validation and joint inversion of teleseismic waveforms for earthquake source models using deep ocean bottom pressure records a case study of the 2006 kuril megathrust earthquake the importance of accurate tsunami simulation has increased since the 2004 sumatra andaman earthquake and the indian ocean tsunami that followed it because it is an important tool for inundation mapping and potentially tsunami warning an important source of uncertainty in tsunami simulations is the source model which is often estimated from some combination of seismic geodetic or geological data a magnitude 8 3 earthquake that occurred in the kuril subduction zone on 15 november 2006 resulted in the first teletsunami to be widely recorded by bottom pressure recorders deployed in the northern pacific ocean because these recordings were unaffected by shallow complicated bathymetry near the coast this provides a unique opportunity to investigate whether seismic rupture models can be inferred from teleseismic waves with sufficient accuracy to be used to forecast teletsunami in this study we estimated the rupture model of the 2006 kuril earthquake by inverting the teleseimic waves and used that to model the tsunami source the tsunami propagation was then calculated by solving the linear long wave equations we found that the simulated 2006 kuril tsunami compared very well to the ocean bottom recordings when simultaneously using p and long period surface waves in the earthquake source process inversion

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

rapid determination of global moment tensor solutions in an effort to improve data services the national earthquake information center has begun a program in cooperation with the incorporated research institutions for seismology data management center iris dmc to produce rapid estimates of the seismic moment tensor for most earthquakes with a body wave magnitude of 5 8 or greater although this program is still undergoing testing and fine tuning an estimate of the moment tensor can usually be produced within 20 minutes of the arrival of the broadband p waveform data from the iris dmc although the speed with which this data can be obtained varies in many cases a solution can be obtained within two hours of the earthquake these solutions do not vary significantly from the final solutions determined using the entire network because of the manner in which the data and the synthetic seismograms are aligned the method is insensitive to the effects of timing errors epicentral mislocation and lateral heterogeneity in earth structure this procedure was implemented in may 1993 the results from that month are presented here

on the initiation of subduction estimates of shear resistance associated with lithospheric thrusting and convergence represent lower bounds on the force necessary to promote trench formation three environments proposed as preferential sites of incipient subduction are investigated passive continental margins transform faults fracture zones and extinct ridges none of these are predicted to convert into subduction zones simply by the accumulation of local gravitational stresses subduction cannot initiate through the foundering of dense oceanic lithosphere immediately adjacent to passive continental margins the attempted subduction of buoyant material at a mature trench can result in large compressional forces in both subducting and overriding plates this is the only tectonic force sufficient to trigger the nucleation of a new subduction zone the ubiquitous distribution of transform faults and fracture zones combined with the common proximity of these features to mature subduction complexes suggests that they may represent the most likely sites of trench formation if they are even marginally weaker than normal oceanic lithosphere

total analysis of the 1993 hokkaido nansei oki earthquake using seismic wave tsunami and geodetic data the fault geometry and slip distribution of the hokkaido nansei oki japan earthquake of july 12 1993 are estimated using seismic wave tsunami and geodetic data the moment tensor rate function inversion from p waves shows one nodal plane shallowly dipping to the west and the other nodal plane steeply dipping to the east the best depth is estimated as 10 15 km the source time history consists of an initial pulse with a duration of 10 s and moment release of 2 1020 nm followed by a complex rupture for at least 40 s the centroid moment tensor cmt solution shows one nodal plane shallowly dipping to the east and the other steeply dipping to the west the overall seismic moment is estimated as 5 5 1020 nm mw 7 8 the joint inversion of geodetic data on okushiri island and tsunami waveforms in japan and korea shows that the largest slip about 6 m occurred at 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 fault dipping to the east is about 2 m the slips on the southern faults dipping steeply to the west are more than 3 m total seismic moment of 4 9 1020 nm estimated from the slip distribution is similar to the estimate from cmt inversion

