the use of multivariate statistics to elucidate patterns of floodplain sedimentation at different spatial scales floodplains are depositional features of riverine landscapes that display complex sedimentation patterns that are amenable to multi scale approaches we examined sedimentation in the lower balonne floodplain queensland australia at three different spatial scales the channel 103 km floodplain process zone 10 km and geomorphic unit 102 m scales and compared scale related patterns evident from stratigraphy with those evident from quantitative multivariate analysis three stratigraphic sequences were found in the lower balonne floodplain generally fining upward episodic fining upward and mud dominated stratigraphical analysis revealed the detailed character of sedimentary sequences embedded within the scale patterns derived from multivariate analysis multivariate statistical analyses of a range of textural and geochemical data revealed different patterns of floodplain sedimentation at each scale at the channel scale sediment texture and geochemistry were more heterogeneous in the culgoa river than in briarie creek at the floodplain process zone scale clear patterns of sediment texture and geochemistry were observed along the upper mid and lower floodplain process zones of briarie creek but not along the culgoa river at the geomorphic unit scale clear patterns of sediment texture and geochemistry were observed among the bank buried channel and flat floodplain units of the culgoa river but were not as clear in briarie creek recognition of rivers as hierarchically organized systems is an emerging paradigm in river science our study supports this paradigm by demonstrating that different sedimentation patterns occur at different scales to reveal a hierarchically organized floodplain environment copyright 2006 john wiley sons ltd

a large mammal site in a meandering fluvial context fonelas p 1 late pliocene guadix basin spain sedimentological keys for its paleoenvironmental reconstruction abstract the fonelas p 1 large mammal site is located stratigraphically in the youngest unit late pliocene pleistocene of the endorheic fill of the guadix basin betic cordillera at the site location this unit is represented by fluvial sediments of the basin s axial drainage system the general succession of the site consists of stacked fining upward cycles basically beginning with gravel and or sand filling a meandering channel and concluding with floodplain mud and carbonate each of the cycles is made up of four facies associations determined by sedimentological analysis of the sections measured in the paleontological excavation of the site these associations correspond to sedimentation in definite areas of the fluvial system a filling of a sinuous channel at maximum activity b levee deposits c abandoned channel and d floodplain in the cycle in which the site is located there is a fifth association e where the main fossil concentration is found fonelas p 1 this is a facies bioturbated by mammals moving over sediments of the abandoned channel association c by space time reconstruction of the fluvial environments we can infer that the morphological depression caused by a meander abandonment due to chute cut off was used as a hyena den the animal settlement ended when overflow from the laterally migrating active channel began to bury the abandoned meander with floodplain sediments

stratigraphic architecture and alluvial geoarchaeology of an ephemeral fluvial infilling climatic versus anthropogenic factors controlling the holocene fluvial evolution in southeastern spain drylands abstract two stages of depositional high discharge fluvial environments are recorded in the infilling of a rock shelter in a canyon of the segura river namely 1 first stage aggradational alluvial gravels in the lower part interpreted as braided channel bars seventh millennium to 2030 cal bc and 2 second stage slackwater flood deposits in the upper part between 2030 cal bc and after 900 ad during a stage of main channel incision reconstructed flood discharges for the second stage were a minimum of 700 m 3 s extreme palaeofloods that inundated the cave from the canyon inlet were successively higher and are correlated to quick rising flash floods the characteristics of cultural remains preserved by flood deposits reveal long periods of human cave occupation and passage through the canyon without extreme floods occurring these long periods of low discharge fluvial flow punctuated by catastrophic flash floods are linked to a torrential fluvial regime the torrential regime is the current hydrologic and climatic scenario in the streams of semi arid southeastern spain it is discusses the climatic versus anthropogenic factors affecting the fluvial development we conclude that the archaeo fluvial record of the pozo rock shelter indicates that the present day semi arid conditions of the southeastern spain drylands extend back to circa 4000 yr bp methodologically the combination of fluvial palaeohydrology and geoarchaeology appears to be a robust tool to reconstruct long term holocene climate changes

