fault activity in the epicentral area of the 1580 dover strait pas de calais earthquake northwestern europe on 1580 april 6 one of the most destructive earthquakes of northwestern europe took place in the dover strait pas de calais the epicentre of this seismic event the magnitude of which is estimated to have been about 6 0 has been located in the offshore continuation of the north artois shear zone a major variscan tectonic structure that traverses the dover strait the location of this and two other moderate magnitude historical earthquakes in the dover strait suggests that the north artois shear zone or some of its fault segments may be presently active in order to investigate the possible fault activity in the epicentral area of the ad 1580 earthquake we have gathered a large set of bathymetric and seismic reflection data covering the almost entire width of the dover strait these data have revealed a broad structural zone comprising several subparallel wnw ese trending faults and folds some of them significantly offsetting the cretaceous bedrock the geophysical investigation has also shown some indication of possible quaternary fault activity however this activity only appears to have affected the lowermost layers of the sediment infilling middle pleistocene palaeobasins this indicates that if these faults have been active since middle pleistocene their slip rates must have been very low hence the ad 1580 earthquake appears to be a very infrequent event in the dover strait representing a good example of the moderate magnitude earthquakes that sometimes occur in plate interiors on faults with unknown historical seismicity

paleotsunami research along the nankai trough and ryukyu trench subduction zones current achievements and future challenges abstract located near japan s most densely populated and industrially active region the nankai trough subduction zone has long been highlighted as a high risk area for damaging earthquakes and tsunamis in contrast less attention has been paid the adjacent ryukyu trench because historical and geological records are scarce in order to develop better quantitative estimates of the timing and size of the earthquakes and tsunamis generated along these subduction zones comprehensive studies using geological seismological and historical methods have been conducted since the 1990s studies of tsunami deposits in this region have contributed to our current understanding of the history of tsunamis over the last 6000 years following the 2011 t hoku earthquake and tsunami paleotsunami research has especially focused on guiding and enhancing tsunami disaster management and mitigation measures the last nine years have seen a rapid increase in paleotsunami data from the nankai trough and ryukyu trench coasts these recent studies reveal that there are significant differences in the size and recurrence pattern of earthquakes and tsunamis along these subduction zones for instance large earthquakes have repeatedly occurred along the nankai trough every 100 200 years on the other hand large earthquakes and tsunamis may not have occurred over the last few thousand years at the junction between these subduction zones there is also no evidence for the occurrence of large earthquakes along the northern and central ryukyu trench over this time period large earthquakes and tsunamis may have occurred every few hundred years at the southern end of the ryukyu trench nevertheless data on the occurrence of these earthquakes are still insufficient both in quantity and quality to estimate the maximum size or recurrence pattern

a 3000 years old sequence of extreme events revealed by marine and shore deposits east of taiwan we have discovered in a marine core located 20 km east of the coastal range of taiwan at the top of a 1200 m deep submarine high sheltered from rivers discharges and gravitational flows a 23 cm thick anomalous sequence topped with broken bivalves and wood fragments based on radiocarbon dating we distinguish five sub events within 100 yrs about 3000 years ago the oldest four sub events are interpreted as the record of local submarine landslides likely triggered by clustered earthquakes that are common in this tectonically active area the last event including shells and wood has a different origin despite the high level of climatic and tectonic recent activity no comparable event has been observed at the same site since that time making it unique during the last 3 75 ka hydrodynamical modeling stimulated with a set of submarine landslide triggered tsunami sources and combined with the regional oceanic circulation dominated by the kuroshio current allow us to better constrain the transport paths of the suspended material the expected run up at the coast and ultimately the trigger and source that best fit our observations the kuroshio current appears as a strong constraint that generally prevents cross shore transport of suspended material even during a major tsunami since the largest aerial debris flow observed along the east coast of taiwan during the last 4 ka was synchronous with the marine deposit our preferred scenario starts with the occurrence of four distinct large earthquakes within less than a century triggering both submarine and aerial landslides in the study area then a giant typhoon reworked the nearshore material as well as the slided material stored upstream resulting in a debris flow it deeply modified the surface current allowing the wood debris and shells to fastly reach the core site

identification of tsunami deposits using a combination of radiometric dating and oxygen isotope profiles of articulated bivalves abstract four tsunami deposits deposits i iv have been identified on ishigaki island southwest japan the youngest tsunami deposit deposit i was caused by the meiwa tsunami which occurred on 24 april 1771 ce as described in reliable historical documents two well preserved specimens of articulated marine bivalve were collected from the youngest tsunami deposit deposit i and an additional two from the second youngest tsunami deposit deposit ii 920 620 cal yr bp the shells were tightly closed and empty inside no encrusting epifauna or evidence of erosion was observed on the inner or outer shell surfaces in each tsunami deposit the 14c ages of the shells are nearly identical the mode of occurrence and coincidence of ages mean that these shells were transported and buried alive by tsunamis we analyzed the oxygen isotope 18o profiles of these bivalves to determine the seasons of their death which provides clues to the seasonal timing of tsunamis tsunami deposits i and ii were formed during spring and fall respectively the former supports the proposal that tsunami deposit i was caused by the 1771 meiwa tsunami and provides regional radiocarbon reservoir age for the late 1700s the latter provides a chronological constraint on the identification of tsunami deposit ii thus a combination of radiometric dating and 18o profiles of articulated bivalves derived from tsunami deposits provides important chronologic constraints for examining paleo tsunami events

the maryport fault the post caledonian tectonic history of southern britain in microcosm the maryport fault forms part of the faulted southern margin of the northumberland solway basin seismic reflection data reveal a complex history of repeated fault reactivation large oblique normal displacements on the fault controlled early carboniferous extensional basin development subsequently variscan basin inversion was accompanied by partial reversal of the fault in permian and mesozoic times renewed oblique normal displacements strongly influenced basin subsidence further partial reverse displacement occurred as the solway basin was again inverted probably in mid tertiary times in response to alpine compression the maryport fault is most unusual therefore in providing direct evidence of the principal post caledonian tectonic events in southern britain

tsunami recurrence revealed by porites coral boulders in the southern ryukyu islands japan information about past tsunami hazards such as their recurrence interval and magnitude is needed for future disaster prediction and mitigation we examined radiocarbon ages of the surfaces of massive coral boulders cast ashore by past tsunamis in the southern ryukyu islands japan where few historical and geological records of past tsunamis are available we selected only non eroded porites coral boulders along the shoreline because their characteristics make it possible to determine the probable timing of their deposition by tsunamis and we applied a dating method that uses the cumulative probability distributions of large numbers of radiocarbon measurements of those boulders to determine the timing of past tsunamis the results demonstrate that the southern ryukyu islands have repeatedly experienced tsunami events since at least 2400 yr ago with a recurrence interval of 150 400 yr the largest porites tsunami boulder that we studied long axis 9 m which is probably the largest single colony tsunami boulder in the world was displaced by the a d 1771 meiwa tsunami although the 1771 meiwa tsunami was likely the largest event in at least the past 700 yr calculations of current velocity show that all identified tsunamis occurring before 1771 were probably large enough to cause considerable damage to human built structures and loss of life this study demonstrates that by reliably dating large numbers of selected coastal boulders it is possible to ascertain the timing recurrence interval and magnitude of past tsunamis in a location where few adequate survey sites of sandy tsunami deposits exist

mesozoic cover over northern england interpretation of apatite fission track data whether a significant thickness of mesozoic cover rocks once rested upon the palaeozoic rocks which form the structural highs of the english lake district and the northern pennines is a subject of long debate which has been revived recently by apatite fission track analysis afta studies evidence from adjacent basins suggests that 1200 1750 m of mesozoic cover was probably formerly present on the highs prior to cenozoic erosion higher estimates c 3000 m of cover thickness based on such fission track derived palaeotemperatures result from underestimation of early cenozoic surface temperatures and from not allowing for the relatively low thermal conductivity of the eroded cover rocks for similar reasons apatite fission track estimates of eroded cover rocks elsewhere in britain may also prove to be overestimates