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

free oscillation of the japan sea excited by earthquakes ii modal approach and synthetic tsunamis summary the free oscillations of the japan sea excited by the 1964 niigata and the 1983 japan sea earthquakes are examined adopting a modal approach normal mode solutions with periods longer than 50 min are obtained numerically for the actual bathymetry provided by the grids of 20km in size the eigenvectors or water height distributions obtained show that the modes with longest eigenperiods are determined by the size and depth of the whole japan sea many modes with shorter eigenperiods are regionally trapped in a shallow part such as the continental shelf where the amplitude of eigenvectors is large the niigata earthquake excites mainly the regional modes whereas the japan sea event excites both kinds of modes equally the difference in excitation is attributed to the different water depth at the source the niigata earthquake occurred on a continental shelf about 100 m deep whereas the depth at the source area of the japan sea event is about 2500 m the synthetic tsunami is computed by a superposition of the normal modes the spectra agree well with those observed in the period range of 50 to 210 min

spectral analysis of tsunami waves separation of source and topography effects a new approach is proposed to separate the influence of source and topography in observed tsunami spectra and to reconstruct the initial source spectrum the method assumes a linear tide gauge response to external forcing and is based on comparative analysis of tsunami and background spectra evaluation of the ratio of tsunami to background spectra gives functional characteristics that are invariant of station location and dependent only on the source parameters three events the urup tsunami of december 22 1991 northwest pacific the hokkaido southwest okushiri tsunami of july 12 1993 sea of japan and the shikotan tsunami of october 4 1994 northwest pacific are used as examples of the proposed approach the source spectra reconstructed from the analysis of different tide gauges were found to be in good agreement with each other and with the seismological geodetic and field survey data

inversion of tsunami waveforms for the estimation of heterogeneous fault motion of large submarine earthquakes the 1968 tokachi oki and 1983 japan sea earthquakes waveform inversion of tsunami data provides independent and reliable information on earthquake source processes the propagation effects of tsunamis are accounted for by computing green s functions using a finite difference method and using the known bathymetry which is much better constrained than the seismic velocity structure the observed tsunami waveforms are corrected for the response of the tide gage system by using the results of in situ measurements using green s functions computed from bathymetric data on a 2 5 km grid and the observed waveforms digitized at 1 min intervals the spatial resolution of the faulting heterogeneity by the present method is as small as 30 km this method is applied to the 1968 tokachi oki and 1983 japan sea earthquakes the slip is concentrated at the northwestern part of the fault plane for the 1968 event for the 1983 event the slip on the fault just north of the epicenter is twice that of the other parts these asperity distributions are similar to those inferred from seismic wave analysis however the recovered total seismic moments are smaller the present method is shown to be a useful technique for estimating heterogeneous fault motion especially for historical events with no or poor seismic records and tsunami earthquakes in which the excitations of seismic and tsunami waves are different

depth distribution of coseismic slip along the nankai trough japan from joint inversion of geodetic and tsunami data coseismic slip distribution on the fault plane particularly in the downdip direction associated with large subduction earthquakes can be estimated by joint inversion of geodetic and tsunami data two large earthquakes the 1944 tonankai earthquake mw 8 1 and the 1946 nankaido earthquake mw 8 3 occurred on the nankai trough southwestern japan where the philippine sea plate is subducting beneath the eurasian plate the source areas of these events extended over both land and ocean coseismic crustal movements on land were measured by leveling while those in ocean were recorded as tsunami waveforms on tide gauges the coseismic slip distribution inverted from these data shows that the slip on the shallower part of the fault plane is comparable to that on the deeper parts this indicates that large coseismic slip can occur beneath an accretionary wedge where current seismicity is low the result has implications for other subduction zones having a similar tectonic environment such as for the pacific northwest region of the united states although the possibility of a large earthquake there is still debated should a large subduction earthquake occur in this region coseismic slip on the shallow part could be large and the potential for large tsunamis is high

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

modeling the seismic source and tsunami generation of the december 12 1992 flores island indonesia earthquake on december 12 1992 a large earthquake m s 7 5 occurred just north of flores island indonesia which along with the tsunami it generated killed more than 2 000 people in this study teleseismicp andsh waves as well aspp waves from distances up to 123 are inverted for the orientations and time histories of multiple point sources by repeating the inversion for reasonable values of depth time separation and spatial separation a 2 fault model is developed next the vertical deformation of the seafloor is estimated from this fault model using a detailed bathymetric model linear and nonlinear tsunami propagation models are tested the data consist of a single tide gauge record at palopo 650 km to the north as well as tsunami runup height measurements from flores island and nearby islands assuming a tsunami runup amplification factor of two the two fault model explains the tide gauge record and the tsunami runup heights on most of flores island it cannot however explain the large tsunami runup heights observed near leworahang on hading bay and riangkroko on the northeast peninsula massive coastal slumping was observed at both of these locations a final model which in addition to the two faults includes point sources of large vertical displacement at these two locations explains the observations quite well

