summer enhancement of arctic sea ice volume anomalies in the september ice zone abstractbecause of its persistence on seasonal time scales arctic sea ice thickness sit is a potential source of predictability for summer sea ice extent sie new satellite observations of sit represent an opportunity to harness this potential predictability via improved thickness initialization in seasonal forecast systems in this work the evolution of arctic sea ice volume anomalies is studied using a 700 yr control integration and a suite of initialized ensemble forecasts from a fully coupled global climate model this analysis is focused on the september sea ice zone as this is the region where thickness anomalies have the potential to impact the sie minimum the primary finding of this paper is that in addition to a general decay with time sea ice volume anomalies display a summer enhancement in which anomalies tend to grow between the months of may and july this summer enhancement is relatively symmetric for positive and negative volume anomalies and peaks in july regardless of the initi

holocene subaqueous paleoseismology of lake tahoe gravity flow deposits recovered in a suite of sediment cores in lake tahoe were examined to determine if the event deposits were triggered by strong shaking from earthquakes on active faults within and in close proximity to the lake tahoe basin the acoustic character and distribution of individual lacustrine deposits as well as potential source regions were constrained by high resolution seismic chirp reflection and multibeam bathymetric data between 14 and 17 holocene event deposits have been identified in lake tahoe and examination of their source areas suggests they originated from different initiation points along the steep margin with some being synchronous around the basin as opposed to flood related deposits lithologic characteristics magnetic susceptibility carbon and nitrogen isotopic signatures opal content and 14 c dating indicate that these event deposits are reworked lacustrine material radiocarbon dates indicate that the emplacement of these event deposit sediments correlates well with the late holocene paleoseismic earthquake record developed for the tahoe basin when taken alone the causality of these events may appear ambiguous but when the evidence is examined comprehensively it suggests that strong shaking may likely have been the primary trigger for many of the event deposits observed in the lake throughout the holocene for example four event deposits are assigned to tahoe basin faults the most recent earthquakes occurred on the incline village fault between 630 and 120 cal yr b p the southern segment of the west tahoe fault between 4510 and 4070 cal yr b p on the central and northern segments of the west tahoe fault 5600 5330 cal yr b p and on the west tahoe fault between 7890 and 7190 cal yr b p the oldest of the four associated tahoe basin events coincides with the beginning of an extended period when lake tahoe was likely not spilling or spilling intermittently and this suggests that active faulting and footwall uplift cut off the outlet at this time exaggerating drought conditions downstream likewise the event between 5600 and 5330 cal yr b p on the west tahoe fault may have exaggerated a smaller drought reflected downstream in pyramid lake this event may also be the most recent event mre on the largest segment of the west tahoe fault if correct the period since the last rupture is approximately twice the estimated average recurrence interval for the rubicon segment of the west tahoe fault a more complete holocene record of strong shaking greatly extends the paleoseismic record in the region and indicates a combined recurrence interval of between 750 and 800 yr for all faults in the region

variations in the age of arctic sea ice and summer sea ice extent 1 three of the past six summers have exhibited record low sea ice extent on the arctic ocean these minima may have been dynamically induced by changes in the surface winds based on results of a simple model that keeps track of the age of ice as it moves about on the arctic ocean we show that the areal coverage of thick multi year ice decreased precipitously during 1989 1990 when the arctic oscillation was in an extreme high index state and has remained low since that time under these conditions younger thinner ice anomalies recirculate back to the alaskan coast more quickly decreasing the time that new ice has to ridge and thicken before returning for another melt season during the 2002 and 2003 summers this anomalously younger thinner ice was advected into alaskan coastal waters where extensive melting was observed even though temperatures were locally colder than normal the age of sea ice explains more than half of the variance in summer sea ice extent

sedimentary features of the seismo turbidites lake biwa japan abstract seismo turbidite layers are deposited at the foot of the steep slope of the half graben in which lake biwa has accumulated sedimentary studies especially of grain size distribution of selected turbidites provide excellent information for clarifying the distinctive features of general seismo turbidites development of the two constituent sublayers lower sandy sublayer and upper silt sublayer lack or limited appearances of traction indicating structures and characteristic grain size distribution in the two constituent sublayers are most remarkable and significant the characteristic grain size distribution features are coarse tail grading in a relatively thick sandy sublayer exceptionally rapid distribution grading through the thin boundary interval between the two sublayers height increase and fluctuation of the silt mode and high clay content brief discussion was made on the causes of these sedimentary features the need and importance of further comparative studies of various turbidites known triggering forces are emphasized

exploring links between arctic amplification and mid latitude weather 1 this study examines observed changes 1979 2011 in atmospheric planetary wave amplitude over northern mid latitudes which have been proposed as a possible mechanism linking arctic amplification and mid latitude weather extremes we use two distinct but equally valid definitions of planetary wave amplitude termed meridional amplitude a measure of north south meandering and zonal amplitude a measure of the intensity of atmospheric ridges and troughs at 45 n statistically significant changes in either metric are limited to few seasons wavelengths and longitudinal sectors however in summer we identify significant increases in meridional amplitude over europe but significant decreases in zonal amplitude hemispherically and also individually over europe and asia therefore we argue that possible connections between arctic amplification and planetary waves and implications of these are sensitive to how waves are conceptualized the contrasting meridional and zonal amplitude trends have different and complex possible implications for midlatitude weather and we encourage further work to better understand these

increased arctic sea ice volume after anomalously low melting in 2013 changes in arctic sea ice volume are difficult to quantify five years of satellite data reveal a reduction in autumn sea ice volume in 2010 2012 but a sharp increase in 2013 and 2014 suggesting that ice volume can recover quickly

tephrostratigraphy of paleoclimatic archives in central mediterranean during the bronze age abstract re examination of central mediterranean paleoclimate archives on tephra layers indicates that three widely dispersed tephra layers occurred during the bronze age namely agnano mt spina from campi flegrei ca 4 4 cal ka bp avellino from somma vesuvius ca 3 9 cal ka bp and fl from etna ca 3 3 cal ka bp stratigraphical correlations of selected archives using these tephra layers indicate that some records have severe chronological biases posing important limitations to the use of these archives for defining the paleoclimate conditions during the bronze age regardless of the temporal mismatches the agnano mt spina tephra layer seems to have occurred at the beginning of a centennial scale period of climatic deterioration while the avellino tephra layer taking place during a wetter period seems to mark the end of this event the dry event bounded by the two tephra layers seems to be correlated with the so called 4 2 event instead the fl tephra from etna seems to herald a new climatic deterioration at ca 3 3 3 2 cal ka bp although the general frame is still incomplete these three tephra layers appear to play a fundamental role in synchronizing archives and can lead to the definition of a detailed paleoclimatic framework of the bronze age in the central mediterranean area

volcanic influence of mt fuji on the watershed of lake motosu and its impact on the lacustrine sedimentary record abstract lacustrine sediments are particularly sensitive to modifications within the lake catchment in a volcanic area sedimentation rates are directly affected by the history of the volcano and its eruptions here we investigate the impact of mt fuji volcano japan on lake motosu and its watershed the lacustrine infill is studied by combining seismic reflection profiles and sediment cores we show evidence of changes in sedimentation patterns during the depositional history of lake motosu the frequency of large mass transport deposits recorded within the lake decreases over the holocene before 8000 cal yr bp large sublacustrine landslides and turbidites were filling the lacustrine depression after 8000 cal yr bp only one large sublacustrine landslide was recorded the change in sedimentation pattern coincides with a change in sediment accumulation rate over the last 8000 cal yr bp the sediment accumulation rate was not sufficient enough to produce large sublacustrine slope failures consequently the frequency of large mass transport deposits decreased and only turbidites resulting from surficial slope reworking occurred these constitute the main sedimentary infill of the deep basin we link the change in sediment accumulation rate with i climate and vegetation changes and ii the mt fuji eruptions which affected the lake motosu watershed by reducing its size and strongly modified its topography moreover this study highlights that the deposition of turbidites in the deep basin of lake motosu is mainly controlled by the paleobathymetry of the lakefloor two large mass transport deposits occurring around 8000 cal yr bp and 2000 cal yr bp respectively modified the paleobathymetry of the lakefloor and therefore changed the turbidite depositional pattern of lake motosu

turbiditic trench deposits at the south chilean active margin a pleistocene holocene record of climate and tectonics the active plate margin of south america is characterized by a frequent occurrence of large and devastating subduction earthquakes here we focus on marine sedimentary records off southern chile that are archiving the regional paleoseismic history over the holocene and late pleistocene the investigated records ocean drilling program odp site 1232 and sonne core 50sl are located at 40 s and 38 s within the peru chile trench and are characterized by frequent interbedded strata of turbiditic and hemipelagic origin on the basis of the sedimentological characteristics and the association with the active margin of southern chile we assume that the turbidites are mainly seismically triggered and may be considered as paleo megaearthquake indicators however the long term changes in turbidite recurrence times appear to be strongly influenced by climate and sea level changes as well during sea level highstands in the holocene and marine isotope stage mis 5 recurrence times of turbiditic layers are substantially higher primarily reflecting a climate induced reduction of sediment availability and enhanced slope stability in addition segmented tectonic uplift changes and related drainage inversions likely influenced the postglacial decrease in turbidite frequencies glacial turbidite recurrence times including mis 2 mis 3 cold substages of mis 5 and mis 6 on the other hand are within the same order of magnitude as earthquake recurrence times derived from the historical record and other terrestrial paleoseismic archives of the region only during these cold stages sediment availability and slope instability were high enough to enable recording of the complete sequence of large earthquakes in southern chile our data thus suggest that earthquake recurrence times on the order of 100 to 200 years are a persistent feature at least during the last glacial period 2008 elsevier b v all rights reserved

