction of the house being carried away the orientations of more than 850 of those bent bolts and iron pipes all that can be measured mostly at okushiri island and fell down direction of about 400 trees clearly display how tsunami behaved on land and caused serious damage at various places the true tsunami height was estimated by using several indicators such as broken tree twigs and a window pane the flow velocity of tsunami on land was determined by estimating the hydrodynamic force exerted on a bent handrail and a bent down guardrail by the tsunami through in situ strength tests

seismic and landslide source of the 1908 straits of messina tsunami sicily italy 1 one hundred years ago december 1908 a devastating tsunami associated with an earthquake struck the straits of messina area causing many casualties on the basis of seismic data and observed runups and arrival times we suggest that the tsunami was likely generated by coseismic seafloor displacement coupled with a small submarine landslide triggered by the earthquake backwards ray tracing using a depth dependent velocity field submarine slope analysis and inferences form the main drainage network allowed us to identify possible locations for the source of the submarine landslide we then performed direct simulations of tsunamis generated by the earthquake and landslides and identified the tsunami source earthquake plus landslide that best fits observational data in a small volume submarine landslide 1 5 km3 located offshore nizza sicily

sedimentology and paleontology of a tsunami deposit accompanying the great chilean earthquake of february 2010 abstract at pichilemu in the northern third of the rupture area of the moment magnitude scale mw 8 8 2010 chile earthquake deposits of the tsunami accompanying the earthquake consist of a lower layer of medium to fine sand mean grain size of 200 m containing rock clasts overlain by a thin silty very fine sand mean grain size of 125 m layer based on a sedimentological model most 90 of the deposit is finer than 401 408 m suggesting tsunami flow velocities were between 7 m s and 13 5 m s ostracods were common in the upper layer along with a small number of broken benthic foraminifera and a single planktonic foraminifera diatoms were abundant throughout species assemblages represent a mixture of diatoms from differing environments life forms and substrate preferences we attribute the mixed assemblages to turbulence within the water column during tsunami inundation with erosion of beaches and salt marshes followed by redeposition of sand and mud inland breakage of fragile diatom valves in the lower layer may also support transport by turbulent flow a higher abundance of diatom species with mud substrate preferences in the upper layer implies a decrease in flow velocity from lower to upper layers

field survey and numerical simulations a review of the 1998 papua new guinea tsunami the papua new guinea png tsunami of 1998 is re examined through a detailed review of the field survey as well as numerous numerical computations the discussion of the field survey explores a number of possible misinterpretations of the recorded data the survey data are then employed by a numerical model as a validation tool a boussinesq model and a nonlinear shallow water wave nlsw model are compared in order to quantify the effect of frequency dispersion on the landslide generated tsunami the numerical comparisons indicate that the nlsw model is a poor estimator of offshore wave heights however due to what appears to be depth limited breaking seaward of sissano spit both numerical models are in agreement in the prediction of maximum water elevations at the overtopped spit by comparing three different hot start initial profiles of the tsunami wave it is shown that the initial shape and orientation of the tsunami wave is secondary to the initial displaced water mass in regard to prediction of water elevations on the spit these numerical results indicate that agreement between numerical prediction of runup values with field recorded values at png cannot be used to validate either a nlsw tsunami propagation model or a specific landslide tsunami hot start initial condition finally with the use of traditional tsunami codes a new interpretation of the png runup measurements is presented