channel migration patterns and related sequences in some alluvial fan systems abstract the pendular displacement of a channel system consisting of an area of higher channel density trunk channel zone on both sides of which channel density progressively decreases secondary channel zone can under favourable subsidence conditions lead to the development of alluvial fans characteristic sequences are found in these fans depending on their position in the sedimentary body a marginal position in the fan is thus recognized by the superposition of fining and thinning upwards ftu cycles the upper part of which is made up of important thicknesses of overbank fines all the backsets of bars dipping in the same direction towards the centre of the cone on the other hand a central position is characterized by a higher number of ftu cycles which are incomplete due to erosion of the upper parts corresponding to the higher concentration of overbank fines and the backsets in each cycle dip alternately in opposite directions the displacement of the channel system in a constant direction may be caused by the preferential accumulation of bars on one of the banks of the channel the change in migratory direction giving rise to the pendular movement is caused by the trunk channel reaching the basin margin or the sedimentation area of an adjoining fan palaeogeographic reconstructions of fans using this technique contribute to the analysis of ancient basins small radius fans with a high sweep angle as are characteristic of basin margins subjected to a low sediment supply subsidence ratio ss sb whereas large radius fans with a low as characterize periods with a high ss sb ratio on the basin margin this model can be applied in economic geology studies as the location of an ancient cone permits delimitation of the axial strip with a higher proportion of coarse highly porous channelled facies and the marginal sectors where thick layers of less porous overbank fines are intercalated we here present the example of the alluvial fans in the guadix fm betic cordillera spain which lie on a basin margin ese where the ss s b ratio increased progressively throughout the lower pliocene the detailed analysis of palaeocurrents on the basis of different criteria throughout the arroyo de gor section helps to locate more precisely and confirm the palaeogeographical distribution of the pliocene cone as deduced from sequential analysis

the role of diagenesis and depositional facies on pore system evolution in a triassic outcrop analogue se spain abstract this study aims at unravelling the diagenetic history and its effect on the pore system evolution of the triassic redbeds exposed in se spain tibem 1 an outcrop analogue of the tagi trias argilo greseux inferieur reservoir berkine ghadames basin algeria similar climatic base level and tectonic conditions of aforementioned alluvial formations developed analogue fluvial facies stacking patterns furthermore interplay of similar detrital composition and depositional facies in both formations resulted in analogue early diagenetic features petrographic observations indicate lithic subarkosic floodplain facies and subarkosic braidplain facies compositions which are considered suitable frameworks for potential reservoir rocks primary porosity is mainly reduced during early diagenesis through moderate mechanical compaction and formation of k feldspar overgrowth gypsum dolomite and phyllosilicate cements early mesodiagenesis is testified by low chemical compaction and quartz cementation telodiagenetic calcite filling fractures and k feldspar dissolution determined the final configuration of analysed sandstones mercury injection capillary pressure technique reveals overbank deposits in the floodplain as the least suitable potential reservoirs because of their lowest open porosity op k k 95 md and greater thickness and lateral continuity so being considered the best potential reservoir the accurate estimation of tibem microscale attributes can provide important input for appraisal and enhanced oil recovery performance in tagi and in others reservoirs consisting on similar fluvial sandy facies

ground motion characteristics and nonlinear soil response observed by donet1 seafloor observation network during the 2016 southeast off mie japan earthquakeground motion characteristics and nonlinear soil response observed by donet1

scattering of teleseismic p waves by the japan trench a significant effect of reverberation in the seawater column abstract we detected a scattered wave train in data from the high sensitivity seismograph network in japan hi net following the arrival of the near vertically incident p wave generated by the 2009 earthquake mw 7 8 off the south island of new zealand the scattered wave train represented predominantly vertical ground motion at a period of 20 to 50 s and with an apparent velocity of 3 5 km s it propagated cylindrically westward through the kanto area of central japan array analysis showed that the scattered wave train developed beneath the pacific ocean near the boso triple junction southeast of the kanto area a 3d finite difference simulation of seismic wave propagation using a high resolution model incorporating subsurface structure topography and bathymetry revealed that the strong scattered waves that were generated along the japan trench and propagated normal to the trench axis represented multiple reverberations of seismic waves between the seafloor and the pacific plate boundary in addition strong reverberation of acoustic waves in the seawater column above the boso triple junction causes elongated scattered waves which reasonably explains our observations

structure of some lower old red sandstone conglomerates kincardineshire scotland deposition from late orogenic antecedent streams a thick succession of early lower old red sandstone ors conglomerates and subordinate sandstones are preserved in a small fault bounded basin in the ne midland valley of scotland the conglomerates associated with the northern margin of this basin are distinguished by a complex provenance which involved both reworking of existing gravels and addition of contemporary volcanic and plutonic detritus this may explain their characteristic bimodal texture deposition was in large probably permanent low sinuosity channels with evidence for both periods of uniform high stage flow and repeated flow stage fluctuations variable palaeoflows in the basal part of the succession suggest deposition on wet type alluvial fans supplied by feeder channels with a high sediment and water discharge the thickness of the succession the poorly developed cyclothems despite active syndepositional faulting evidence for rapid aggradation and the inferred scale of channel bars and coarsening upward units produced by bar migration suggest the basin may have been externally drained transverse antecedent streams are invoked to account for the structure of alluvium during the early devonian central scotland lay close to the boundary between regions suffering scandian orthogonal shortening and acadian strike slip shear the tectonic controls which governed the preservation of early lower ors sediments may have been largely uncoupled from those determining the supply and dispersal of the sediment