tsunami imprints on the leeward netherlands antilles aruba curacao bonaire and their relation to other coastal problems abstract tsunami are one of the major natural hazards in the caribbean the historical record lists 88 tsunami from local events to teletsunami in the time period from 1489 to 1998 this study focuses on the spatial distribution and geomorphologic evidence related to coarse littoral sediment and boulder deposition by tsunami events of holocene age in the southern caribbean at a worldwide scale these debris deposits represent the most extensive and impressive records of holocene paleo tsunami so far studied hitherto the leeward lesser antilles consisting of the islands of aruba curacao and bonaire were not known to have had tsunami affecting their coastlines the possible contribution of tsunami to configuring coastlines e g the questions of embayment development the coastal environment changes and the absence of holocene fringing reefs along the windward coasts is discussed

submarine active normal faults completely crossing the southwest ryukyu arc abstract several identified active faults located in the southwest ryukyu area may be an origin of m5 class earthquakes taking place frequently every year sometimes of m7 class earthquakes which cause a severe geohazard in this area the east ishigaki fault one of the officially identified active faults was studied precisely by multibeam echo sounding and the in situ rov observation the survey expedition figured the topographic feature of the fault clearly and more precisely than that mapped by the hydrographic department of japan the survey also identified the locations of northwestern and southeastern termini of the fault which revealed the total length to be 44 km corresponding to a m7 4 earthquake the new topographic map shows that the fault is composed of four or five segments with maximum vertical offset of 80 m in the southernmost segment not all of the segment can slip at once a reconnaissance survey of three of these segments by the rov hyper dolphin dives during the same expedition revealed that the headwall scarp is an outcrop made up of the ryukyu limestone of the middle pleistocene and that the lower scarp and the trough are covered with mostly talus apparently from the headwall at least two of these segments look fresher in fault activity rather than the others though all the observations show very recent activities along the fault based on these results the east ishigaki fault at least some of the segments might cause the 1771 tsunami and also future tsunamis with the similar magnitude

the structural development of the wessex basin the mesozoic and cenozoic structures of southern england form part of a system of disturbances which extends across the channel into northern france they are reviewed in the light of published data from south dorset basin development started with permo triassic rifting and is believed to have continued through the jurassic and early cretaceous with intermittent growth on deep seated listric normal faults probably associated with roll over anticlines this regime had ceased by the aptian and the basin passed through a period of relative stability in the late cretaceous followed by tectonic inversion and in the miocene by northwards compressive movement along the former normal faults this partially restored the earlier separative displacement at depth and probably accentuated pre existing roll over anticlines it was expressed in the surficial upper cretaceous palaeogene sequence as monoclinal flexuring the early rifting and the change from overall n s crustal stretching to compression may reflect plate tectonic events in the north atlantic region

a re examination of the evidence for a plio pleistocene marine transgression on the chiltern hills iii deposits a petrological re examination of the deposits that wooldridge and linton used as evidence for a plio pleistocene marine transgression on the chiltern hills indicates that many are fluvial and some have been reworked in a periglacial climate however those from little heath and rothamsted hertfordshire and lane end buckinghamshire are confirmed as marine and plio pleistocene subsidence during the pleistocene is suggested by the northeasterly decline in height of the few truly marine deposits

a mechanism for the formation of overconsolidated horizons within estuarine floodplain alluvium implications for the interpretation of holocene sea level curves

short term fluctuations in regional radiocarbon reservoir age recorded in coral skeletons from the ryukyu islands in the north western pacific radiocarbon 14c dating is a widely used and powerful tool for determining the ages of samples in studies of palaeoclimatology palaeoseismology and archaeology 14c ages of marine samples often require correction for local reservoir age r although r in the mid to low latitudes has varied through time few spatiotemporal reconstructions of r have been published for those regions here we report on new and previously published r data for the early 1900s to 1950 obtained from coral skeletons from the kuroshio region off southern japan the data presented here show a marked positive to negative shift of r from the early 1900s to the 1940s which has important implications for calibration of radiocarbon ages in the region and for understanding the relationship of r in the western pacific with both the el nino southern oscillation and the pacific decadal oscillation

characteristics and hydrodynamics of boulders transported by storm waves at kudaka island japan abstract this study investigates the size position and the long axis orientation of 210 boulders at kudaka island japan these boulders were deposited from the reef crest to the slope of the back reef moat distributed within 275 m from the reef edge most boulders were rectangular to ellipsoidal without sharp broken edges they are reef rock fragments estimated as

dating of tsunami boulders from ishigaki island japan with a modified viscous remanent magnetization approach abstract reworked boulders are expected to acquire a viscous remanent magnetization vrm approximately parallel to earth s modern magnetic field the magnitude of such a vrm depends on several factors including the time since reworking and ambient temperature for which there are well known theoretical relationships vrm unblocking temperature can therefore be a powerful tool for determining the reworking age of boulders and can be used to assess the timing of geological hazards such as landslides and tsunami events in this study vrm unblocking temperatures for twenty seven samples from four coral tsunami boulders on ishigaki island japan are compared with three candidate time temperature relationships for vrm acquisition for the pullaiah nomogram which is applicable to single domain magnetite particle assemblages nineteen samples from four boulders agree well with the expected unblocking temperature derived from previously reported 14c ages two samples have low unblocking temperatures and six samples appear to have anomalously high vrm unblocking the walton nomogram which is used for lognormal grain size distributions relates acquisition temperatures required to produce equal magnetic paleo intensities and cannot explain the high unblocking temperatures it produces younger predicted ages than the youngest boulder 14c age we find that an alternative time temperature relationship defined by a stretched exponential law has the potential to yield reworking ages for the anomalous boulders that are consistent with the 14c ages we suggest that future vrm dating can be undertaken using a combination of the pullaiah nomogram and the stretched exponential law

seafloor morphology and sediment magnetic fabric in a putative 1771 meiwa tsunami source region in the southern ryukyu islands southwest japan

extremely high energy wave deposits inside the great barrier reef australia determining the cause tsunami or tropical cyclone abstract a hydrodynamic approach is used to determine whether tsunami or cyclone generated waves were responsible for the deposition of fields of well imbricated rock boulders up to 290 tonnes along the coast of cairns inside the great barrier reef australia calculations of the overturning moments show that only tsunami are capable of moving such large boulders in this environment it is hypothesised that large tsunami 11 m have been able to penetrate the great barrier reef through wide 5 10 km 50 70 m deep passages between individual reefs three such passages each approximately 35 km apart and oriented in the same direction exist in the cairns region it is possible that these passages have funnelled and amplified palaeotsunamis the preferential location of eroded coral boulders up to 3 m in length on reef flats alongside these passages and their absence on other reefs throughout the region provide further evidence that extremely high energy waves have been able to penetrate the great barrier reef into the inner channel adjacent to the mainland carbon 14 ages of the coral boulders on these reef flats matches closely the ages of coral fragments pinned below the very large rock boulders along the coast these ages suggest that the cairns region has experienced large tsunami twice over the last millennium

numerical models of tsunami sediment transport current understanding and future directions abstract researchers who study tsunami deposits share common ultimate goals of their work which are to better assess the magnitude information of paleotsunamis and to contribute to the assessment of future tsunami risks numerical modeling of tsunami sediment transport is an important piece of interdisciplinary research that fills the gap between geological studies and practical utilization of tsunami deposits forward and inverse numerical models that address tsunami transport of sand and boulders have been developed over the last two decades forward models are capable of delineating the time evolution of tsunami hydrodynamics sediment transport and the resulting morphological changes associated with erosion and deposition inverse models estimate tsunami characteristics such as flow speed and depth from deposits numerical modeling can be used not only to quantify paleotsunamis but also to enhance our understanding of tsunami sedimentology and hydrodynamics to make progress towards the ultimate goal of improved tsunami risk assessment development of an in depth mutual understanding between modelers and geologists of the advantages limitations and uncertainties in both numerical modeling and geological records is an important challenge