solar and proxy sensitivity imprints on paleohydrological records for the last millennium in west central europe this paper presents a lake level record established for the last millennium at lake saint point in the french jura mountains a comparison of this lake level record with a solar irradiance record supports the hypothesis of a solar forcing of variations in the hydrological cycle linked to climatic oscillations over the last millennium in west central europe with higher lake levels during the solar minimums of oort around ad 1060 wolf around ad 1320 sporer around ad 1450 maunder around ad 1690 and dalton around ad 1820 further comparisons of the saint point record with the fluctuations of the great aletsch glacier swiss alps and a record of rhone river floods from lake bourget french alps give evidence of possible imprints of proxy sensitivity on reconstructed paleohydrological records in particular the great aletsch record shows an increasing glacier mass from ad 1350 to 1850 suggesting a cumulative effect of the little ice age cooling and or a possible reflection of a millennial scale general cooling until the mid 19th century in the northern hemisphere in contrast the saint point and bourget records show a general trend toward a decrease in lake levels and in flood magnitude anti correlated with generally increasing solar irradiance

holocene earthquake records from the cascadia subduction zone and northern san andreas fault based on precise dating of offshore turbidites abstract we present preliminary evidence for a 10 000 year earthquake record from two major fault systems based on sediment cores collected along the continental margins of western north america new stratigraphic evidence from cascadia demonstrates that 13 earthquakes ruptured the entire margin from vancouver island to at least the california border since the eruption of the mazama ash 7700 years ago the 13 events above this prominent stratigraphic marker have an average repeat time of 600 years and the youngest event 300 years ago coincides with the coastal record we also extend the record of past earthquakes to the base of the holocene at least 9800 years ago during which 18 events correlate along the same region the sequence of holocene events in cascadia appears to contain a repeating pattern of events a tantalizing first look at what may be the long term behavior of a major fault system the northern california margin cores show a cyclic record of turbidite beds that may represent holoce

holocene climate variability as reflected by mid european lake level fluctuations and its probable impact on prehistoric human settlements abstract a data set of 180 radiocarbon tree ring and archaeological dates obtained from sediment sequences of 26 lakes in the jura mountains the northern french pre alps and the swiss plateau was used to construct a holocene mid european lake level record the dates do not indicate a random distribution over the holocene but form clusters suggesting an alternation of lower and higher climatically driven lake level phases they provide evidence of a rather unstable holocene climate punctuated by 15 phases of higher lake level 11 250 11 050 10 300 10 000 9550 9150 8300 8050 7550 7250 6350 5900 5650 5200 4850 4800 4150 3950 3500 3100 2750 2350 1800 1700 1300 1100 750 650 cal bp and after 1394 ad a comparison of this mid european lake level record with the gisp2 polar circulation index pci record the north atlantic ice rafting debris ird events and the 14 c record suggests teleconnections in a complex cryosphere ocean atmosphere system correlations between the gisp2 pci the mid european lake level the north atlantic ird and the residual 14 c records suggest that changes in the solar activity played a major role in holocene climate oscillations over the north atlantic area

predicting regional and pan arctic sea ice anomalies with kernel analog forecasting predicting arctic sea ice extent is a notoriously difficult forecasting problem even for lead times as short as one month motivated by arctic intraannual variability phenomena such as reemergence of sea surface temperature and sea ice anomalies we use a prediction approach for sea ice anomalies based on analog forecasting traditional analog forecasting relies on identifying a single analog in a historical record usually by minimizing euclidean distance and forming a forecast from the analog s historical trajectory here an ensemble of analogs is used to make forecasts where the ensemble weights are determined by a dynamics adapted similarity kernel which takes into account the nonlinear geometry on the underlying data manifold we apply this method for forecasting pan arctic and regional sea ice area and volume anomalies from multi century climate model data and in many cases find improvement over the benchmark damped persistence forecast examples of success include the 3 6 month lead time prediction of arctic sea ice area the winter sea ice area prediction of some marginal ice zone seas and the 3 12 month lead time prediction of sea ice volume anomalies in many central arctic basins we discuss possible connections between kaf success and sea ice reemergence and find kaf to be successful in regions and seasons exhibiting high interannual variability

holocene palaeohydrological changes in the northern mediterranean borderlands as reflected by the lake level record of lake ledro northeastern italy a lake level record of lake ledro northern italy spans the entire holocenewith a chronology derived from51 radiocarbon dates it is based on a specific sedimentological approach that combines data fromfive sediment profiles sampled in distinct locations in the littoral zone on a millennial scale the lake level record shows two successive periods from 11 700 to 4500 cal yr bp and from 4500 cal yr bp to the present characterized by lower and higher average lake levels respectively in addition to key seasonal and inter hemispherical changes in insolation the major hydrological change around 4500 cal yr bp may be related to a non linear response of the climate system to orbitally driven gradual decrease in insolation the ledro record questions the notion of an accentuated summer rain regime in the northern mediterranean borderlands during the boreal insolation maximum moreover the ledro record highlights that the holocenewas punctuated by successive centennial scale highstands correlations with the preboreal oscillation and the 8 2 ka event and comparisonwith the atmospheric 14c residual record suggest that short lived lake level fluctuations developed at ledro in response to 1 final steps of the deglaciation in the north atlantic area and 2 variations in solar activity

influence of the sea ice thickness distribution on polar climate in ccsm3 abstract the sea ice simulation of the community climate system model version 3 ccsm3 t42 gx1 and t85 gx1 control simulations is presented and the influence of the parameterized sea ice thickness distribution itd on polar climate conditions is examined this includes an analysis of the change in mean climate conditions and simulated sea ice feedbacks when an itd is included it is found that including a representation of the subgrid scale itd results in larger ice growth rates and thicker sea ice these larger growth rates represent a higher heat loss from the ocean ice column to the atmosphere resulting in warmer surface conditions ocean circulation most notably in the southern hemisphere is also modified by the itd because of the influence of enhanced high latitude ice formation on the ocean buoyancy flux and resulting deep water formation changes in atmospheric circulation also result again most notably in the southern hemisphere there are indications that the itd also modifies simulated sea

lake sediments record high intensity shaking that provides insight into the location and rupture length of large earthquakes on the alpine fault new zealand abstract understanding the seismic hazard posed by large earthquakes requires paleoseismic investigation because most faults have not ruptured repeatedly during the period of historic records however determining the location and length of fault ruptures using paleoseismic data remains challenging our study demonstrates that lake sediments record the high intensity shaking that occurs proximal to fault rupture allowing the location and length of ruptures to be reconstructed in two lakes adjacent to the alpine fault new zealand seismic shaking is recorded as subaqueous mass wasting derived turbidites formed by coseismic subaqueous slope failures which are overlain by sets of hyperpycnites representing elevated fluvial sediment fluxes from earthquake induced landslides precise radiocarbon age models show that shaking events are synchronous between the two lake sites and correlate with the timing of known alpine fault earthquakes modelled shaking intensities for the last two alpine fault earthquakes show that subaqueous mass wasting occurs when shaking intensities exceed modified mercalli scale mm vi vii and that fluvial sediment fluxes from earthquake induced landslides occur when shaking intensities exceed mm ix the data demonstrate that lake records distinguish between strong mm vi and violent mm ix shaking at a lake site the ability to map the spatial extent of mm ix shaking provides new insights into the timing and extent of rupture for the last five earthquakes on the alpine fault the study demonstrates that lake deposits constrain the spatial extent of rupture during large earthquakes and may yield long records of the spatial and temporal patterns of fault rupture

solar forcing of climatic change during the mid holocene indications from raised bogs in the netherlands two cores of mid holocene raised bog deposits from the netherlands were 14 c wiggle match dated 14 c as a proxy for changes in solar activity is validated this paper adds to the increasing body of evidence that solar variability forced climatic changes during the holocene 14 c wiggle match dating mid holocene wet shifts

changes in arctic melt season and implications for sea ice loss the arctic wide melt season has lengthened at a rate of 5 days decade 1 from 1979 to 2013 dominated by later autumn freezeup within the kara laptev east siberian chukchi and beaufort seas between 6 and 11 days decade 1 while melt onset trends are generally smaller the timing of melt onset has a large influence on the total amount of solar energy absorbed during summer the additional heat stored in the upper ocean of approximately 752 mj m 2 during the last decade increases sea surface temperatures by 0 5 to 1 5 c and largely explains the observed delays in autumn freezeup within the arctic ocean s adjacent seas cumulative anomalies in total absorbed solar radiation from may through september for the most recent pentad locally exceed 300 400 mj m 2 in the beaufort chukchi and east siberian seas this extra solar energy is equivalent to melting 0 97 to 1 3 m of ice during the summer

reemergence mechanisms for north pacific sea ice revealed through nonlinear laplacian spectral analysis abstractthis paper studies spatiotemporal modes of variability of sea ice concentration and sea surface temperature sst in the north pacific sector in a comprehensive climate model and observations these modes are obtained via nonlinear laplacian spectral analysis nlsa a recently developed data analysis technique for high dimensional nonlinear datasets the existing nlsa algorithm is modified to allow for a scale invariant coupled analysis of multiple variables in different physical units the coupled nlsa modes are utilized to investigate north pacific sea ice reemergence a process in which sea ice anomalies originating in the melt season spring are positively correlated with anomalies in the growth season fall despite a loss of correlation in the intervening summer months it is found that a low dimensional family of nlsa modes is able to reproduce the lagged correlations observed in sea ice data from the north pacific ocean this mode family exists in both model output and observations and i