on the duration of seismic motion incident onto the valley of mexico for subduction zone earthquakes summary we have used finite difference simulations in 2 d models of the lithosphere to estimate the duration of long period 2 s ground motion incident onto the valley of mexico for subduction zone earthquakes our simulations suggest that two heterogeneous structures extend the duration of the ground motion between the subduction zone and mexico city by more than 1 min 1 the mexican volcanic belt and 2 two low velocity layers in the coastal region the accretionary prism and the water layer the duration generated by a crustal model including these structures is similar to that for earthquake records observed in between the coast and mexico city in the valley of mexico our models including only regional scale heterogeneity reproduce approximately one half of the observed duration the results suggest that both the regional and the local scale low velocity structures must be taken into account in order to explain the observed extended signal duration in the valley of mexico

constraining shallow slip and tsunami excitation in megathrust ruptures using seismic and ocean acoustic waves recorded on ocean bottom sensor networks abstract great earthquakes along subduction zone plate boundaries like the 2011 magnitude 9 0 tohoku oki japan event deform the seafloor to generate massive tsunamis tsunami wave heights near shore are greatest when excitation occurs far offshore near the trench where water depths are greatest and fault slip is shallow the tohoku event featuring over 30 m of slip near the trench exemplifies this hazard unfortunately the rupture process that far offshore is poorly constrained with land based geodetic and even most seafloor deformation measurements and seismic inferences of shallow slip are often nonunique here we demonstrate through dynamic rupture simulations of the tohoku event that long period guided waves in the ocean specifically leaking oceanic p wave modes known as pl waves can resolve the shallow rupture process and tsunami excitation near the trench with predicted pressure changes of 0 1 1 mpa along most of the seafloor landward of the trench and periods of several seconds these pl waves should be observable with ocean bottom pressure sensors and or seismometers with cabled sensor networks like those being deployed offshore japan and in other subduction zones these waves could be used to rapidly quantify shallow slip and near trench seafloor uplift and improve local tsunami early warning systems

fdm simulation of seismic wave propagation for an aftershock of the 2009 suruga bay earthquake effects of ocean bottom topography and seawater layer abstract feasibility studies on simulating seismic wave propagation in media for a suboceanic earthquake including both land and ocean bottom topographies and a seawater layer are scarce some of the conventional staggered grid finite difference method fdm simulations use a simplified structure model without a seawater layer and with a flat ocean bottom topography in this study we apply our heterogeneity oceanic layer and topography scheme hot fdm and a 3d structure model including land and ocean bottom topographies a seawater layer and a fluid solid boundary condition to an aftershock m w 5 8 of the 2009 suruga bay earthquake we attempt to reproduce observations at seismic stations near the coast and then simulate waveforms in the ocean bottom stations our results show that a large difference between the cases with and without topographies can be seen in the coda part after the s wave in the simulated waveforms in terms of amplitudes and elongations the synthetic waveforms in the model with topographies are in agreement with the observed waveforms our results also show that a significant difference in the amplification of the coda part between the cases with and without the seawater layer can be found at the ocean bottom stations this coda part is the s and rayleigh wave propagation associated with the ocean and the underlying sediment layers our results show that a realistic model with topographies and a seawater layer is needed in fdm simulations in order to precisely reproduce observed waveforms or predict seismic motion for a suboceanic earthquake

sedimentary basin destruction inferred from the evolution of drainage systems in the betic cordillera southern spain the guadix continental basin developed during the uppermost miocene the pliocene and the pleistocene one axial fluvial system and two transverse systems are interpreted in its alluvial infill in addition there are areas of lacustrine sedimentation permanent in the eastern sector and ephemeral in the western part of the basin from a sedimentological point of view the holocene drainage network shows significant similarities with that which occupied the ancient basin although there are some differences in location these provide information about the processes involved in the transformation of the sedimentary basin into an erosional basin with external drainage most of the data seem to indicate that the capture of drainage from the guadix basin by the guadalquivir river was accelerated principally by tectonic processes related to a recent uplift of a sector of the betic cordillera together with the disappearance of subsident points of the basin the high rate of holocene erosion is partially conditioned by the type of sediment deposited in the basin a low degree of lithification textural heterogeneity etc in comparison with the basement and mainly by the position of the ancient basin in relation to the new relative base level located almost 500 m lower than the position actually occupied by the pleistocene relative base level of the basin