can the okhotsk plate be discriminated from the north american plate the plate geometry in northeast asia has been a long standing question with a major issue being whether the sea of okhotsk and northern japanese islands are better regarded as part of the north american plate or as a separate okhotsk plate this question has been difficult to resolve because earthquake slip vectors along the kuril and japan trenches are consistent with either pacific north america or pacific okhotsk plate motion to circumvent this difficulty we also use slip vectors of earthquakes along sakhalin island and the eastern margin of the japan sea and compare them to the predicted eurasia okhotsk and eurasia north america motions for a model with a separate okhotsk plate we invert 10 eurasia okhotsk and 255 pacific okhotsk slip vectors with pacific north america and eurasia north america nuvel 1 data alternatively for a model without an okhotsk plate those eurasia okhotsk and pacific okhotsk data are regarded as eurasia north america and pacific north america data respectively the model with an okhotsk plate fits the data better than one in which this region is treated as part of the north american plate because the improved fit exceeds that expected purely from the additional plate the data indicate that the okhotsk plate can be resolved from the north american plate the motions on the okhotsk plate s boundaries predicted by the best fitting euler vectors are generally consistent with the recent tectonics the eurasia okhotsk pole is located at northernmost sakhalin island and predicts right lateral strike slip motion on the nne striking fault plane of the may 27 1995 neftegorsk earthquake consistent with the centroid moment tensor focal mechanism and the surface faulting along the northern boundary of the okhotsk plate the north america okhotsk euler vector predicts left lateral strike slip consistent with the observed focal mechanisms on the nw boundary of the okhotsk plate the eurasia okhotsk euler vector predicts e w extension discordant with the limited focal mechanisms and geological data this misfit may imply that another plate is necessary west of the magadan region in southeast siberia but this possibility is hard to confirm without further data such as might be obtained from space based geodesy

u pb zircon geochronology of lower jurassic and paleozoic stikinian strata and tertiary intrusions northwestern british columbia new u pb zircon ages are reported from western stikinia devonian and pennsylvanian ages of volcanic rocks at oweegee dome confirm the presence of pre permian strata and with paleozoic and triassic detrital zircons from lower jurassic sandstone they help to demonstrate pre lower jurassic deformation and uplift the absence of pre paleozoic inherited zircon from all samples is consistent with nd sr isotopic data which suggest that stikinia consists mainly of juvenile crust u pb ages for posttectonic intrusions suggest that structures in skeena fold belt in the kinskuch area formed prior to eocene time five ages for felsic volcanic rocks from stratigraphically well constrained upper parts of the hazelton arc are approximately 196 199 ma and suggest near contemporaneity for cessation of volcanism in the areas studied the sinemurian or late sinemurian early pliensbachian ages are older than previously reported u pb and biostratigraphic ages for presumed correlative rocks to the west and westward migra

tsunamis caused by offshore active faults and their deposits abstract this paper reviews the variable features of coastal tsunamis caused by offshore active faults along the eastern margin of the japan sea emjs based on the historical records and modern observations of earthquakes and tsunamis tsunami deposits discovered along the emjs coast were also introduced and categorized depending on their sedimentary environments the offshore active faults which are densely distributed along the emjs and generate tsunamis are originated from the opening of the japan sea back arc basin during the late oligocene to miocene period the magnitudes of the earthquakes that caused large tsunamis in the emjs were under 8 0 the size of the fault plane approximately equal to the tsunami source area was approximately 10 100 and several tens of kilometers in length the slip distance of the reverse type faults was less than 20 m the sedimentary characteristics and depositional processes of tsunami deposits were obtained from deposits in various environments such as coastal lowlands marine terraces coastal lagoons and inland ponds certain unique approaches used to identify tsunami deposits were reviewed such as gravel layers that intercalate inorganic soils and a holocene marine terrace dinoflagellate cysts and foraminiferal linings which are potentially derived from the sea and chemical features e g the ca2 mg2 ratio as indicators of seawater inflow into a coastal lagoon the spatial distribution and recurrence of earthquakes and tsunamis in the emjs were found based on previous paleo tsunami studies the difference between tsunami deposits caused by offshore active faults and those by megathrust earthquakes only manifests itself in the horizontal and vertical directions but not in the sedimentary environments and structures the data thus inferred can be used for the estimation of offshore active fault models and validation of previous tsunami disaster reconstructions in the future