calendar dated glacier variations in the western european alps during the neoglacial the mer de glace record mont blanc massif holocene glacier records from the western european alps are still sparse although a number of sites are well suited to constraining pre and early little ice age lia glacier advances the present study provides the first dendrochronologically based and calendar dated neoglacial glacier chronology for the mont blanc massif french alps it is based on the analysis of over 240 glacially buried pinus cembra subfossil logs and wood remains found either embedded in till or as detrital material in the mer de glace right lateral moraine only a few of the samples were found to be formally in situ but we show that some logs were virtually in situ not rooted but showing little or no evidence of reworking and could be used to accurately reconstruct past glacier margin behavior in space and time uncertainties regarding the other samples may relate to original growth location and or to outer wood decay the resulting dates followed by a were therefore considered maximum limiting ages for glacier advances the main burial events interpreted as glacier advances occurred between ca 1655 and 1544 bc between ca 1230 and 1105 bc between ca 1013 and 962 937 bc at ca 802 777 bc after 608 bc between 312 and 337 ad between ca 485 ad and 606 ad between 1120 and 1178 ad between ca 1248 and 1278 1296 ad and after 1352 ad these advances predate the late lia maxima known from historical sources the magnitude of the advances gradually increased to culminate in three near neoglacial maxima during the 7th 12th and 13th centuries ad followed by a first lia neoglacial maximum in the second half of the 14th century ad the pattern of neoglacial events described here is coherent with central and eastern alpine glacier chronologies this indicates marked synchronicity of late holocene glacier variability and forcing at a regional scale although occasional differences could be detected between western and eastern records the mer de glace record also confirms the link between the timing of sediment erosion in a high elevation glaciated alpine catchment and subsequent deposition in the sub alpine lake bourget

simulating the ice thickness distribution in a coupled climate model climate simulations in a global coupled model are investigated using a dynamic thermodynamic sea ice and snow model with sophisticated thermodynamics and a subgrid scale parameterization for multiple ice thicknesses in addition to the sea ice component the model includes a full primitive equation ocean and a simple energy moisture balance atmosphere we introduce a formulation of the ice thickness distribution that is lagrangian in thickness space the method is designed to use fewer thickness categories because it adjusts to place resolution where it is needed most and it is free of diffusive effects that tend to smooth eulerian distributions experiments demonstrate that the model does reasonably well in simulating the mean arctic climate we find the climate of the arctic and northern north atlantic is sensitive to resolving the ice thickness distribution when comparing the model results to a simulation with a two level sea ice model the ice thickness distribution causes ice export through fram strait to be more variable and more strongly linked to meridional overturning in the north atlantic ocean the lagrangian formulation of the ice thickness distribution allows for the inclusion of a vertical temperature profile with relative ease compared to an eulerian method we find ice growth rates and ocean surface salinity differ in our model with a well resolved vertical temperature profile in the ice and snow and an explicit brine pocket parameterization compared to a simulation with semtner zero layer thermodynamics although these differences are important for the climate of the arctic the effects of an ice thickness distribution are more dramatic and extend into the northern north atlantic sensitivity experiments indicate that five ice thickness categories with 50 cm vertical temperature resolution capture the effects of the ice thickness distribution on the heat and freshwater exchange across the surface in the presence of sea ice in these simulations

sea ice albedo climate feedback mechanism abstract the sea ice albedo feedback mechanism over the arctic ocean multiyear sea ice is investigated by conducting a series of experiments using several one dimensional models of the coupled sea ice atmosphere system in its simplest form ice albedo feedback is thought to be associated with a decrease in the areal cover of snow and ice and a corresponding increase in the surface temperature further decreasing the areal cover of snow and ice it is shown that the sea ice albedo feedback can operate even in multiyear pack ice without the disappearance of this ice associated with internal processes occurring within the multiyear ice pack e g duration of the snow cover ice thickness ice distribution lead fraction and melt pond characteristics the strength of the ice albedo feedback mechanism is compared for several different thermodynamic sea ice models a new model that includes ice thickness distribution the ebert and curry model the maykut and untersteiner model and the semtner level 3 an

lake sediments as natural seismographs a compiled record of late quaternary earthquakes in central switzerland and its implication for alpine deformation central switzerland lies tectonically in an intraplate area and recurrence rates of strong earthquakes exceed the time span covered by historic chronicles however many lakes are present in the area that act as natural seismographs their continuous datable and high resolution sediment succession allows extension of the earthquake catalogue to pre historic times this study reviews and compiles available data sets and results from more than 10 years of lacustrine palaeoseismological research in lakes of northern and central switzerland the concept of using lacustrine mass movement event stratigraphy to identify palaeo earthquakes is showcased by presenting new data and results from lake zurich the late glacial to holocene mass movement units in this lake document a complex history of varying tectonic and environmental impacts results include sedimentary evidence of three major and three minor simultaneously triggered basin wide lateral slope failure events interpreted as the fingerprints of palaeoseismic activity a refined earthquake catalogue which includes results from previous lake studies reveals a non uniform temporal distribution of earthquakes in northern and central switzerland a higher frequency of earthquakes in the late glacial and late holocene period documents two different phases of neotectonic activity they are interpreted to be related to isostatic post glacial rebound and relatively recent re activation of seismogenic zones respectively magnitudes and epicentre reconstructions for the largest identified earthquakes provide evidence for two possible earthquake sources i a source area in the region of the alpine or sub alpine front due to release of accumulated north west south east compressional stress related to an active basal thrust beneath the aar massif and ii a source area beneath the alpine foreland due to reactivation of deep seated strike slip faults such activity has been repeatedly observed instrumentally for example during the most recent magnitude 4 2 and 3 5 earthquakes of february 2012 near zug the combined lacustrine record from northern and central switzerland indicates that at least one of these potential sources has been capable of producing magnitude 6 2 to 6 7 events in the past

lacustrine turbidites produced by surficial slope sediment remobilization a mechanism for continuous and sensitive turbidite paleoseismic records turbidite records along ocean margins and in lake basins are increasingly used as paleoseismic proxies however the slope remobilization processes that formed the earthquake related turbidity currents are poorly understood and therefore it is difficult to assess the consistency of turbidite paleoseismic records we analyzed the sedimentary imprint of the giant ad 1960 mw 9 5 chile earthquake in four south central chilean lakes mass transport deposits and turbidites were compared by interpreting reflection seismic profiles sedimentary facies volume balances and proxies for turbidite composition i e grain size radionuclides sediment color organic matter sediment lightness was used as a proxy for organic matter content comparison of lightness of turbidites and the underlying sediments shows that earthquake triggered turbidites in the four lakes result from remobilization of a thin veneer on average about 5 cm of slope sediments and do not result from disintegration of subaquatic landslides statistical analysis of 34 turbidites in a new 5200 year sedimentary record does not show any correlation between inter event time and turbidite thickness and thus volume this means that inter event slope recharging is not a dominant factor governing turbidite recurrence and that initiation of turbidity currents by remobilization of surficial sediments is different to slope failure related to subaquatic landslides we conclude that surficial slope sediment remobilization forms a valid mechanism that explains why turbidite paleoseismic records can be of excellent continuity and high sensitivity moreover based on correlations between seismic intensity turbidite volume and stratigraphic remobilization depth we propose that surficial slope sediment remobilization allows for turbidite records containing information about paleo earthquake intensity

historical nankai suruga megathrust earthquakes recorded by tsunami and terrestrial mass movement deposits on the shirasuka coastal lowlands shizuoka prefecture japan geological investigations of coastal sediment sequences play a key role in verifying earthquake and tsunami characteristics inferred from historical records in this paper we present a multi proxy investigation of a coastal lowland site facing the nankai suruga megathrust and appraise evidence for tsunamis and earthquake triggered terrestrial mass movements occurring over the last 800 years combining a high resolution chronology with x ray computed tomography and analyses of particle size diatoms pollen non pollen palynomorphs and aerial photographs we present the most compelling geological evidence of the 1361 ce koan also known as shohei tsunami reported to date from any site along the megathrust this finding is consistent with either of two recent hypotheses a single larger rupture of both the nankai and tnankai regions or two smaller ruptures separated by a few days enhancing the site chronology using bayesian age modelling we verify evidence for inundation during the 1498 ce mei tsunami while previous investigations identified evidence for historically recorded tsunamis in 1605 1707 and 1854 ce and a storm surge in 1680 or 1699 ce we encountered a thick sand layer rather than discrete extreme wave deposits in this interval the overprinting of evidence highlights the potential for geological records to underestimate the frequency of these events a terrestrial mass movement also deposited a sand layer at the site radionuclide dating and aerial photographs provide independent confirmation that this may have been triggered by intense shaking in 1944 ce during the most recent great nankai suruga megathrust earthquake

sedimentary features of seismoturbidites triggered by the 1983 and older historical earthquakes in the eastern margin of the japan sea abstract both mass failure deposits and turbidites are widely distributed in the epicentral area of the 1983 earthquake mw 7 9 in the eastern margin of the japan sea this basin is semi enclosed with no active conduits for the entrance of coarse detrital sediments seismic reflection surveys and sediment cores reveal that mass failure deposits which are distributed on the continental slopes merge into turbidites in the basin plain hence the mass wasting process is a major transportation process in this region one gravity core gh93 816 was recovered from the southeastern margin of the japan basin close to the epicentral area of the 1983 japan sea earthquake sedimentological results show that five turbidite beds are intercalated in the top 68 cm of the column occurrence of the b tm tephra at the depth of 68 71 cm indicates that these turbidite beds were developed during the last 1000 years the high 137cs concentration in the top 20 cm of the core implies that the uppermost turbidite bed was deposited after 1954 based on these age limits for the top and the bottom of the studied interval we estimate the recurrence intervals of turbidites as 160 330 years we suggest that these turbidites were generated by submarine slides which were triggered by the 1983 and older historical earthquakes in this region these seismoturbidites are characterized by amalgamated beds irregular structure sequences grain size breaks fluctuations abrupt changes in composition within bed and variable composition among beds from these features we infer that deposition resulted from a series of turbidity currents associated with multiple or line sources for example multiple shallow slides that were regionally initiated by the same earthquake the sedimentary features described herein may be useful as criteria for identifying modern seismoturbidites in other settings as well as seismoturbidites in the geologic record however further study is needed for the distinction of this type of turbidites from other types e g tempestites reflected turbidites