interference of long period seismic wavefield observed by the dense hi net array in japan 1 in order to recover small signals of long period ground motions recorded by a short period seismometer we designed a time domain recursive filter that simulates seismic waves recorded with broadband seismometers we applied the time domain filter to seismograms recorded by the dense hi net array which consists of 800 stations at intervals of approximately 20 km the effectiveness of the time domain filter is demonstrated through the comparison of broadband waveforms obtained by the filter and sts 2 true broadband seismograms from the f net at the same site good agreement is observed between filtered and true broadband waveforms with high correlation coefficients for periods of up to 100 s for waveforms from the 2007 sumatra earthquake m7 9 which occurred approximately 5000 5800 km away from japan the applicability of the time domain filter to the recovery of long period signals from the record of a short period seismometer depends on the signal to noise ratio as a result a limited bandwidth of broadband signal is recovered for smaller earthquake from the spatiotemporal variation of the long period t 20 100 s wavefield obtained by the time domain filter we newly found an anomalous phase pattern of splitting of polarity along the wavefront particularly for the relatively short period band of from 20 50 s array analysis of the dense broadband waveforms revealed multipathing of the rayleigh waves which propagated toward central japan from two directions with slightly different slowness vectors the interference of two rayleigh waves caused such splitting of wavefield

alluvial and fluvial fans on saturn s moon titan reveal processes materials and regional geology fans landforms that record the storage and transport of sediment from uplands to depositional basins are found on saturn s moon titan a body of significantly different process rates and material compositions from earth images obtained by the cassini spacecraft s synthetic aperture radar reveal morphologies roughness textural patterns and other properties consistent with fan analogues on earth also viewed by synthetic aperture radar the observed fan characteristics on titan reveal some regions of high relative relief and others with gentle slopes over hundreds of kilometres exposing topographic variations and influences on fan formation there is evidence for a range of particle sizes across proximal to distal fan regions from c 2 cm or more to fine grained which can provide details on sedimentary processes some features are best described as alluvial fans which implies their proximity to high relief source areas while others are more likely to be fluvial fans drawing from larger catchment areas and frequently characterized by more prolonged runoff events the presence of fans corroborates the vast liquid storage capacity of the atmosphere and the resultant episodic behaviour fans join the growing list of landforms on titan derived from atmospheric and fluvial processes similar to those on earth strengthening comparisons between these two planetary bodies

synthesizing ocean bottom pressure records including seismic wave and tsunami contributions toward realistic tests of monitoring systems the present study proposes a method for synthesizing the ocean bottom pressure records during a tsunamigenic earthquake firstly a linear seismic wave simulation is conducted with a kinematic earthquake fault model as a source then a nonlinear tsunami simulation is conducted using the sea bottom movement calculated in the seismic wave simulation by using these simulation results this method can provide realistic ocean bottom pressure change data including both seismic and tsunami contributions a simple theoretical consideration indicates that the dynamic pressure change caused by the sea bottom acceleration can contribute significantly until the duration of 90 s for a depth of 4000 m in the ocean the performance of a tsunami monitoring system was investigated using the synthesized ocean bottom pressure records it indicates that the system based on the hydrostatic approximation could not measure the actual tsunami height when the time does not elapse enough the dynamic pressure change and the permanent sea bottom deformation inside the source region break the condition of a simple hydrostatic approximation a tsunami source estimation method of tfish is also examined even though the synthesized records contain a large dynamic pressure change which is not considered in the algorithm tfish showed a satisfactory performance when 5 min after the earthquake occurrence the pressure records synthesized in this study including both seismic wave and tsunami contributions are more practical for evaluating the performance of our monitoring ability whereas most tsunami monitoring tests neglect the seismic wave contribution

fault parameters of the 1896 sanriku tsunami earthquake estimated from tsunami numerical modeling the june 15 1896 sanriku earthquake generated devastating tsunamis with the maximum run up of 25 m and caused the worst tsunami disaster in the history of japan despite its moderate surface wave magnitude ms 7 2 and weak seismic intensity this is a typical tsunami earthquake which generates anomalously larger tsunamis than expected from its seismic waves previously proposed mechanisms of tsunami earthquakes include submarine slumping and slow rupture in the accretionary wedge or in the subducted sediments in this paper we estimate the fault parameters of the 1896 tsunami earthquake by numerically computing the tsunami and comparing the waveforms with those recorded at three tide gauge stations in japan the result indicates that the tsunami source is very close to the japan trench and the fault strike is parallel to the trench axis the fault width is about 50 km suggesting that the tsunami earthquake is a slow rupture in the subducted sediments beneath the accretionary wedge

