the discovery of emerged boring bivalves at cape omaezaki shizuoka japan evidence for the 1361 ce tokai earthquake along the nankai trough abstract this study found several in situ fossil shells of the boring bivalve penitella gabbii exposed in mudstone at an elevation of 1 05 1 35 m above mean sea level in a wave cut platform at cape omaezaki shizuoka central japan this region faces the nankai trough where great earthquakes m 8 occur with a recurrence interval of 90 200 years based on the upper limit of living p gabbii 0 8 m above mean sea level and geodetic data the total uplift of shells since the time of their active is estimated to be up to 2 5 m using 14c dates from the uplifted terrace deposits around the study area and shell fossils we propose that the emerged fossils provide new evidence for the pairing of the 1361 ce shohei koan tokai earthquake rupture of suruga trough and the eastern half of the nankai trough with the 1361 ce shohei koan nankai earthquake rupture of the western half of the nankai trough

wave current bottom shear stresses and sediment resuspension in cleveland bay australia the bottom sediment resuspension is an important process in cleveland bay north australia hydrodynamics and suspended sediment concentrations ssc were measured from january to april 1993 during this field work two high sediment resuspension events were observed an iterative method of calculating the bottom shear stress under wave current motion has been applied using the calculated bottom shear stresses the resuspension mechanisms of bottom sediment in cleveland bay has been investigated by analysing data collected during two periods in january and march 1993 swell has been found to be the most important factor in sediment suspensions for both high ssc events wind waves have little effect on ssc levels tidal currents are too weak to stir up bottom sediment particles into the flow but affect the detailed ssc structure by tidal convection the critical shear stress for sediment resuspension in cleveland bay is about 2 0 n m2

evidence for sea level oscillations by the characteristic thickness of marine deposits from raised terraces of southern calabria italy abstract clastic deposits associated with marine terraces can provide evidence for detecting eustatic oscillations the method is based on the characteristic thickness ct of beach formations which are generally deposited on a wave cut platform between the breakpoint and the swash upper limit on any present day coast ct reflects equilibrium related to current shore processes with a constant sea level it represents a local threshold t cr as when sea level rises ct increases by a value equal to the rise amplitude this amount is reduced in uplifted areas by the magnitude of coeval uplifting the amplitude of sea level variations detected by ct can be calculated knowing ct t cr uplift rate and the duration of an oscillation the method is applied to the clastic deposits of 23 marine terraces stepped between 52 and 172 m and shaped over the mis 5 mis 4 period along the calabria coast of the messina strait not only the great orbital oscillations mis 5 5 mis 5 3 mis 5 1 and mis 3 are recorded but also several rapid and low amplitude events are detected into each substage the most surprising result is the ten small oscillations during mis 5 5 the duration of which ranges between 2 ka and less than 1 ka while sea level oscillates from 0 5 to 12 m in amplitude by calculating initial relative sea level highstands and also lowstands preceding them detailed eustatic oscillations of the curve are drawn

pollen based quantitative reconstructions of holocene climate variability in nw romania abstract a modern analogue technique is applied to two high resolution pollen sequences from nw romania to provide the first quantitative evidence for winter summer and annual temperatures and for precipitation across the holocene in this region the pollen based climate reconstructions allow the identification of four main intervals i an early less stable period between 11 700 and 11 200 cal yr bp ii generally stable conditions between 11 200 and 8300 cal yr bp with winter and annual temperatures and precipitation higher than at present and summer temperatures about the same iii lower winter and annual temperatures and higher summer temperatures and precipitation between 8000 and 2400 cal yr bp iv warmer winter and annual temperatures and lower precipitation for the last 2400 years whereas summer temperatures became cooler at steregoiu and remained stable at preluca tiganului the pollen based climate reconstructions at the two sites show similar patterns in annual and winter temperatures and precipitation changes during the holocene but the trends appear to be less consistent for summer temperatures our pollen based reconstructions revealed several short term climatic oscillations during the holocene the strongest of which occur between 10 300 10 100 8300 8000 6800 6400 5100 4900 4000 3600 and 3200 3000 cal yr bp

tectonic interpretations of holocene marine terraces east coast of coastal range taiwan abstract the east coast of the coastal range in taiwan is well known for its multiple holocene marine terraces and their very rapid uplift the study area extends from hualien to taitung over ca 150 km of coastline here we present some new data on the age and height of holocene marine terraces and we discuss their significance for holocene coastal tectonics the holocene marine terrace sequence is subdivided into a maximum of 10 steps the highest and oldest terrace mostly underlain by transgressive deposits represents the sea level position of the culmination of holocene sea level rise and reaches up to ca 80 m above sea level transgressive deposits are radiocarbon dated at several sites back to ca 13 000 yr bp the lower terraces are mostly erosional ones overlain by thin coral beds in situ less than 1 m thick and indicate successive lowering of relative sea level during the late holocene the uplift rate of the coast is very high ranging from 5 to 15 m ka three tectonic subregions a c are identified based on the pattern of marine terrace features and uplift rate the presence of many steps during holocene time implies that intermittent uplifts associated with large earthquakes at intervals of one thousand to several hundred years have repeatedly occurred in this coastal area but with different time and amount at each subregion the uplift of subregion a resulted from an onshore active fault milun fault causative faults for the uplift of the subregions b and c are not identified offshore active faults striking obliquely to the coastline appear to be causative faults

late pleistocene and halocene sea level changes in japan implications for tectonic histories and mantle rheology abstract it is very important to separate the tectonic and glacial isostatic components in the observed holocene and late pleistocene sea level changes in tectonically active areas such as japan for studying tectonic processes and for constraining mantle rheology the separation can be achieved by considering the spatial dependence of the relative sea level on the geometry of the coastline around the site where sea level is evaluated in fact the relative sea level caused by the last deglaciation at sites in the embayment such as tokyo and osaka has a sea level curve with a high stand at mid holocene and that site situated on the tip of peninsula has a sea level curve culminating towards the present the geometric effect also causes the regional difference of the sea level variations in the late glacial phase in the japanese islands the regional difference of the predicted relative sea level is about 5 m at 6000 years ago 20 m at 10 000 years ago and 30 m at 18 000 years ago comparison between observations and predictions indicates that the observations at several sites in japan are consistent with the predicted sea level variations more systematic data is required for the period 18 000 years ago to the present in order to examine tectonic processes and mantle rheology

seismogenic faults along the major suture of the plate boundary deduced by dislocation modeling of coseismic displacements of the 1951 m7 3 hualien taitung earthquake sequence in eastern taiwan abstract research at plate boundaries generally focuses on the kinematics of plate motions the genesis of large earthquake and natural resources however often the present state of knowledge is still insufficient to reveal the details of such dynamic systems to define in more detail the dynamics of a major plate boundary fault the coastal range fault eastern taiwan we use seismologic and geodetic data to unravel its subsurface geometry and relevant fault behavior by recomputing the archive triangulation datasets 1917 1978 and using a dislocation algorithm we determine that it consists of three segments our model results are consistent with the observation of the 1951 m7 3 hualien taitung earthquake sequence that the southern two segments are both oblique slip faults with significant thrust components while the northern segment is a pure strike slip fault according to our model each segment has the potential to produce an earthquake larger than m7 however based on gps observations and seismic records slip on the southern segment may take the form of aseismic creep and multiple moderate earthquakes rather than large events with long recurrence interval as occur on the two more northerly segments with regard to the central segment the epicenter distribution of catalogued earthquakes occurring after 1951 reveals the presence of a seismic gap indicating that slip on this segment is predominantly coseismic with a correspondingly higher potential for large earthquakes in the future

tectonic significance of holocene marine terraces in the coastal range eastern taiwan abstract well developed marine terraces on the coast of eastern taiwan between chengkung and hualien can be divided into three morphotectonic sectors 1 i chengkung kueian 2 ii shuilien and its vicinity 3 iii north of shuilien sector i displays at least five terrace levels and has undergone northward tilting and uplift the available 234 u 230 th and 14 c ages suggest that one of its holocene terraces rises to about 40 m and locally to 70 m above msl the average uplift rate for the holocene in this sector decreases northward from 9 10 mm yr to about 2 3 mm yr few traces of former shorelines or marine terraces higher than 5 m are found in sector ii north of shuilien in sector iii terrace elevation increases gradually and indicates an uplift rate of about 2 3 mm yr the uplift pattern agrees with geodetic data obtained between 1985 and 1988 the high uplift rates in sector i may represent compression and shortening of the northwestern corner of the philippine sea plate the low rates in sector ii may correlate with the region where the ryukyu trench meets the eastern coast of taiwan