climate change versus land management in the po plain northern italy during the bronze age new insights from the vp vg sequence of the terramara santa rosa di poviglio abstract the sedimentary infilling of the moat surrounding the villaggio piccolo of the terramara santa rosa di poviglio was analysed in order to obtain palaeoenvironmental inferences from sediments and pollen assemblage the high resolution stratigraphic sequence preserves evidence of the environmental changes that occurred in the po plain in northern italy during the late holocene our interdisciplinary approach permitted to study climatic and anthropic contributions to the environmental changes in this region the relationships between these changes and land use changes were investigated focussing on adaptive strategies of the terramare people during the middle and recent bronze ages 1550 1170 yr bc the terramare are archaeological remains of banked and moated villages located in the central alluvial plain of the po river the terramara of santa rosa consists of two adjoining settlements villaggio grande and villaggio piccolo the moat that separates the two parts of the site is c 23 m large and reaches a maximum depth of 4 m from the extant ground level the stratigraphic sequence vp vg exposed by archaeological excavation inside the moat was sampled for pedosedimentary thin section and pollen analyses chronology is based on archaeological evidence stratigraphic correlations and radiocarbon dating pedosedimentary features and biological records pollen of aquatics and algal remains demonstrate that shallow water probably subjected to seasonal water level oscillations has always been present in the moat in the lower units of the sequence the laminations indicate standing water while occurrence of reworked pollen testified the supply of sediments to the plain from catchment zones located in the apennine open vegetation was widespread economy was based on wood management fruit collection on the wild or from cultivated woody plants crop fields with a fairly diversified set of cereals especially increasing in variety during dryness or phases of water crisis probably grapevines were cultivated near the moat where the wet habitat was favourable to the growing of wild plants the extraordinary high resolution of this sequence makes visible the management of woods including coppicing at the middle bronze and early recent bronze ages the economy of santa rosa di poviglio should have been probably less based on animal breeding than it was in the other terramare villages already studied for pollen this research also confirms the chronological correspondence between an environment stressed by dry conditions and the collapse of the terramare civilization

reconstruction of the holocene seismotectonic activity of the southern andes from seismites recorded in lago icalma chile 39 s abstract south central chile is one of the most geodynamically active areas in the world characterized by frequent volcanic eruptions and numerous earthquakes which are both recorded in lake sediments in lago icalma 39 s long piston and short gravity coring as well as 3 5 khz high resolution seismic profiling have been carried out in order to study the holocene sedimentary infill of the lake with a special focus on earthquake triggered deposits macroscopic description of sediment cores and detailed grain size analyses allow us to identify four types of seismically induced deposits or seismites slump deposits chaotic deposits turbidites s s and homogenites homogenites are characterized by the occurrence of three distinct units on grain size profiles i e a coarse base a thick homogeneous unit topped by a thin layer of very fine sediment and by the typical distribution of the grain size parameters in a skewness sorting diagram while turbidites s s are characterized by a continuous fining upward trend radiocarbon 210pb dating and tephrochronology allow us to demonstrate that the regional seismotectonic activity was probably very high between 2200 and 3000 cal years bp as well as between 7000 and 8000 cal years bp and that none of the historically documented earthquakes has triggered a seismite in lago icalma the most recent seismite recognized in the sediments of lago icalma is a slump deposit dated at 1100 100 ad i e older than the period covered by historical records the remarkable record of seismites between 2200 and 3000 cal years bp is probably influenced by a major eruption of sollipulli volcano at 3000 cal years bp which has rejuvenated the stock of terrigenous particles available for erosion by depositing a thick layer of pumices all over the watershed of lago icalma and by clearing the vegetation covering the volcanic ash soils this paper demonstrates that the record of seismically triggered deposits in lake sediments is not only controlled by the intensity of the triggering earthquake and the occurrence of unstable sediment along the lake slopes but also by the presence of particles available for erosion remobilisation in the watershed

glacier and lake level variations in west central europe over the last 3500 years on the basis of glacier and lake level records this paper attempts for the first time a comparison between high resolution palaeohydrological and palaeoglaciological data in west central europe over the past 3500 years a data set of tree ring width radiocarbon and archaeological data in addition to historical sources were used to reconstruct fluctuations of the great aletsch the gorner and the lower grindelwald glaciers in the swiss alps the three ice streams experienced nearly synchronous advances at c 1000 600 bc and ad 500 600 800 900 1100 1200 and 1300 1860 these glacier fluctuations show strong correspondence with lake level variations reconstructed in eastern france jura mountains and pre alps and on the swiss plateau this supports the hypothesis of climatically driven fluctuations historical data available for the period since ad 1550 reveal in detail various meteorological conditions behind the successive glacier advances however in agreement with the general trend shown by th

paleoseismicity of the cascadia subduction zone evidence from turbidites off the oregon washington margin cores from cascadia deep sea channel contain sequences of turbidites that can be correlated and dated by the first occurrence of volcanic glass from the mount mazama eruption 6845 50 radiocarbon yrbp turbidity currents from the tributaries appear to have occurred synchronously to form single deposits in the main channel there being only 13 turbidite deposits in the lower main channel since the mazama eruption instead of the twice as many expected if the tributaries had behaved independently in addition to the cascadia channel 13 post mazama turbidites have been deposited in the astoria canyon and at two sites off cape blanco sample locations that span 580 km of the oregon washington margin pelagic intervals deposited between the turbidites suggest that in each place the turbidity currents occurred fairly regularly every 590 170 years on average the best explanation of the spatial and temporal extent of the data is that the turbidity currents were triggered by 13 great earthquakes on the cascadia subduction zone the variability of turbidite timing is similar to that for great earthquake cycles the thickness of the topmost pelagic layer suggests the last event was 300 60 years ago from three places along the margin but this number may be a biased underestimate it is however consistent with the youngest sudden subsidence event on the washington coast the turbidite data demonstrate that the near term hazard of a great earthquake on the cascadia subduction zone is of the order of 2 10 in the next 50 years

takarkori rock shelter sw libya an archive of holocene climate and environmental changes in the central sahara abstract rock shelters in the central saharan massifs preserve anthropogenic stratigraphic sequences that represent both a precious archive for the prehistory of the region and a powerful proxy data for holocene palaeoenvironments the geoarchaeological micromorphology and archaeobotanical pollen analysis approaches were integrated to investigate the anthropogenic sedimentary sequence preserved within the takarkori rock shelter a holocene archaeological site located in the libyan central sahara southern tadrart acacus massif the site was occupied throughout the early and middle holocene african humid period by groups of hunter gatherers before and by pastoral communities later the investigation on the inner part of the sequence allows to recognize the anthropogenic contribution to sedimentation process and to reconstruct the major changes in the holocene climate at the bottom of the stratigraphic sequence evidence for the earliest frequentation of the site by hunters and gatherers has been recognized it is dated to c 10 170 cal yr bp and is characterized by high availability of water freshwater habitats and sparsely wooded savannah vegetation a second early holocene occupation ended at c 8180 cal yr bp this phase is marked by increased aridity sediments progressively richer in organics testifying to a more intense occupation of the site and pollen spectra indicating a decrease of grassland and the spreading of cattails which followed a general lowering of lake level or widening of shallow water marginal habitats near the site after this period a new occupational phase is dated between c 8180 and 5610 cal yr bp this period saw the beginning of the frequentation of pastoral groups and is marked by an important change in the forming processes of the sequence sediments and pollen spectra confirm a new increase in water availability which led to a change in the landscape surrounding the takarkori rock shelter with the spreading of water bodies the upper part of the sequence dating between c 5700 and 4650 cal yr bp records a significant environmental instability towards dryer climatic conditions consistent with the end of the african humid period though some freshwater habitats were still present increasing aridity pushed the expansion of the dry savannah the final transition to arid conditions is indicated by the preservation of ovicaprines dung layers at the top of the sequence together with sandstone blocks collapsed from the shelter s vault on the contrary the outer part of the sequence preserves a significantly different palaeoenvironmental signal in fact the surface was exposed to rainfall and a complex pedogenetic evolution of the sequence occurred encompassing the formation of an argillic laminar horizon at the topsoil the evolution of a desert pavement and the deposition of mn rich rock varnish on stones these processes are an effect of the general environmental instability that occurred in the central sahara since the middle holocene transition finally the local palaeoclimatic significance of the sequence fits well with holocene regional and continental environmental changes recorded by many palaeohydrological records from north africa this highlights the potential of geoarchaeological and archaeobotanical investigations in interpreting the palaeoenvironmental significance of anthropogenic cave sediments in arid lands

a volcanically induced climate warming and floral change preceded the onset of oae1a early cretaceous the aptian oceanic anoxic event 1a oae1a is preceded by a prominent negative c isotope excursion ncie attributed to major volcanism on the ontong java plateau that is supposed to lead to a pco2 increase and a climate change lower aptian sporomorph assemblages in two pelagic sections from the southern tethys margin n italy were analysed in order to test if the postulated climate changes affected the terrestrial vegetation at the base of the ncie the sporomorph assemblages comprise abundant bisaccate pollen reflecting a warm temperate climate several tens of kiloyears ka after the start of the ncie decreasing bisaccate pollen and increasing classopollis spp and araucariacites spp suggest the beginning of a long term temperature rise palynomorphs indicate that maximum temperatures were reached several tens of ka after the end of the ncie and the onset of oae1a the highest temperatures coincide with arid conditions which could reflect a northward shift of the hot arid northern gondwana floral province as a result of an increasing pco2 over 200 ka after the onset of oae1a reduced volcanic activity and or increased black shale deposition allowed for a drawdown of most of the excess co2 and a southward shift of floral belts