deep crustal structure and carboniferous basin development within the iapetus convergence zone northern england seismic reflection data from northern england are interpreted to show a northward dipping caledonian thrust zone lying beneath the faulted southern margin of the northumberland trough the thrust zone lies upon the updip projection of a northward dipping high conductivity layer in the middle and lower crust identified by magnetotelluric sounding together these features indicate the presence of a crustal scale caledonian shear zone dipping north at an average angle of 20 25 extensional reactivation of the middle and upper crustal parts of the shear zone in carboniferous times led to development of the northumberland trough reappraisal of the birps nec seismic profile suggests the presence of the same or similar crustal shear zone reactivated to form the offshore extension of the northumberland trough the shear zone probably formed as a major compressive or transpressive feature during late caledonian acadian continental collision in the lower crust the shear zone lies close to or may actually represent the iapetus suture at middle to upper crustal levels the shear zone lies wholly within avalonian english crust well to the south of the faunally determined iapetus suture westward extrapolation of the shear zone indicates that it may crop out within the northern lake district perhaps as the causey pike and associated thrusts the faunal suture is likely to subcrop north of the lake district and alston block beneath the central part of the northumberland trough

pleistocene sediments soils and landscape evolution at stebbing essex pleistocene sediments and soils exposed at stebbing in central essex england are described analysed and interpreted the sand and gravel units above eocene london clay and upper pliocene red crag are shown to be a high level member of the kesgrave formation with a surface immediately beneath that of the westland green gravels which are tentatively assigned to the pre pastonian a stage of the british quaternary succession the rubified argillic soil developed in the surface of these fluvial deposits is a composite of the valley farm and barham soils and displays micromorphological evidence of several phases of clay illuviation gleying and clay coating disruption originally truncated and buried beneath anglian gelifluction deposits cover sand and till the soil has been exhumed in most places by subsequent erosion the full succession however is preserved within large gulls that formed by periglacial cambering prior to this erosion more recent loess incorporation and pedogenesis have modified the exhumed soil and the materials within the gulls

localized tsunamigenic earthquakes inferred from preferential distribution of coastal boulders on the ryukyu islands japan the occurrence of large earthquakes and tsunamis along the ryukyu trench is a subject of continuing interest the key to which is the long term geological record here we describe the clast size and spatial distributions of 2900 boulders on the reefs of the ryukyu islands japan as markers of paleotsunamis and causative tsunamigenic earthquakes boulders of tsunami origin were observed only at a specific island group at the southern end suggesting the local occurrence of tsunamigenic earthquakes there in contrast in the central to northern ryukyu islands no evidence exists of tsunamis larger than those at the southern end of the ryukyu islands during the past 2000 3000 yr these islands have numerous boulders deposited by storm waves during the past 2300 yr or earlier their spatial distribution has not been disturbed by large tsunamis this suggests that large tsunamis did not strike this area during that period nevertheless these regions are seismically active our study shows that coastal boulder deposits present great potential to not only ascertain the histories and effects of paleotsunamis but also to constrain fault models of the causative earthquakes

tectonic evolution of the northumberland basin the effects of renewed extension upon an inverted extensional basin the northumberland sedimentary basin has a history of repeated extensional and contractional tectonic phases and a study of the deformation interference pattern and sedimentary record allows the identification of the tectonic state through time initial rifting is represented by a thick dinantian sedimentary fill but carboniferous extension is thought to have ceased by the early namurian in order to explain the development of certain facies patterns during the westphalian thermal subsidence phase of the evolution of the northumberland basin some syn depositional extensional fault movements are required at other times in the westphalian compaction induced subsidence was the dominant control on facies distribution a single phase of e w to se nw variscan compression commenced during or after late westphalian times and ceased prior to the intrusion of the whin sills and dykes subsequent permo mesozoic extension with a right lateral shear component re activated pre existing normal fault lines these later structures may be interpreted as being listric in form shallowing onto decollement surfaces within the carboniferous basin fill and overlie the buried faulted margin at the southern side of the basin

thames river sediments of the british early and middle pleistocene abstract the thames drainage system contains the most complete record of fluvial sediments in the british quaternary the kesgrave sands and gravels form the main body of this sediment having been deposited over an interval that spans the later part of the early pleistocene and most of the middle pleistocene conventional stages pre pastonian a through to early anglian ca 1 2 ma this deposit provides a stratigraphic context for related bio morpho and pedostratigraphic evidence and for the recognition of pre anglian pre oi stage 12 upland glaciation in the welsh mountains and intense periglaciation in lowland england it also facilitates correlation with the stratigraphy of northern europe and the global pattern of orbitally forced climatic change this paper describes the first catchment wide correlation of thames river sediments and proposes a formal redefinition of the lithostratigraphic units concerned the scheme outlined here is based on two lithologically distinctive formations defined at type areas reflecting significant changes in catchment dimensions the earlier sudbury formation was formed when the thames catchment extended into wales and drained northwards across east anglia the later colchester formation was formed after the upper catchment had been reduced in extent to that of the present river but continued to flow across east anglia the whole sediment body is now named the kesgrave group

large boulder deposits by tsunami waves along the ionian coast of south eastern sicily italy abstract the ionian coast of south eastern sicily between the towns of augusta and siracusa is characterized by the occurrence of anomalous calcareous boulders they are mostly scattered along large terraces located 2 5 m above sea level gently sloping towards the sea boulders are up to 182 t in weight and are arranged either in isolated elements or small groups composed of a few stacked elements several boulders show biogenic encrustations serpulids balanids lithophaga all over their surface which suggest that they were dragged from the mid sublittoral zone other boulders are partially covered by biogenic encrustations and show morphological features karstic pools exposed fracture surfaces suggesting that they were detached and scattered from the mid supralittoral zone direct observations on each boulder distance from the shoreline size and weight together with statistical analysis of the storm regime of the area allowed to operate hydrodynamic estimations useful to verify if tsunami or storm waves were responsible for their detachment and transport while radiocarbon age determinations on marine organisms constrained the timing collected data compared to historical catalogues suggest that in the last 1000 years three seismic events with local sources could have triggered tsunami waves associated with the boulder deposits occurring in the area the first two were probably triggered by the earthquakes of february 4 1169 and january 11 1693 which destroyed south eastern sicily according to geological data and numerical modelling the seismogenic source could be located in the ionian offshore between catania and siracusa the third tsunami was generated by the strong earthquake which took place in the strait of messina on december 28 1908

stretched exponential relaxation of viscous remanence and magnetic dating of erratic boulders viscous remanence continuously increases with the duration of reorientation of rocks and the remanence gets partially overprinted in rocks parallel to the earth s magnetic field this overprinted viscous remanence is unblocked at a certain temperature that enables the estimation of the time required for the rock to acquire the magnetism by assuming the exponential law of neel s single domain theory however previous results of dating the rocks by the exponential law have shown older ages than radiometric or cosmogenic exposure ages neel s exponential decay law is applicable to a system whose magnetic grains have an identical relaxation time however in real systems the expected behavior is not usually observed because relaxation times vary for individual grains moreover the variation of viscous remanence with the logarithmic law for a distribution of relaxation times is predicted to be concave downwards here we found that the stretched exponential law exp t 1 n with 0 n 1 explains previously published data on viscous decay the observed stretched exponential relaxation can be interpreted in terms of the global relaxation of a system containing many relaxing species each of which decays exponentially in time with a specific fixed relaxation rate using this law we derived an extended time temperature relationship of magnetite involving the neel s exponential decay law with n 0 and a system containing many relaxing times with variable n the extended time temperature relationship shows that the age of a coral tsunami boulder with high anomalous unblocking temperatures can be fitted with an assigned radiometric age

tsunami deposits and recurrence on a typhoon prone coast of northern taiwan from the last millennium abstract widely known for its hazardous history taiwan holds valuable records of nw pacific tsunamis and typhoons despite the similarity between tsunami and typhoon deposits historical accounts enabled the identification of the 1867 tsunami deposit on the northern coast through matching with the record setting inundation however the identification of prehistoric tsunami deposits has been hindered by severe sediment reworking and post depositional changes produced by the typhoon prone tropical and humid climate in this study we investigated the upper holocene facies and their sediment sources and radiocarbon ages on distal floodplains and rocky backshores of the northern coast where sediment reworking is less intense four decimetre thick gravelly layers were identified intercalated with fluvial mud and colluvium the gravelly layers are composed of beach derived quartz rich sand and rounded gravels of the sedimentary basement rocks longshore drift andesite and stranded pumice the remarkable layer thickness gravel size and quartz richness were determined to have endured post depositional changes the event layers are sharp based matrix supported and poorly sorted and have recorded scouring sediment entrainment and rapid fallout of suspension rich turbulent flows that probably originated with tsunamis the event layers occur 0 5 0 8 km inland and 3 11 5 m above sea level matching the 1867 tsunami inundation and wave height respectively radiocarbon dating tied the event layers to the 1867 tsunami and three prehistoric events that occurred in the periods 1545 to 1810 1293 to 1414 and 1090 to 1235 representing a recurrence interval of 83 436 years over the last millennium