late holocene history of the moldova river valley romania abstract this paper describes the results of geomorphological sedimentological and 14 c analyses of late holocene fluvial sequences in the moldova river valley of romania this river originates from the carpathians mountains and is known for the extent of its large floodplain and sediment thickness between the molid and timisesti localities river length 86 km numerous large fossil trunks of oak poplar and beech trees are exposed in the riverbanks six wood samples were selected for radiocarbon absolute dating conventional method and their ages ranged from 410 to 3200 cal yrs bp the thickness of the alluvial sediments above the sampled fossil trunks varied between 2 and 3 m and these sediments predominantly consisted of coarse gravel materials that had similar granulometry to sediments that were present in the modern riverbed additionally in the same investigated areas successive floodplain cross sections were constructed based on more than 20 hydrogeological boreholes for each cross section all data were used to calculate the local values of bed loads and these values were compared to the absolute ages of the fossil trunks and were in the range of 300 m 3 m and 5500 m 3 m based on the calculated values during the last 780 years the floodplain sedimentation rates were estimated to be in the range of 0 4 m 3 year at the molid section which was located in the mountainous area of the valley and 44 km downstream from the river headwater and during the last 410 years the sedimentation rate at the praxia section which was located 125 km downstream from the river headwater was 13 3 m 3 year in the past 100 years the fluvial processes along the moldova river were dominated by a narrowing by an average of 76 and an incision up to 2 5 m and a channel metamorphosis from braided to wandering was reported these results are discussed in the context of late holocene regional and local palaeoclimatic reconstructions as well as that of human interventions

measurement of local bed shear stress in streams using a preston static tube local bed shear stress t w is a fluid dynamic parameter of importance in determining the physical and biological characteristics of stream bed environments unfortunately it is often difficult to measure t w under field conditions herein we describe the use of a preston static tube which is essentially a surface mounted pitot static tube to measure t w in mountain streams our results indicate that it is possible to measure local shear stress quickly consistently and inexpensively in the field this technique also provides high spatial resolution which should allow for detailed in situ studies of local shear stress at scales relevant to lotic organisms such information will be invaluable in studies of benthic organisms and hydraulically relevant phenomena in the near bottom zone of lotic systems

deglacial sea level record from tahiti corals and the timing of global meltwater discharge the timing of the last deglaciation is important to our understanding of the dynamics of large ice sheets1 and their effects on the earth s surface2 3 moreover the disappearance of the glacial ice sheets was responsible for dramatic increases in freshwater fluxes to the oceans which probably disturbed the ocean s thermohaline circulation and hence global climate4 7 sea level increases bear witness to the melting of continental ice sheets but only two such records from barbados8 9 and new guinea10 11 corals have been accurately dated but these corals overlie active subduction zones where tectonic movements are large and often discontinuous especially in new guinea so the apparent sea level records may be contaminated by a complex tectonic component here we date fossil corals from tahiti which is far from plate boundaries and thus is likely to be tectonically relatively stable and remote from the locations of large former ice sheets the resulting record indicates a large sea level jump shortly before 13 800 calendar years bp which corresponds to meltwater pulse 1a in the barbados coral records8 9 the timing of this event is more accurately constrained in the tahiti record revealing that the meltwater pulse coincides with a short and intense climate cooling event12 15 that followed the initiation of the bolling allerod warm period12 16 but preceded the younger dryas cold event by about 1 000 years

in situ study of the spatiotemporal variability of sediment erodibility in a microtidal estuary abstract seabed erosion is a vital process for sediment transport in estuaries and coasts in this study we investigated the seabed erosion process and its spatiotemporal variability in the pearl river estuary china via in situ observations and laboratory experiments it is found that the seabed was more erodible in the channel than at the shoal in most cases due to the difference in sediment size in a neap spring neap tidal cycle a laminated seabed with different sediment ages was inferred to form due to deposition on flood tides and erosion on ebb tides the seabed was more erodible during spring tides than neap tides because of the difference in sediment availability at the unconsolidated fresh layer furthermore the erosion curve showed evident flood ebb asymmetry which was found to be related to the variations of sediment availability and bottom stress besides erosion experiments with different sediment consolidations revealed that sediment erodibility decreased with the growth of consolidation this study promotes our understanding on the spatiotemporal variability of sediment erodibility and has significant implications for simulation and prediction of estuarine sediment transport and morphological evolution

coastal quaternary morphologies on the northern coast of the south china sea china and their implications for current tectonic models a review and preliminary study marine terraces tidal notches and sediments along a 1200 km long stretch of the northern coast of the south china sea passive margin were studied and divided into five areas with varying tectonic characters up to three marine terraces occur that have elevations reaching up to 60 m above mean sea level amsl and two marine notches occur up to 11 m amsl chronology of the morphologies and deposits was obtained mainly by comparison with quaternary sea levels derived from the oxygen isotope curve however prior to the last interglacial highstand mis 5e c 125 ka evidence of history of events is less well constrained leading to less precision on sea level positions prior to mis 5e using the morphological features of mis 5e as a marker mean coastal uplift rates in the last c 125 ka range from 0 07 mm yr to 0 18 mm yr the pattern of deformations is slightly higher than those observed on passive margin coasts in other parts of the world the cause of uplift of the south china coastline is not clear but may relate to the himalayan collision zone or any other large scale phenomena

evidence of large prehistoric offshore earthquakes deduced from uplifted holocene marine terraces in pangasinan province luzon island philippines abstract uplifted holocene marine terraces in pangasinan province westernmost luzon island philippines are reported here for the first time as geomorphic evidence of large prehistoric offshore earthquakes we recognized up to three holocene terrace steps elevations of shoreline angles are ti 1 to 5 m tii 2 to 7 m and tiii 4 to 11 m above mean sea level amsl the lateral variation in the elevation of terrace steps indicates differential uplift along the coast the staircase topography characterized by horizontal abrasion platforms meter scale terrace risers and wave cut notches suggests that these geomorphic features were formed by large coseismic uplift events terrace morphology and radiocarbon ages further suggest that at least three coseismic coastal uplift events have occurred since the culmination of the post glacial sea level rise 6000 years ago we interpret tiii to be the holocene transgressive surface 6000 ybp and estimated a maximum uplift rate of 1 7 mm yr which is almost the same as the late pleistocene uplift rate of 1 3 mm yr we infer that proximity to offshore seismic sources has contributed to the deformation pattern of holocene terraces and variation in the number of terrace steps uplift patterns of marine terraces also suggest that the magnitude and location of prehistoric earthquakes may have varied between individual coseismic uplift events we conducted simple elastic dislocation modeling to evaluate the source parameters of the causative faults our preliminary models show that a landward dipping offshore reverse fault located at the base of a steep slope separating the fore arc basin and continental shelf could be responsible for coastal uplift along the western pangasinan peninsula

late quaternary paleolandslides on the coral terraces of huon peninsula papua new guinea abstract many landslides disrupt the coral terraces at northeast huon peninsula papua new guinea each landslide is younger than the youngest terrace which it intersects and is older than the oldest coral reef or shoreline that overlies it the ages of the raised coral reefs and terraces were established by previous studies using radiocarbon and uranium series dating the times of occurrence of 26 late quaternary landslides are reported here 7 are based on new radiocarbon dates from in situ corals or molluscs associated with landslide deposits and the remainder are based on terrace ages that were established previously the landslides include slumps block slides and block flows which mostly involve failure of coral limestones of the terraces and debris flows which originate from large landslides that cut through the coral limestones into underlying fan delta and tuffaceous sedimentary rocks the proportion of terrace area affected by late quaternary landslides ranges from 50 per km2 and depends on average gradient of the landsurface tectonic uplift rate and the thickness and geometry of the raised reefs and terraces clusters of landslides which occurred at about 800 1250 and 6300 7800 yr bp may have been triggered by large earthquakes which also caused metre scale coseismic uplift however we did not identify landslides that could have been associated with every large coseimic uplift that has been documented in this region