paleoseismicity along the southern kuril trench deduced from submarine fan turbidites abstract large m 8 damaging interplate earthquakes occur frequently in the eastern hokkaido region northern japan where the pacific plate is subducting rapidly beneath the okhotsk north american plate at approximately 8 cm yr 1 with the aim of estimating the long term recurrence intervals of earthquakes in this region seven sediment cores were obtained from a submarine fan located on the forearc slope along the southern kuril trench japan the cores contain a number of turbidites some of which can be correlated among the cores on the basis of the analysis of lithology chronology and the composition of sand grains foraminiferal assemblages and the composition of sand grains indicate that the upper middle slope 1000 m water depth is the source of the turbidites the deep sea origin of the turbidites is consistent with the hypothesis that they were derived from slope failures initiated by strong shaking associated with earthquake events the recurrence intervals of turbidite deposition are 113 439 yr for events that occurred over the past 7 kyr the short intervals are recorded in the cores obtained from levees on the middle fan although many large earthquakes 150 cm s 2 of peak ground acceleration at the inferred slump sources occurred during the 19th and 20th centuries the pilot core from the upper fan contains only three turbidites located stratigraphically above layers of 17th century volcanic ash the results of 210pbex and 137cs dating combined with simulations of the ground accelerations of historical earthquakes enable correlation of the three turbidites with known historical earthquakes the 1952 tokachi oki and the 1961 and 1973 nemuro oki earthquakes the turbidites within the sampled cores potentially record about half of the large earthquakes known to have occurred over the interval covered by the cores the fact that any single core records only a portion of the known seismic events suggests that the recurrence interval of earthquakes in this region is less than 113 yr during holocene

circum mediterranean fire activity and climate changes during the mid holocene environmental transition 8500 2500 cal bp a mid to late holocene synthesis of fire activity from the mediterranean basin explores the linkages among fire climate variability and seasonality through several climatic and ecological transitions regional fire histories were created from 36 radiocarbon dated sedimentary charcoal records available from the global charcoal database during the mid holocene thermal maximum around 7500 4500 cal bp charcoal records from the northern mediterranean suggest an increase in fire while records from the southern mediterranean indicate a decrease associated with wetter than present summers a north south partition between 40 and 43 n latitude is apparent in the central and western mediterranean relatively abrupt changes in fire activity are observed c 5500 5000 cal bp records of holocene fire activity appear sensitive to both orbitally forced climate changes and shorter lived excursions which may be related to north atlantic cold events possibly modulated by an nao like climate mechanism in cases wh

sedimentary earthquake records in the izmit gulf sea of marmara turkey abstract sedimentary earthquake records of the last 2400 a including that of the devastating 17 august 1999 izmit earthquake mw 7 4 were studied in cores from the 210 m deep central karamursel basin of the izmit gulf in the eastern sea of marmara using laser grain size physical properties stable o and c isotopes and xrf core scanner analyses and dated by radionuclide and radiocarbon methods the earthquake records are represented by turbidite homogenite mass flow units thu that commonly contain a basal coarse layer a middle laminated silt layer and an overlying homogeneous mud layer the coarse basal part has a sharp and sometimes scoured lower boundary and includes multiple coarse sand silt layers or laminae showing normal size grading multiple coarse layers and occasional bi directional cross bedding suggest deposition from a bed load during water column oscillations or seiche effect the grain size characteristics of the overlaying laminated silt and the homogeneous mud units indicate deposition from weak oscillating currents and homogeneous suspension respectively high mn value just below the base of thus suggests diagenetic enrichment at oxic anoxic redox boundary before the mass flow event sharp decrease in mn with very low values within the thus suggests transient redox conditions following the mass flow variable geochemical compositions of the basal coarse layers indicate different sediment sources for different thus eight sedimentary earthquake records observed in the last 2400 a in the izmit gulf can be confidently correlated with the historical earthquakes of 1999 1509 ad ms 7 2 1296 ad i vii 865 ad i viii 740 ad i viii 268 ad i viii 358 ad i ix and 427 bc this gives an earthquake recurrence time of ca 300 a with the interval between consecutive events ranging from 90 to 695 a

1822 earthquake triggered homogenite in lake le bourget nw alps high resolution textural signatures of an earthquake induced historical homogenite layer are presented as well as its 3d distribution this homogeneous deposit is correlated with the ad 1822 event vii viii msk intensity the main historical earthquake of the french outer alps using 210pb dating and historical chronicles during this earthquake a violent lake water oscillation was reported seiche effect in the present study we discuss the influence of lake water oscillations during earthquake induced subaqueous slide through a pluridisciplinary analysis of subbottom sediments including high resolution seismic sidescan sonar and short gravity coring

reconstructing historical seismicity from lake sediments lake laffrey western alps france sediment archives from a mountain lake are used as indicators of seismotectonic activity in the grenoble area french western alps 45n sedimentological analysis texture and grain size characteristics exhibits several layers resulting from instantaneous deposits in lake laffrey six debris flow events up to 8 cm thick can be attributed to slope failure along the western flank of the basin dating with 210 pb and 137 cs gamma counting techniques and the reconnaissance of historical events provide a constrained age depth model over the last 250 years five of such debris flow deposits could be related to historical earthquakes of msk intensities greater than vi over an area of 60 km one debris flow deposit triggered at the beginning of the last century can be related to an historical landslide possibly triggered by the artificial regulation of the lake level

turbidite paleoseismology in the calabrian arc subduction complex ionian sea 1 the calabrian arc subduction system is part of the africa eurasia plate boundary is one of the most seismically active regions in the mediterranean sea and has been struck repeatedly by destructive historical earthquakes in this study we investigate the effects of historical earthquakes on abyssal marine sedimentation through the analysis of the turbidite record we collected gravity cores in tectonically controlled basins where the eastern mediterranean pelagic sequence is interbedded with resedimented units textural micropaleontological geochemical and mineralogical signatures reveal three turbidite events in the last millennium we dated the turbidite sequences from two different cores using different radiometric methods whereas the average time interval between successive turbidite beds was estimated from pelagic sediment thickness and sedimentation rates chronologies were refined through age modeling that provided age ranges 2 of each turbidite bed the results suggest that turbidite emplacement was triggered by three historical earthquakes recorded in the area i e the 1908 1693 and 1169 events their magnitude epicentral location and associated tsunamis support causative faults located in the ionian sea the source for all the turbidites as inferred from their mineralogy is the metamorphic basement outcropping in southern calabria and or northeastern sicily turbidite composition and cable breaks for the 1908 event have been used to infer likely traveling paths and seismogenic faults in the subduction system our findings suggest that ionian sea turbidites represent more than 80 of sedimentation and may be seabed archives of paleo earthquakes capable of reconstructing seismicity back in time during several earthquake cycles

turbidites as records of intense palaeoearthquakes in lake biwa japan abstract some 20 turbidites were collected in the uppermost 3 m of surface sediments in lake biwa southwest japan these turbidites correlate in age to historical earthquakes that caused severe loss of lives and property near lake biwa the age of each turbidite was estimated precisely based on sedimentation rate by weight and the age of tephra markers below the turbidites the magnitudes and epicentres of major historical earthquakes during the last 1300 years are available from historical documents empirical equations relating intensity distance to the epicentre and magnitude enable us to calculate the ground shaking at lake biwa from these historical earthquakes earthquakes having intensity stronger than grade iv l on the japan meteorological agency jma earthquake scale that is 44 gal acceleration at lake biwa all coincide with the turbidite ages this intensity is apparently the lower threshold for turbidity current initiation in lake biwa

formal subdivision of the holocene series epoch a discussion paper by a working group of intimate integration of ice core marine and terrestrial records and the subcommission on quaternary stratigraphy international commission on stratigraphy this discussion paper by a working group of intimate integration of ice core marine and terrestrial records and the subcommision on quaternary stratigraphy sqs of the international commission on stratigraphy ics considers the prospects for a formal subdivision of the holocene series epoch although previous attempts to subdivide the holocene have proved inconclusive recent developments in quaternary stratigraphy notably the definition of the pleistocene holocene boundary and the emergence of formal subdivisions of the pleistocene series epoch mean that it may be timely to revisit this matter the quaternary literature reveals a widespread but variable informal usage of a tripartite division of the holocene early middle or mid and late and we argue that this de facto subdivision should now be formalized to ensure consistency in stratigraphic terminology we propose an early middle holocene boundary at 8200 a bp and a middle late holocene boundary at 4200 a bp each of which is linked to a global stratotype section and point gssp should the proposal find a broad measure of support from the quaternary community a submission will be made to the international union of geological sciences iugs via the sqs and the ics for formal ratification of this subdivision of the holocene series epoch copyright 2012 john wiley sons ltd

late quaternary palaeoecology palynology and palaeolimnology of a tropical lowland swamp rawa danau west java indonesia abstract sedimentological limnological and palynological analyses of a sediment core from a lowland site in west java indonesia provide a detailed palaeoenvironmental record for the late glacial and the holocene the record suggests open vegetation under inferred drier climatic conditions for the late glacial however there is no unequivocal evidence for cooler conditions at this time the onset of the holocene coincides with a change to more humid climatic conditions with the development of a fern rich closed forest vegetation type dramatic changes in diatom community composition provide a striking record of habitat change associated with lake shallowing but this process appears to be a result of basin in filling rather than variations in precipitation evaporation balance associated with climatic fluctuations evidence for human impact on the vegetation development is restricted to the last few hundred years

depositional age and triggering event of turbidites in the western kumano trough central japan during the last ca 100 years abstract for correlating a turbidite record with a detailed land record of natural disasters during the last ca 100 years the depositional age of the surface hemipelagic sediments of the kumano trough located in central japan were estimated we attempted to extract mass accumulation rate of hemipelagic fallout from hemipelagic intervals on the basis of 137 cs geochronology x radiograph dry bulk density and grain size distribution based on assumptions of the biogenic mixing effect on the 137 cs appearance horizon and hemipelagite erosion by turbidity current the reconstructed turbidite record from hemipelagic fallout mass accumulation rate is well correlated with the record of major natural disasters in the kumano area based on the correlation most of turbidite layers are flood storm origin except for a well sorted seismo turbidite induced by the tonankai earthquake that occurred the mid 20th century although the wide distribution of a flood induced turbidite layer due to the 19th century tostukawa flood which was a huge disaster in the area caused by heavy rain and dams breaching it does not show a hyperpycnite succession the flood by dams breaching may cause surge like flow angular to subangular sand sized lithic fragments in the turbidite show that sand grains were transported from the kumano river directly plant debris and microfossils are common in both seismo turbidite and flood storm induced turbidites

arctic sea ice reemergence the role of large scale oceanic and atmospheric variability abstractarctic sea ice reemergence is a phenomenon in which spring sea ice anomalies are positively correlated with fall anomalies despite a loss of correlation over the intervening summer months this work employs a novel data analysis algorithm for high dimensional multivariate datasets coupled nonlinear laplacian spectral analysis nlsa to investigate the regional and temporal aspects of this reemergence phenomenon coupled nlsa modes of variability of sea ice concentration sic sea surface temperature sst and sea level pressure slp are studied in the arctic sector of a comprehensive climate model and in observations it is found that low dimensional families of nlsa modes are able to efficiently reproduce the prominent lagged correlation features of the raw sea ice data in both the model and observations these families provide an sst sea ice reemergence mechanism in which melt season spring sea ice anomalies are imprinted as sst anomalies and stored over the summer months allowing for