modeling of long period ground motions in the nankai subduction zone model simulation using the accretionary prism derived from oceanfloor local s wave velocity structures the accretionary prism in the subduction zone which consists of thick low velocity oceanic sediments significantly affects the propagation of seismic waves for shallow offshore earthquakes including large interplate earthquakes in order to simulate long period 5 s ground motions in the nankai subduction zone we constructed a three dimensional 3d seismic velocity structure model of the accretionary prism by interpolation extrapolation of local s wave velocity structures beneath 46 oceanfloor seismic stations donet which are deployed just above the accretionary prism off the southern kii and eastern shikoku regions we modeled local s wave velocity structures using a simple two parameter depth varying velocity function to investigate the effects of the accretionary prism on ground and seafloor motions we conducted numerical simulations of seismic wave propagation for three local earthquakes that occurred in southwestern japan the simulations reasonably reproduced the observed seismograms not only for the period ranges of the moment tensor inversion 50 s but also for the strong long period ground motions in the sedimentary basins 5 s especially in the region where donet stations are densely deployed since depth varying local s wave structures significantly improve the reproducibility of long period ground motions our modeling procedure is useful for modeling long period ground motions of local and regional offshore subduction zone earthquakes

spatial relationship between shallow very low frequency earthquakes and the subducted kyushu palau ridge in the hyuga nada region of the nankai subduction zone

smooth inversion of vsp traveltime data vertical seismic profile vsp direct arrivals provide an insitu measurement of traveltime with depth into the earth in this note we describe a weighted damped least squares inversion of vsp traveltimes for a smooth velocity depth function that inherently reveals the resolution of the data smooth velocity depth profiles of this type are suitable for migration or as a starting models for waveform inversion or tomography the application of this inversion is particularly simple requiring only the value of the damping parameter to be determined and this value is determined from residual statistics

major controls on sedimentation during the evolution of a continental basin pliocene pleistocene of the guadix basin betic cordillera southern spain abstract sequence stratigraphy based on climatic tectonic and base level parameters can be used to understand carbonate sedimentation in continental basins the uppermost continental fill of the guadix basin betic cordillera containing both siliciclastics and carbonates is investigated here in its central sector a thick succession of fluvio lacustrine sediments appear hosting several important pliocene and pleistocene macrovertebrate sites fonelas project the need to characterize the stratigraphic and sedimentologic context of these important paleontologic sites has lead to litho magneto and biostratigraphic studies these data together with the sedimentologic analysis of the pliocene and pleistocene siliciclastic and carbonate successions establish a sedimentary model for the fluvio lacustrine sedimentation of the two last stages of sedimentation in the guadix basin units v and vi unit v comprises mostly fluvial siliciclastic sediments with less abundant carbonate beds interpreted as floodplain lakes or ponds the latter unit vi is dominated by vertically stacked carbonate palustrine successions using two pre existent continental stratigraphic models the influence of climate tectonism and stratigraphic base level during the last 3 5 ma on the sedimentary evolution of the fluvio lacustrine system in the guadix basin especially the carbonate sedimentation patterns is outlined

structures and textures in triassic braided stream conglomerates bunter pebble beds in the sherwood sandstone group north staffordshire england in the northern parts of the needwood and stafford eccleshall basins england the pebble beds of the sherwood sandstone group contain thick successions of texturally mature fluvial pebble cobble conglomerates which are organized into either horizontal or cross stratified sets the horizontally lying sets generally coarser grained and more poorly sorted than the cross bedded sets are usually disorganized and either matrix or clast supported although thin lenses of well sorted occasionally openwork units interpreted as falling stage phenomena are often present the cross stratified conglomerates have foresets exhibiting remarkable textural organization with a coarse bimodal sometimes matrix supported part grading upwards or being abruptly overlain by a finer well sorted occasionally openwork part and finally capped by sandstone these rhythmic textural changes are attributed partly to an avalanche process at high stage and partly to falling stage conditions the most common types of vertical association are thick successions of horizontally bedded conglomerates up to 20 m and sequences of an upwards coarsening nature 2 12 m in which cross stratified sets are overlain by flat lying sets the environment of deposition of the gravels is interpreted as one in which water depths at high stage were greater than depths in most modern braided stream plains proglacial or alluvial fan but shallower than depths associated with the pleistocene catastrophic floods from which texturally mature giant gravel bars have been recorded recent braided streams with relatively confined channels and considerable bar channel relief are better analogues in particular medial or mid channel bars with a two tier structure subaqueous and partly emergent portions may explain the upward coarsening sequences in which horizontally lying conglomerates overlie cross stratified conglomerates the thicker sequences of horizontally stratified conglomerates represent proximal longitudinal bar deposits sheets of pebbly sandstone and argillaceous sandstone lying between the conglomerates and commonly occurring towards the top of the succession largely represent deposition from sandwaves and dunes finer interbedded argillaceous sandstones siltstones and mudstones are interpreted as overbank and waning flood deposits basin forming tectonism of increasing intensity probably caused the initial coarsening upwards of the lower part of the succession whilst more stable tectonic conditions and decreasing relief on the margins of the basins and in the areas of provenance in the midlands and the hercynides account for the upwards fining of the upper part of the succession