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

vertical structure of dissipation in the nearshore abstract the vertical structure of the dissipation of turbulence kinetic energy was observed in the nearshore region 3 2 m mean water depth with a tripod of three acoustic doppler current meters off a sandy ocean beach surface and bottom boundary layer dissipation scaling concepts overlap in this region no depth limited wave breaking occurred at the tripod but wind induced whitecapping wave breaking did occur dissipation is maximum near the surface and minimum at middepth with a secondary maximum near the bed the observed dissipation does not follow a surfzone scaling nor does it follow a log layer surface or bottom boundary layer scaling at the upper two current meters dissipation follows a modified deep water breaking wave scaling vertical shear in the mean currents is negligible and shear production magnitude is much less than dissipation implying that the vertical diffusion of turbulence is important the increased near bed secondary dissipation maximum results from a decrease in the tu

numerical model on the flow dynamics around the sediment water interface in the tidal coastal area abstract investigating flow dynamics around the sediment water interface is one of difficult issues in marine environment it has important significance to study the physical chemical and biological activities between the overlying water and sedimentary layer with tidal forcing in this study we established a numerical model to investigate the flow dynamics around the sediment water interface in the tidal coastal area the model reflected the hydrodynamics of periodic reciprocating unsteady flow in the overlying water layer and the fully coupled simulation of flow movement between the overlying water layer and sedimentary layer a sedimentary layer an overlying water layer and an air layer were all treated as the fluid zone the unsteady reynolds averaged navier stokes equations and the reynolds stress model with porosity were solved by the finite volume method moreover the drag source term in the momentum equation was modified as the darcy forchheimer extended form the model showed a strong performance in simulating the hydrodynamics of coupled flow around the sediment water interface with tidal forcing in a coastal area with considering the sedimentary layer the benthic boundary layer velocity distributions were more accurate than those obtained by a wall function model around the sediment water interface there was inertial loss in the flow furthermore velocity increased with increasing porosity and velocity gradient became larger compared with models with darcy s law the numerical model in this study had better performance in the turbulent characteristics of sediment water interface layer the model can lead to better understanding of the exchange mechanisms of oxygen nitrogen and nutrient between overlying water and sediment

cyclic crustal movement steady uplift of marine terraces and evolution of the island arc trench system in southwest japan summary in southwest japan where the philippine sea plate is descending beneath the eurasian plate at the nankai trough we can observe cyclic crustal movement related to the periodic occurrence of interplate earthquakes with the time interval of 102 yr steady uplift of the marine terraces formed by eustatic sea level changes for the last 105 yr and gradual evolution of the island arc trench system through the last 4 x 106 yr we demonstrate that these phenomena with very different characteristic time scales can be consistently explained by a single plate subduction model in our model the lithosphere asthenosphere system is represented by a stratified viscoelastic half space under gravity consisting of a high viscosity surface layer and a low viscosity substratum and interaction between oceanic and continental plates by steady slip motion over the whole plate boundary and its perturbation associated with the periodic occurrence of earthquakes the effects of accretion of oceanic sediments at plate boundaries erosion on land and sedimentation on inner trench walls are also considered in the model from comparison of theoretical results with observed data we obtained the following conclusions valid for young subduction zones observed deformation cycles cannot be explained by a simple rebound model in which the effect of steady plate subduction is ignored the steady plate subduction brings about steady uplift of marine terraces the present patterns of surface topography and gravity anomalies are held nearly stable by the balance of erosion sedimentation rates and substantial growth rates

early holocene catastrophic mass wasting event and fan delta development on the hua tung coast eastern taiwan abstract landslides and debris flows rarely occurred during historical times in the tectonically active coastal range of eastern taiwan this topographic stability however contrasts greatly with the widespread existence of terraced alluvial fans and fan deltas on the hua tung coast which fringes the range this study focuses on the two largest fan terrace systems on the hua tung coast both of which consist of alluvial fans plane view areas up to 8 km 2 larger than their contributing catchments stratigraphic data show that both systems were in sandy wave dominated settings during de glacial times the systems were then disturbed by a catastrophic landslide debris flow event or events which brought enormous amounts of gravel facies gm into the systems deforming previously deposited marine sands facies sm and shallowing the seafloor the combined gm sm complex yields multiple radiocarbon dates ranging from 11 3 to 8 3 ka cal bp with a cluster around 8 6 ka cal bp this mass wasting event has been unique since the emergence of its contributing catchment 0 2 0 3 ma ago the low frequency of such an event could reflect the great resistance of rock mass in the source areas to weathering and erosion the common blockage of valley floors by giant boulder piles which limits channel incision and sediment transport could also increase the apparent stability of the mountain the trigger of landslides in the coastal range has been linked to large earthquakes additionally we propose that the great magnitude and duration of the observed early holocene event were caused by the contemporaneous prolonged rainfall and or high frequency of typhoons associated with the east asian summer monsoon maximum

an igneous origin for features of a candidate crater lake system in western memnonia mars the association of channels inner terraces and delta like features with martian impact craters has previously been interpreted as evidence in favor of the past existence of crater lakes on mars however examination of a candidate crater lake system in western memnonia suggests instead that its features may have formed through igneous processes involving the flow and ponding of lava accumulations of material in craters and other topographic lows throughout much of the study region have characteristics consistent with those of volcanic deposits and terraces found along the inner flanks of some of these craters are interpreted as having formed through drainage or subsidence of volcanic materials channels previously identified as inlets and outlets of the crater lake system are interpreted instead as volcanic rilles these results challenge previous interpretations of terrace and channel features in the study region and suggest that candidate crater lakes located elsewhere should be reexamined

late quaternary coseismic uplift events on the huon peninsula papua new guinea deduced from coral terrace data up to six regressive terraces occur on the holocene raised reef tract and up to 15 occur on late pleistocene raised reef tracts along 40 km of coastline at huon peninsula papua new guinea we suggest that the regressive terraces represent repeated episodic uplift caused by great earthquakes ages of holocene coseismic uplift events are established by radiocarbon dating the late pleistocene events are bracketed by u series ages of the raised reef tracts on which they occur the mean recurrence interval of great earthquakes that caused the uplift events is 970 to 1165 years in the holocene and probably the same in the late pleistocene the interval ranged from about 200 to 1900 years the uplift rate increases parallel to the coast from northwest to southeast and the amplitude of coseismic uplifts generally increases similarly although some events produced uplift with little shore parallel tilting the mean amplitude of coseismic uplifts throughout the study area is 3 m in for both holocene and late pleistocene sequences large late quaternary landslides are numerous and some probably were triggered by the great earthquakes that caused coseismic uplift there appears to be no continuum between historical large earthquakes at huon peninsula of magnitudes 7 that produced no or only minor uplift and the great earthquakes represented by meter scale coseismic uplifts and very large landslides two tectonic subregions are recognized which were uplifted together by some holocene events but not by others there is no surface trace of holocene faulting between the subregions and a buried fault is thought to separate them

a traversing system to measure bottom boundary layer hydraulic properties this study describes a new convenient and robust system developed to measure benthic boundary layer properties with emphasis placed on the determination of bed shear stress and roughness height distribution within estuarine systems by using velocity measurements this system consisted of a remotely operated motorised traverser that allowed a single adv to collect data between 0 and 1 m above the bed as a case study we applied the proposed traversing system to investigate bottom boundary layer bbl hydraulic properties within coombabah creek queensland australia four commonly employed techniques 1 log profile lp 2 reynolds stress rs 3 turbulent kinetic energy tke and 4 inertial dissipation id used to estimate bed shear stresses from velocity measurements were compared bed shear stresses estimated with these four methods agreed reasonably well of these the lp method was found to be most useful and reliable additionally the lp method permits the calculation of roughness height which the other three methods do not an average value of bed shear stress of 0 46 n m2 roughness height of 4 3 mm and drag coefficient of 0 0054 were observed within coombabah creek results are consistent with that reported for several other silty bed estuaries

using uplifted holocene beach berms for paleoseismic analysis on the santa maria island south central chile major earthquakes m 8 have repeatedly ruptured the nazca south america plate interface of south central chile involving meter scale land level changes earthquake recurrence intervals however extending beyond limited historical records are virtually unknown but would provide crucial data on the tectonic behavior of forearcs we analyzed the spatiotemporal pattern of holocene earthquakes on santa maria island smi 37 degrees s located 20 km off the chilean coast and approximately 70 km east of the trench smi hosts a minimum of 21 uplifted beach berms of which a subset were dated to calculate a mean uplift rate of 2 3 0 2 m ky and a tilting rate of 0 022 0 002 degrees ky the inferred recurrence interval of strandline forming earthquakes is similar to 180 years combining coseismic uplift and aseismic subsidence during an earthquake cycle the net gain in strandline elevation in this environment is similar to 0 4 m per event