2300 yr history of seismicity from silting events in lake tadoussac charlevoix quebec silt layers in organic rich lake sediments are interpreted to represent the historic earthquakes of 1638 1663 1791 1870 and 1925 of the charlevoix region of eastern canada this interpretation is based on the relative spacing of the layers and the accelerator mass spectrometer sup 14 c dating of a twig in one of the cores the silt layers were presumably caused by landslides on tributary streams and by resuspension of the sediment the cores contain up to 22 layers 1 to 45 mm thick over a depth equivalent to about 2300 yr if there is a correlation between thickness and magnitude there would have been four events of richter magnitude 7 5 or greater in a d 1663 1320 60 and 320 b c the 18 other layers could correspond to earthquakes of magnitude 6 to 7 the recurrence interval from 300 b c to a d 800 is 120 yr followed until a d 1500 by a quiet period when there was a single large event the recurrence interval from a d 1500 to the present is 75 yr

palaeolimnology of lake sapanca and identification of historic earthquake signals northern anatolian fault zone turkey abstract lake sapanca is located on a strand of the northern anatolian fault zone nafz turkey where a series of strong earthquakes ms 6 0 have occurred over the past hundred years identifying prehistoric earthquakes in and around lake sapanca is key to a better understanding of plate movements along the nafz this study contributes to the development of palaeolimnological tools to identify past earthquakes in lake sapanca to this end several promising proxies were investigated specifically lithology magnetic susceptibility grain size thin section and laser analysis geochemistry pollen concentration diatom assemblages 137cs and 210pb sedimentological indicators provided evidence for reworked turbidite like or homogeneous facies event layers in several short cores

a 2000 yr rupture history for the alpine fault derived from lake ellery south island new zealand determining the earthquake segmentation of plate boundary transform faults remains a scientific challenge because paleoseismic data sets rarely resolve the end points of past ruptures in this study we test whether lacustrine paleoseismology can be used to assess rupture end points and the earthquake segmentation of the alpine fault one of the longest and fastest slipping plate boundary transform faults on earth sediment cores from lake ellery record eight episodes of high intensity shaking modified mercalli intensity mm ix from alpine fault earthquakes as event sequences of a turbidite produced by coseismic subaqueous mass wasting overlain by deposits representing sediment flux from co and postseismic landsliding in the fluvial catchment age depth modeling constrains the timing of shaking events at a decadal resolution facilitating correlation with two previously published lake records to reconstruct the spatial distribution of mm ix shaking along 150 km of the alpine fault when resolved with existing on and near fault paleoseismic records the lake data set demonstrates that independent ruptures of the south westland and central segments occurred in a d 845 775 and a d 739 646 and a d 646 592 and a d 416 370 respectively lakes adjacent to the alpine fault provide paleoseismic records with sufficient spatial and temporal resolution to define along strike differences in the pattern of rupture capable of distinguishing rupture termination at a geometric segment boundary this multilake study suggests that locating the end points of ruptures using lacustrine paleoseismology will be most applicable in midlatitude convergent plate boundary settings where along strike topography and quaternary glaciation have resulted in the widespread distribution of suitable lakes

a systematic review of geological evidence for holocene earthquakes and tsunamis along the nankai suruga trough japan the nankai suruga trough the subduction zone that lies immediately south of japan s densely populated southern coastline generates devastating great earthquakes magnitude 8 characterised by intense shaking crustal deformation and tsunami generation forecasting the hazards associated with future earthquakes along this 700 km long fault requires a comprehensive understanding of past fault behaviour while the region benefits from a long and detailed historical record palaeoseismology has the potential to provide a longer term perspective and additional crucial insights in this paper we summarise the current state of knowledge regarding geological evidence for past earthquakes and tsunamis along the nankai suruga trough incorporating literature originally published in both japanese and english and enhancing available results with new age modelling approaches we summarise and critically evaluate evidence from a wide variety of sources palaeoseismic evidence includes uplifted marine terraces and biota marine and lacustrine turbidites liquefaction features subsided marshes and tsunami deposits in coastal lakes and lowlands while 75 publications describe proposed evidence from 70 sites only a limited number provide compelling well dated evidence the best available records enable us to map the most likely rupture zones of twelve earthquakes that occurred during the historical period this spatiotemporal compilation suggests that the 1707 ce earthquake ruptured almost the full length of the subduction zone and that earthquakes in 1361 ce and 684 ce may have been predecessors of similar magnitude intervening earthquakes were of lesser magnitude highlighting the variability in rupture mode that characterises the nankai suruga trough intervals between ruptures of the same seismic segment range from 450 years during the historical period over longer timescales palaeoseismic evidence suggests intervals between earthquakes ranging from 100 to 700 years however these figures reflect a range of thresholds controlling the creation and preservation of evidence at any given site as well as the genuine intervals between earthquakes at present there is no geological data that suggest the occurrence of a larger magnitude earthquake than that experienced in 1707 ce however few studies have sought to establish the relative magnitudes of different earthquake and tsunami events along the nankai suruga trough alongside the lack of research designed to quantify the maximum magnitude of past earthquakes we emphasise issues over alternative hypotheses for proposed palaeoseismic evidence the paucity of robust chronological frameworks and insufficient appreciation of changing thresholds of evidence creation and preservation over time as key issues that must be addressed by future research

historical seismicity of the mont dore volcanic province auvergne france unraveled by a regional lacustrine investigation new insights about lake sensitivity to earthquakes lake sediments are relevant natural seismographs over long time scale however because tectonic events are not systematically recorded in lake sediments one forthcoming challenge for paleoseismology is to better assess lake sensitivity to earthquakes to this end a limnogeological investigation including hydroacoustic mapping techniques core sampling and multi proxy sediment analyses has been conducted within four small volcanic lakes located in the mont dore province auvergne france an area with a moderate seismo tectonic activity results show the existence of several gravity reworking processes in the lakes over the last millennium around ad 1300 the occurrence of synchronous events in lakes pavin chauvet montcineyre and guery 100 km 2 area highlights an undocumented earthquake as a common trigger for slope failures in disconnected basins at regional scale the record of this tectonic event may have been favored by human induced increase in sediment load chauvet and montcineyre and or after an abrupt lake level drop pavin affecting the sediment stability in addition synchronous turbidites and mass wasting deposits mwd recorded in lakes pavin and guery provide evidence for a seismic activity during the xix th century potential triggers are historical earthquakes that occurred either in the mont dore area or in the southern part of the limagne fault at this time despite moderate seismic activity in this intraplate volcanic domain these results highlight the role of tectonics as a major trigger in the sedimentary processes dominating these lacustrine infills within the diversity of studied sites it appears that lake sensitivity to earthquakes was not constant over time this sensitivity can be expressed as a combination of external factors namely earthquake magnitude and lake epicenter distance and internal factors such as lake morphology nature of sediment lake level fluctuations and human induced changes in catchment sedimentary load

comment on late holocene rupture of the northern san andreas fault and possible stress linkage to the cascadia subduction zone by chris goldfinger kelly grijalva roland burgmann ann e morey joel e johnson c hans nelson julia gutierrez pastor andrew ericsson eugene karabanov jason d chaytor jason patton and eulalia gracia goldfinger et al 2008 conclude that in the northern san andreas fault and cascadia margins holocene turbidites i e deposits of turbidity currents were triggered by earthquakes however their conclusion falters because of 1 selective data sets that were used for establishing seismicity as the sole triggering mechanism of turbidites 2 flawed sedimentological concepts and criteria that were applied for interpreting turbidites and 3 faulty methodologies that were employed for correlating turbidites over long distances this same turbidite i e sedimentological theme has also been published previously by goldfinger et al 2003a b 2006 2007 as with the recent article in bssa their previous publications on the subject matter were published in journals that are concerned primarily with geophysical topics as a result critical sedimentological conclusions which are an integral part of the articles by goldfinger et al have not been subjected to a rigorous scrutiny therefore i would like to comment on the following three issues along the washington oregon california margin potential triggering mechanisms of sediment failures and related turbidity currents are 1 earthquake adams 1990 2 tectonic oversteepening greene et al 2006 3 tsunami adams 1990 geist 2005 4 cyclone adams 1990 shanmugam 2008a fig 4 5 ebb tidal current puig et al 2003 6 submarine volcanic activity davis et al 2002 7 sediment loading adams 1990 and 8 gas hydrates chapman et al 2004 the link between gas hydrate decomposition and mass movements on the norwegian margin was discussed by mienert et al 2005 in the cascadia margin a total of 40 cyclones along the oregon coast were reported for the 1984 2006 period moritz and moritz 2006 a total of 24 tsunamis were reported along the oregon coast for the 1868 1994 period table 1 cyclones and tsunamis are powerful agents of sediment failures shanmugam 2008a on the outer continental shelf of the gulf of mexico for example the