coral boulders on melekeok reef in the palau islands an indicator of wave activity associated with tropical cyclones abstract waves generated by tropical cyclones and tsunamis cause various impacts such as coastal erosion and damage to infrastructure the intensity of tropical cyclones will probably increase in the near future as a result of global warming therefore predicting the likely impacts of these storms is a prime concern boulder deposits are one of the key proxies that assist our understanding of previous tropical cyclones and tsunamis and are important if we are to accurately project their future impacts in december 2012 typhoon bopha hit the palau islands and many boulders were probably deposited on the east coast of babeldaob island during the event this area is one of the few locations where it is possible to distinguish between deposits that were generated by tropical cyclone waves and tsunamis this study records the distribution of boulders from the shore to the reef crest at melekeok reef on babeldaob island and evaluates the relationship between the movement of boulders and the hydraulic forces generated by the waves using a hydrodynamic model and wave calculations in addition this study projects the coastal impacts of tropical cyclone waves in the near future many boulders have been deposited on the reef crest within 100 m of the reef edge and the maximum weight of the boulders is 2 2 tons the boulders are composed of massive corals e g platygyra and they originated from the upper reef slope the results of the hydrodynamic modeling indicate that these boulders were transported and deposited by the waves generated by typhoon bopha significant wave height 8 7 m or tcs with a similar intensity of typhoon bopha moreover there are no boulder deposits at the shore which implies that the reef has not been affected by tsunamis even if one or more tsunamis have inundated the reef the associated hydraulic forces appear to have been lower than those of typhoon bopha these findings indicate that typhoon bopha has probably generated the most intense wave event in recent times however it is likely that tropical cyclones more intense than typhoon bopha will affect the reef in the near future as the climate continues to warm through the 21st century consequently the study site will probably face an increased risk of coastal erosion and destruction of property if no plans are developed to reduce and manage such impacts

u and th concentrations and isotope ratios in modern carbonates and waters from the bahamas the short residence times of th and pa in seawater make them very responsive to changes in the ocean environment we use a new multi ion counting technique to make th and pa isotope measurements in seawaters from a near shore environment in which oceanic chemical tracers are not overwhelmed by terrestrial inputs the bahamas an unusual feature of the bahamas setting is the shallow depth of water residing on the bank tops these waters have significantly lower 232th 230th 10 000 than those immediately adjacent to the banks 24 000 31 000 and a 231pa 230th near the production ratio 0 1 the change in 232th 230th and 231pa 230th on the bank tops is explained by almost quantitative removal of th and pa by scavenging and their replacement with a mixture of 230th and 231pa alpha recoiled from the underlying carbonates together with th from dust dissolution analysis of a water profile in the tongue of the ocean which separates the great and little bahama banks allows us to trace the movement of bank top water to depth a distinct minimum in both 232th 230th 13 000 and 231pa 230th 0 5 is observed at 430 m and is interpreted to reflect density cascading of bank top water with entrained carbonate sediment these results suggest that th and pa can be used as water mass tracers in near shore environments uranium concentration measurements on the same waters demonstrate that u is conservative across a range in salinity of 2 psu with a concentration of 3 33 ppb at a salinity of 35 the incorporation of u and th isotopes into marine carbonates has also been assessed by analyzing carbonate samples from the same location as these bahamas waters such incorporation is critical for u th geochronology u isotope analyses demonstrate that seawater 234u averages 146 6 and does not vary by more than 2 5 o and that carbonates capture this value additional high precision measurements 1 o on modern carbonates confirm that all oceans have identical 234u modern marine carbonates are shown to have 232th 230th ratios that reflect the local seawater in which they formed

storm cycles in the last millennium recorded in yongshu reef southern south china sea large storm relocated porites coral blocks are widespread on the reef flats of nansha area southern south china sea detailed investigations of coral reef ecology geomorphology and sedimentation on yongshu reef indicate that such storm relocated blocks originated from large porites lutea corals growing on the spurs within the reef front living coral zone because the coral reef has experienced sustained subsidence and reef development during the holocene dead corals were continuously covered by newly growing coral colonies for this reason the coral blocks must have been relocated by storms from the living sites and therefore the ages of these storm relocated corals should approximate the times when the storms occurred rapid emplacement of these blocks is also evidenced by the lack of coral overgrowth encrustation or subtidal alteration u series dating of the storm relocated blocks as well as of in situ reef flat corals suggests that during the last 1000 years at least six strong storms occurred in 1064 30 1210 5 1201 4 1336 9 1443 9 1685 8 1680 6 1872 15 ad respectively with an average 160 year cycle 110 240 years the last storm which occurred in 1872 15 ad also led to mortality of the reef flat corals dated at similar to 130 years ago thus the storm had significant impacts on coral reef ecology and morphology c 2004 elsevier b v all rights reserved

ice age terminations 230th dated oxygen isotope records of stalagmites from sanbao cave china characterize asian monsoon am precipitation through the ends of the third and fourthmost recent ice ages as a result am records for the past four glacial terminations can now be precisely correlated with those from ice cores and marine sediments establishing the timing and sequence of major events in all four cases observations are consistent with a classic northern hemisphere summer insolation intensity trigger for an initial retreat of northern ice sheets meltwater and icebergs entering the north atlantic alter oceanic and atmospheric circulation and associated fluxes of heat and carbon causing increases in atmospheric co2 and antarctic temperatures that drive the termination in the southern hemisphere increasing co2 and summer insolation drive recession of northern ice sheets with probable positive feedbacks between sea level and co2

the structure and evolution of the northumberland trough from new seismic reflection data and its bearing on modes of continental extension an 18 km long n s seismic reflection profile has been acquired across the faulted boundary between the alston block and the northumberland trough a nw se geological cross section has been constructed across the trough by integrating this line with other data and a tricentrol seismic profile confirms the suitability of this model the trough has a markedly asymmetric form with a thickness of more than 4 2 km of dinantian strata adjacent to its faulted southern margin the present day surface faults stublick ninety fathom are related to variscan and later inversion and transpression and do not everywhere correspond precisely to the earlier syn depositional normal faults the basin is believed to have formed in response to reactivation of the iapetus suture in a dominantly n s extensional stress field basin evolution has been analysed by fault restorations and subsidence modelling the fault restorations indicate an upper crustal extension factor of 1 15 to 1 19 subsidence modelling indicates a whole crustal extension factor of 1 30 with similar sub crustal lithospheric extension it is possible that the difference between the inferred extension factors is due to non uniform increasing downwards lithospheric extension but the uncertainties inherent in both methods are such that this cannot yet be confirmed

historic 1771 meiwa tsunami confirmed by high resolution u th dating of massive porites coral boulders at ishigaki island in the ryukyus japan 1 the chronicles of the ryukyu kingdom describe at least four coastal inundation events at ishigaki island during the seventeenth through nineteenth centuries the 1771 meiwa earthquake tsunami which killed 12 000 people another earthquake tsunami 1687 and two events with unrecorded causes 1625 and 1714 we used a high resolution u th method to date well preserved surface parts of massive porites spp coral head boulders that had been cast ashore and found that the ages of two boulders correspond to the 1771 event one large porites boulder diameter 4 m was dated to 1625 suggesting that that event was also a large inundation event calibrated 14c ages based on a newly estimated local value for the radiocarbon marine reservoir effect clustered around 1625 and 1771 suggesting that these events were larger than the others our study demonstrated that porites boulders have enormous potential value for studies of paleoinundation events such as tsunamis and extreme storms