observations and predictions of run up for a significant range of offshore wave conditions and foreshore slopes run up observations are compared to semiempirical formulations and predictions of an existing numerical model based on the depth averaged one dimensional nonlinear shallow water equations with bore like breaking wave dissipation and quadratic bottom friction the numerical model is initialized with time series of sea surface elevation and cross shore velocity observed in 80 cm mean water depth approximately 50 m offshore of the mean shoreline on a gently sloping beach and in 175 cm water depth 100 m offshore of the shoreline on a steep concave beach run up was measured with a stack of resistance wires at elevations 5 10 15 20 and 25 cm above and parallel to the beach face at sea swell frequencies nominally 0 05 f 0 18 hz run up energy is limited by surf zone dissipation of shoreward propagating waves so that increasing the offshore wave height above a threshold value does not substantially increase the predicted or observed sea swell run up excursions e g run up is saturated existing semiempirical saturation formulations are most consistent with the observations and numerical model predictions of run up excursions nearest the bed in contrast at infragravity frequencies 0 004 f 0 05 hz where surf zone dissipation is relatively weak and reflection from the beach face is strong e g saturation formulas are not applicable the run up excursions increase approximately linearly with increasing offshore wave height the numerical model also accurately predicts that the tongue like shape of the run up results in sensitivity of run up measurements to wire elevation for instance run up excursions and mean vertical superelevation above the offshore still water level increase with decreasing wire elevation and continuous thinning of the run up tongue during the wave uprush can result in large phase differences between run up excursions measured at different wire elevations numerical model simulations suggest that run up measured more than a few centimeters above the bed cannot be used to infer even the sign of the fluid velocities in the run up tongue

finite element modeling of the july 12 1993 hokkaido nansei oki tsunami a fault plane model and a finite element hydrodynamic model are applied to the simulation of the hokkaido nansei oki tsunami of july 12 1993 the joint performance of the models is assessed based on the overall ability to reproduce observed tsunami waveforms and to preserve mass and energy during tsunami propagation while a number of observed characteristics of the waveforms are satisfactorily reproduced in particular amplitudes and arrival times at tidal gauges relatively close to the source and general patterns of energy concentration others are only marginally so notably wave periods at the same gauges and wave heights along okushiri differences between observations and simulations are traceable to both the fault plane and the hydrodynamic models nonnegligible losses of energy occur throughout the simulated tsunami propagation these losses seem to be due to a combination of factors including numerical damping and possible deficiencies of the shallow water equations in preserving energy

the 2009 samoa and 2010 chile tsunamis as observed in the ionosphere using gps total electron content 1 ground based global positioning system gps measurements of ionospheric total electron content tec show variations consistent with atmospheric internal gravity waves caused by ocean tsunamis following two recent seismic events the samoa earthquake of 29 september 2009 and the chile earthquake of 27 february 2010 both earthquakes produced ocean tsunamis that were destructive to coastal communities near the epicenters and both were observed in tidal gauge and buoy measurements throughout the pacific ocean we observe fluctuations in tec correlated in time space and wave properties with these tsunamis using the jet propulsion laboratory s global ionospheric mapping software these tec measurements were band pass filtered to remove ionospheric tec variations with wavelengths and periods outside the typical range for tsunamis observable variations in tec appear correlated with the tsunamis in some locations hawaii and japan but not in others southern california or near the epicenters where variations are observed the typical amplitude tends to be 0 1 0 2 tec units for these events on the order of 1 of the background tec value these observations are compared to estimates of expected tsunami driven tec variations produced by embry riddle aeronautical university s spectral full wave model an atmosphere ionosphere coupled model and are found to be in good agreement significant tec variations are not always seen when a tsunami is present but in these two events the regions where a strong ocean tsunami was observed coincided with clear tec observations while a lack of clear tec observations coincided with smaller sea surface height amplitudes there exists the potential to apply these detection techniques to real time gps tec data providing estimates of tsunami speed and amplitude that may be useful for early warning systems