high accuracy synchronism for seismic reflectors and 14c ages holocene prodelta succession of the kiso river central japan abstract horizons at 500 yr intervals for the past 6000 years can be inferred in two cores drilled along a high resolution seismic line in the prodelta of the kiso river ise bay central japan these horizon ages clearly indicate that a given seismic reflection line in the profile is isochronous synchronism between ages and reflectors in the succession is especially distinct for the interval from 5000 to 2500 yr bp despite the reflectors having inclined planes and having the same ages at different depths these data indicate that the kiso river delta prograded to form a downlap surface before the maximum flooding stage of the post glacial relative sea level rise at about 6000 yr bp delta progradation beginning late in the transgressive stage was caused by the flow of large amounts of sediment into this steep river that is part of the active japanese volcanic arc

lacustrine turbidites as a tool for quantitative earthquake reconstruction new evidence for a variable rupture mode in south central chile understanding the long term earthquake recurrence pattern at subduction zones requires continuous paleoseismic records with excellent temporal and spatial resolution and stable threshold conditions south central chilean lakes are typically characterized by laminated sediments providing a quasi annual resolution our sedimentary data show that lacustrine turbidite sequences accurately reflect the historical record of large interplate earthquakes among others the 2010 and 1960 events furthermore we found that a turbidite s spatial extent and thickness are a function of the local seismic intensity and can be used for reconstructing paleo intensities consequently our multilake turbidite record aids in pinpointing magnitudes rupture locations and extent of past subduction earthquakes in south central chile comparison of the lacustrine turbidite records with historical reports a paleotsunami subsidence record and a marine megaturbidite record demonstrates that the valdivia segment is characterized by a variable rupture mode over the last 900 years including i full ruptures mw 9 5 1960 1575 1319 9 1127 44 ii ruptures covering half of the valdivia segment mw 9 1837 and iii partial ruptures of much smaller coseismic slip and extent mw 7 5 8 1737 1466 4 also distant or smaller local earthquakes can leave a specific sedimentary imprint which may resolve subtle differences in seismic intensity values for instance the 2010 event at the maule segment produced higher seismic intensities toward southeastern localities compared to previous megathrust ruptures of similar size and extent near concepci n

dynamic preconditioning of the minimum september sea ice extent abstractthere has been an increased interest in seasonal forecasting of the arctic sea ice extent in recent years in particular the minimum sea ice extent here a dynamical mechanism based on winter preconditioning is found to explain a significant fraction of the variance in the anomaly of the september sea ice extent from the long term linear trend to this end a lagrangian trajectory model is used to backtrack the september sea ice edge to any time during the previous winter and quantify the amount of sea ice advection away from the eurasian and alaskan coastlines as well as the fram strait sea ice export the late winter anomalous sea ice drift away from the coastline is highly correlated with the following september sea ice extent minimum it is found that the winter mean fram strait sea ice export anomaly is also correlated with the minimum sea ice extent the following summer to develop a hindcast model of the september sea ice extent which does not depend on a priori knowledge of the minimu

late holocene rupture of the northern san andreas fault and possible stress linkage to the cascadia subduction zone we relate the late holocene northern san andreas fault nsaf paleo seismic history developed using marine sediment cores along the northern california continental margin to a similar dataset of cores collected along the cascadia margin including channels from barclay canyon off vancouver island to just north of mon terey bay stratigraphic correlation and evidence of synchronous triggering imply earthquake origin and both temporal records are compatible with onshore paleoseis mic data in order to make comparisons between the temporal earthquake records from the nsaf and cascadia we refine correlations of southern cascadia great earth quakes including the land paleoseismic record along the nsaf during the last 2800 yr 15 turbidites including one likely from the great 1906 earthquake establish an average repeat time of 200 yr similar to the onshore value of 240 yr the combined land and marine paleoseismic record from the southern cascadia subduction zone includes a similar number of events during the same period while the average recurrence interval for full margin cascadia events is 520 yr the southern cascadia margin has a repeat time of 220 yr similar to that of the nsaf thirteen of the 15 nsaf events were preceded by cascadia events by 0 80 yr averaging 25 45 yr as compared to 80 400 yr by which cascadia events follow the nsaf based on the temporal association we model the coseismic and cumulative post seismic deformation from great cascadia megathrust events and compute related stress changes along the nsaf in order to test the possibility that cascadia earth quakes triggered the penultimate and perhaps other nsaf events the coulomb fail ure stress cfs resulting from viscous deformation related to a cascadia earthquake over 60 yr does not contribute significantly to the total cfs on the nsaf however the coseismic deformation increases cfs on the northern san andreas fault nsaf b y up to about 9 bars offshore of point delgada most likely enough to trigger that fault to fail in north to south propagating ruptures

the terramare and the surrounding hydraulic structures a geophysical survey of the santa rosa site at poviglio bronze age northern italy abstract the terramara santa rosa is a middle and late bronze age archaeological site located in the po alluvial plain northern italy it is constituted of two moated villages delimited by earthen ramparts the peripheral structures of the site are sealed by fine textured flood plain deposits and they have not been fully explored through excavation due to their large extent because the shape of the villages and their relation to moats and the fluvial network are of paramount importance to understanding the landscape management and the use of water resources in the terramare civilisation a geophysical survey was planned to extend the results of the existing archaeological excavations to the site scale a frequency domain electro magnetic sounding fdem and electrical resistivity imaging eri covered an area of approximately 26 ha eri was conducted for a total length 9000 m despite the predominance of electrically conductive fine textured sediments electrical resistivity anomalies were observed and they were attributed to subtle lithological differences in the sedimentary context of the alluvial plain the geophysical interpretation after the calibration with the excavation data revealed the structures of the terramara and of the surrounding hydraulic network which are not visible at the surface due to flood plain deposits the santa rosa site was founded in a favourable geomorphological position on the top of a crevasse splay lobe of the adjoining po palaeo channel rising above the surrounding alluvial plain the terramara and their surroundings were delineated through an artificial modification of this pre existing crevasse splay lobe and a well targeted urban design with the objective of diverting water most likely from a palaeo channel of the po river through the digging of peripheral moats used to collect water around the site and to distribute it to the surrounding fields for irrigation the water management documented by this study in the terramara santa rosa can be considered as paradigmatic for the whole terramare civilisation which is therefore responsible of the introduction of the irrigated agriculture into western europe for the first time

use of flood chronology for detailed environmental analysis a case study of lake kizaki in the northern japanese alps central japan this paper presents a study of the usefulness of flood layers as a time marker in sediments and a report of a case study of lake kizaki in central japan a flood layer can be identified as a layer having a higher density coarser grain size lower tn content and higher c n ratio than those of the upper and lower horizons it can also be characterized by a hyperpycnal sequence composed of a basal coarsening upward unit and a top fining upward unit when flood layers can be correlated with heavy rains in meteorological records detailed age markers are well established in the sediment five flood layers were identified in the surface sediment of lake kizaki and they could be attributed to the historical heavy rainfalls that took place on july 12 1995 september 28 1983 august 25 1974 september 26 1959 and september 1 1949 under the constraint of an age model a precise age model is essential to clarify the environmental changes such as the pollutant history in detail

mollusca stable isotope record of a core from lake frassino northern italy hydrological and climatic changes during the last 14 ka a core retrieved from lake frassino northern italy provided evidence of palaeohydrological change in this area during the last 14 ka lithological malacological and in particular stable isotope composition of freshwater shells allowed the delineation of the main phases of lake evolution between the lateglacial and holocene lateglacial conditions were drier than the holocene although a wetter period was inferred before c 14 ka according to the oxygen isotope composition of freshwater shells the holocene showed a clear bipartition the first part which lasted from 9100 to 7000 yr bp was drier and was followed by a rapid increase in humidity at 7000 6800 yr bp between 6800 and 5000 yr bp there were wetter and more stable conditions as indicated by smaller 18 o oscillations of pisidium and valvata shells from c 5000 to 2600 yr bp the record is characterized by larger fluctuations which may indicate that short term and particularly pronounced alternation of wet and dry periods occurred

water management and land use in the terramare and a possible climatic co factor in their abandonment the case study of the terramara of poviglio santa rosa northern italy abstract the terramare archaeological sites generated by a civilisation which settled the centre of the po plain since the middle bronze age were abruptly abandoned at the end of the recent bronze age the reason for this abandonment is still a matter of debate in the context of a multi causal explanation this paper discusses a possible climatic factor inferred from recent discoveries at the site of poviglio santa rosa northern italy the culture of the terramare produced a systematic and intensive agricultural and pastoral exploitation of the environment and caused heavy deforestation water was a critical resource and was carefully managed the moat which typically surrounded most of the sites was meant to concentrate and redistribute water to the fields through a network of irrigation ditches the study of the water wells discovered at the fringe of the terramara of santa rosa reveals a drop in the water table during the late recent bronze age caused by a dry event of regional relevance chronological contiguity supported by the archaeological context between this occurrence and the abandonment of the terramare system strongly suggests a causative link between the two events the climatic event a minor episode in the history of the holocene climate nevertheless acted as a catalyst in a stressed environment whose resources were over exploited by rising demographic pressure

giant earthquakes in south central chile revealed by holocene mass wasting events in lake puyehue abstract very high resolution reflection seismic profiling 3 5 khz revealed nine holocene mass wasting events in lake puyehue south central chile these events are made up of numerous coeval mass wasting deposits and some homogenites which are radiocarbon dated the two youngest mass wasting events could be attributed to the giant ad 1960 and ad 1575 valdivia earthquakes the most extensive event took place around 1660 cal yr bp evaluation of all possible slope failure processes led us to infer that giant earthquakes roughly comparable to the ad 1960 valdivia earthquake mw 9 5 are the most likely trigger mechanisms of all mass wasting events in lake puyehue these occurred with a mean recurrence rate of 1000 yr although relatively aperiodically ranging between 500 and 2000 yr quantitative comparison of mass wasting events related to historically reported earthquakes ad 1960 and ad 1575 showed significant differences although these earthquakes are assumed to have had a comparable strength a lowered background sedimentation rate could be responsible for this variable earthquake recording which highlights the importance of a thorough assessment of the depositional history before using lacustrine records for quantitative paleoseismic analysis