boulder emplacement and remobilisation by cyclone and submarine landslide tsunami waves near suva city fiji the characteristics of a reef top boulder field created by a local submarine landslide tsunami are presented for the first time our examination of large reef derived boulders deposited by the 1953 tsunami near suva city fiji revealed that shorter than normal period tsunami waves generated by submarine landslides can create a boulder field resembling a storm boulder field due to relatively short boulder transport distances the boulder inferred 1953 tsunami flow velocity is estimated at over 9 m s 1 at the reef edge subsequent events for example cyclone kina 1993 appear to have remobilised some large boulders while prior research has demonstrated headward retreat of suva canyon in response to the repeated occurrence of earthquakes over the past few millennia our results highlight the lingering vulnerability of the fijian coastlines to high energy waves generated both in the presence tsunami and absence storm of submarine failures and or earthquakes to explain the age discrepancies of u th dated coral comprising the deposited boulders we introduce a conceptual model showing the role of repeated episodes of tsunamigenic submarine landslides in removing reef front sections through collapse subsequent high energy wave events transport boulders from exposed older sections of the reef front onto the reef where they are deposited as new boulders alongside freshly detached sections of the living reef in similar situations where anachronistic deposits complicate the deposition signal age dating of the coral boulders should not be used as a proxy for determining the timing of the submarine landslides or the tsunamis that generated them c 2017 elsevier b v all rights reserved

the carbonate hosted lisheen zn pb ag deposit county tipperary ireland the lisheen zn pb ag deposit located in county tipperary in southeast central ireland consists of a group of strata bound pyritic sulfide lenses containing 22 mt of ore with an overall grade of 11 5 percent zn 1 9 percent pb 26 g t ag and 16 percent fe hosted in lower carboniferous early mississippian carbonate rocks sulfide bodies at lisheen are restricted to the waulsortian mudbank complex and the lisduff oolite unit of the ballysteen limestone which compose the stratigraphically lowest nonargillaceous carbonate horizons in the local lower carboniferous succession the deposit is located within a major right stepping relay zone of a segmented normal fault system sulfide bodies occur adjacent to the normal faults thickest development of sulfides generally occurs at points of maximum throw metal zoning is well developed relative to these structures the waulsortian mudbank complex and portions of the overlying succession were subjected to an early premineralization regional scale dolomitizing event that increased permeability the regional dolostone produced by this event is cut and replaced by hydrothermal dolomite referred to as black matrix breccia and white matrix breccia associated with mineralization hydrothermal dolomitization was most intense in the waulsortian mudbank complex though it locally affected rocks from the silurian basement to more than 200 m above the level of major sulfide precipitation the majority of the lisheen deposit consists of fe zn pb ag sulfides hosted in the black matrix breccia regional dolomite and to a much lesser extent undolomitized limestone of the waulsortian complex sulfide bodies at lisheen consist of pyrite marcasite sphalerite and galena with subsidiary sulfosalt minerals arsenopyrite and copper sulfides sulfides replace carbonate minerals and infill dissolution cavities gangue minerals intergrown with sulfides include dolomite calcite barite and quartz mineral textures indicate a regular paragenetic sequence of sulfide deposition from early precipitation of colloform iron sulfide containing minor sphalerite and galena through deposition of a complex assemblage of sphalerite galena iron sulfides sulfosalt minerals and copper sulfides distribution of alteration and sulfide zones indicates that the lisheen deposit formed as a prograding hydrothermal system textural and mineralogic evidence suggests that the hydrothermal fluids were relatively acidic and that reaction with the carbonate host rocks was a primary reason for sulfide precipitation on the basis of the probable age of faulting and crosscutting relationships of the regional and hydrothermal dolomite the maximum age of mineralization at lisheen was at least 10 m y after host rock deposition

competing mechanisms for boulder deposition on the southeast australian coast this study investigates the role of late holocene sea level change large storms and possible pre historic tsunami in the deposition of boulder features on an exposed headland and sheltered rock ramp large accumulations of boulders are found on coastal rock platforms cliff tops and ramps in the jervis bay region of southeastern australia these deposits are elevated above sea level and in places exhibit obvious signs of imbrication as a response to flow in a landward direction the event history of these features is controversial and holocene sea level change storms and tsunami can be considered as possible non mutually exclusive mechanisms of deposition it is apparent that even if the detachment site transport distance elevation and final orientation of a boulder can be identified deciphering the event history remains a difficult task

discrimination of boulders deposited by tsunamis and storm waves at ishigaki island japan abstract the ryukyu islands japan where numerous boulders are deposited on the reef and on land might be ideal research fields of boulders deposited by tsunami and storm waves because many typhoons and several tsunamis attacked the same area during its history this study investigates the size position and the long axis orientation of 626 boulders at ibaruma and shiraho reefs at ishigaki island japan to elucidate the sedimentary differences of boulders deposited by tsunamis and storm waves in one area two distinct groups of boulders were found at these reefs boulders on the reef crest group 1 and along the shoreline group 2 boulders in group 1 porites sp of moat origin the group 2 boulders were remarkably heavier 14 c age based on results of this study we infer that tsunami boulders in these islands so called tsunami ishi can be discriminated from boulders of storm wave origin based on their sedimentary differences this sedimentological approach is expected to be applicable to other boulder fields throughout the world our results further suggest that the spatial and grain size distribution of tsunami boulders are very useful to elucidate local flow characteristics of the tsunami for example the group 2 tsunami boulders were deposited below the high tide line irrespective of size some were split into several pieces they were probably deposited below the high tide line by the remarkable reduction of the current velocity of the tsunami because of the local topography the reduction of the current velocity must have been drastic to have made the boulders hit the ground with sufficient force to split them

traces of tsunami preserved in inter tidal lacustrine and marsh deposits some examples from northeast japan the japan sea earthquake of may 26 1983 triggered a large scale tsunami that surged over the coast of ne japan and caused considerable damage the tsunami resulted in peculiar sedimentary processes on the coast depending on the hydraulic scale of the tsunami three kinds of sedimentary processes were recognized each of which left unique deposits such deposits are expected to remain in sedimentary sequences preserving remarkable sedimentary facies borehole samples drilled at different localities in coastal regions have been examined to detect traces of ancient tsunamis sedimentological and geochemical studies of the samples reveal that layered deposits similar to those developed by the tsunami of the japan sea earthquake are common in the drilled cores estimated ages of these deposits are exactly equivalent to the dates of ancient tsunamis documented in historical records these results show that the invasion of tsunamis is recorded in coastal depositional sequences from analyses of long borehol

geological records of western pacific tsunamis in northern taiwan ad 1867 and earlier event deposits abstract located in the western circum pacific seismic zone taiwan is an ideal area for recording tsunamis that originate in the tectonically and volcanically active systems of the ryukyu arc okinawa trough and luzon arc however because of taiwan s short historical record there is only credible evidence for one disastrous tsunami which occurred in northern taiwan in ad 1867 to better understand the western pacific tsunamis an upper holocene deposit of a coastal plain inundated by the ad 1867 tsunami was investigated to search for geological evidence of tsunamis based on facies characteristics and sediment composition we identified two sharp based decimetre thick marine quartzose sandy layers that fine upward and landward intercalated with floodplain marsh sand and mud the fluvium are rusty red rich in volcanic clasts and fe and comparable to modern riverine sediments of local andesitic provenance extending 0 8 km inland the marine quartzose sandy layers are light coloured and rich in quartz and si have high ca ti values and are comparable to the modern beach dune sediments of regional siliciclastic provenance radiocarbon dating indicates that the marine sandy layers are correlated with the ad 1867 tsunami and an older event at the boundary between the 17th and 18th centuries both events were probably associated with reported earthquakes involving normal faulting in addition the distribution patterns of the two marine sandy layers are similar suggesting that the inundation distances run ups and flow heights of the two events are comparable this indicates that the disastrous tsunamis were frequent in the area between northern taiwan and the okinawa trough of the western circum pacific seismic zone

