holocene tsunamis in the southwestern bering sea russian far east and their tectonic implications the bering sea coast of kamchatka overlies a boundary between the proposed okhotsk and bering blocks or micro plates of the north american plate in the russian far east a history of tsunamis along this coast for the past 4000 yr indicates that the zone north of the kuril kamchatka subduction zone produces tsunamigenic earthquakes every few centuries such a record is consistent with convergence of the proposed okhotsk and bering blocks along the bering sea coast of kamchatka a tsunami deposit from the 1969 m w 7 7 ozernoi earthquake helps us interpret older tsunami deposits newly studied tephra layers from shiveluch volcano as well as previously established marker tephra layers in northern kamchatka provide age control for historic and prehistoric tsunami deposits based on 50 measured sections along 14 shoreline profiles tsunami deposit frequencies in the southwestern bering sea are about five per thousand years for tsunamis generated north of the kuril kamchatka trench

extreme fractionation of 234u238u and 230th234u in spring waters sediments and fossils at the pomme de terre valley southwestern missouri isotopic fractionation as great as 1600 exists between 234u and 238u in spring waters sediments and fossils in the pomme de terre valley southwestern missouri the activity ratios of 234u238u in five springs range from 7 2 to 16 in water which has been discharged for at least the past 30 000 years the anomalies in 234u238u ratio in deep water have potential usefulness in hydrologic investigations in southern missouri clayey units overlying the spring bog sediments of trolinger spring are enriched in 230th relative to their parent 234u by as much as 720 the results indicate that both preferential displacement via alpha recoil ejection and the preferential emplacement via recoiling and physical entrapment are significant processes that are occurring in the geologic environment

on the response of the fjord gullmaren under ice cover an analysis is presented of current salinity and temperature records obtained under ice cover near the mouth of the fjord gullmaren on the sweden skagerrak coast results are compared with an earlier analysis from spring and summer conditions shaffer and djurfeldt 1983 large amplitude vertical fluctuations of the density field of several week periods regularly occurring in the winter season appear to be associated with variations in the baltic sea outflow the local alongshore wind seems to force motions of several day periods in the fjord even under ice cover through interaction with the coastal zone internal seiches prominent features during spring and summer are essentially absent under ice cover which implies that these motions are forced most effectively by the direct action of the local wind on the fjord a method is presented for the determination of significance levels in empirical orthogonal function analysis in the frequency domain

relationship between the maximum extent of tsunami sand and the inundation limit of the 2011 tohoku oki tsunami on the sendai plain japan abstract this paper focuses on the relationship between the maximum extent of sandy tsunami deposits and inundation distance of the 2011 tohoku oki tsunami inundation limits of the tohoku oki tsunami were assessed over seven shore normal transects along the sendai coastal plain inundation distances were found to range from 0 6 to 4 0 km at the maximum extent of the tsunami deposit the sand unit ranged in thicknesses from 0 1 to 4 0 cm the maximum limit of the 0 5 cm thick sand layer extended to over 90 of the inundation distance where the inundation distance was less than 2 5 km this observation is consistent with previous studies that examined characteristics of recent tsunami events that had inundation distances of at least 2 km the maximum limit of the 0 5 cm thick sand layer extended to 3 km 57 76 of the inundation distance where the inundation distance was more than 2 5 km our results are important for estimating paleo tsunami inundation distances based on the landward extent of sand deposits and valuable for the assessment of future tsunami risks in other coastal areas in the world which have been devastated by huge tsunamis in the past

on the low frequency fluctuations in the eastern skagerrak and in gullmaren abstract an analysis is presented of the fluctuations with periods exceeding approximately one day in the coastal zone of the eastern skagerrak and in the fjord gullmaren based primarily on data from a three month field experiment during the spring of 1979 mean flow in the coastal zone consisted of a strong persistent northward flow in a wedge of brackish water near the coast the baltic current superimposed on a weaker general barotropic northward flow three distinct low frequency bands characterized by high degrees of organized motion and different spatial structure are identified in the coastal zone by coherence and phase analysis for a two day or more band alongshore flow appears to be driven locally by the wind topographic vortex modes in the skagerrak may explain highly organized 56 h fluctuations for the 5 6 day band the fluctuations are related more to the wind stress over the northern north sea than to the local one topographic waves propagating eastward along the norwegian trench may comm