a deep outer rise reverse fault earthquake immediately triggered a shallow normal fault earthquake the 7 december 2012 off sanriku earthquake mw 7 3 1 teleseismic body wave analysis revealed that the 7 december 2012 off sanriku earthquake mw 7 3 at the outer rise of japan trench consisted of two successive subevents the first subevent with reverse fault mechanism event 1 mw 7 1 at 56 km depth was followed by approximately 20 s later the second subevent with normal fault mechanism event 2 mw 7 2 at 6 km depth finite fault slip models show that the slip of event 1 was concentrated around the initial rupture point with the maximum of 2 7 m and that event 2 had two asperities with the maximum of 4 5 m at both sides of the initial rupture point the static coulomb failure function analyses suggested that event 1 triggered event 2 and that both subevents were promoted by the 2011 tohoku earthquake mw 9 1

fdm simulation of seismic waves ocean acoustic waves and tsunamis based on tsunami coupled equations of motion we have developed a new unified modeling technique for the total simulation of seismic waves ocean acoustic waves and tsunamis resulting from earthquakes based on a finite difference method simulation of the 3d equations of motion using the equilibrium between the pressure gradient and gravity in these equations tsunami propagation is naturally incorporated in the simulation based on the equations of motion the performance of the parallel computation for the newly developed tsunami coupled equations using a domain partitioning procedure shows a high efficiency coefficient with a large number of cpu cores the simulation results show how the near field term associated with seismic waves produced by shallow earthquakes leads to a permanent coseismic deformation of the ground surface which gives rise to the initial tsunami on the sea surface propagation of the tsunami along the sea surface as a gravity wave and ocean acoustic waves in seawater with high frequency multiple p wave reflections between the free surface and sea bottom are also clearly demonstrated by the present simulations we find a good agreement in the tsunami waveform between our results and those obtained by other simulations based on an analytical model and the navier stokes equations demonstrating the effectiveness of the tsunami coupling simulation model based on this simulation we show that the ratio of the amplitude of ocean acoustic waves to the height of the tsunami both of which are produced by the earthquake strongly depends on the rise time of the earthquake rupture this ratio can be used to obtain a more detailed understanding of the source rupture processes of subduction zone earthquakes and for implementing an improved tsunami alert system for slow tsunami earthquakes

insight into complex rupturing of the immature bending normal fault in the outer slope of the japan trench from aftershocks of the 2005 sanriku earthquake mw 7 0 located by ocean bottom seismometry 1 the distribution of aftershocks of a large mw 7 0 normal faulting earthquake beneath the outer slope of the japan trench in 2005 measured in 2007 using ocean bottom seismographs indicates that the earthquake was involved with a set of conjugate normal faults although the faults reach to the upper mantle the estimated vp and vp vs show no remarkable changes that can be related to extensive hydration in the crust or uppermost mantle the absence of horst graben topographic structure in the rupture area suggests that immaturity of the bending fault system is responsible for the relatively unhydrated lithosphere several earthquakes below the aftershock zone may belong to the lower plane seismicity of the shallow double seismic zone because no earthquakes were recorded in the area for more than 80 years before the 2005 event shallow extensional and deep compressive earthquakes may be activated concurrently in the focal area of this earthquake

anomalous propagation of long period ground motions recorded in tokyo during the 23 october 2004 mw 6 6 niigata ken chuetsu japan earthquake unusually large 5 cm and prolonged shaking associated with long period ground motions at periods of about 7 sec were observed in central tokyo during the mw 6 6 niigata ken chuetsu earthquake of 23 october 2004 the long period ground motions caused significant resonance in high rise buildings of about 70 floors in height thus it is an urgent matter to understand the development and amplification properties of long period ground motions in tokyo associated with large earthquakes in this study we use numerous waveform records from 585 stations in a nationwide accelerometer network k net kik net and 495 intensity meters in the area around tokyo the data reveal that the long period ground motion is characterized in most part by a surface rayleigh wave generated at the northern edge of kanto basin and the surface wave is developed as propagating through a thick cover of sediments 3000 4000 m that overlies rigid bedrock to complement the observational data we conducted a large scale computer simu lation of seismic wave propagation by employing the earth simulator supercomputer with a detailed source slip model and a high resolution 3d sedimentary structural model of central japan the results of the computer simulation demonstrate that the anomalously prolonged ground shaking of the long period signal recorded in the center of tokyo occurred because of the stagnation of seismic energy resulting from the multipathing and focusing of rayleigh waves toward the bottom of the kanto basin from surrounding mountain regions with interaction to the 3d basin structure