the february 23 1887 tsunami recorded on the ligurian coast western mediterranean the catastrophic ligurian earthquake on february 23 1887 caused significant damage and numerous casualties in northwestern italy and southeastern france the first main shock estimated magnitude of 6 2 6 5 produced tsunami waves observed along 250 km of the ligurian coast from genoa to cannes typical tsunami run up heights were 1 2 m the first wave was found to be negative supporting the assumption that the earthquake was produced by release of stress along an offshore normal fault computed tsunami waveforms are in qualitative agreement with observed run ups unique 1887 tsunami records in genoa and nice harbors were found and analyzed numerical computations of eigenoscillations for the old 1887 genoa harbor were made and found to be in a good agreement with the tsunami observations the dominant observed period of 22 5 min was shown to be related to the fundamental helmholtz mode of the old port long ringing and slow decay of tsunami oscillations in genoa are associated with pumping of wave energy from the external basin several wave trains are revealed in the record that occur at 2 2 5 h intervals they are interpreted as edge waves propagating along the ligurian shelf and reflecting from its borders

investigating the effect of earthquakes on open pit mine slopes abstract this paper develops a database for studying the circumstances under which dynamic loading of earthquake can cause slope failure in deep open pit mines with a long lifetime the database includes 177 open pit mines hit by earthquake and 95 natural slopes and 37 tailing dams which have been failed by earthquakes both earthquake parameters and geomechanical characteristics involved in each case study are investigated from this information the elements playing role in the earthquake triggered failures in natural slopes and tailing dams are identified and used to indicate conditions that may result in earthquake induced failures in open pit mines the result shows that even though the valley shape geometry and absence of the top weathered layer make open pit mines less prone to earthquake induced failures excessive pore pressure in pit slopes still carries the risk of earthquake triggered failures in open pit slopes only limited numbers of open pit mines have been so far exposed to earthquakes with the same parameters as those causing failure in natural slopes and tailing dams that is the response of open pit mines to higher magnitude shallower and closer earthquakes is still unknown studying the earthquakes that have caused failure in other slopes it is concluded that open pit mines may still experience reportable failures if struck by earthquakes with local depth of less than 40 km epicentral distance of less than 100 km and magnitude of greater than 6 0 the necessity of accounting for seismic loading in slope stability analyses and active dewatering for open pit mines located in seismically active areas are also discussed

tsunami squares approach to landslide generated waves application to gongjiafang landslide three gorges reservoir china we have developed a new method named tsunami squares for modeling of landslides and landslide generated waves the approach has the advantages of the previous tsunami ball method for example separate special treatment for dry and wet cells is not needed but obviates the use of millions of individual particles simulations now can be expanded to spatial scales not previously possible the new method accelerates and transports squares of material that are fractured into new squares in such a way as to conserve volume and linear momentum the simulation first generates landslide motion as constrained by direct observation it then computes induced water waves given assumptions about energy and momentum transfer we demonstrated and validated the tsunami squares method by modeling the 2008 three gorges reservoir gongjiafang landslide and river tsunami the landslide s progressive failure the wave generated and its subsequent propagation and run up are well reproduced on a laptop computer tsunami square simulations flexibly handle a wide variety of waves and flows and are excellent techniques for risk estimation