the tohoku tsunami of 11 march 2011 the key event to understanding tsunami sedimentation on the coasts of closed bays of the lesser kuril islands the tohoku tsunami of 11 march 2011 manifested in the region of the south kuril islands although as a rule the run up heights in this region did not exceed 3 m in closed bays that were covered with ice before the tsunami the eroding capacity of tsunami waves was aggravated by the ice fragments they carried here mud sheets formed reaching up to 106 m inland the 2012 studies have shown well preserved tsunami deposits evident 1 5 years after the event a comparative analysis of tsunami deposits from the periphery and from the near field area close to the tsunami source was performed this was important for understanding the deposition mechanism during the event as it had different strengths on different shores the difference in run up heights determined the considerable differences in erosion sedimentation distribution of tsunami deposits the formation of sedimentary structures grain size composition and diatom and foraminifera assemblages the sources of the material also varied significantly from each other the material came from offshore in closed bays located in the tsunami source periphery while in the near field region close to the epicenter the most active erosion occurred in the inundation area in the latter area the main sources of sand were beaches and dunes while soil erosion was the source of mud studies of the tohoku tsunami on the coasts of the lesser kuril islands demonstrated that mud layers in the sections of coastal lowlands in closed bays could contain preserved detailed geological records of paleotsunamis even those with a small height run up in the sections of coastal peatlands of closed bays on shikotan island up to 7 9 layers of mud and silty sands were found these can easily be traced for more than 500 m inland the grain size composition of the mud is similar to the deposits of the 2011 tohoku tsunami the marine origin of these deposits is confirmed by the diatom analysis data

predicting head cut erosion and migration in concentrated flows typical of upland areas 1 soil erosion due to head cut development and migration can devastate agricultural lands yet current prediction technology does not address this important erosion process here an analytical model of this erosional phenomenon is presented realistic physically based approximations to the laws governing mass momentum and energy transfer in the neighborhood of the scour hole result in closed form predictive algorithms for the magnitude of the plunge pool erosion and the rate of head cut migration the model introduces a special treatment of nonventilated overfall conditions is limited to homogeneous unbounded soil layers and is validated by available experimental measurements

the internal seiches in gullmar fjord part i dynamics abstract internal seiche motions with period 1 3 days in gullmar fjord are investigated based on mooring data with high vertical and time resolution the period and structure of the internal seiches are well described by a simple analytical three layer model taking into account blocking of the basin water at the sill energy budgets for forcing and damping of the seiches are estimated the internal seiches are forced by direct wind stress on the surface and by internal coastal waves of frequency close to the seiches the latter contribution being a little larger the e folding timescale for the internal seiche damping is approximately equal to the seiche periods which means that the seiches are effectively damped but also that the forcing must be in near resonance in order to maintain the observed seiche motions in the basin water the seiches manifest themselves with large vertical motions and clear upward phase propagation the phase propagation is related with a continuous rather than strictly layer

tsunami geomorphology erosion and deposition from the 15 november 2006 kuril island tsunami the 15 november 2006 kuril earthquake mw 8 1 8 4 and tsunami enabled us to collect a compelling data set of coastal geomorphic change in the kuril islands from 3 months before to 9 and 21 months after the tsunami our pre tsunami and post tsunami surveys of the islands including four topographic profi les measured in 2006 and reoccupied in 2007 allow us the confi dence to attribute many changes to the tsunami in spite of an absence of eyewitness accounts in the central islands areas with low runup 15 m underwent massive erosion that dramatically altered the coastline tsunami deposits roughly corresponded with the extent of tsunami runup and inundation the amount of sediment eroded by the tsunami far outweighed the amount deposited on land in all cases studied the tsunami was dominantly erosive in the kuril islands because the high relief topography of the coastline accelerated tsunami outfl ow

the 1994 shikotan earthquake tsunamis the 1994 shikotan earthquake was one of the greatest earthquakes in recent years with a magnitude of m s 8 0 a tsunami survey was conducted by russian and u s geophysicists from october 16 30 1994 less than two weeks after the earthquake the survey results and a numerical hindcast simulation are reported tsunami focusing effect at locations supposedly sheltered by the island chain is discussed based on the obtained data tsunamis which attacked shikotan island are characterized as long waves the order of 10 20 min wave period with a positive leading wave possible consequences of the positive leading wave form are discussed in relation to the observed minimal destruction of beach vegetation and relatively small transport of marine sediment onto the shore the high quality tide gage record in malokurilskaya bay indicates the occurrence of a 53 cm subsidence at the site

tsunamigenic earthquakes past and present milestones we review a number of events which taken individually have significantly affected our understanding of the generation of tsunamis by earthquake sources and our efforts at mitigating their hazards notably through the development of warning algorithms starting with the 1700 cascadia earthquake we examine how significant tsunamis have changed our views in fields as diverse as seismotectonics the diversity of earthquake cycles the development of warning algorithms the response of communities at risk to warnings and their education the latter being either formal or rooted in ancestral heritage we discuss in detail lessons from the 2004 sumatra disasters and review the performance of warning centers and the response of affected populations during the nine significant tsunamis which have taken place since 2004