japan s sediment flux to the pacific ocean revisited abstract quantifying volumes and rates of delivery of terrestrial sediment from island arcs to subduction zones is indispensable for refining estimates of the thickness of trench fills that may eventually control the location and timing of submarine landslides and tsunami generating mega earthquakes despite these motivating insights knowledge about the rates of erosion and sediment export from the japanese islands to their pacific subduction zones remains patchy regardless of the increasing availability of highly resolved data on surface deformation climate geology and topography traditionally natural erosion rates across the island arc have been estimated from regression of topographic catchment metrics and reservoir sedimentation rates that were recorded over several years to decades we review current research in this context correct for a systematic bias in one of the most widely used predictions and present new estimates of decadal to millennial scale erosion rates of japan s terrestrial inner forearc we draw on several independent and unprecedented inventories of mass wasting reservoir sedimentation and concentrations of cosmogenic 10be in river sands we find that natural 10be derived denudation rates of several mm yr 1 in the japanese alps have been sustained over several centuries to millennia and are within error roughly consistent with sediment yields inferred from artificial reservoir sedimentation local exceptions may likely result from release of sediment storage or regional landsliding episodes that trigger transient sediment pulses our synopsis further reveals that catchments draining japan s eastern seaboard differ distinctly in their tectonic lithological topographic and climatic characteristics between the tohoku japanese alps and nankai inner forearc segments which is underscored by a marked asymmetric pattern of erosion rates along the island arc erosion rates are highest up to at least 3 mm yr 1 in the japanese alps that mark the collision of two subduction zones where high topographic relief hillslope and bedrock channel steepness foster rapid denudation by mass wasting comparable if slightly lower erosion rates characterise the nankai inner forearc in southwest japan most likely due to higher typhoon driven rainfall totals and variability rather than its high topographic relief in contrast our estimated erosion and flux rates are lowest in the tohoku inner forearc catchments that feed sediment into the japan trench we conclude that collisional mountain building of the japanese alps drives some of the highest erosion rates in the island arc despite similar uplift and precipitation controls in southwest japan we infer that prior to extensive river damming reservoir construction and coastal works the gross of japan s total sediment export to the pacific ocean entered the accretionary margin of the nankai trough as opposed to the comparatively sediment starved japan trench compared to documented contemporary rates of sediment flux from mountainous catchments elsewhere in the pacific the rivers draining japan s inner forearc take an intermediate position despite high relief steep slopes very high seismicity and frequent rainstorms however the average rates of millennial scale denudation in the japanese alps particularly are amongst the highest reported worldwide local mismatches between these late holocene and modern rates emphasise the anthropogenic fingerprint on sediment retention that may have significantly reduced the island arc s mass flux to its subduction zones as is the case elsewhere in east and southeast asia

holocene sea level rise and coral reef growth on a tectonically rising coast huon peninsula papua new guinea abstract eighty eight conventional radiocarbon age measurements of corals collected from holocene transgressive reefs at huon peninsula have been published previously but except for 29 dates from a 52 m drillhole the data have not been systematically analysed from these data we show that post glacial reef growth tracked rising sea level keep up growth at huon peninsula from 70 m at 11 200 yr bp the holocene reef emerged about 6300 yr bp in the southeast of the region where uplift rate is highest 3 3 m ka 1 and at about 5950 yr bp in the northwest where uplift rate is 1 9 m ka 1 the uplift process is dominated by metre scale coseismic uplift events the difference in timing of reef emergence between northwest and southeast is related to differences in the stepwise uplift of the two regions although uplift is stepwise the uplift corrected age height data from the dated corals fall within a tight envelope which represents a well defined eustatic sea level curve for the calibrated age interval from 7000 to 13 000 yr bp

fossil tubeworms link coastal uplift of the northern noto peninsula to rupture of the wajima oki fault in ad 1729 abstract the active fault zone on the seafloor off the northern coast of the noto peninsula of central japan is divided into four segments from west to east monzen oki saruyama oki wajima oki and suzu oki to examine the latest event that occurred in these segments we investigated the dates and elevations of fossilized intertidal tubeworms along the northern coast of the noto peninsula located on the hanging wall sides of the faults using radioactive carbon dating and global positioning measurements for each fossil we calculated the difference between the past and present elevation thereby estimating the elevation of the sea level at the date of the fossil using a curve for sea level change this calculation provided us with the elevation change at each site the vertical changes estimated from the elevations and ages of the intertidal tubeworms revealed that the coastal emergence probably occurred between 1600 and 1800 ad this area of coastal emergence lies adjacent to active faults within the wajima oki segment a model for rectangular faults with three fault planes and a moment magnitude of 6 6 for the wajima oki segment reproduced the observed pattern of coastal emergence well only one damaging earthquake that in 1729 is known to have occurred in this part of the northern noto peninsula between 1600 and 1800 ad and there has not been one since 1800 ad the slip distribution of the fault predicted by the model is consistent with the distribution of shaking related damage documented in 1729 we conclude that rupture of the wajima oki segment caused the 1729 earthquake

velocity field of gps stations in the taiwan area abstract the 131 stations of the taiwan gps network were surveyed 4 6 times from 1990 to 1995 with dual frequency geodetic receivers the standard deviation of an observed baseline length with its linear trend removed is in the range of 6 10 mm for a 3 120 km long baseline the average rates of length change for all baselines of the network and those from nine continuously monitoring permanent stations are used in a least squares adjustment to estimate the velocities of the gps stations relative to paisha penghu situated at the chinese continental margin to the south of fengping in the northern coastal range the velocity vectors of stations in lanhsu lutao and the coastal range trend in the directions of 306 322 with rates of 56 82 mm yr in contrast there is a dramatic decrease in the rates to the north of fengping this may be caused by the motion along the ne sw trending thrusts which obliquely cut the northern coastal range a discontinuity of about 30 mm yr in the rates along with a remarkable change in the directions of station velocity is observed across the longitudinal valley then the moving directions gradually shift to the west for the stations in the western foothills in the kaohsiung pingtung coastal area the station velocities are even directed toward the southwest to the north of the peikang high the velocity vectors of the stations change direction from the west gradually to the north and finally to the east and southeast significant nw se extensional deformation is found in the ilan plain and northern taiwan in general the pattern of the velocity field for gps stations in the taiwan area is quite consistent with the directions of present day tectonic stress

late holocene coseismic uplift on the hua tung coast eastern taiwan evidence from mass mortality of intertidal organisms abstract the evidence of coseismic uplift on the dynamic wave dominated hua tung coast fringing the active coastal range eastern taiwan has been equivocal due to complex controls by wave and terrestrial sediment over morphological and ecological systems of the coast this study by applying radiocarbon dating methods demonstrates coseismic uplift nature of the coast by finding synchronously killed intertidal organisms mostly boring shell jouannetia sp stranded at different sites of the coast with distinct physiographic characters based on these data together with evidence from wave cut notch sequences two coseismic uplift systems are recognized one centers around the northern middle part of the coast and yields events with uplift amounts of maximal 3 6 m and an average recurrence interval of at least several hundred years the most recent activity of this system influencing at least 70 km of coast occurred at 0 9 ka the earthquake generating this event also triggered extensive landslides debris flows in the region another system exemplified by the uplift associated with the 2003 cheng kung earthquake centers on the southern part of the coast and yields uplift of likely

holocene tectonic uplift deduced from elevated shorelines eastern coastal range of taiwan abstract this paper is concerned with the tectonic trends that can be deduced from the holocene raised shorelines between ch eng kung and hsin she along a 65 km long coastal sector in the eastern coastal range of taiwan sequences of up to eight superimposed shorelines have been identified in a single section twelve new radiocarbon dates six of which were obtained by accelerator mass spectrometry of in situ marine samples up to 40 m in altitude have confirmed a holocene age however it is difficult to define clearly the upper marine boundary in the highest holocene coastal terraces which have been uplifted to 65 70 m but have been capped by and often also interfingered with alluvial deposits high uplift rates ranging from 2 5 3 0 to over 8 mm yr have been inferred along the coast providing evidence of differential uplift in some cases uplift movements appear to have occurred by steps probably spasmodically recurrence periods of fast uplifts seem to be of the order of at most 1000 yr this means that a new spasmodic movement may be imminent because the last displacement 4 6 m has been dated about 1000 yr bp

a synthesis of the geologic evolution of taiwan abstract the island arc of taiwan is composed of cenozoic geosynclinal sediments more than 10 000 m thick lying on a pre tertiary metamorphic basement pleistocene to miocene andesitic islands surround the main island and are related mostly to arc magmatism the penghu island group in the taiwan strait is covered with pleistocene flood basalt neogene shallow marine clastic sediments are exposed mainly in the western foothills with pleistocene andesitic extrusives at the northern tip and the northeastern offshore islands a thick sequence of paleogene to miocene argillitic to slaty metaclastic rocks underlies the western central range and forms the immediate sedimentary cover on the pre tertiary metamorphic complex to the east which represents an older mesozoic arc trench system the coastal range in eastern taiwan is a neogene andesitic magmatic arc including also a large variety of volcaniclastic and turbiditic sediments cenozoic taiwan is the site of arc continent collision where the luzon arc on the philippine sea plate overrides the chinese continental margin on the eurasian plate east and northeast of taiwan the polarity of subduction changes whereby the oceanic philippine sea plate is subducting beneath the ryukyu arc system on the eurasian plate continent arc collision in taiwan island is anomalous and may occur in a broad belt of deformation rather than along a well defined plate boundary or subduction zone