geologic setting field survey and modeling of the chimbote northern peru tsunami of 21 february 1996 whereas the coast of peru south of 10 s is historically accustomed to tsunamigenic earthquakes the subduction zone north of 10 s has been relatively quiet on 21 february 1996 at 21 51 gmt 07 51 local time a large tsunamigenic earthquake harvard estimate m w 7 5 struck at 9 6 s 79 6 w approximately 130 km off the northern coast of peru north of the intersection of the mendana fracture zone with the peru chile trench the likely mechanism inferred from seismic data is a low angle thrust consistent with subduction of the nazca plate beneath the south american plate with relatively slow rupture characteristics approximately one hour after the main shock a damaging tsunami reached the peruvian coast resulting in twelve deaths we report survey measurements from 7 7 s to 11 s on maximum runup 2 5 m between 8 and 10 s maximum inundation distances which exceeded 500 m and tsunami sediment deposition patterns observations and numerical simulations show that the hydrodynamic characteristics of this event resemble those of the 1992 nicaragua tsunami differences in climate vegetation and population make these two tsunamis seem more different than they were this 1996 chimbote event was the first large m w 7 subduction zone interplate earthquake between about 8 and 10 s in peru since the 17th century and bears resemblance to the 1960 m w 7 6 event at 6 8 s together these two events are apparently the only large subduction zone earthquakes in northern peru since 1619 est latitude 8 s est m w 7 8 these two tsunamis also each produced more fatalities than any other tsunami in peru since the 18th century we concur with pelayo and wiens 1990 1992 that this subduction zone in northern peru resembles others where the subduction zone is only weakly coupled and convergence is largely aseismic subduction zone earthquakes when they occur are slow commonly shallow and originate far from shore near the tip of the wedge thus they are weakly felt and the ensuing tsunamis are unanticipated by local populations although perhaps a borderline case the chimbote tsunami clearly is another wake up example of a tsunami earthquake

runup of solitary waves on a circular island this is a study of the interactions of solitary waves climbing up a circular island a series of large scale laboratory experiments with waves of different incident height to depth ratios and different crest lengths is described detailed two dimensional run up height measurements and time histories of surface elevations around the island are presented a numerical model based on the two dimensional shallow water wave equations including runup calculations was developed numerical model predictions agreed very well with the laboratory data and the model was used to study wave trapping and the effect of slope under certain conditions enhanced runup and wave trapping on the lee side of the island were observed suggesting a possible explanation for the devastation reported by field surveys in babi island off flores indonesia and in okushiri island japan

modelling of tsunami generated by the giant late bronze age eruption of thera south aegean sea greece summary tsunami generated by the late bronze age lba eruption of thera were simulated using synthetic tide records produced for selected nearshore 20 m depths sites of northern crete the cyclades islands sw turkey and sicily inundation distances inland were also calculated along northern crete modelling was performed by incorporating fully non linear boussinesq wave theory with two tsunamigenic mechanisms the first involved the entry of pyroclastic flows into the sea assuming a thick 55 m 30 km3 flow entering the sea along the south coast of thera in three different directions all directed towards northern crete then a thin pyroclastic flow 1 m 1 2 km3 entering the sea along the north coast of thera directed towards the cyclades islands flows were modelled as a solid block that slowly decelerates along a horizontal surface the second mechanism assumed caldera collapse of 19 km3 and 34 km3 modelled as a dynamic landslide producing rapid vertical displacements calculated nearshore wave amplitudes varied from a few metres to 28 m along northern crete from pyroclastic flows and up to 19 m from caldera collapse 34 km3 volume inundation distances on crete were 250 450 m waves produced by pyroclastic flows were highly focused however as a function of sea entry direction smaller volume pyroclastic flows produced nearshore wave amplitudes up to 4 m in the cyclades islands north of thera wave amplitudes in the cyclades from smaller volume caldera collapse 19 km3 were up to 24 m whereas in sw turkey were as low as 2 1 and 0 8 m didim and fethye where lba tsunami deposits have been found wave amplitudes for the larger volume caldera collapse 34 km3 were generally 2 5 3 times larger than those generated by the smaller volume collapse 19 km3 these results provide estimates for understanding possible consequences of tsunami impact in lba coastal zones thus providing criteria at archaeological sites for detecting inundation damage as well as for contemporary hazard assessment they also provide additional criteria for deciphering homogenite layers in the abyssal stratigraphy of the ionian and eastern mediterranean seas

source models for the 1993 hokkaido nansei oki earthquake tsunami a source model for the 1993 hokkaido nansei oki tsunami must satisfy certain conditions such conditions are presented in this paper and two methods are used to determine the best source model for this event a trial and error method selects dcrc 17a as the best among 24 different models this model has three fault planes dipping westward to reproduce well the tide gauge records at two locations an inversion analysis is used to modify the dislocation of dcrc 17a