field survey and geological effects of the 15 november 2006 kuril tsunami in the middle kuril islands the near field expression of the tsunami produced by the 15 november 2006 kuril earthquake mw 8 1 8 4 in the middle kuril islands russia including runup of up to 20 m remained unknown until we conducted a post tsunami survey in the summer of 2007 because the earthquake occurred between summer field expeditions in 2006 and 2007 we have observations topographic profiles and photographs from three months before and nine months after the tsunami we thoroughly surveyed portions of the islands of simushir and matua and also did surveys on parts of ketoi yankicha ryponkicha and rasshua tsunami runup in the near field of the middle kuril islands over a distance of about 200 km averaged 10 m over 130 locations surveyed and was typically between 5 and 15 m local topography strongly affected inundation and somewhat affected runup higher runup generally occurred along steep protruding headlands whereas longer inundation distances occurred on lower flatter coastal plains sediment transport was ubiquitous where sediment was available deposit grain size was typically sand but ranged from mud to large boulders wherever there were sandy beaches a more or less continuous sand sheet was present on the coastal plain erosion was extensive often more extensive than deposition in both space and volume especially in areas with runup of more than 10 m the tsunami eroded the beach landward stripped vegetation created scours and trim lines cut through ridges and plucked rocks out of the coastal plain

independent active microplate tectonics of northeast asia from gps velocities and block modeling 1 independent okhotsk and amurian microplate motions are tested using velocities from 123 gps sites 80 from within the proposed okh and amu plate boundaries used to constrain the plate kinematics of northeast asia a block modeling approach is used to incorporate both rigid block rotation and near boundary elastic strain accumulation effects in a formal inversion of the gps velocities models include scenarios with and without independent okh and amu plate motion our modeling favors scenarios with independent okh and amu motion based on the application of f test statistics the independent okh plate rotates 0 231 deg myr clockwise with respect to north america about a pole located north of sakhalin the modeled amu plate rotates 0 298 deg myr counterclockwise with respect to nam about a pole located west of the magadan region the plate motion parameters of the independent plates are consistent with the kinematics inferred from earthquake focal mechanism solutions along their boundaries

tsunami sources of the november 2006 and january 2007 great kuril earthquakes abstract along the northern kuril trench a great interplate earthquake occurred in november 2006 followed by an outer rise normal fault event in january 2007 surface wave magnitudes m s 7 8 and 8 2 indicate that the 2007 event was larger while the global cmt solutions m w 8 3 and 8 1 indicate that the 2006 event was larger tsunamis from both events were recorded at tide gauge stations in japan russia and the united states as well as deep ocean assessment and reporting of tsunamis dart systems and cabled tsunami sensors installed on deep ocean bottom inversion of 52 tsunami waveforms indicates that the 2006 tsunami source was about 200 km long extending from the epicenter to northeast the largest slips of 4 7 m are estimated on the northeastern subfaults for the 2007 event inversion of 32 waveforms shows that the tsunami source was about 120 km long with the largest slip of 3 5 m on the northeastern subfault the agreements between the observed and synthetic tsunami waveforms are generally good for both events not only within the inversion time windows but also for the later phases which were not used in inversions the slip distributions yield the seismic moment of m w 8 1 for the 2006 event and m w 7 9 for the 2007 event the seismic moment of the 2006 event was larger than the 2007 event from comparison of tsunami data regardless of fault model

the great 2006 and 2007 kuril earthquakes forearc segmentation and seismic activity of the central kuril islands region we present a structural study of the central kuril islands forearc region where the great megathrust tsunamigenic earthquake m w 8 3 occurred on november 15 2006 based on new bathymetry and seismic profiles obtained during two research cruises of r v akademik lavrentiev in 2005 and 2006 ten crustal segments with along arc length ranging from 30 to 100 km separated by ns and nw trending transcurrent faults were identified within the forearc region the transcurrent faults may serve as barriers impeding stress transfer between the neighboring segments so that stress accumulated within separate forearc segments is usually released by earthquakes of moderate to strong magnitudes however the great november 15 2006 earthquake ruptured seven of the crustal segments probably following a 226 year gap since the last great earthquake in 1780 the geographic extent of earthquake rupture zones aftershock areas and earthquake clusters correlate well with forearc crustal segments identified using the geophysical data based on segmented structure of the central kuril islands forearc region we consider and discuss three scenarios of a great earthquake occurrence within this area although the margin is segmented we suggest that a rupture could occupy the entire seismic gap with a total length of about 500 km in such a case the earthquake magnitude m w might exceed 8 5 and such an event might generate tsunami waves significantly exceeding in height to those produced by the great 2006 2007 kuril earthquakes