middle to late holocene fire history and the impact on mediterranean pine and oak forests according to the core rf93 30 central adriatic sea the high resolution adriatic rf93 30 core shows changes in its microcharcoal record which correlate to terrestrial fires from the last 7000 years pollen and microcharcoals were transported by win

stratigraphic variations in lacustrine sediment gravity flow deposits intercalated in varved diatomite an example from the hiruzenbara formation okayama prefecture southwest japan abstract the hiruzenbara formation which is distributed within the hiruzenbara basin of southwest japan includes a section of varved diatomite representing ca 8000 y of deposition in a dammed lake formed during the middle pleistocene the varve on average ca 1 5 mm thick consists of light and dark green laminae sets and is predominately composed of planktonic diatoms several facies types of sediment gravity flow deposits are intercalated in the varved diatomite in this study we examined the sedimentary facies lateral changes and stratigraphic variations of these sediment gravity flow deposits in addition we also analyzed a time series of varve thickness fluctuations based on their sedimentary facies composition and diatom species sediment gravity flow deposits in the varved diatomite can be classified as flood generated or slope failure generated sedimentary facies analysis indicates that the slope failure deposits were deposited by slope failure within the lake since no significant segregation of rip up clasts is observed in the deposits a proximal depositional setting at the base of the lake slope is suggested the flood generated deposits have eroded lower contacts which indicate deposition by hyperpycnal flows in contrast deposits with no basal erosion indicate deposition by homopycnal or hypopycnal flows the thickness time series of the varve shows a thickening upward trend indicating an increase in diatom production or in diatom shells sizes running mean thicknesses show non stationary periodicities of 200 500 y the frequency of the deposit varies but is approximately 10 events per 400 y flood deposits in the middle part of the section are dominated by volcaniclastic silt this suggests that vegetation around the lake was reduced by ash fall resulting in frequent flood events during this interval the frequency and thickness of slope failure deposits increases in the lower part of the succession together with the occurrence of slump scars the frequency of the deposits in the upper part of the section is approximately 100 500 y similar to the postulated interval at activity of the nearby yamasaki fault system the results of this study improve our knowledge of paleoenvironmental changes in the study site and also provide new criteria for classifying sediment gravity flow deposits in lacustrine sedimentary cores

patterns of sea ice retreat in the transition to a seasonally ice free arctic abstractthe patterns of sea ice retreat in the arctic ocean are investigated using two global climate models gcms that have profound differences in their large scale mean winter atmospheric circulation and sea ice drift patterns the community earth system model large ensemble cesm le presents a mean sea level pressure pattern that is in general agreement with observations for the late twentieth century the community climate system model version 4 ccsm4 exhibits a low bias in its mean sea level pressure over the arctic region with a deeper icelandic low a dynamical mechanism is presented in which large scale mean winter atmospheric circulation has significant effect on the following september sea ice extent anomaly by influencing ice divergence in specific areas a lagrangian model is used to backtrack the 80 n line from the approximate time of the melt onset to its prior positions throughout the previous winter and quantify the divergence across the pacific and eurasian sectors of the arctic i

increased marine sediment suspension and fluxes following an earthquake earthquakes are commonly cited as one possible triggering mechanism for turbidity flows dense sediment water plumes that can transport large volumes of sediment great distances down slope in both marine and lacustrine settings1 2 3 4 5 6 heezen and ewing1 were the first to make such a suggestion attributing breaks in a sea floor telephone cable in the north atlantic ocean to turbidity flows generated by the 1929 grand banks earthquake anumber of workers have consequently used sedimentary turbidite records to reconstruct the earthquake histories of various regions2 7 8 here we present direct observations of a seismically induced turbidity flow measurements of light scattering and sediment fluxes in the cariaco basin indicate that the earthquake that occurred along the coast of northern venezuela on 9 july 1997 resulted in considerable downslope displacement of sediments probably 105 tonnes into the deep part of the basin in such a seismically active region this mechanism of sediment transport may be responsible for a significant component of the long term sediment accumulation in the basin furthermore this process may result in the sequestration in deep sea sediments of large amounts of carbon initially deposited at shallow depths

holocene seasonality changes in the central mediterranean region reconstructed from the pollen sequences of lake accesa italy and tenaghi philippon greece this study presents pollen based climate reconstructions of holocene temperature and precipitation seasonality for two high resolution pollen sequences from the central lake accesa central italy and eastern mediterranean tenaghi philippon greece regions the quantitative climate reconstruction uses multiple methods to provide an improved assessment of the uncertainties involved in palaeoclimate reconstructions the multimethod approach comprises partial least squares regression weighted average partial least squares regression the modern analogues technique and the non metric multidimensional scaling generalized additive model method we find two distinct climate intervals during the holocene the first is a moist period from 9500 to 7800 cal bp characterised by wet winters and dry summers resulting in a strongly seasonal hydrological contrast stronger than today that is interrupted by a short lived event around 8200 cal bp this event is characterised by wet winters and summers at accesa wh

winter coastal divergence as a predictor for the minimum sea ice extent in the laptev sea abstractseasonal predictability of the minimum sea ice extent sie in the laptev sea is investigated using winter coastal divergence as a predictor from february to may the new ice forming in wi

late pleistocene to holocene sedimentary fills of the cinarcik basin of the sea of marmara a giant rv marion dufresne piston core md01 2425 recovered from the 1276 m deep cinarcik basin of the sea of marmara documents characteristics of deep basin sedimentation influenced by large scale gravity controlled mass wasting processes and associated turbidite deposition during the late pleistocene to holocene a visual lithological description of the core reveals twenty major seismoturbidite layers 20 cm thick intercalated in hemipelagic type fine grained calcareous and slightly siliceous clays the thickness and frequency of the sesimoturbidite layers deposited during the lacustrine period prior to 12 3 cal ka bp is much greater than during the holocene marine period the sedimentary processes during deposition of seismoturbidites in the basin have been determined in this study using a combination of grain size parameters often the seismoturbidites show strong grain segregation with a sharp boundary between a coarse lower and a homogeneous upper part the traction carpet deposits formed at the base of a turbulent suspension and were produced in the lower coarse grained part whereas the homogeneous upper part was deposited by uniform suspensions following bedload deposition

rupture lengths and temporal history of significant earthquakes on the offshore and north coast segments of the northern san andreas fault based on turbidite stratigraphy piston gravity and jumbo kasten cores were collected from channel and canyon systems draining the northern california continentalmargintoinvestigatetherecordofperiodicholoceneturbiditesforpossibleconnectiontolargemagnitudeearthquakeson the adjacent northern san andreas fault poorly known channel systems were mapped with multibeam sonar to define pathways and channel confluences cores sampled all major and many minor channel systems extending from cape mendocino to just north of monterey bay sampling both along and across channels was done and particular attention was paid to channel confluences as these areas afford opportunities to test for synchronous triggering of turbidity currents while at sea all cores were scanned using a geotek multisensor core logger mscl which collects high resolution photography p wave velocity gamma ray density and magnetic susceptibility data from the unsplit cores lithology was logged visually and cores were later imaged with x radiography we use 14 c ages relative dating tests at channel confluences and stratigraphic correlation using physical properties to determine

time dependent recurrence of strong earthquake shaking near plate boundaries a lake sediment perspective abstract accurate probabilistic seismic hazard analysis requires a good knowledge of the recurrence parameters of the strongest earthquakes in a region due to the typical short temporal span of instrumental and historical data it is often unclear whether one should adopt a time dependent or time independent poissonian recurrence model the choice of which has large repercussions on the probability estimates for new strong events the rapidly growing discipline of lacustrine paleoseismology aims at producing long continuous records of strong seismic shaking which integrate the activity of all significant seismic sources in a region and allow a reliable determination of recurrence patterns the typical continuous sedimentation regime in lakes can lead to complete sensitive paleoseismic records and a reduced temporal uncertainty in recurrence intervals here i present a worldwide compilation of published long lacustrine paleoseismic records grouped per tectonic domain and statistically explore the variability of their recurrence intervals expressed by the coefficient of variation cov a cov 1 indicates a time independent process whereas cov 1 may be related to changes in the sensitivity of the lacustrine paleoseismograph or to real earthquake clustering due to e g stress transfer between neighboring faults the most useful lacustrine paleoseismic records can be retrieved in high seismicity settings where many paleoseismic events can be recorded in a relatively short time span i e

a sedimentary record of holocene surface runoff events and earthquake activity from lake iseo southern alps italy this study presents a record of holocene surface runoff events and several large earthquakes preserved in the sediments of pre alpine lake iseo northern italy a combination of high resolution seismic surveying detailed sediment microfacies analysis non destructive core scanning techniques and ams 14c dating of terrestrial macrofossils was used to detect and date these events based on this approach our data shed light on past seismic activity in the vicinity of lake iseo and the influence of climate variability and human impact on allochthonous detrital matter flux into the lake the 19 m long investigated sediment sequence of faintly layered lake marl contains frequent centimetre to decimetre scale sandy silty detrital layers during the early to mid holocene these small scale detrital layers reflecting sediment supply by extreme surface runoff events reveal a distinct centennial scale recurrence pattern this is in accordance with regional lake level highstands and minima in solar activity and thus apparently mainly climate controlled after c 4200 cal yr bp intervals of high detrital flux occasionally also correlate with periods of enhanced human settlement activity in consequence deposition of small scale detrital layers during the late holocene apparently reflects a rather complex interplay between climatic and anthropogenic influences on catchment erosion processes besides the small scale detrital layers five up to 2 40 m thick large scale detrital event layers composed of basal mass wasting deposits overlain by large scale turbidites were identified which are supposed to be triggered by strong earthquakes the uppermost large scale event layer can be correlated to a documented mw 6 0 earthquake in ad 1222 in brescia the four other large scale event layers are supposed to correspond to previously undocumented local earthquakes these occurred around 350 bc 570 bc 2540 bc and 6210 bc and most probably also reached magnitudes in the order of mw 5 0 6 5