the a d 900 930 seattle fault zone earthquake with a wider coseismic rupture patch and postseismic submergence inferences from new sedimentary evidence stratigraphic evidence for coseismic uplift a tsunami and a sandy debris flow linked to the a d 900 930 seattle fault zone earthquake and subsequent submergence is present at gorst at the terminus of sinclair inlet washington this study indicates that at least 3 m of uplift preceded a tsunami followed by a sandy debris flow though the seattle and tacoma fault zones ruptured within the error of ages of the tsunami deposit model simulations indicate the seattle fault generates an order of magnitude larger tsunami in the vicinity of the field area than the tacoma fault and is the more likely generator of the tsunami simulations indicate amplitude from a seattle fault zone generated wave train was 4 5 m and stratigraphy shows the tsunami left a sandy deposit soft sediment deformation narrows the time window for the debris flow to the hours to months after the tsunami slope failure in unconsolidated glacial sands likely initiated a debris flow that surged at least 2 km down gorst creek valley and left a more than 40 cm thick deposit along the creek and in the wetlands submergence of a thuja plicata western red cedar swamp into the intertidal zone indicates at least 1 5 m of submergence in the last 1100 years this submergence indicates uplift on nearby marine terraces associated with the seattle fault zone was likely higher and the a d 900 930 earthquake was potentially larger than previously recognized

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

twenty five years of progress in the science of geological tsunamis following the 1992 nicaragua and flores events we review a set of 47 tsunamis of geological origin triggered by earthquakes landslides or volcanoes which have occurred over the past 25 years and provided significant new insight into theoretical experimental field or societal aspects of tsunami science among the principal developments in our command of various aspects of tsunamis we earmark the development of the w phase inversion for the low frequency moment tensor of the parent earthquake the abandonment of the concept of a maximum earthquake magnitude for a given subduction zone controlled by simple plate properties the development and implementation of computer codes simulating the interaction of tsunamis with initially dry land at beaches thus introducing a quantitative component to realistic tsunami warning procedures and the recent in situ investigation of current velocities in addition to the field of surface displacements during the interaction of tsunamis with harbors continued research remains warranted notably in the field of the real time identification of tsunami earthquakes whose tsunamis are larger than expected from their seismic magnitudes especially conventional ones the recent tragedy during the 2018 krakatau flank collapse along a scenario which had been quantitatively forecast also emphasizes the need for a continued effort in the education of the populations at risk

laboratory experiments of tsunami runup on a circular island laboratory experiments of a 7 2 m diameter conical island were conducted to study three dimensional tsunami runup the 62 5 cm tall island had 1 on 4 side slopes and was positioned in the center of a 30 m wide by 25 m long flat bottom basin solitary waves with height to depth ratios ranging from 0 05 to 0 20 and source lengths ranging from 0 30 to 7 14 island diameters were tested in water depths of 32 and 42 cm twenty seven capacitance wave gages were used to measure surface wave elevations at incident and four radial transects on the island slope maximum vertical runup measurements were made at 20 locations around the perimeter of the island using rod and transit a new runup gage was located on the back or lee side of the island to record runup time series

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

the global reach of the 26 december 2004 sumatra tsunami numerical model simulations combined with tide gauge and satellite altimetry data reveal that wave amplitudes directionality and global propagation patterns of the 26 december 2004 sumatra tsunami were primarily determined by the orientation and intensity of the offshore seismic line source and subsequently by the trapping effect of mid ocean ridge topographic waveguides

simulation of andaman 2004 tsunami for assessing impact on malaysia mistakenly perceived as safe from the hazards of tsunami malaysia faced a rude awakening by the 26 december 2004 andaman tsunami since the event malaysia has started active research on some aspects of tsunami including numerical simulations of tsunami and the role of mangrove as a mitigation measure against tsunami hazards an in house tsunami numerical simulation model tuna has been developed and applied to the 26 december 2004 andaman tsunami to simulate the generation propagation and inundation processes along affected beaches in malaysia mildly nonlinear bottom friction term in the deeper ocean is excluded as it is insignificant to the simulation results consistent with theoretical expectation on the other hand in regions with shallow depth near the beaches friction and nonlinearity are significant and are included in tuna simulation results with tuna indicate satisfactory performance when compared with comcot and on site survey results