crustal uplift in southern england evidence from the river terrace records abstract much of the past work on the quaternary rivers of northwest europe has been concerned with river terraces which characterise almost every valley while these terraces are undoubtedly striking features of the landscape the incision achieved by quaternary rivers is equally significant in terms of river behaviour and for an understanding of the factors affecting landform development during the quaternary this paper examines the incision achieved during the quaternary by the thames in both its upper and lower catchments and by the hampshire avon in southern england valley incision rates of ca 0 07 0 10 m ka 1 have been identified although in the lower catchment of the thames these have been enhanced by additional incision in response to glacio isostasy and valley shortening a model is proposed in which regional uplift is recognized as the primary cause of incision by these quaternary rivers possible mechanisms for regional uplift are considered

upper palaeozoic basins of the british isles caledonide inheritance versus hercynian plate margin processes hypotheses to explain the origin and location of upper palaeozoic sedimentary basins are presented group a basins were those old red sandstone basins whose location and subsidence were controlled by caledonide features including active and remnant fore arc basins midland valley and major transcurrent movements orcadian basin newer granite plutonic magmas in the southern uplands subduction complex post dated subduction and resulted from post collision cratonization processes as yet little understood group b basins were those whose initial positions in space were controlled by palaeo plate factors in particular the location of granitoid plutons but whose subsidence was controlled by active hercynian neoplate processes some group a basins were regenerated by this process midland valley a new hypothesis is presented to account for the origin of a carboniferous rift to sag trend similar to that proven in modern continental margin basins such as the north sea the hypothesis is an adaptation of mckenzie9s lithospheric stretching model some of whose major features are well shown in the carboniferous history of the north and central british isles group b processes were controlled by ligurian bretonic plate consumption in the s brittany massif central vosges areas group c basins in the rheno hercynian zone also owe their location and origin to back arc rifting and continental crustal oceanization processes caused by liguro bretonic subduction

palaeo stress fields in the variscan foreland during the carboniferous from microstructural analysis in the british isles abstract north of the variscan front the carboniferous series of the british isles is affected by mainly n s trending folds which are almost perpendicular to this e w oriented front flat and unconformable overlying permian strata demonstrate a variscan age for the deformation a microtectonic survey made in dinantian and to a lesser extent namurian calcareous layers has revealed two successive events according to chronological criteria the first event maximum stress e w trending led to the formation of n s folds with local reorientation in the vicinity of major pre existing faults this compression may have been active since the namurian it pre dates a second compressional event orientated n s which is related to the final emplacement of the variscan nappes

coral boulders along the coast of the lanyu island offshore southeastern taiwan as potential paleotsunami records abstract in the last decade several disastrous tsunamis hit a large area of coastal east asia and produced numerous casualties and economic losses as a country that is also prone to tsunami hazards taiwan is in urgent need for more knowledge of past tsunami records and potential tsunamigenic sources on the basis of detailed geomorphic mapping and field investigations we identified six sites in the northern part of the lanyu island offshore southeastern taiwan with large coral boulders resting on holocene uplifted coral reef terraces boulders of these six sites are all likely moved by extremely strong waves and four sites have better constraints to suggest that the boulders may indeed be transported during a paleotsunami event the ages of the boulders suggest that the extremely strong wave events occurred at least several times since the mid holocene high stand of sea level the youngest event may correlate with the 1771 meiwa tsunami of the southern ryukyu islands but it is more likely to be produced by some undocumented event along the eastern coast of taiwan the locations of the coral boulder sites along the northern coast of the lanyu island suggest that the sources of the events are located to the north of the island we believe that our results would provide further information for future tsunami hazard assessments along the eastern coastal area of taiwan as well as surrounding areas

holocene antarctic melting and lithospheric uplift history of the southern okinawa trough inferred from mid to late holocene sea level in iriomote island ryukyu japan abstract relative sea level deduced from fossil oysters and mangroves are reported for iriomote island ryukyus southwestern japan radiocarbon dated fossil oysters as well as previously analyzed mangrove muds are compared to geophysical and glacio hydro isostatic adjustment gia models that describe earth deformation due to changing surface loading the holocene high stand hhs inferred from oyster fossils saccostrea echinata and saccostrea malaboensis is 2 7 m at ca 3500 years ago after which sea level gradually fell to present level the hhs magnitude attributed to gia for the last ca 4000 is between 1 and 1 5 m above present day sea level and the residual indicates the long term lithospheric uplift rate of the island the timing of peak hhs also indicates that late holocene melting mainly from antarctica ceased by approximately 4000 years ago

paleomagnetism reveals the emplacement age of tsunamigenic coral boulders on ishigaki island japan abstractwe use temperature dependent viscous remanent magnetization to estimate the emplace ment age of tsunamigenic coral boulders along the shorelines of ishigaki island japan the boulders consist of the hermatypic coral porites and the time of their deposition by tsuna mis has been established using radiocarbon dating recently deceased corals at reef edges around ishigaki island record the earth s current magnetic field present earth field pef as a remanence parallel to the field in the skeleton since the time when the coral skeletons were emplaced on the shorelines as boulders by destructive tsunami waves a new viscous magne tization was partially overprinted in the boulder parallel to the pef the results of thermal demagnetization indicated that the boulders were rotated at least once and their emplace ment ages determined from l neel s relaxation theory for single domain magnetite agree well with the radiocarbon ages although there are traces of multidomain magnetites new applica tion of neel s theory to tsunamigenic coral boulders gives us an opportunity to ascertain the age and transportation mode of individual tsunamigenic coral boulders in this area

activation of very low frequency earthquakes by slow slip events in the ryukyu trench long term activity of shallow very low frequency earthquakes vlfes in the ryukyu trench unassociated with recent large thrust earthquakes was analyzed using a broadband seismometer network the distribution of shallow vlfes was divided into three large clusters the activity of the vlfes is modulated by repetitive slow slip events and the activity of these vlfes increases to 2 3 times its ordinary rate at 10 20 days after the onset of the slow slip events the activation of vlfes could be generated by small increases on the order of approximately 0 1 0 5 kpa in coulomb failure stress suggesting that stress in the plate interface where the vlfes occur is frequently released in small amounts moreover the distribution of vlfes is complementary to the historical tsunami source area and locked area the distribution of the vlfes indicates heterogeneity in interplate coupling along the trench

identifying storm surge deposits in the muddy intertidal zone of ena bay central japan abstract storm surge and tsunamis deposits provide essential information for those tasked with mitigating the impacts of natural disasters on coastal lowlands in low and middle latitude regions and also along active margins however studying these deposits in coastal lowland strata is becoming increasingly difficult particularly in residential regions because of extensive anthropogenic disturbance researchers have therefore had to extend the scope of their work to include shallow marine deposits such as bay sediments and some have also worked on storm surge deposits related to recent storm events in this study we identified and examined sandy storm surge deposits of up to 14 cm thick that were deposited by 2017 typhoon lan lowest pressure of 915 hpa the largest storm in the past 60 years within the tidal flat sediments of ena bay in the southern coastal area of metropolitan tokyo central japan we compared these deposits with the tsunami deposits 10 50 cm thick found on the tidal flats of koajiro bay near ena bay that resulted from the kanto earthquake magnitude 8 these differences mean that the thickness of such deposits is a valid criterion for distinguishing between storm surge and tsunami deposits on tidal flats

source of high tsunamis along the southernmost ryukyu trench inferred from tsunami stratigraphy abstract four paleotsunamis deposits are exposed in a trench on the coastal lowland north of the southern ryukyu subduction zone trench radiocarbon ages on coral and bivalve shells show that the four deposits record tsunamis date from the last 2000 yrs including a historical tsunami with a maximum run up of 30 m in 1771 for an average recurrence interval of approximately 600 yrs ground fissures in a soil beneath the 1771 tsunami deposit may have been generated by stronger shaking than recorded by historical documents the repeated occurrence of the paleotsunami deposits supports a tectonic source model on the plate boundary rather than a nontectonic source model such as submarine landslides assuming a thrust model at the subduction zone the seismic coupling ratio may be as low as 20

