empirical predictive models for earthquake induced sliding displacements of slopes earthquake induced sliding displacement is the parameter most often used to assess the seismic stability of slopes the expected displacement can be predicted as a function of the characteristics of the slope yield acceleration and the ground motion e g peak ground acceleration yet there is significant aleatory variability associated with the displacement prediction using multiple ground motion parameters to characterize the earthquake shaking can significantly reduce the variability in the prediction empirical predictive models for rigid block sliding displacements are developed using displacements calculated from over 2 000 acceleration time histories and four values of yield acceleration these empirical models consider various single ground motion parameters and vectors of ground motion parameters to predict the sliding displacement with the goal of minimizing the standard deviation of the displacement prediction the combination of peak ground acceleration and peak ground velocity is the tw

new empirical relationships between arias intensity and peak ground acceleration abstract arias intensity i a and peak ground acceleration pga have been widely used as measures of the intensity of strong ground motions this study employs a large set of data consisting of 7034 horizontal and 3474 vertical strong motion records from 173 worldwide earthquakes m w 4 3 7 9 to refine the relationship between i a and pga and investigates its potential dependence on variables such as earthquake magnitude m w local site condition v s 30 focal mechanism and fault distance the dataset from the 2011 m w 9 0 tohoku earthquake and the 2013 m w 6 8 lushan earthquake is used to demonstrate the usability and necessity of our models the results reveal that the logarithm of i a increases linearly with the increase of the logarithm of pga and m w and the decrease of the logarithm of v s 30 and this kind of correlation is not significantly affected by focal mechanism and fault distance new global empirical relationships for both horizontal and vertical components are developed to estimate i a as a function of pga m w and v s 30 the resulting correlation equations presented in this article represent a significant advancement by incorporating such important features as magnitude and v s 30 and enable an improved way of estimating i a from pga online material table of earthquake parameters

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

early holocene climate oscillations recorded in three greenland ice cores a new ice core chronology for the greenland dye 3 grip and ngrip ice cores has been constructed making it possible to compare the 18 o and accumulation signals recorded in the three cores on an almost annual scale throughout the holocene we here introduce the new time scale and investigate 18 o and accumulation anoma lies that are common to the three cores in the early holocene 7 9 11 7 ka before present three time periods with significant and synchronous anomalies in the 18 o and accumulation signals stand out the well known 8 2 ka event an event of shorter duration but of almost similar amplitude around 9 3 ka before present and the preboreal oscillation during the first centuries of the holocene for each of these sections we present a 18 o anomaly curve and a common accumulation signal that represents regional changes in the accumulation rate over the greenland ice cap

the response of the southern greenland ice sheet to the holocene thermal maximum to determine the long term sensitivity of the greenland ice sheet to a warmer climate we explored how it responded to the holocene thermal maximum 8 5 cal kyr b p calibrated to calendar years before present i e a d 1950 when lake records show that local atmospheric temperatures in greenland were 2 4 c warmer than the present records from five new threshold lakes complemented with existing geological data from south of 70 n show that the ice margin was retracted behind its present day extent in all sectors for a limited period between ca 7 and 4 cal kyr b p and in most sectors from ca 1 5 to 1 cal kyr b p in response to higher atmospheric and ocean temperatures ice sheet simulations constrained by observations show good correlation with the timing of minimum ice volume indicated by the threshold lake observations the simulated volume reduction suggests a minimum contribution of 0 16 m sea level equivalent from the entire greenland ice sheet with a centennial ice loss rate of as much as 100 gt yr for several millennia during the holocene thermal maximum our results provide an estimate of the long term rates of volume loss that can be expected in the future as regional air and ocean temperatures approach those reconstructed for the holocene thermal maximum

integration of modern and past pollen accumulation rate par records across the arctic tree line a method for more precise vegetation reconstructions abstract in order to assess the potential role of the boreal forest in the early to mid holocene global dynamics it is critical that the tree line reconstructions are based on precise palaeorecords pollen accumulation rate par calculations provide a technique for estimating past plant population densities independently for each species when considering tree lines an important concept is the threshold par value for the absence presence and dominance of the most common tree species such threshold values are often based on modern lake sediment core top par values in northern fennoscandia records obtained through pollen monitoring now add an important element to these studies as they allow more precise definitions of the temporal and spatial limits of par values here we compare modern par values based on pollen monitoring data with sediment core top data to evaluate the robustness of the threshold values for the major tree species of finnish lapland we apply these threshold values to two fossil par records from this tree line region and as an example of the potential of the approach map the vegetation patterns in the area at 7000 cal yr bp the results indicate that the extent of the mid holocene tree line advance in northern fennoscandia was substantially less than climate vegetation model simulations have predicted despite their value and potential in vegetation reconstructions the use of par values requires careful validation of the data we stress the importance of basin size of precise and reliable sediment dating age depth modelling and assessment of the sedimentary processes in each study basin as prerequisites for par based studies