baroclinic wave drag from two closely spaced sills in a narrow fjord as inferred from basin water mixing 1 the dynamics of the entrance to the ringdalsfjord idefjord at the swedish norwegian border is described for the first time a 1 month long high resolved data set shows that the mixing rate is extremely high in the basin water between the two sills at bjallvarpet and svinesund and that the accompanying horizontal mean buoyancy flux is about 25 mw m 2 during two periods in the observations the density decrease rate d dt below 17 m depth was estimated to be 0 90 and 1 20 kg m 3 d 1 respectively our observations support the idea that the tide is subjected to baroclinic wave drag due to generation of internal tides at sills when a densimetric froude number based on tidal speed and basin stratification is subcritical for supercritical values of the froude number basin stratification becomes unimportant and the tide is subjected to large scale topographic drag with jets developing on the lee side of the sills the total energy loss due to baroclinic wave drag and large scale topographic drag during the two periods are 268 and 198 kw respectively all power supplied to the internal tides and 1 6 of the power supplied to the jets is assumed to sustain the turbulence in the basin water beneath the depths of the sills with a flux richardson number of 0 06 determined from investigations in many fjord basins we find that a process based mixing model explains the observed mixing between the sills to within 90

large trench parallel gravity variations predict seismogenic behavior in subduction zones we demonstrate that great earthquakes occur predominantly in regions with a strongly negative trench parallel gravity anomaly tpga whereas regions with strongly positive tpga are relatively aseismic these observations suggest that over time scales up to at least 1 million years spatial variations of seismogenic behavior within a given subduction zone are stationary and linked to the geological structure of the fore arc the correlations we observe are consistent with a model in which spatial variations in frictional properties on the plate interface control trench parellel variations in fore arc topography gravity and seismogenic behavior

spatial variability of diapycnal mixing and turbulent dissipation rates in a stagnant fjord basin two microstructure profilers two ships and four moorings with acoustic doppler current profilers and conductivity temperature loggers were used in an intensive effort to map the spatial and temporal variations of vertical mixing in the stagnant deep basin of gullmar fjord sweden during three days in the beginning of august 2001 a continuous time series of turbulent kinetic energy dissipation profiles was obtained with one microstructure profiler at a fixed position near the deepest part of the fjord during the same period the other microstructure profiler was used to obtain six sections of dissipation through the length of the basin two moorings were deployed in the fjord basin for one month from the end of july to the end of august the mapping of dissipation rates reveals that the dissipation in the deep basin is confined to areas just inside the sill more than 77 of the dissipation in the fjord basin happens above the sloping bottoms closest to the sill

resistance to barotropic tidal flow in straits by baroclinic wave drag energy transfer from barotropic tides to baroclinic motions may take place at the ends of straits connecting stratified basins implying generation of internal waves propagating into the basins different aspects of this have been described in the literature including quantification of the energy transfer studies of the resulting internal tides and the relationship to diapycnal mixing in the basins however the accompanying resistance to oscillatory barotropic strait flows by so called baroclinic wave drag has not been implemented earlier in models for strait flow in the present paper a formulation for the instantaneous baroclinic wave drag force is suggested this leads to a linear relationship between the strait flow and the synoptic sea level difference between the adjacent basins the model is used to study tidal response in land locked basins the response is computed for three fjords where the resistance to the barotropic flow comes essentially from baroclinic wave drag it is concluded that the strait flow model handles baroclinic wave drag in a satisfactory way since the observed responses are well predicted by the model baroclinic wave drag should provide the major resistance to surface tides in the deep ocean which indicates its importance in a wider context several mechanisms may cause resistance to barotropic flow in straits and channels friction against the sea bed is certainly the most commonly considered type of flow resistance it is often modeled with a quadratic relationship between the bottom stress and the barotropic velocity using a drag coefficient to characterize the frictional properties of the sea bed another type of flow resistance is due to large scale longitudinal variations of the vertical cross sectional area of the strait causing contraction followed by expansion of the flow this class of flow resistance appropriately termed barotropic form drag includes the resistance caused by contraction expansion induced by the ends of straits having smaller vertical cross sectional areas than the adjacent basins in the cases of frictional drag and largescale form drag barotropic energy is transferred to turbulence in the bottom boundary layer in the strait and to large scale eddies in the expanding current downstream of the strait respectively the present paper however draws attention to a third class of resistance operating on oscillating barotropic strait flow it is due to generation of baroclinic internal waves in the adjacent stratified basins by the ends of the strait and is