source fault model of the 1771 yaeyama tsunami southern ryukyu islands japan inferred from numerical simulation the 1771 yaeyama tsunami is successfully reproduced using a simple faulting model without submarine landslide the yaeyama tsunami m 7 4 which struck the southern ryukyu islands of japan produced unusually high tsunami amplitudes on the southeastern coast of ishigaki island and caused significant damage including 12 000 casualties previous tsunami source models for this event have included both seismological faults and submarine landslides however no evidence of landslides in the source has been obtained despite marine surveying of the area the seismological fault model proposed in this study describing a fault to the east of ishigaki island successfully reproduces the distribution of tsunami runup on the southern coast of the ryukyu islands the unusual runup heights are found through the numerical simulation attributable to a concentration of tsunami energy toward the southeastern coast of ishigaki island by the effect of the shelf to the east thus the unusual runup heights observed on the southeastern coast of ishigaki island can be adequately explained by a seismological fault model with wave ray bending on the adjacent shelf

fault model of the 1771 yaeyama earthquake along the ryukyu trench estimated from the devastating tsunami 1 the 24 april 1771 yaeyama earthquake generated a large tsunami with a maximum runup of 30 m causing significant damage in south ryukyu japan despite the weak ground shaking previously proposed mechanisms of the tsunami include intraplate faulting or submarine landslide in the forearc slope in this study i estimate the fault parameters of the 1771 earthquake by numerically computing the tsunami heights and comparing them with the recorded heights the result indicates that the source fault of the tsunami is very close to the ryukyu trench the results are consistent with a thrust faulting earthquake that had a fault width of less than 50 km the 1771 yaeyama tsunami was caused by a tsunami earthquake mw 8 0 that occurred in the subducted sediments beneath the accretionary wedge

the iapetus suture zone in england scotland and eastern ireland a reconciliation of geological and deep seismic data deep seismic profiles in the irish and north seas have successfully imaged crustal structure across the iapetus suture zone a problem with current interpretations is that the reflectors chosen as the suture project to the top of the basement well to the south of the solway line the palaeontologically defined trace of the suture we present a revised interpretation in which a reflectivity boundary common to all the profiles is identified as the leading edge of imbricated avalonian crust in effect the footwall of the suture zone this projects to the surface close to the solway line obviating the need to invoke northward backthrusting of the suture

a reconstruction of subtropical western north pacific sst variability back to 1578 based on a porites coral sr ca record from the northern ryukyus japan we present a seasonal reconstruction of sea surface temperature sst from 1578 to 2008 based on a porites coral sr ca record from the northern ryukyus within the kuroshio southern recirculation gyre interannual sst anomalies are generally 0 5 c making sr ca derived sst reconstructions a challenging task replicate measurements along adjacent coral growth axes enabled by the laser ablation inductively coupled plasma mass spectrometry technique used here give evidence of rather large uncertainties nonetheless derived winter sst anomalies are significantly correlated with the western pacific atmospheric pattern which has a dominant influence on winter temperature in east asia annual mean ssts show interdecadal variations notably cold intervals between 1670 and 1700 during the maunder minimum mm and between 1766 and 1788 characterized by a negative phase of the north atlantic oscillation cold summers in 1783 and 1784 coincide with the long lasting laki eruption that had a profound impact on the northern hemisphere climate including the severe tenmei famine in japan the decades between 1855 and 1900 are significantly cooler than the first half of the twentieth century while those between 1700 and 1765 following the mm are warmer than average sst variability in the ryukyus is only marginally influenced by the pacific decadal oscillation so that external forcing remains the main driver of low frequency temperature changes however the close connection between the kuroshio extension ke and its recirculation gyre suggests that decadal sst anomalies associated with the ke front also impact the ryukyus and there is a possible additional role for feedback of the kuroshio oyashio variability to the large scale atmosphere at decadal timescale

long term controls on continental scale bedrock river terrace deposition from integrated clast and heavy mineral assemblage analysis an example from the lower orange river namibia abstract establishing relationships between the long term landscape evolution of drainage basins and the fill of sedimentary basins benefits from analysis of bedrock river terrace deposits these fragmented detrital archives help to constrain changes in river system character and provenance during sediment transfer from continents source to oceans sink thick diamondiferous gravel terrace deposits along the lower orange river southern namibia provide a rare opportunity to investigate controls on the incision history of a continental scale bedrock river clast assemblage and heavy mineral data from seven localities permit detailed characterisation of the lower orange river gravel terrace deposits two distinct fining upward gravel terrace deposits are recognised primarily based on mapped stratigraphic relationships cross cutting relationships and strath and terrace top elevations and secondarily on the proportion of exotic clasts referred to as proto orange river deposits and meso orange river deposits the older early to middle miocene proto orange river gravels are thick up to 50 m and characterised by a dominance of karoo supergroup shale and sandstone clasts whereas the younger plio pleistocene meso orange river gravels 6 23 m thick are characterised by more banded iron formation clasts mapping of the downstepping terraces indicates that the proto gravels were deposited by a higher sinuosity river and are strongly discordant to the modern orange river course whereas the meso deposits were deposited by a lower sinuosity river the heavy minerals present in both units comprise magnetite garnet amphibole epidote and ilmenite with rare titanite and zircon grains the concentration of amphibole epidote in the heavy minerals fraction increases from the proto to the meso deposits the decrease in incision depths recorded by deposit thicknesses above strath terraces and the differences in clast character size and roundness and type between the two units are ascribed to a more powerful river system during proto orange river time rather than reworking of older deposits changes in provenance or climatic variations in addition from proto to meso orange river times there was an increase in the proportion of sediments supplied from local bedrock sources including amphibole epidote in the heavy mineral assemblages derived from the namaqua metamorphic complex this integrated study demonstrates that clast assemblages are not a proxy for the character of the matrix and vice versa because they are influenced by the interplay of different controls therefore an integrated approach is needed to improve prediction of placer mineral deposits in river gravels and their distribution in coeval deposits downstream

a numerical model for the transport of a boulder by tsunami 1 we have conducted hydraulic experiments in an open channel with cubic and rectangular shaped solid blocks on the slope for investigating the boulder transport process by tsunami in our experiments the block was mainly seen to be transported by a bore due to rolling or saltation rather than by sliding previous models for the boulder transport by tsunamis assumed sliding as a mode of transport for the boulder therefore these models underestimated the distance of the boulder moved by the tsunami when it was transported due to rolling or saltation in this study we have developed a practical model for the transport of a boulder by tsunami which takes into account the various transport modes we introduce an empirical variable coefficient of friction by assuming that the coefficient decreases with decrease in ground contact time when the block was transported by rolling or saltation with the aid of this parameter the model can explain various modes of transport i e sliding rolling and saltation and reproduces the experimental results well we further applied this improved model to a tsunami boulder at inoda area in ishigaki island japan which was transported by the 1771 meiwa tsunami the calculated distance of transport of the boulder was approximately 650 m which is consistent with the description in the historical document based on our calculations we estimated hydraulic values of the tsunamis estimation of such hydraulic values is important for understanding the behavior and power of the historical tsunamis besides aiding future disaster mitigation efforts

variation of initial 230th 232th and limits of high precision u th dating of shallow water corals one hundred eighty u th data including 23 isochrons on 24 pristine modern and holocene corals and 33 seawater samples were analyzed using sector field mass spectrometry to understand the variability of initial 230th 232th 230th 232th0 this dataset allows us to further assess the accuracy and precision of coral 230th dating method by applying quality control including careful sampling and subsampling protocols and the use of contamination free storage and workbench spaces the resulting low procedural blanks give an equivalent uncertainty in age of only 0 2 0 3 yr for 1 2 g of coral sample using site specific 230th 232th0 values or isochron techniques our study demonstrates that corals with an age less than 100 yrs can be 230th dated with precisions of 1 yr six living subtidal coral samples were collected from two continental shelf sites nanwan off southern taiwan in the western pacific and son tra off central vietnam in the south china sea one coral core was drilled from an open ocean site santo island vanuatu in the western tropical pacific and modern and fossil intertidal coral slabs 17 in total were cut from six sites around the islands of simeulue lago north pagai and south pagai of sumatra in the eastern indian ocean the results indicate that the main source of thorium is the dissolved phase of seawater with variation of 230th 232th0 depending on local hydrology with intense input of terrestrial material low 230th 232th0 atomic ratios of 4 9 10 6 and 3 2 10 6 with a 10 variation are observed in nanwan and son tra respectively at the santo site we find a value of 5 6 10 6 at 4 horizons and one high value of 24 10 6 in a sample from ad 1974 6 0 5 likely due to the upwelling of cold water during a la nina event between ad 1973 and 1976 the natural dynamics of 230th 232th0 recorded in the intertidal corals at sites in the sumatran islands are complicated so that this value varies significantly from 3 0 to 9 4 10 6 three of the 141 modern coral 230th ages differ from their true ages by 23 to 4 indicating the presence of detrital material with anomalous 230th 232th values duplicate measurement of coeval subsamples is therefore recommended to verify the age accuracy this improved high precision coral 230th dating method raises the prospects of refining the age models for band counted and tracer tuned chronologies and of advancing coral paleoclimate research