wind and buoyancy driven horizontal exchange in shallow embayments of a tropical reservoir lake argyle western australia many factors including depth vegetation density wind and gyres may act to influence the littoral exchange in a water body but very few studies have investigated the interaction between more than two of these factors at any time to investigate these controls on horizontal exchange in a large tropical reservoir we conducted a 9 d intensive field experiment in lake argyle western australia the experiment began with a 7 d cooling period that generated water in the shallows of the reservoir embayments that was persistently cooler than the interior this led to an underflow of dense water that moved from the lake boundary toward the center of the reservoir a three dimensional hydrodynamic model elcom was able to adequately reproduce this thermal structure and was used to demonstrate its sensitivity to wind sheltering effects and submerged macrophyte presence further analysis of the predictions indicated that when the ratio of the shear and buoyancy force averaged over 6 h b6h and 6 h averaged wind speed in the direction of the embayment u6h was 1 greater than 0 5 ms 1 and 4 5 ms 1 respectively the exchange was dominated by a topographic gyre formation 2 when 0 1 b6h 0 5 and 2 4 ms 1 u6h 4 5 ms 1 the resulting circulation was a combination of differential cooling flows and a topographic gyre circulation and 3 when u6h fell below 2 4 ms 1 purely buoyancy driven flow occurred but only if the buoyancy forces across the embayments were an order of magnitude greater than wind induced velocity shear

holocene paleoseismicity in the fold and thrust belt of the hikurangi subduction zone eastern north island new zealand abstract along the 500 km long eastern coastline of the north island new zealand there are at most seven distinct holocene marine terraces aged 7 ka b p or less the highest of the terraces is 27 m above present day mean sea level the coastal region is subdivided into fourteen distinct subregions based on radiocarbon ages of marine deposits overlying wave cut shore platforms and geographic distribution of similarly aged terraces holocene marine terraces are the result of uplift associated with large earthquakes co seismic deformation this conclusion is based on characteristic stepped terrace morphology clustering of ages of terrace deposits within subrogions and the occurrence of co seismic uplift in historic time differential uplift across structures and distinct age variations at subregion boundaries are also characteristic recurrence intervals of uplift in any one terrace sequence vary from 0 4 ka to 2 0 ka and individual amounts of uplift vary from 1 0 m to 4 0 m in the past 2 5 ka ages from all terraces within subrogions indicate at least 21 paleoseismic events affecting coastal areas of eastern north island in that period these events cluster in time and in separate parts of eastern north island several earthquakes occurred 0 3 0 6 1 0 1 5 2 1 and 2 3 ka b p our data strongly support the concept of segmentation of deformation along the subduction margin the likely cause of coastal uplift is movement on steep reverse faults local structures rather than the subduction thrust that propagate from or near the subduction thrust some 20 25 km below the region earthquakes of moment magnitude 7 3 8 0 are estimated to be associated with these fault movements

stratigraphic modeling of the western taiwan foreland basin sediment flux from a growing mountain range and tectonic implications abstract sediment flux signals from source to sink in foreland basins preserve a record of tectonics sea level and climate through erosion and sedimentation however longitudinal sediment transport often occurs in foreland basins thus removing part of the orogenic material flux from foreland basin records here we use mass balance calculation and stratigraphic simulations of sediment fluxes for the taiwan orogen to provide an order of magnitude estimate of how much orogenic material may bypass a foreland basin our results indicate a significant potentially more than 50 mismatch between sediment volume currently preserved in the basin and the amount of material presumably eroded from the orogen since the onset of collision in taiwan this suggests either a significant overestimation of average erosion rates over the period concerned with orogenic development of taiwan or it supports previous paleogeographic work suggesting that longitudinal sediment transport in the paleo taiwan strait served as a major bypass conduit of importance for the establishment of a steady state orogen we identify candidate submarine topography in the south china sea that may preserve taiwan s missing erosional mass

estimating local bed shear stress from velocity observations replicate velocity observations using conventional equipment under typical field conditions are used to evaluate the precision of different methods for estimating local boundary shear stress from velocity measurements the bed shear velocity u can be estimated within 3 using the depth averaged velocity in the vertically averaged logarithmic velocity profile to be accurate this method is limited to relatively simple flow geometries which may be expected to have the appropriate velocity structure estimates of u made using a single near bed velocity observation are less precise by a factor of 3 because of the larger uncertainty associated with a single observation accuracy of this method requires appropriate flow conditions only near the bed so it may be applied in a wider range of flow conditions including spatially variable flow estimates of u from the slope of the near bed velocity profile are the least precise and require the most restrictive flow conditions for accuracy but offer the advantage that they may be made without independent knowledge of the bed roughness different methods for estimating roe should be useful in judging the precision of estimates made under similar conditions these estimates of precision together with considerations of convenience and model accuracy provide the basis for select ing the most appropriate or advantageous method for different conditions and purposes

the potential for a great earthquake along the southernmost ryukyu subduction zone interseismic gps data along the hualien suao coast ne taiwan shows a pattern of strain accumulation that is consistent with a potential future large shallow earthquake along the southernmost ryukyu subduction zone the measured shortening rate parallel to the ryukyu trench is 80 mm yr about twice of the shortening rate perpendicular to the ryukyu trench we invert for slip deficit rates and the geometric configuration of the plate interface our preferred fault model dips 10 northward and extends about 70 km from the ryukyu trench to a depth of 13 km the slip deficit rate exhibits a left lateral motion of 78 mm yr and a normal motion of 36 mm yr on a 290 trending fault the slip rate budget of the southernmost ryukyu subduction zone is close to the plate convergence rate suggesting the plate interface is fully locked assessments of seismic hazard in this region need to consider the potential threat from m w 7 5 8 7 tsunami earthquakes generated by shallow ruptures

late miocene vegetation reconstruction with the caraib model abstract climatic outputs from the atmospheric general circulation model echam4 coupled to a mixed layer ocean model are used as inputs to the caraib global vegetation model to reconstruct the distribution of vegetation and the biosphere carbon stocks over the continents during the late miocene tortonian the results show significant changes in the geographical distribution of vegetation during the late miocene compared to the present with a reduction of desert areas and an expansion of tropical seasonal forests which reached temperate latitudes these changes in vegetation distribution are accompanied by a moderate increase of the total biosphere carbon stock by 159 gt sensitivity tests to atmospheric co 2 have also been performed with the vegetation model only i e while keeping constant all climatic variables to their reference tortonian state these tests point out the potential importance of co 2 fertilization both regarding vegetation distribution and biosphere carbon storage the impact of an atmospheric co 2 decrease from 280 to 200 ppmv or increase from 280 to 560 ppmv on the vegetation distribution appears to be at least as large as that of the climate change between the tortonian and the present while in terms of carbon storage the impact of atmospheric co 2 is far much larger than the climatic one although the actual response of vegetation to co 2 fertilization may be much smaller than its theoretical response in the model these results emphasize the need to consider atmospheric co 2 as an important parameter for palaeovegetation reconstructions

estimates of bottom roughness length and bottom shear stress in south san francisco bay california a field investigation of the hydrodynamics and the resuspension and transport of particulate matter in a bottom boundary layer was carried out in south san francisco bay south bay california during march april 1995 using broadband acoustic doppler current profilers detailed measurements of turbulent mean velocity distribution within 1 5 m above bed have been obtained a global method of data analysis was used for estimating bottom roughness length zo and bottom shear stress or friction velocities u field data have been examined by dividing the time series of velocity profiles into 24 hour periods and independently analyzing the velocity profile time series by flooding and ebbing periods the global method of solution gives consistent properties of bottom roughness length zo and bottom shear stress values or friction velocities u in south bay estimated mean values of zo and u for flooding and ebbing cycles are different the differences in mean zo and u are shown to be caused by tidal current flood ebb inequality rather than the flooding or ebbing of tidal currents the bed shear stress correlates well with a reference velocity the slope of the correlation defines a drag coefficient forty three days of field data in south bay show two regimes of zo and drag coefficient as a function of a reference velocity when the mean velocity is 25 30 cm s 1 the ln zo and thus the drag coefficient is inversely proportional to the reference velocity the cause for the reduction of roughness length is hypothesized as sediment erosion due to intensifying tidal currents thereby reducing bed roughness when the mean velocity is 25 30 cm s 1 the correlation between zo and the reference velocity is less clear a plausible explanation of scattered values of zo under this condition may be sediment deposition measured sediment data were inadequate to support this hypothesis but the proposed hypothesis warrants further field investigation