radioelements radiogenic helium and age relationships for groundwaters from the granites at stripa sweden abstract the solution of radioelements and radiogenic 4he by groundwaters in fractured rocks is dependent upon the radioelement distribution in the rock matrix and the extent of the rock water interface the 234 u 238 u activity ratio and the dissolved u rn and he contents of such groundwaters respond to changes in the flow regime with time although 234 u 238 u activity ratios change with groundwater residence time as a consequence of 234th recoil induced solution of 234u the activity ratio is strongly influenced by the u distribution within fractures by the extent of the rock water interface and by the amount of 238u in solution a model for the quantitative evaluation of these effects is presented groundwaters from depths up to 880 m in the stripa granite have variable dissolved uranium contents and 234 u 238 u activity ratios the uranium geochemistry is primarily determined by variations in flow path rather than by groundwater age dissolved radiogenic 4he in the groundwaters increases with their depth of origin and is dependent upon the u content of the granite and upon its fracture porosity it increases with groundwater residence time but movement of 4he by diffusion and transport processes make the actual groundwater age indeterminate

hydrothermal alteration processes at midocean ridges experimental and theoretical constraints from ca and sr exchange reactions and sr isotopic ratios diabase and basalt were reacted with na ca k cl fluids of seawater chlorinity at 375 425 c 375 400 bars and fluid rock mass ratios of 0 5 1 0 to assess the role of basalt chemistry and texture on sr and ca mobility during high temperature hydrothermal alteration an additional experiment utilizing an 84sr spiked fluid was performed to help quantify reaction rates of processes affecting sr mobility the experimental results help to constrain reaction processes responsible for the chemistry of hot spring fluids at midocean ridges alteration of basalt and diabase is characterized by formation of tremolite actinolite smectite chlorite and clinozoisitic epidote smectite chlorite respectively diabase alteration produced dissolved sr ca ratios similar to those observed for ridge crest hot spring fluids whereas alteration of a mostly crystalline basalt produced significantly lower ratios this observation supports the premise that the sr ca ratios observed in vent fluids may be produced during deep seated reaction of the hydrothermal fluids with diabase dikes and or gabbro at relatively low fluid rock ratios and suggests that hydrothermal alteration of primary igneous minerals at relatively high temperatures 400 c leads to formation of a mineral with low dsr ca possibly hydrothermal plagioclase results of the 84sr spiked experiment indicated that only 4 of the sr in basalt was mobilized after 800 hours of reaction despite the fact that b and li were nearly quantitatively leached it is thus suggested that b and li are good indicators of the amount of fresh rock encountered by fluids while sr concentration and isotopic data can be used to estimate the degree of alteration that the sr bearing primary minerals have undergone the degree of alteration of subsurface reservoirs may be estimated by dividing the fluid rock ratio obtained for highly mobile elements by the fluid rock ratio obtained from path integrated sr isotope and concentration data based on this method for example it can be estimated that only 5 of the primary sr bearing minerals encountered by fluids in the subsurface at epr 21 n are actually converted to secondary phases

coastal sedimentation associated with the december 12th 1992 tsunami in flores indonesia this paper presents the result of a detailed granulometric investigation of sediments deposited by a modern tsunami the 1992 tsunami in flores indonesia eyewitness accounts indicate that sediments were deposited upon coastal lowlands over wide areas as a result of the tsunami inundation distinctive vertical and lateral variations in particle size composition are characteristic features of the tsunami deposits and these are intimately related to sedimentary processes associated with flood inundation the geomorphological and sedimentary evidence is used here to establish a preliminary model of tsunami sedimentation this information is believed to be of great value in understanding sedimentary processes associated with tsunami flooding and in the interpretation of palaeo tsunami deposits

from asia to the americas by boat paleogeography paleoecology and stemmed points of the northwest pacific abstract rising postglacial seas have flooded the world s continental shelves limiting our ability to reconstruct human migrations the history of settlement along pleistocene coastlines and the antiquity of coastal shell middens this includes the southern coast of beringia where dramatic landscape changes make it difficult to test the coastal migration theory which proposes that upper paleolithic peoples followed pacific shorelines from northeast asia to the americas to help overcome such problems this paper discusses the paleogeography and paleoecology of late pleistocene north pacific coastlines then examines pacific rim technologies for possible evidence of a coastal migration by 16 000 1000 cal bp the pacific rim was a plausible migration route entirely at sea level with rich and diverse resources from both marine and terrestrial ecosystems within this vast region scattered late pleistocene technological assemblages that include leaf shaped bifaces and stemmed projectile points found in coastal or peri coastal sites from japan and kamchatka to western north america and much of south america may support the idea that a coastal migration contributed to the peopling of the americas