analysis and automatic processing in near field of eight 1992 1994 tsunamigenic earthquakes improvements towards real time tsunami warning we study eight tsunamigenic earthquakes of 1992 1994 with data from single near field 3 component long period stations the analysis is made from the standpoint of tsunami warning by an automatic process which estimates the epicentral location and the seismic moment through the variable period mantle magnitude m m simulations of early warning based on the real time computation of the seismic moment are also tested with this system which would give a justified warning in each region of tsunami potentiality by exploiting the dependence of moment rate release with frequency the system has the capability of recognizing both tsunami earthquakes such as the 1992 nicaragua and 1994 java events as well as instances of the opposite case of low frequency deficiency interpreted as indicating a deeper than normal source 1993 guam event we report both the results of delayed time processing of the near field stations and the actual real time warnings at ppt which confirm the former

hikurangi margin tsunami earthquake generated by slow seismic rupture over a subducted seamount abstract tsunami earthquakes generate much larger tsunami than their surface wave magnitude would suggest and are a problem for tsunami warning systems they are often not accompanied by intense or even strong ground shaking and hence do not provide a natural warning for self evacuation the lesser known 1947 offshore poverty bay and tolaga bay earthquakes along the east coast of the north island new zealand share many characteristics with other well known tsunami earthquakes including low amplitude shaking long durations and anomalously large tsunami however these two new zealand events are rare in that their source area has been imaged directly by long offset 2d seismic reflection profiles in this contribution we propose a source model for the 1947 offshore poverty bay tsunami earthquake recognising that the hypocentre occurs in a region where seismic reflection and magnetic data support the existence of a shallow m 7 earthquakes with complex low velocity rupture scenarios that enhance tsunami waves and their role in seismic hazard should not be under estimated

mars gravity data analysis of the crater antoniadi topography and gravity information for this 370 km crater are analyzed to determine a depth of compensation using an airy isostatic model a least squares fit to the gravity profile produces an estimate of 115 km for the depth of compensation

time and size of a giant earthquake in cascadia inferred from japanese tsunami records of january 1700 geological evidence shows that great earthquakes have occurred in the recent prehistoric past in the cascadia subduction zone off the pacific coast of north america the most recent event or series of events is dated at about 300 years ago1 4 but the precise date and magnitude have not been determined geological investigations have not been able to distinguish a single giant earthquake from a series of great earthquakes occurring over a timespan of a decade or two4 although this information is important for the assessment of future hazard5 we have found several tsunami records in japan from ad 1700 with no indication of a local cause historical earthquake records and palaeoseismic evidence indicate the absence of a large earthquake in 1700 in south america alaska or kamchatka leaving cascadia as the most likely source of this tsunami the estimated time of the earthquake is the evening about 21 00 local time of 26 january 1700 the magnitude is estimated as 9 from the tsunami heights in which case the earthquake ruptured the entire length of the cascadia subduction zone2 these estimates are consistent with native american legends that an earthquake occurred on a winter night6

tsunami inundation at crescent city california generated by earthquakes along the cascadia subduction zone 1 we model tsunami inundation and runup heights in crescent city california triggered by possible earthquakes on the cascadia subduction zone csz the csz is believed capable of producing great earthquakes with magnitudes of mw 9 0 or greater we simulate plausible csz rupture scenarios and calculate inundation using most we benchmark our csz inundation projections against mapped flooded areas and tide gauge data from the 1964 tsunami which destroyed 29 city blocks and also from the damaging 15 november 2006 kuril islands tsunami results suggest that inundation from csz tsunamis could extend over 3 km inland twice as far as the limits of the 1964 inundation crescent city is most vulnerable to slip on the gorda segment of the csz rupture of the northern or juan de fuca segment produces lower water heights than the 1964 event at crescent city csz ruptures produce a leading elevation wave that arrives only minutes after the earthquake educational and self evacuation are essential to save lives