modern vertical deformation rates and mountain building in taiwan from precise leveling and continuous gps observations 2000 2008 1 to characterize the present day vertical displacement field in the active taiwan orogenic belt 1843 precise leveling and 199 continuous gps measurements from 2000 to 2008 are collected and analyzed in this study vertical velocities derived from the leveling data are placed in a reference frame of the chinese continental margin using continuous gps observations at nearby sites the leveling and gps vertical velocities generally reveal a dome shaped pattern with uplift of 0 2 18 5 mm yr in the interior of the mountain range and subsidence on the flanks of the mountains and coastal plains modern uplift rates in the active fold and thrust belt are generally consistent with geologic uplift rates however present day uplift rates in the central range are faster than the million years averaged exhumation rates the modern subsidence rates are generally consistent with geologic rates except for the rates in western coastal areas due to groundwater pumping present day subsidence in the southern central range and northern coastal range is however inconsistent with long term uplift which may reflect interseismic elastic strain accumulation across faults present day subsidence in northern taiwan occurs in a region of postcollisional orogenic collapse we model the present day and geologic vertical velocities and published gps horizontal velocity data across southern taiwan using a 2 d lithospheric model the model suggests a combined slip rate of 40 mm yr on the frontal thrusts and 45 mm yr on the longitudinal valley fault the model requires an additional source of crustal thickening under the central range to match the observed present day uplift rates

new insights into holocene marine terrace development caused by seismic and aseismic faulting in the coastal range eastern taiwan abstract the coastal range in eastern taiwan which has resulted from arc continent collisions involves well developed holocene uplifted marine terraces along a 140 km long stretch of the coast this is the first study that unraveled the aseismic generation of marine terraces associated with coseismic uplift along the creeping fault we organized dems lidar mapping and field surveys to obtain detailed and systematic measurements of the inner and outer edges and wave cut platform elevations along thirty three stream profile transects allowing us to locate the bedrock profile spatial and temporal variations in the 14c age are characterized by an offlapping built feature of significant seaward younging trend of ages across the marine terrace caused by aseismic and coseismic uplift thus heights of the bedrock riser and platform are caused by coseismic large earthquake and aseismic plus moderate coseismic vertical deformations during a large earthquake cycle respectively this indicates that each terrace duration and paleoshoreline ages can be used to infer the recurrence interval and the timing of large earthquake events respectively results of the age of the paleoshoreline indicate six paleoseismic events at 8500 6300 4800 3400 1700 and 700 yr bp this implies that the chihshang creeping fault could be capable of producing large earthquakes greater than m7 at millennial time scales associated with larger coseismic deformations the creep faulting associated with seismic and aseismic uplift is a dominant process constraining the holocene marine terrace evolution

modes rates and geomorphological consequences of active tectonics in the marmara region nw turkey a critical overview based on seismotectonic field observations abstract the marmara region is a tectonically active belt in northwestern turkey where field evidence of the collusion escape and strike slip tectonics is manifested the effect of tectonics on the modification of coastal and morphological features of nw turkey is although extensive relatively unknown and rarely appreciated active tectonics in the region has normal and reverse forms of dip slip namely uplift and subsidence and strike slip as is plainly demonstrated by the 1999 marmara earthquake sequence along the north anatolian fault naf these tectonic effects are presently related to the geometry of the naf the mode of lateral movement along it and proximity to the fault the 1999 earthquakes provided data indicating that over a return period of about 250 years seismotectonic strike slip movements recur up to 5 m and dip slip movements up to 2 6 m suggesting the rate of tectonics along the naf in the marmara region is on the order of 20 mm a for strike slip and 10 mm a for dip slip movements these rates are sufficiently large to form during the late quaternary prominent features of the landscape in the marmara region

submerged notches coastal changes and tectonics in the rijeka area nw croatia abstract submerged coastal notches characterize the coast of the wider rijeka area nw croatian coast adriatic sea these notches originate from a notch formed approximately 2 000 years ago their depth ranges between 0 50 and 1 15 m and their subsidence history is a matter of debate a detailed study of all the available data in relation to the tectonics of the area was made using signal analysis techniques our analysis revealed that the notch depth reflects the superimposition of two different effects a quasi regional relative sea level rise of about 55 cm and of a subsequent local tectonic subsidence with amplitude gradually increasing to 60 cm in the vicinity of the major thrust in the bakar bakar vinodol area elastic dislocation modeling permitted to explain this last local subsidence in terms of loading of the footwall of this thrust and provide evidence for an unrecorded earthquake of minimum magnitude m w 6 8 which occurred most probably in the last few centuries this result indicates that the convergence between the southern alps and the adria is at least partly accommodated by earthquakes and puts some constraints in the estimations of the seismic risk in the wider region

variable uplift rate through time holocene coral reef and neotectonics of lutao eastern taiwan abstract significant discrepancies have existed regarding rate and timing of the uplift of lutao green island located at the border of the ongoing collision between the eurasia continental plate and the philippine sea plate to document its neotectonic history two cores were drilled into holocene coral reefs exposed at the southeastern coast of lutao twelve pristine fossil corals nine taken from cores and three on the surface were 230th dated the results show that the coral reefs started to develop at 8 736 56 yr bp before 1950 ce with uplift rate varying from 3 6 mm yr during 8 7 6 0 kyr bp to 1 2 mm yr in the past six thousand years our study strongly suggests that the uplift rate can vary significantly on millennial time scale caution should be used when extrapolating uplift rate estimates based on mid late holocene corals to early times for tectonic active locations such as lutao

estimating bottom stress in tidal boundary layer from acoustic doppler velocimeter data bed stresses in the bottom boundary layer of the york river estuary virginia were estimated from three dimensional near bottom velocities measured by acoustic doppler velocimeters advs and also by a profiling array of electromagnetic current meters by assuming the measurements were made in a constant stress layer four methods of stress estimation were evaluated using advs direct covariance cov measurement turbulent kinetic energy inertial dissipation utilizing the kolmogorov spectrum and log profile the four methods yielded similar estimates of frictional velocity u based on adv output from both 14 cm and 44 cm above bed all eight estimates of average u were consistent with the overall mean of 1 10 cm s to within the 95 confidence interval for individual burst estimates the cov method worked slightly better nearer the bed possibly because of the sensitivity of cov to the upper limit of the constant stress layer the inertial dissipation method performed marginally well at 14 cm above bed likely because of sediment induced stratification and insufficient separation of turbulent production and dissipation scales the log profile method was the most variable and appeared most sensitive to stratification and to the thickness of the constant stress layer the turbulent kinetic energy method was the most consistent at both heights and appears most promising for further development results encourage future use of the adv in estuarine environments but also favor the simultaneous use of several methods to estimate bottom stress

holocene coral reef terraces and coseismic uplift of huon peninsula papua new guinea abstract as many as six levels of emerged holocene coral terraces occur along 40 km of coastline on the huon peninsula papua new guinea recording uplift history since culmination of the postglacial transgression the holocene reef crest ca 6000 yr b p is tilted down to the northwest parallel to the coast and concordant with the deformation of the last interglacial coral reef terrace and descends from 23 to 12 m in the study area the pattern and rate of deformation have been uniform in the late quaternary because average uplift rates have remained the same since the last interglaciation the holocene terraces described here are erosional features with regressive encrusting corals developed upon the holocene transgressive reef the multiple levels represent episodic probably coseismic uplift which has occurred repeatedly in the last ca 6000 yr significant longshore variation in the age of the lowest terrace from 1700 to 2500 yr b p suggests independent coseismic uplift on different sectors of the coast this is supported by age height relationships of the higher holocene terraces nonlinear uplift during the holocene with recurrence intervals increasing toward the present is clearly recorded by the regressive terraces in each subregion some of the holocene regressive terraces grade laterally into fluvial terraces capped with debris flow deposits probably reflecting seismically triggered mass movement

marine deposits of late glacial times exposed by tectonic uplift on the east coast of taiwan abstract marine sediments deposited some 14 000 years ago when the sea level was between 80 and 100 m below the present sea level have been found exposed at about 17 m in altitude near tu lan on the east coast of taiwan this implies a minimum average uplift rate of 7 6 0 9 mm yr similar values of tectonic uplift are not uncommon on the eastern coastal range of taiwan such rates of tectonic uplift among the highest reported in the literature are of the same order as present day maximum glacio isostatic uplift rates

a mass wasting dominated quaternary mountain range the coastal range in eastern taiwan abstract fluvial bedrock incision which creates topographic relief and controls hillslope development has been considered the key medium linking denudation and tectonic uplift of unglaciated mountains this article however shows a different scenario from the coastal range in eastern taiwan this range with the steepness inherited from pre orogenic volcanoes has been subject to mass wasting even before its emergence above sea level no earlier than middle pleistocene numerous terraced alluvial fans fan deltas record the ancient mass movements of the range including rock avalanches multiple radiocarbon dates 1 km 2 alluvial terraces are typically exhibited close to the source ridges of mass movements and strath terraces along the downstream parts of rivers both were created when enormous sediment supply had exceeded or matched the prevailing river transport capacity this process along with the protection by giant boulders from mass movement disturbed the long term incision trend of rivers in response to tectonic uplift as a result the observed holocene bedrock incision at most sites has not kept pace with the tectonic uplift the spatial contrast in mass wasting histories further accounts for the great diversity of the terrace sequences even in areas with similar tectonic and base level conditions