free oscillation of the japan sea excited by earthquakes i observation and wave theoretical approach summary tsunamis caused by the 1964 niigata and the 1983 japan sea earthquakes continued for a long time and appeared to have excited the free oscillation of the almost closed japan sea the spectral analysis of the tide gauge records of those tsunamis shows that there are distinct peaks above the noise level in the frequency range between 0 08 and 0 4mhz finitedifference computations of tsunami for the whole japan sea using a supercomputer reproduce those peaks and confirm that they represent the free oscillation of the japan sea the computation is also made for a region including only the se half of the japan sea with an artificial radiation condition on the n and w boundaries a comparison between the results of these two computations shows the effect of reflections from the nw coast and of the geometry and size of the whole japan sea the simulated spectrum from the se half region almost agrees with that from the whole japan sea for the niigata tsunami indicating that the niigata earthquake excites mainly the regional oscillations for the 1983 japan sea earthquake only a few peaks are reproduced by the computation for the se half region indicating that the free oscillation of the whole japan sea is the essential part of the spectrum for the japan sea event thus the excitation of the free oscillation depends on the earthquake location

phases representing source lengths of tsunami in tide gauge records we identified a phase representing the source length of tsunami s in the tide gauge records around japan this phase was observed at tide stations located in the direction of the long axis of the sources for four large tsunamis 1964 niigata 1968 tokachi oki 1983 nihonkaichubu and 1993 hokkaido nanseioki the phase consists of two continuous crests starting as the initial arrival and has a time length of 15 47 minutes this is the time required to propagate across the source area along the long axis strong evidence that the phase is generated at the source is the good correlation between waveform observed at one side and time inversed waveform at another side the correlation results from the instantaneous generation of the source the source lengths of 74 254 km were obtained under an assumption of sea depths at the sources and verified to coincide with ones within a relative error of 15 that were previously obtained by other methods

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

re examination of the 1940 shakotan oki earthquake and the fault parameters of the earthquakes along the eastern margin of the japan sea abstract the fault model of the 1940 shakotan oki japan earthquake of aug 1 1940 is re examined on the basis of magnitude aftershock distribution and tsunami data from a careful examination of the s p time distribution of aftershocks and comparison of the tide gauge records with numerical simulation of tsunami the fault area is estimated to be 100 km 35 km the slip 1 5 m and the seismic moment 2 4 1027 dyn cm the fault parameters estimated in this study are significantly different from those of fukao and furumoto and do not support their conclusion that this event has a very long duration and is a tsunami earthquake the source process time is estimated to be 30 s which is normal for an earthquake of this size fault parameters of six earthquakes along the eastern margin of the japan sea including the shakotan oki event are compiled and compared with those of inter plate earthquakes in the pacific ocean different relations from well known scaling laws of the inter plate shocks are found for the earthquakes in the japan sea dip angles aspect ratios of the fault and the average stress drop are larger in the japan sea than those of the pacific events although the seismic moment release per unit fault length is the same the differences can be interpreted in terms of a recent plate boundary model in which the young immature boundary between the north american and the eurasian plates lies at the eastern margin of the japan sea they also partially reflect the different excitation of the tsunami in the japan sea and the pacific ocean

age and speciation of iodine in groundwater and mudstones of the horonobe area hokkaido japan implications for the origin and migration of iodine during basin evolution abstract this paper reports the concentration speciation and isotope ratio 129i 127i of iodine from both groundwater and host rocks in the horonobe area northern hokkaido japan to clarify the origin and migration of iodine in sedimentary rocks cretaceous to quaternary sedimentary rocks deposited nearly horizontally in tenpoku basin and in the horonobe area were uplifted above sea level during active tectonics to form folds and faults in the quaternary samples were collected from the pliocene koetoi and late miocene wakkanai formations fms which include diatomaceous and siliceous mudstones the iodine concentration in groundwater up to 270 mol l is significantly higher than that of seawater with the iodine enrichment factor relative to seawater reaching 800 1500 the iodine concentration in the rocks decreases from the koetoi to wakkanai fms suggesting that iodine was released into the water from the rocks of deeper formations the iodine concentration in the rocks is sufficiently high for forming iodine rich groundwater as found in this area x ray absorption near edge structure xanes analysis shows that iodine exists as organic iodine and iodide i in host rocks whereas it exists mainly as i in groundwater the isotope ratio is nearly constant for iodine in the groundwater at 0 11 0 23 10 12 and it is higher for iodine in rocks at 0 29 1 1 10 12 giving iodine ages of 42 60 ma and 7 38 ma respectively some iodine in groundwater must have originated from paleogene and even late cretaceous fms which are also considered as possible sources of oil and gas in view of the old iodine ages of the groundwater the iodine ages of the rocks are older than the depositional ages implying that the rocks adsorbed some iodine from groundwater which was sourced from greater depths the iodine concentration in groundwater decreases with decreasing chlorine concentration due to mixing of iodine rich connate water and meteoric water a likely scenario is that iodine rich brine formed during the long term basin evolution from the cretaceous to quaternary and that this brine was diluted by mixing with meteoric water during uplifting and denudation of the area