karst subsidence as a control on the accumulation and preservation of aeolian deposits a pleistocene example from a proglacial outwash setting ebro basin spain meltwater flows emanating from the pyrenees during the pleistocene constructed a braided outwash plain in the ebro basin and led to the karstification of the neogene gypsum bedrock synsedimentary evaporite dissolution locally increased subsidence rates and generated dolines and collapses that enabled the accumulation and preservation of outwash gravels and associated windblown deposits that were protected from erosion by later meltwater flows in these localized depocentres maximum rates of wind deceleration resulted from airflow expansion enabling the accumulation of cross stratified sets of aeolian strata climbing at steep angles and thereby preserving up to 5 m thick sets the outwash plain was characterized by longitudinal and transverse fluvial gravel bars channels and windblown facies organized into aeolian sand sheets transverse and complex aeolian dunes and loess accumulations flat lying aeolian deposits merge laterally to partly deformed aeolian deposits encased in dolines and collapses synsedimentary evaporite dissolution caused gravels and aeolian sand deposits to subside such that formerly near horizontal strata became inclined and generated multiple internal angular unconformities during episodes when the wind was undersaturated with respect to its potential sand transporting capacity deflation occurred over the outwash plain and coarse grained lags with ventifacts developed subsequent high energy flows episodically reached the aeolian dune field leading to dune destruction and the generation of hyperconcentrated flow deposits composed in part of reworked aeolian sands lacustrine deposits in the distal part of the outwash plain preserve rhythmically laminated lutites and associated gilbert type gravel deltas which developed when fluvial streams reached proglacial lakes this study documents the first evidence of an extensive pleistocene proglacial aeolian dune field located in the ebro basin 41 50 n south of what has hitherto been considered to be the southern boundary of pleistocene aeolian deposits in europe a non conventional mechanism evaporite karst related subsidence for the preservation of aeolian sands in the stratigraphic record is proposed

quantitative geomorphology of the mars eberswalde delta the eberswalde delta is composed of six separate depositional lobes that have prograded some 17 km from their apex crosscutting distributary relationships and compensated depositional lobes are clearly visible in images acquired by the mars global surveyor mars orbiter camera here several lobe systems have been examined for sinuosity radius of channel curvature meander bend width and channel width parameters channel sinuosities of between 1 2 and 1 8 defi ne low to moderate sinuosity systems typical of the type transporting bedload or mixed grain size loads channel systems increase in sinuosity as they get older however some of the younger systems show specifi c reaches of increased sinuosity these localized changes may be due to either abutment against resistant beds of older lobes or rise in base level at the channel system terminus if the former such an effect of older deposits on the morphology of the channels suggests that these older lobes were fairly well indurated prior to the deposition of the youngest progradational lobes eighty six percent of distributaries in the mars eberswalde delta are 100 240 m wide comparatively 62 and 44 of distributaries in the atchafalaya and wax lake deltas of louisiana respectively are of similar size small distributaries may indicate lower average and shorter duration fl ows or coarser sediment in mars distributaries than those typical of the gulf coast systems the volume of the material in the mars deposit suggests long periods of sediment deposition sinuosity indexes meander bend migration and ridge and swale point bar topography suggest periods of stable discharge on the delta surface

fdm simulation of an anomalous later phase from the japan trench subduction zone earthquakes we investigated the development of a distinct later phase observed at stations near the japan trench associated with shallow outer rise earthquakes off the coast of sanriku northern japan based on the analysis of three component broadband seismograms and fdm simulations of seismic wave propagation using a heterogeneous structural model of the japan trench subduction zone snapshots of seismic wave propagation obtained through these simulations clearly demonstrate the complicated seismic wavefield constructed by a coupling of the ocean acoustic waves and the rayleigh waves propagating within seawater and below the sea bottom by multiple reflections associated with shallow subduction zone earthquakes we demonstrated that the conversion to the rayleigh wave from the coupled ocean acoustic waves and the rayleigh wave as they propagate upward along the slope of seafloor near the coast is the primary cause of the arrival of the distinct later phase at the station near the coast through a sequence of simulations using different structural models of the japan trench subduction zone we determined that the thick layer of seawater along the trench and the suddenly rising sea bottom onshore of the japanese island are the major causes of the distinct later phase the results of the present study indicate that for realistic modeling of seismic wave propagation from the subduction zone earthquakes a high resolution bathymetry model is very crucial although most current simulations do not include a water column in their simulation models