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

a great earthquake doublet and seismic stress transfer cycle in the central kuril islands temporal variations of the frictional resistance on subduction zone plate boundary faults associated with the stick slip cycle of large interplate earthquakes are thought to modulate the stress regime and earthquake activity within the subducting oceanic plate here we report on two great earthquakes that occurred near the kuril islands which shed light on this process and demonstrate the enhanced seismic hazard accompanying triggered faulting on 15 november 2006 an event of moment magnitude 8 3 ruptured the shallow dipping plate boundary along which the pacific plate descends beneath the central kuril arc the thrust ruptured a seismic gap that previously had uncertain seismogenic potential although the earlier occurrence of outer rise compressional events had suggested the presence of frictional resistance within minutes of this large underthrusting event intraplate extensional earthquakes commenced in the outer rise region seaward of the kuril trench and on 13 january 2007 an event of moment magnitude 8 1 ruptured a normal fault extending through the upper portion of the pacific plate producing one of the largest recorded shallow extensional earthquakes this energetic earthquake sequence demonstrates the stress transfer process within the subducting lithosphere and the distinct rupture characteristics of these great earthquakes illuminate differences in seismogenic properties and seismic hazard of such interplate and intraplate faults

effects of landforms on tsunami flow in the plains of banda aceh indonesia and nam khem thailand abstract mapping on high resolution satellite images and in the field shows differences in landforms and characteristics of tsunami flow on two contrasting coastal plains following the giant earthquake on december 26 2004 the plain of banda aceh on the northern tip of the sumatra island indonesia and the nam khem plain in the andaman sea coast of thailand the landforms of the banda aceh coastal plain are characterized as deltaic lowland with tidal plains in the western and central parts and strand plain with beach ridges in the eastern part the run up tsunami flow invaded areas about 3 4 km from the coast strong tsunami flow severely damaged the tidal plain and the landforms along the coast except coastal dunes in the east most of the landforms except sand dunes along the coast had almost no effect on the protection against the tsunami but the higher micro landforms such as beach ridges and natural levees prevented the flow of the tsunami from its invasion into the inland near the end of tsunami inundation the tsunami inundation spread out over the entire nam khem coastal plain with an average depth of 4 5 m the direction of run up flow was almost perpendicular to the coastline whereas backwash flow directions were controlled by topography backwash flow was concentrated in the lower portions of the plain for example in small stream channels wedge shaped channels in the lower parts of the streams were formed due to the concentration of backwash flow the existence of the swales between parallel beach ridges corresponds well with the distribution of thick tsunami deposits coastal erosion of the plain was caused by the direct attack of tsunami waves and the lower reaches of small rivers were eroded by strong backwash flow

tsunami sedimentation associated with the 1923 kamchatka earthquake abstract the kuril kamchatka region is notorious for the occurrence of earthquake tsunamis and historical documents show that they have caused repeatedly considerable damage since the 1750s the great tsunami generated in april 1923 around the northern kamchatka trench flooded the coast of ust kamchatsk depositing a thin sand layer which is traceable up to 3 km or more inland beyond the present coastline local government documents indicate that the 1923 tsunami flooded low lying coastal areas covered by thick snow the unusual process of tsunami run up without loss of tractive load is interpreted to have resulted from the smoothing of fields by the ice covered surface we conclude that the tsunami flooded snowfields and deposited an extensive sheet of sand a mixture of snow and seawater flooded over the area and caused damage to vegetation

partition of energy loss from the barotropic tide in fjords abstract as the barotropic tide propagates into and out of a fjord it loses energy to friction internal tides and high frequency internal waves estimates of these losses for three british columbia fjords using current meter data indicate that friction is negligible in two but important in one inlet the length and depth of the sill determines the importance of friction when friction is not important most of the energy lost goes into the internal tide but less than half of this energy propagates away from the sill simple models of the internal tide predict the correct energy transfer to satisfy an energy budget but do not agree with observations of the internal tidal energy flux away from the sill energy loss from the internal tide in or near the generation zone would account for the discrepancy the energy flux of the high frequency internal wave field is relatively small about 2 of the energy lost