isotopic climate record in a holocene stalagmite from ursilor cave romania the pu 2 stalagmite from ursilor cave provides the first dated romanian isotope record for the holocene the overall growth rate of the speleothem was 3 5 cm kyr 1 corresponding to a temporal resolution of 142 y between each isotope analysis the hendy tests indicate that isotopic equilibrium conditions occurred during the formation of pu 2 and hence that it is suitable for palaeoclimatic studies the relationship between 18 o and temperature was found to be positive this can be interpreted either as rain out with distance from the west northwest ocean source of evaporation or shifts in air mass source with changing north atlantic oscillation indices applying five u th thermal ionisation mass spectrometric tims dates to a 17 5 cm isotope profile 18 o

a 9000 year record of cyclic vegetation changes identified in a montane peatland deposit located in the eastern carpathians central eastern europe autogenic succession or regional climatic influences abstract we present a high resolution continuous plant macrofossil remains record complemented by a pollen sequence from t ul muced bog in the eastern carpathian mountains romania the record spans the last 9000 years and we test whether peatland development in the eastern carpathians is linked to climate change or to autogenic succession we find that sphagnum magellanicum was the dominant peat forming species for ca 8000 years but we also identify ten phases of increased representation of eriophorum vaginatum at approximately 8100 7550 6850 6650 5900 4650 3150 1950 1450 and 750 cal yr bp visual inspection and wavelet analysis show that the episodic increases in the relative abundances of eriophorum vaginatum were simultaneous with decreased abundances of sphagnum magellanicum and sphagnum angustifolium comparison with published palaeoclimatic records in this region suggests that these cyclical successions of s magellanicum and e vaginatum appear to be primarily a result of climate changes with e vaginatum developing mainly during dry phases and s magellanicum during wetter periods we therefore suggest that the development of this peatland was largely influenced by changing climatic conditions although the role of autogenic plant succession cannot be excluded our results show the value of ombrotrophic peat deposits as archives of past climate change

sensitivity of bed shear stress estimated from vertical velocity profiles the problem of sampling resolution bed shear stress in open channel flows is often estimated from the logarithmic vertical velocity profile however most measuring devices used in the field do not allow for flow velocity to be measured very close to the bed the lack of near bed measurements is a critical loss of information which may affect bed shear stress estimates detailed velocity profiles obtained from a field acoustic doppler velocimeter over three different bed roughnesses clearly show that the inclusion of near bed points is critical for the estimation of bed shear stress in a shallow river environment moreover the results indicate that using the full flow depth instead of the bottom 20 per cent of the profile generates an underestimation of the shear stress when flow is uniform 1998 john wiley sons ltd

active coastal thrusting and folding and uplift rate of the sahel anticline and zemmouri earthquake area tell atlas algeria abstract major uplifts of late quaternary marine terraces are visible along the coastline of the tell atlas of algeria located along the africa eurasia convergent plate boundary the active tectonics of this region is associated with large shallow earthquakes m 6 5 numerous thrust mechanisms and surface fault related fold we conducted a detailed levelling survey of late pleistocene and holocene marine notches in the algiers region that experienced 0 50 m coastal uplift during the 2003 zemmouri earthquake mw 6 8 east of algiers holocene marine indicators show three pre 2003 main notch levels formed in the last 21 9 ka west of algiers on the sahel anticline the levelling of uplifted marine terraces shows a distinct staircase morphology with successive notches that document the incremental folding uplift during the late pleistocene and holocene the timing of successive uplifts related to past coseismic movements along this coastal region indicates episodic activity during the late holocene modelling of surface deformation in the zemmouri earthquake area implies a 50 km long 20 km wide ne sw trending se dipping fault rupture and an average 1 3 m coseismic slip at depth further west the 70 km long sahel fold is subdivided in 3 sub segments and shows 0 84 1 2 mm yr uplift rate in the last 120 140 ka the homogeneous holocene uplift of marine terraces and the anticline dimensions imply the possible occurrence of large earthquakes with mw 7 in the past the surface deformation and related successive uplifts are modelled to infer the size and characteristics of probable future earthquakes and their seismic hazard implications for the algiers region

continuous gps array and present day crustal deformation of japan a gps array with about 1 000 permanent stations is under operation in japan the gps array revealed coseismic deformations associated with large earthquakes and ongoing secular deformation in the japanese islands based on daily coordinate data of the gps stations strain rate distribution is estimated most regions with a large strain rate are related to plate boundaries and active volcanoes in addition the niigata kobe tectonic zone nktz is recognized as a region of large strain rate along the japan sea coast and in the northern chubu and kinki districts this newly found tectonic zone may be related to a hypothetical boundary between the eurasian or amurian and the okhotsk or north america plates precise observation of crustal deformation provides important boundary conditions on numerical modeling of earthquakes and other crustal activities appropriate computation methods of continuous deformation field are directly applicable to data assimilation for such numerical simulations

seabed stress determinations using the inertial dissipation method and the turbulent kinetic energy method direct measurements of seabed stress are difficult especially in field conditions several methods for estimating these stresses using current meter data are available two of these methods the inertial dissipation method and the turbulent kinetic energy method are described below and a matlab program is used to analyse data from a wave current environment

seismotectonic characteristics of the northernmost longitudinal valley eastern taiwan structural development of a vanishing suture abstract the longitudinal valley in eastern taiwan is generally considered as the suture of the collision between the philippine sea and the eurasian plates and has attracted numerous geologic and seismologic studies in the northernmost part of the valley however constraints on how structures develop as the suture turns into the ryukyu subduction system offshore are still very limited therefore we analyzed relocated seismicity distributions and focal mechanisms of earthquake sequences together with tectonic geomorphic investigations to further understand the seismotectonic characteristics of this area in our seismologic observations we found two previously unidentified reverse faults in the northernmost part of the longitudinal valley suture one is an e w striking south dipping reverse fault near the liwu river fan delta and the other is a n s striking east dipping reverse fault near the eastern central range front both these structures connect with a detachment at 10 km deep and may connect with each other to form a curved structural system the meilun fault a well known active structure that ruptured in a m7 3 earthquake in october 1951 is not seismically active in the past two decades and may just be part of a secondary branch of the major structural system in the northernmost part of the longitudinal valley suture we propose that as the coastal range bedrocks subduct northward beneath the eurasian plate with the philippine sea plate the shallow sediments of the longitudinal valley being a buoyant block do not subduct but overthrust northward and westward instead

review of paleoseismological and active fault studies in taiwan in the light of the chichi earthquake of september 21 1999 abstract this paper reviews the research on active and earthquake faults in taiwan conducted prior and after the 1999 chichi earthquake the chichi earthquake plays as a turning point of the relevant studies since the 1999 coseismic surface rupture exactly follows preexisting fault scarps created in turn by previous seismic events along the chelungpu fault this fact indicates that the precise mapping on the other active faults is fundamental to predict the location of surface rupture caused by large future earthquakes since 1999 many trenching studies have been carried out along the chichi earthquake fault a few of them demonstrates that the penultimate event is as young as probably only 200 430 years old however some others show a rather old age of several hundreds years or even older for the last faulting event before 1999 more trenching studies are necessary for such a long fault in order to understand the possible segmentation features and the correlation of the paleoseismic events identified along the entire fault length in addition we further discuss the offshore faulting associated with seismic event along the eastern coast of taiwan where the multiple holocene terraces are well known

evidence for coseismic and aseismic uplift in the last 1000 years in the focal area of a shallow thrust earthquake on the noto peninsula west central japan 1 raised shorelines on the noto peninsula on the western coast of central japan suggest a millennial history of recurrent uplift emergence of the coastline by up to 50 cm was recently recorded in association with a moderate earthquake m w 6 7 on 25 march 2007 the shoreline uplift is indicated by the displacement of sessile organisms such as calcareous tubeworms which can also be examined as indicators of past shifts in shoreline level three levels of pre 2007 paleoshorelines are thus identified on this stretch of the japan sea coast the lowest of these dated at ad 1720 1950 tilts northward away from the likely source of a pair of ca m 6 4 earthquakes in 1892 which occurred in a different area to the 2007 earthquake the middle paleo shoreline dated at ad 1430 1655 records a 30 40 cm emergence that may be aseismic the high paleo shoreline dated at ad 1025 1235 records a coseismic uplift of 50 cm and is limited to the area raised coseismically in 2007 the most recent event preceding the 2007 earthquake thus appears to have occurred approximately 1000 years ago