ejection landslide at northern terminus of beichuan rupture triggered by the 2008 mw 7 9 wenchuan earthquake on 12 may 2008 the mw 7 9 wenchuan earthquake triggered wide spread damaging landslides in many parts of the longmen shan area among these landslides the donghekou ejection landslide is quite special it is located at the north east end of the beichuan rupture and it has caused a great loss of life at the villages of donghekou qinchuan and sichuan provinces because of its special location this ejection landslide differs from landslides caused by gravity or rainstorms only the sliding surface is not uniformly continuous instead two sections can be distin guished an upper section with a step sliding surface and a lower section more gently dipping the landslide started with material ejection caused by large local seismic acceleration throwing rocks into the air with a parabolic trajectory before they fell back to the ground in this paper we analyze geologic and geomorphologic conditions that favored the occurrence of this landslide and we introduce a simple tectonic geomorphology model to explain the mechanism that led to the ejection landslide we find that the location of the landslide zone along with the domino like ground tension cracks observed on both sides of the beichuan rupture is controlled by the propagation of the rupture our result also suggests that in addition to local seismic shaking intensity horizontal acceleration and geomorphologic and geologic condi tions the vertical acceleration and the style of faulting could also play an important role in the occurrence of earthquake triggered landslides

holocene climatic instability a prominent widespread event 8200 yr ago the most prominent holocene climatic event in greenland ice core proxies with approximately half the amplitude of the younger dryas occurred 8000 to 8400 yr ago this holocene event affected regions well beyond the north atlantic basin as shown by synchronous increases in windblown chemical indicators together with a significant decrease in methane widespread proxy records from the tropics to the north polar regions show a short lived cool dry or windy event of similar age the spatial pattern of terrestrial and marine changes is similar to that of the younger dryas event suggesting a role for north atlantic thermohaline circulation possible forcings identified thus far for this holocene event are small consistent with recent model results indicating high sensitivity and strong linkages in the climatic system

calibrated pollen accumulation rates as a basis for quantitative tree biomass reconstructions recent investigations show that the pollen accumulation rate par of the common tree taxa is directly related to the biomass and by inference to the population size of the taxa around the study site fossil par records preserved in lakes provide therefore a potential proxy for quantitative biomass and population reconstructions we use the high resolution par records obtained from two accurately dated lake sediment cores in finland to generate quantitative holocene biomass records for pinus picea and betula the most common tree taxa of the european boreal forest par values were calibrated to biomass values by comparing the modern par values with the modern biomass values and assuming a linear relationship between the past par and biomass values the obtained par and biomass values and trends are remarkably coherent between the two records pinus has a stable holocene biomass size and its modern biomass about 20 t ha corresponds with the natural pinus biomass in the study regions in contrast picea immigrated from the east during the mid holocene had a maximum biomass 50 60 t ha at 3500 1000 cal yr bp and declined strongly during the last 1500 1000 years as a result of increased human activity and related rise of fire frequency thus the modern picea biomass in the study regions about 22 t ha is only 35 40 of the natural picea biomass the results of this pilot study demonstrate the potential of the calibrated par data in quantitative biomass and population reconstructions such reconstructions can provide fresh insights into the structure of past plant communities and when combined with records reflecting palaeoclimates natural disturbances and human activity can help to disentangle the long term importance of different enviromental drivers to changes in plants populations and ecosystems less

the greenland 8200 cal yr bp event detected in loss on ignition profiles in norwegian lacustrine sediment sequences high resolution loss on ignition analyses of lacustrine sediment cores from both proglacial and non glacial lakes in southern norway have revealed a specific pattern characterised by a significant two peaked reduction of the loss on ignition values in the basal half of the cores in non glacier fed lakes the loss on ignition variations are interpreted to reflect mainly lake productivity and hence variability in surface summer air temperature sediments deposited in proglacial lakes however reflect mainly the glacier activity in the lake catchment bulk ams radiocarbon dates from the core sequences and the loss on ignition curve pattern suggest that this event correlates with the 8200 cal yr bp event recorded in the grip and gisp2 greenland ice cores termed the finse event in southern norway copyright 2001 john wiley sons ltd