subduction zone paleoseismology along the pacific coast of northeast japan progress and remaining problems abstract this paper reviews recent progress in tsunami geology and the history of coastal uplift subsidence along the pacific coasts of hokkaido and tohoku facing the kuril and japan trenches respectively in the last 20 years research by tsunami geologists in northeast japan has focused on extending the record of tsunamis beyond the range of historical documents in the region which span too little time to reveal much of the earthquake history over the last millennia along the coast of hokkaido recurrent sandy deposits are evidence of historical and prehistoric large tsunamis at kiritappu marsh for example at least 15 identified tsunami deposits occurred between 200 and 6 000 years ago the spatial distribution of the most recent prehistoric tsunami deposit that of the so called 17th century earthquake and tsunami exceeds historical and recent tsunami inundations in eastern hokkaido numerical simulations of this event require a multi segment fault model with variable slip mw 8 8 encompassing both the tokachi oki and nemuro oki regions to reproduce the observed deposit distribution in eastern hokkaido the recurrence interval of such multi segment earthquakes along the southern kuril trench is estimated to be 100 800 years based on tephrochronological and radiocarbon evidence tsunami deposits are also associated with historical earthquakes in 1843 and 1894 in eastern hokkaido and with the 1640 komagatake eruption in western hokkaido the 17th century earthquake probably triggered postseismic coastal deformation diatom based transfer functions suggest rapid subsidence before the event and gradual uplift afterward and historical volcanic ash layers indicate that gradual postseismic uplift occurred over decades a simple dislocation model can explain such gradual uplift as an aseismic fault extension after the 17th century event in the tohoku region a tsunami deposit associated with the 869 jogan earthquake has been identified and the inundation area of this event has been constrained based on the lateral extent of the tsunami deposit and its stratigraphic position beneath the historical to a tephra 915 ce land level changes at odaka fukushima prefecture associated with the jogan event have been estimated based on changes of fossil diatom assemblages below and above the tsunami deposit numerical simulations based on geological evidence and observations of the 2011 tohoku tsunami deposit suggest that the jogan event was a plate boundary rupture at least 200 km long along the japan trench mw 8 3 8 6 the 1454 kyotoku tsunami is also considered to have been generated by a rupture area including the miyagi oki region part of the jogan rupture it remains unclear whether the 869 1454 and 2011 tsunamis were similar in size and source if they were the recurrence intervals of such events near sendai are less than 600 years and more regular than those for multi segment earthquakes along the kuril trench

propagation of the storegga tsunami into ice free lakes along the southern shores of the barents sea this paper is part of anders romundset s doctoral thesis which is available in munin at http hdl handle net 10037 2703

an amalgamated meter thick sedimentary package enabled by the 2011 tohoku tsunami in el garrapatero galapagos islands abstract tsunamis and storms instigate sedimentological and geomorphological changes to the coastal system both long term and ephemeral to accurately predict future coastal hazards one must identify the records that are generated by the processes associated with these hazards and recognize what will be preserved using eyewitness accounts photographs and sedimentology this study documents pre and post tsunami conditions and constrains the timing and process of depositional events during and following the 11 march 2011 tohoku tsunami in the coastal system at el garrapatero galapagos islands while the tsunami acted as both an erosional and depositional agent the thick fan like sand sheet in el garrapatero was primarily emplaced by overwash deposition during high tide from swell waves occurring between 19 25 march and 17 22 april 2011 the swell waves were only able to access the terrestrial coastal system via a channel carved by the 2011 tohoku tsunami through the barrier sand dune this combined deposit could result in an overestimation of the hazard if interpreted to be the result of only one event either tsunami or wind generated waves an analogous sand layer younger than 1390 1530 cal yr bp may record a similar prior event

an extension of the e m0 tsunami earthquake discriminant θ to regional distances the slowness parameter the logarithmic ratio of the estimated energy radiated by an earthquake ee to its moment m0 is a robust indicator of tsunami earthquakes when calculated from waveforms recorded at teleseismic epicentral distances 35 80 however values calculated from waveforms recorded at regional epicentral distances 5 35 are unreliable this is because the necessary use of a differentiable traveltime t curve smoothed through transition zone caustic distances leads to the systematic overestimation of ee and hence of for waveforms recorded at or near these distances using a data set comprised of 67 global oceanic dip slip earthquakes occurring in the last 20 yr that includes six recognized tsunami earthquakes we empirically develop a correction for waveforms recorded at regional epicentral distances application of the correction to our data set allows the recovery of values fully consistent with those calculated using only teleseismic waveforms the incorporation of this correction into existing tsunami warning algorithms has the potential to significantly advance near field warning efforts