seismic and tsunami wave propagation of the 2011 off the pacific coast of tohoku earthquake as inferred from the tsunami coupled finite difference simulation abstract the 2011 tohoku earthquake m 9 0 caused significant hazards including strong ground motion coseismic ground deformation and tsunamis for a deeper understanding of these phenomena we conducted a large scale parallel computer simulation by means of the finite difference method fdm with newly developed tsunami coupled equations of motion this method is based on the equations of motion for an elastic medium treating seawater as elastic material having zero s wave velocity tsunami waves are included by taking into account gravity and their equilibrium with the pressure gradient an effective method of fdm simulation using the state of the art massively parallelized k computer is also studied with the use of a 3d layered velocity structure that includes topography and bathymetry basement structure moho depth and plate boundaries and use of the appropriate source rupture model based on joint inversion of seismic waves and geodetic observations the simulated seismic waves demonstrate anomalous seismic wave propagation by the thick 3d basin structure inland we also found that the sea column acts as a strong absorber of seismic waves for shallow up dip slip on the ocean side coseismic deformation and tsunamis are dynamically generated in this simulation tsunami attacks on the subsided pacific coast are simulated without any additional assumptions we also modeled the tsunami and seismic records of ocean bottom pressure gauges above the fault because sea bottom tsunami and seismic observation is powerful but very complex recording both seismic and tsunami waves the use of these coupled numerical simulations has great potential for resolving complex source fault rupture processes in a 3d heterogeneous structure online material mpeg movies of fault slip seismic wave propagation seafloor and ground displacement and tsunamic propagation

differential features of alluvial fans controlled by tectonic or eustatic accommodation space examples from the betic cordillera spain abstract the creation of accommodation space in subaerial sedimentary environments is closely linked to uplift the source area along basin margin faults or to a rise in base level depending amongst others on the relative importance of these two factors the margins of terrestrial sedimentary basins where alluvial fans develop produce aggradational progradational or retrogradational stratigraphic architecture we studied a total of 43 quaternary alluvial fans in the granada and bajo segura basins betic cordillera spain the analysis of their stratigraphic architecture and sedimentary facies has revealed the existence of three groups characterised by distinct stratal stacking patterns which is the result of differences in eustasy and tectonics the qualitative and quantitative analysis of these alluvial fans and their drainage basins has allowed us to define certain characteristic geomorphological patterns related in each case to the main mechanism operative in the creation of accommodation space these patterns are described as follows 1 alluvial aggradation is the main result of high tectonic subsidence with the development of quite open but small fans with a constant steep slope lacking incised channels and headward eroding gullies 2 in contrast when the principal mechanism in creating accommodation space is low tectonic subsidence progradation occurs and the fans are narrower and larger moreover the slopes of such fans are less steep in relation to the drainage area than in the above case being constant or even concave in longitudinal profile they also have short deep incised channels culminating downfan in a depositional lobe in inactive zones long deep headward eroding gullies develop 3 areas of extremely low tectonic subsidence and base level rise produce very open fans in the sedimentary basin although with a pronounced mountain embayment which gives them a characteristic mushroom shape in plan view in the latter case retrogradation is the typical stratigraphic stacking pattern and the fans are quite extensive with respect to their drainage areas usually showing a segmented longitudinal profile with a low gradient the feeder channels do not surpass stream order 3 and various extremely long and shallow incised channels can appear 4 contrary to the case of fans developing under a regime of subsidence when the accommodation is due to base level rise the fan slopes bear no relation to the extent of the catchment basins in such a case the overall fan slope is strongly influenced by the extent of the mountain embayment because it determines the distributions of debris and sheet flows over the alluvial surface

late pleistocene and holocene mid latitude palaeoclimatic and palaeoenvironmental reconstruction an approach based on the isotopic record from a travertine formation in the guadix baza basin spain a comprehensive palaeoenvironmental reconstruction of the last 219 ka has been carried out by determining the isotopic signatures 18 o and 13 c in 766 samples of a thermogene travertine formation in the guadix baza tertiary basin granada se spain this travertine formation was dated from 220 to 5 ka by means of the alpha spectrometry technique initially the study of the 18 o values of the travertine formation was carried out because they are excellent indicators of the overall palaeoclimatic condition of a particular site likewise the evolution of 13 c values which can be directly related to the biomass development of the site has also been studied finally an integrated study of both isotopic records has been performed identifying a total of 12 climatic periods based on their palaeoclimatic and palaeoenvironmental conditions these periods are grouped into four climatic scenarios scenario a characterized by warm and dry periods scenario b characterized by cold and humid periods scenario c constituted by warm and humid periods and scenario d which is characterized by cold and dry periods palaeoclimatic scenarios a and b mainly characterized the palaeoclimatic evolution of the site while in northern europe the palaeoclimatic evolution is mainly characterized by scenarios c and d therefore it is suggested that the palaeoenvironmental evolution at lower latitudes on the iberian peninsula is the opposite of that identified in northern europe however the main climatic events identified at higher latitudes are also reflected in the studied area