midges as quantitative temperature indicator species lessons for palaeoecology calibration data sets give a unique opportunity to establish patterns of biological existence and their statistical associations with environmental variables by use of calibration data sets environmental variables can be inferred quantitatively the resulting long time series may assist in distinguishing natural environmental variability from human induced variability both in terms of climate change and biotic turnover however the validity of the palaeoenvironmental reconstructions depends on their accuracy precision and sensibility before performing palaeoenvironmental inferences key mechanisms controlling contemporary species distribution abundances and dynamics should be identified and understood an inference model is developed to produce reconstructions a major challenge lies in validating and interpreting the reconstructions calibration data sets involving midges diptera chironomidae suggest that climate has a broad scale regional control over midge existence and abundance often ove

lateglacial and early holocene climates of the atlantic margins of europe stable isotope mollusc and pollen records from orkney scotland the margins of mainland europe and especially those areas coming under the influence of north atlantic weather systems are ideally placed to record changing palaeoclimates cores from an infilled lake basin at crudale meadow in mainland orkney revealed basal deposits of calcareous mud marl beneath sedge peat stable isotope palynological and molluscan analyses allowed the establishment of palaeoenvironmental changes through the devensian lateglacial and the early holocene the 18omarl record exhibited the existence of possibly four climatic oscillations in the lateglacial one of which within event cf gi 1c is not often commented upon as well as the preboreal oscillation and other holocene perturbations the cold episodes succeeding the preboreal oscillation were demarcated conservatively and one of these event c5 11 0 ka may have previously been unremarked while the putative 9 3 and 8 2 ka events seem not to produce corresponding palynologically visible floristic changes the events at crudale meadow are consistent with those recorded at other sites from britain ireland and elsewhere and can be correlated with isotopic changes shown by the greenland ice cores the multi proxy approach enriches the environmental reconstructions from the site although the synchronicity of the response of the various proxies is sometimes equivocal depending upon the time period concerned taphonomy and the nature of the deposits the site may contain the most northerly lateglacial isotope record from northwest europe and it has yielded one of the best archives for the demonstration of abrupt early holocene events within britain

the size distribution and mobility of landslides caused by the 2015 mw7 8 gorkha earthquake nepal abstract coseismic landslides pose immediate and prolonged hazards to mountainous communities and provide a rare opportunity to study the effect of large earthquakes on erosion and sediment budgets by mapping landslides using high resolution satellite imagery we find that the 25 april 2015 m w 7 8 gorkha earthquake and aftershock sequence produced at least 25 000 landslides throughout the steep himalayan mountains in central nepal despite early reports claiming lower than expected landslide activity our results show that the total number area and volume of landslides associated with the gorkha event are consistent with expectations when compared to prior landslide triggering earthquakes around the world the extent of landsliding mimics the extent of fault rupture along the east west trace of the main himalayan thrust and increases eastward following the progression of rupture in this event maximum modeled peak ground acceleration pga and the steepest topographic slopes of the high himalaya are not spatially coincident so it is not surprising that landslide density correlates neither with pga nor steepest slopes on their own instead we find that the highest landslide density is located at the confluence of steep slopes high mean annual precipitation and proximity to the deepest part of the fault rupture from which 0 5 2 hz seismic energy originated we suggest that landslide density was determined by a combination of earthquake source characteristics slope distributions and the influence of precipitation on rock strength via weathering and changes in vegetation cover determining the relative contribution of each factor will require further modeling and better constrained seismic parameters both of which are likely to be developed in the coming few years as post event studies evolve landslide mobility in terms of the ratio of runout distance to fall height is comparable to small volume landslides in other settings and landslide volume runout scaling is consistent with compilations of data on larger slope failures in general the size ratios of landslide source area to full landslide area are smaller than global averages and hillslope length seems to largely control runout distance which we propose reflects a topographic control on landslide mobility in this setting we find that landslide size dictates runout distance and that more than half of the landslide debris was deposited in direct connection with stream channels connectivity which is defined as the spatial proximity of landslides to fluvial channels is greatest for larger landslides in the high relief part of the high himalaya although these failures are less abundant than those at lower elevations they may have a disproportionate impact on sediment dynamics and cascading hazards such as landslide reactivation by monsoon rainfall and landslide dams that lead to outburst floods the overall high fluvial connectivity of coseismic landsliding in the gorkha event suggests coupling between the earthquake cycle and sediment geochemical budgets of fluvial systems in the himalaya