moment spectra in a simple model of an earthquake fault the behavior of a simple one dimensional homogeneous deterministic model of an earthquake fault is examined on the timescale of the rupture process the model generates a complex spatial and temporal distribution of events from a frictional instability i measure the frequency spectra of the moment release rate for events of different sizes and observe power laws for the spectra a bend in the spectra of large events is also observed the paper concludes with a discussion of how these results may be relevant to real earthquake faults

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

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

historical tsunami records on russian island the sea of japan in this article we provide data evidencing tsunamis on russian island over the last 700 years reconstructions are developed based on the analyses of peat bog sections on the coast of spokoynaya bay including layers of tsunami sands ancient beach sands under peat were deposited during the final phase of transgression of the medieval warm period we used data on diatoms and benthic foraminifers to identify the marine origin of the sands the grain size compositions of the tsunami deposits were used to determine the sources of material carried by the tsunamis the chronology of historical tsunamis was determined based on the radiocarbon dating of the underlying organic deposits there was a stated difference between the deposition environments during tsunamis and large storms during the goni 2015 and lionrock 2016 typhoons tsunami deposits from 1983 and 1993 were found in the upper part of the sections the inundation of the 1993 tsunami did not exceed 20 m or a height of 0 5 m a m s l 0 3 above high tide the more intensive tsunami of 1983 had a run up of 0 65 m a m s l and penetrated inland from the shoreline up to 40 m sand layer of tsunami 1940 extend in land up to 50 m from the present shoreline evidence of six tsunamis was elicited from the peat bog sections the deposits of which are located 60 m from the modern coastal line the deposits of strong historic tsunamis in the japan sea region in 1833 1741 1614 or 1644 1448 the xiv xv century and 1341 were also identified on russian island their run ups and inundation distances were also determined the strong historic tsunamis appeared to be more intensive than those of the xx century and considering the sea level drop during the little ice age the inundation distances were as large as 250 m

tsunami hazard posed to new zealand by the kermadec and southern new hebrides subduction margins an assessment based on plate boundary kinematics interseismic coupling and historical seismicity we assess the tsunami hazard posed to new zealand by the kermadec and southern new hebrides subduction margins neither of these subduction zones has produced tsunami large enough to cause significant damage in new zealand over the past 150 years of well recorded history however as this time frame is short compared to the recurrence interval for major tsunamigenic earthquakes on many of the earth s subduction zones it should not be assumed that what has been observed so far is representative of the long term for each of these two subduction zones we present plate kinematic and fault locking results from block modelling of earthquake slip vector data and gps velocities the results are used to estimate the current rates of strain accumulation on the plate interfaces where large tsunamigenic earthquakes typically occur we also review data on the larger historical earthquakes that have occurred on these margins as well as the global cmt catalogue of events since 1976 using this information we have developed a set of scenarios for large earthquakes which have been used as initial conditions for the comcot tsunami code to estimate the subsequent tsunami propagation in the southwest pacific and from these the potential impact on new zealand has been evaluated our results demonstrate that there is a significant threat posed to the northland and coromandel regions of new zealand should a large earthquake m w 8 5 occur on the southern or middle regions of the kermadec trench and that a similarly large earthquake on the southern new hebrides trench has the potential to strongly impact on the far northern parts of new zealand close to the southern end of the submarine three kings ridge we propose logic trees for the magnitude frequency parameters of large earthquakes originating on each trench which are intended to form the basis for future probabilistic studies

centroid moment tensor solutions for july september 1993 abstract centroid moment tensor solutions are presented for 186 earthquakes that occurred during the third quarter of 1993 the solutions are obtained using corrections for aspherical earth structure represented by a whole mantle shear velocity model sh8 u4l8 of dziewonski and woodward