paleotsunamis from the central kuril islands segment of the japan kuril kamchatka subduction zone abstract paleotsunami records from the central kuril island segment of the japan kuril kamchatka subduction zone indicate that the region has been frequently inundated by tsunamis as many as 20 22 tsunami deposits are recognized on matua island for the past 3300 yr with an average tsunami recurrence interval of 150 yr and 34 36 tsunami deposits are evident on simushir island for the past 2350 yr with an average recurrence of 65 yr these intervals are short but comparable to other segments of the japan kuril kamchatka subduction zone results from all survey locations reveal shortening recurrence intervals toward the present especially for the last 600 yr indicating a possible preservation bias on simushir tsunamis at least 11 m higher than the modern tsunamis in 2006 and 2007 occurred every 300 yr on average on matua tsunamis with slightly farther inundation than the 2006 and 2007 tsunamis occurred every 215 yr while those with at least 100 m farther inland inundation occur every 750 yr our paleotsunami record almost certainly includes tsunamis that are not from great subduction zone earthquakes in the central kuril segment we expect the matua record includes volcanic tsunamis and the simushir record includes tsunamis from the southern kuril segment

uranium geochemistry in groundwater from tertiary sediments abstract dissolved u concentrations and activity ratios ars of the u isotopes in the 238 u decay series were measured in ground and surface waters as part of an investigation to delineate the water quality in a proposed uranium mining area of northwest nebraska in oxidizing groundwaters from 67 wells completed in the tertiary sediments increasing u concentrations in the direction of groundwater flow generally were associated with a maturation of the formation water as evidenced by evolutionary trends in major ion character the increased u levels probably are associated with leaching as shown by the positive correlation between u concentrations and total dissolved solids tds r 0 83 the inverse relationships between tds and u ars r 0 73 and u levels and ars r 0 72 indicate that the decay of excess u 234 is related to maturation of the formation water and to sediment leaching along the flowpath the data are described by a model which incorporates etching decay and recoil and suggests that aquifer residence time can be estimated from the tds level the levels of soluble u in a reducing uraniferous hydrogeologic unit near crawford nebraska are affected by the proximity of the sample collection to ore in groundwater samples having similar chemistries na so 4 cl type similar ehs and collected from a close knit pattern u concentrations ranged from 0 01 to 2 037 g l 1 and ars ranged from 0 75 to 12 6 this high variability in u levels and ars is indicative of uranium ore in small areal studies where low ars almost always are associated with high u concentrations

assessing historical rate changes in global tsunami occurrence summary the global catalogue of tsunami events is examined to determine if transient variations in tsunami rates are consistent with a poisson process commonly assumed for tsunami hazard assessments the primary data analyzed are tsunamis with maximum sizes 1m the record of these tsunamis appears to be complete since approximately 1890 a secondary data set of tsunamis 0 1m is also analyzed that appears to be complete since approximately 1960 various kernel density estimates used to determine the rate distribution with time indicate a prominent rate change in global tsunamis during the mid 1990s less prominent rate changes occur in the early and mid 20th century to determine whether these rate fluctuations are anomalous the distribution of annual event numbers for the tsunami catalogue is compared to poisson and negative binomial distributions the latter of which includes the effects of temporal clustering compared to a poisson distribution the negative binomial distribution model provides a consistent fit to tsunami event numbers for the 1m data set but the poisson null hypothesis cannot be falsified for the shorter duration 0 1m data set temporal clustering of tsunami sources is also indicated by the distribution of interevent times for both data sets tsunami event clusters consist only of two to four events in contrast to protracted sequences of earthquakes that make up foreshock main shock aftershock sequences from past studies of seismicity it is likely that there is a physical triggering mechanism responsible for events within the tsunami source mini clusters in conclusion prominent transient rate increases in the occurrence of global tsunamis appear to be caused by temporal grouping of geographically distinct mini clusters in addition to the random preferential location of global m 7 earthquakes along offshore fault zones

observed damping of barotropic seiches through baroclinic wave drag in the gullmar fjord baroclinic wave drag due to internal wave generation at steep topography is shown to be a mechanism that effectively subdues barotropic seiches in fjords a two layer model for a fjord with a sill at the mouth is applied to the gullmar fjord sweden the damping of the fundamental seiche mode observed from sea level records is well predicted by the model this includes the observed seasonal variation in damping due to the corresponding variation in vertical stratification it is shown that ordinary bottom friction should contribute less than 1 to the damping in this fjord simultaneous current records from different depths obtained on the slope of the sill in the fjord are analyzed spectra of all records show a significant energy peak at the seiche frequency the vertical variation of the phase of the current at this frequency shows that the motion is essentially baroclinic