age and height distribution of holocene transgressive deposits in eastern north island new zealand abstract holocene transgressive deposits are frequently exposed near the present day coastline of the study area along eastern north island new zealand they occur in sites of former estuaries that were filled during the postglacial rise in sea level we present one hundred radiocarbon dates of holocene transgressive deposits from the study area ranging in age from ca 10 000 to 5500 yr b p relative sea level curves up to ca 6000 yr b p were reconstructed for six locations the curves have similar slopes prior to about 7000 yr b p indicating that sea level rise was much more rapid than any tectonic uplift at that time the postglacial rise in sea level in new zealand is considered in general to have culminated at about 6500 yr b p but the upper limit ages of transgressive deposits in our study area vary from ca 5500 to 7000 yr b p at sites where the uplift rate is high the postglacial transgression culminated rather earlier than ca 6500 yr b p and at sites where there is subsidence or there is very low uplift the culmination is later than ca 6500 yr b p nine of fourteen dates from fossil trees in growth position that grew in and were buried by estuarine silt cluster in the age range ca 8000 8400 yr b p these data support the view that there was a minor regression or stillstand in the eustatic sea level rise at that time eleven tectonic subregions are recognized in the study area on the basis of average uplift rate most of these subregions coincide with those established from the number and ages of younger holocene marine terraces of probable coseismic origin

a model for the termination of the ryukyu subduction zone against taiwan a junction of collision subduction separation and subduction boundaries 1 the nw moving philippine sea plate psp collides with the eurasian plate eup in the vicinity of taiwan and at the same time it subducts toward the north along sw ryukyu the ryukyu subduction zone terminates against eastern taiwan while the ryukyu trench is a linear bathymetric low about 100 km east of taiwan closer to taiwan it cannot be clearly identified bathymetrically owing to the deformation related to the collision making the location of the intersection of the ryukyu with taiwan difficult to decipher we propose a model for this complex of boundaries on the basis of seismicity and 3 d velocity structures in this model the intersection is placed at the latitude of about 23 7 n placing the northern part of the coastal range on eup as psp gets deeper along the subduction zone it collides with eup on the taiwan side only where they are in direct contact thus the eurasian plate on the taiwan side is being pushed and compressed by the nw moving philippine sea plate at increasing depth toward the north offshore of northeastern taiwan the wedge shaped eup on top of the ryukyu subducting plate is connected to the eup on the ryukyu side and coupled to the nw moving psp by friction at the plate interface the two sides of the eup above the western end of the subduction zone are not subjected to the same forces and a difference in motions can be expected the deformation of taiwan as revealed by continuous gps measurements geodetic movement along the east coast of taiwan and the formation of the hoping basin can be understood in terms of the proposed model

coastal uplift mechanisms at pakarae river mouth constraints from a combined holocene fluvial and marine terrace dataset abstract one of the major environmental controls on sedimentary systems is tectonics and thus in order to make quantitative explanations and predictions of the behaviour of sedimentary systems it is important to quantify tectonic rates and mechanisms in this study we show how a combined holocene fluvial and marine terrace dataset can be used to place constraints on coastal uplift mechanisms at pakarae river mouth to the east of the waipaoa sedimentary system mapping and surveying of fluvial terraces shows that the terraces can be divided into three sets i pgt a fill terrace formed during post glacial sea level rise 10000 7000 cal yr bp ii a sequence of post 7000 cal yr bp degradation terraces and iii historical post ad 1880 flood terraces a conceptual model of terrace evolution proposes that coseismic uplift has resulted in the observed back tilting downstream divergence and successive abandonment of tectonic terraces coastal uplift mechanisms are then examined by comparing the fluvial and marine terrace uplift distribution and the uplift per event from the marine terraces with those predicted by forward elastic dislocation models the models agree with the interpretation that the terrace uplift can be explained by coseismic slip on a steeply west dipping reverse fault located close to the shore possibly in combination with rupture of the hikurangi margin subduction interface 10 24 km below this study also provides insights into the tectonic drivers and impacts on the adjacent waipaoa sedimentary system including the possible role of subduction earthquakes growth of structures on the shelf and upper slope and the role that the interplay between sea level and tectonic controls has on sediment dispersal

tectonic and morphosedimentary features of the 2010 chile earthquake and tsunami in the arauco gulf and mataquito river central chile abstract effects of the 2010 chilean earthquake and tsunami were evaluated at coastal sites between two zones of different coseismic deformations land deformation run up inundation extent and deposit extent and thickness were measured in the field providing insights into the processes and morphological changes associated with tsunami inundation and backwash three to five waves of up to 10 m height deposited several related layers along the coast the thickness of these sandy deposits does not exceed 80 cm and is generally less than 30 cm coseismic deformation measured by means of bio and geomorphic markers agrees well both with model deformation and measured gps there is no relationship between the run up height and the trend of coseismic deformation uplift or subsidence mainly because the effects of the tsunami were influenced locally by offshore bathymetry and coastal morphology

holocene forest dynamics in northwestern romnania pollen analyses and ams radiocarbon measurements were carried out on peat deposits from the former crater lake preluca tiganului located in a mid altitude area of the gutaiului mountains nw romania in order to reconstruct the postglacial vegetation history at the lateglacial holocene transition the open vegetation was replaced by forest suggesting a fast response to climatic warming the rapid expansion of pinus betula and later picea may be due to their existence in the area during the lateglacial at approximately 11 250 cal yr bp the dense forest was composed primarily of ulmus and some picea betula and pinus a small population of ulmus might also have survived in the area during the lateglacial at 10750 cal yr bp quercus tilia and fraxinus followed by corylus at c 10200 cal yr bp expanded significantly in the forest the delay of approximately 550 years in their establishment as compared to the expansion of ulmus was probably due to their immigration from more distant localities

marine reservoir correction for the pacific coast of central japan using 14c ages of marine mollusks uplifted during historical earthquakes in this study we utilize marine shell samples from two levels of historically uplifted sessile mollusk assemblages and raised wave cut benches to evaluate the marine reservoir correction r for the pacific coast of central japan elevation measurements of the uplifted marine shells indicate that the lower assemblage emerged during the 1923 taisho kanto earthquake m7 9 whereas uplift of the upper assemblage is most likely but less confidently ascribed to the 1703 genroku kanto earthquake m8 2 radiocarbon dating of carefully selected samples from the upper and lower assemblages yielded very similar r values of 82 33 and 77 32 yr respectively we regard the former r value as a representative and more reliable value given the uncertainty in correlation of the upper assemblage with the 1703 earthquake this result is consistent with previously reported r values for the pacific coast of south central japan and areas around the sea of japan that are influenced by warm ocean currents radiocarbon dating of coseismically uplifted shells can aid in estimating marine reservoir ages in the tectonically active japan islands

pleistocene alluvial deposits dating along frontal thrust of changhua fault in western taiwan the cosmic ray exposure point of view abstract to tackle the history of active thrusts it is necessary to open the observation window on time scales on the order of 104 105 years by studying the surface morphologies resulting from their activities because fluvial systems are particularly sensitive to recent environmental changes geomorphic features such as alluvial terraces are frequently used as markers to gauge tectonic deformation together with the measurement of cumulative displacements the chronological framework of emplacement and abandonment of these geomorphic markers is thus fundamental to determine long term fault slip rates in taiwan the geomorphic features associated with fault activity have been studied in detail with a high level of resolution however the use of deformed and partially preserved alluvial terraces is often hampered by the absence of well documented ages the purpose of this paper is two fold first we take the opportunity to review the chronological constraints that have been published in taiwan so far second we present how the cosmogenic dating method in situ produced 10be can be used to constraint the chronological framework of alluvial deposits over a pleistocene time scale thanks to a comparison of our cosmogenic derived ages with existing data we present a consistent regional chronological framework for the pakua tadu area along the changhua fault one of the most active frontal thrusts in the western foothills of the taiwan mountain belt we also discuss its relationships with global eustatism and its tectonic implications for the timing of propagation of the deformation front during the last 450 kyr

activity of the yoro fault system determined from coseismic subsidence events recorded in the holocene delta sequence of the nobi plain central japan the holocene delta sequence of the nobi plain central japan records coseismic subsidence in the western part of the plain caused during the past 6000 years by movement on the yoro fault we identified four episodes of upward fining deposition and increasing electrical conductivity in delta front deposits that occurred 600 200 1300 900 4200 3800 and 5600 4700 years ago suggesting that episodes of sea level rise interrupted progradation of the kiso river delta considering the general trend of relative sea level fall during the middle to late holocene under the influence of eustasy and hydroisostasy the temporal correspondence of rises of relative sea level with activity on the yoro fault suggests they reflect coseismic subsidence due to yoro fault activity the timing of the coseismic subsidence events identified in this study also corresponds with that of previously reported faulting events at the kuwana fault to the south of the yoro fault these results are consistent with the previous interpretation that the yoro and kuwana faults comprise a behavioral segment within the yoro fault system our off fault paleoseismic study shows that coseismic subsidence events detected in holocene delta sequences can provide further evidence of faulting events inferred from the on fault paleoseismic studies