coral geochemical signals and growth responses to coseismic uplift during the great sumatran megathrust earthquakes of 2004 and 2005 abstract the annual banded skeletons of reef corals potentially record past earthquakes events we examined cores of five living porites coral heads in simeulue island indonesia near the epicenter of the 2004 sumatra andaman and the 2005 nias simeulue earthquakes these sites showed 0 4 1 4 m of uplift we measured skeletal strontium magnesium and calcium carbon and oxygen isotopic ratios and skeletal density extension and calcification rates from 1994 to 2010 coral geochemistry fluctuates more than are expected from strictly environmental causes however stress bands reduced growth rates and changed skeletal 13c appear to reflect the tsunami and seismic uplift the step change in skeletal 13c results equated to 0 31 0 10 m in response to the 2004 uplift and 0 23 0 03 m to the 2005 uplift

dating earthquakes with high precision thorium 230 ages of very young corals mass spectrometric techniques have recently yielded significant increases in precision and sensitivity over previous methods for measuring 230 th abundance in corals to assess the accuracy of 230 th ages three corals from vanuatu whose ages were known from counting annual growth bands were analyzed for each sample the date of growth determined by 230 th analysis a d 1969 3 1932 5 and1806 5 2 uncertainties based on analytical error was indistinguishable from the date determined by counting bands a d 1971 1973 1935 1937 and 1804 1810 indicating that the 230 th dates are accurate 230 th dates were also determined for two adjacent emerged heads from santo is vanuatu which were thought to have died when they were raised above sea level during coseismic uplift the dates a d 1864 4 1866 4 were the same indicating that the heads died at the same time and consistent with the idea that they were killed by coseismic emergence around a d 1865 the difference between this date and the date of the only major historically documented earthquake that caused uplift a d 1973 m s 7 5 suggests a seismic recurrence interval of108 4y for santo analogous emerged corals from malekula is vanuatu yielded 230 th dates that were similar to each other a d 1729 3 1718 5 and are inferred to have died during coseismic emergence around a d 1729 in conjunction with the date of the only large historically documented earthquake that caused uplift a d 1965 m s 7 5 the recurrence interval for malekula is236 3y if similar emerged corals can be found this appraoch may be extended back in time and to other localities because it appears that such features can now be dated both accurately and precisely

uplift driven valley incision and climate controlled river terrace development in the thames valley uk abstract the sequence of terraces of the river thames in southeast england has previously been shown to span the period from the earliest pleistocene to the present this terrace sequence contains biostratigraphical and sedimentary evidence that testifies to the high amplitude climatic changes of the quaternary large scale fluvial incision resulting in basin wide terrace formation appears to have been concentrated at the warming limbs of the major climatic glacial interglacial cycles when sediment supply was greatly reduced this incision and subsequent valley floor widening created the accommodation space for the later aggradation of the terrace sediments during the following warm cold transitions and during the cold stages when high sediment supply conditions prevailed although the timing of terrace aggradation may be controlled by climate change the progressive valley incision recorded by terrace staircases cannot easily be explained in terms of quaternary climatic change alone and recently developed models suggest that long term incision by the thames has been driven by uplift this paper presents an overview of the available terrace data and tabulates incision amounts and rates between key stratigraphic horizons superimposed upon these broad changes revealed by the complex internal sedimentary architecture of many terrace sediments are the geomorphological system responses to both higher frequency climate driven changes and more localized intrinsic fluvial system adjustments

development of the thames drainage system in early and middle pleistocene times pre anglian terrace stages of the proto thames system are traced from the present middle thames area into essex and south east anglia gravel composition indicates that each of the main terrace stages is associated with an influx of far travelled material probably signifying at least three phases of pre anglian glaciation in the south midlands gravel composition also indicates the occurrence of major changes during early and middle pleistocene times in the extent of the thames catchment and in the disposition of the main drainage lines the important role of the goring gap in the development of the drainage system is noted and the nature and distribution of anglian fluvioglacial gravels are described

understanding the microscale spatial distribution and mineralogical residency of re in pyrite examples from carbonate hosted zn pb ores and implications for pyrite re os geochronology abstract accurate and precise geochronology using the re os isotopic system in pyrite is an invaluable tool for developing and confirming genetic models of ore systems however as a bulk method the results produced by pyrite re os geochronology are commonly complex and many imprecise isochrons exist in the literature using la icpms methods it is now possible to map and quantify re distribution at the ppb level allowing an unprecedented look into the re os systematics of pyrite bearing ore two samples from the lisheen zn pb ore deposit in ireland showing disparate re os isotopic behavior were investigated in situ sulfur isotope measurements using sims an analytical technique not previously attempted on the irish deposits was used to supplement the re os dataset a massive pyrite sample from the main zone produced a precise low scatter isochron 346 6 3 0 ma mswd 1 6 the re distribution in this sample is relatively homogeneous with the re budget dominated by pyrite containing 1 5 ppb re but the 34s varies significantly from 45 2 to 8 2 a second more paragenetically complex sample from the derryville zone produced a younger age with high scatter 322 11 ma mswd 206 and this also displays a large variation in 34s 53 to 4 the cores of grains of main stage iron sulfide are depleted in trace elements and show low re abundances a second re os dataset from zn pb mineralization at hawker creek nunavut canada was produced from massive pyrite that displays low re concentrations in general therefore the complexities of pyrite re os geochronology can result from impurities in mineral separates attempts to eliminate impurities through different mineral separation techniques e g crushing heavy liquid separation magnetic separation acid leaching are frequently only partially successful and therefore full characterization of any resulting mineral separates is extremely important we conclude that la icpms mapping of re and mo distributions is essential for the identification of such impurities although other trace element la icpms maps in situ sulfur isotope measurements and petrographic evidence were of limited use in assessing the re budget of a sample they are invaluable in linking the documented re distribution obtained through la icpms to re os geochronological results

understanding the history of extreme wave events in the tuamotu archipelago of french polynesia from large carbonate boulders on makemo atoll with implications for future threats in the central south pacific abstract numerous large carbonate boulders up to 164 tonnes in mass were investigated on the reef flat and beaches of makemo atoll in the tuamotu archipelago of french polynesia to reveal the past occurrence and to anticipate the future potential threat of extreme wave events possibly generated by tropical cyclones and tsunamis the modern reef edge and emerged mid holocene coastal landforms were identified as sources of boulders mobilized during extreme wave events in the past the minimum flow velocities produced by extreme wave events were estimated to exceed 5 4 15 7 m s at the reef edge on different parts of the atoll comparison of uranium thorium ages of boulder coral fabric with written historical records indicates that two large boulders 77 and 68 tonnes were possibly emplaced on the reef flat by a powerful cyclone in february 1878 although most boulder dates are older than the earliest historical cyclone and tsunami records in french polynesia their ages concur with the following a periods of storminess i e increased cyclone activity compared to today in the central south pacific over the last millennium and b periods of high sea surface temperature sst at the great barrier reef possibly associated with higher than normal ssts pacific wide that facilitated the generation of cyclones affecting the central south pacific ocean none of the boulders on makemo were dated younger than ce1900 implying that the last century has not experienced extreme waves of similar magnitude in the past nevertheless the findings suggest that waves of comparable magnitudes to those that have transported large boulders on makemo may recur in the tuamotus and threaten island coasts across the central south pacific in the future