the sensitivity of hillslope bedrock erosion to precipitation decoupling the impacts of climate and tectonics on hillslope erosion rates is a challenging problem hillslope erosion rates are well known to respond to changes in hillslope boundary conditions e g channel incision rates through their dependence on soil thickness and precipitation is an important control on soil formation surprisingly though compilations of hillslope denudation rates suggest little precipitation sensitivity to isolate the effects of precipitation and boundary condition we measured rates of soil production from bedrock and described soils on hillslopes along a semi arid to hyperarid precipitation gradient in northern chile in each climate zone hillslopes with contrasting boundary conditions actively incising channels versus non eroding landforms were studied channel incision rates which ultimately drive hillslope erosion varied with precipitation rather than tectonic setting throughout the study area these precipitation dependent incision rates are mirrored on the hillslopes where erosion shifts from relatively fast and biologically driven to extremely slow and salt driven as precipitation decreases contrary to studies in humid regions bedrock erosion rates increase with precipitation following a power law from 1 m ma 1 in the hyperarid region to 40 m ma 1 in the semi arid region the effect of boundary condition on soil thickness was observed in all climate zones thicker soils on hillslopes with stable boundaries compared to hillslopes bounded by active channels but the difference in bedrock erosion rates between the hillslopes within a climate region slower erosion rates on hillslopes with stable boundaries decreased as precipitation decreased the biotic abiotic threshold also marks the precipitation rate below which bedrock erosion rates are no longer a function of soil thickness our work shows that hillslope processes become sensitive to precipitation as life disappears and the ability of the landscape to respond to tectonics decreases copyright 2010 john wiley sons ltd

seismic performance of loess mudstone slope in tianshui centrifuge model tests and numerical analysis abstract dynamic behavior and failure mechanism of slope during earthquake are hot topics in geotechnical engineering community in tianshui area northwest of china the deformation features of loess mudstone slopes induced by earthquakes are still not well understood the current study aims to discuss the dynamic behavior of the slope under earthquake by performing a series of centrifuge shaking table tests and numerical simulations the results are processed for pga amplificatory effect study and to evaluate the earthquake induced deformation mechanism better agreement is obtained between the results of numerical simulations and centrifuge tests the results indicated that the acceleration response of the loess mudstone slope showed several amplifying characteristic the height effect lithologic effect and surface effect it also proves that the displacements in the loess layer are much larger than mudstone as the input amplitude increased the shear plastic zone developed along a further slide surface tension plastic zone mainly occurred at the crest roughly the regions of earthquake induced deformation state increased with the increase in amplitude of earthquake wave deformations occurred at the upper part of the slope tensile cracks evolved on the crest and the upper part of slope in loess layer moreover failures occurred at slope surface and only slight deformation at slope toe deformations with continuous shear cracks and slope surface upheavals developed at the middle part of slope

experimental case study of seismically induced loess liquefaction and landslide abstract the 1920 haiyuan ms 8 5 earthquake induced a large number of fluidized loess landslides in china characterized by low slope angles long run out distances and fluidized movement the mechanism of these landslides has aroused considerable interest although additional research is needed to understand more fully the behavior of the loess and the failure mechanism field investigation was conducted on the shibeiyuan landslide and loess samples collected for later laboratory analysis by conventional geotechnical tests triaxial compression tests and ring shear tests the field survey revealed that the shibeiyuan landslide occurred on a concave slope

latest pleistocene and holocene alpine glacier fluctuations in scandinavia abstract during the early holocene abrupt decadal to centennial scale climate variations caused significant glacier variations in norway increased freshwater inflow to the north atlantic and arctic oceans has been suggested as one of the most likely mechanisms to explain the abrupt and significant lateglacial and early holocene climatic events in nw europe the largest early holocene glacier readvances occurred 11 200 10 500 10 100 9700 9200 and 8400 8000 cal yr bp the studied norwegian glaciers apparently melted away at least once during the early mid holocene the period with the most contracted glaciers in scandinavia was between 6600 and 6000 cal yr bp subsequent to 6000 cal yr bp the glaciers started to advance and the most extensive glaciers existed at about 5600 4400 3300 2300 1600 cal yr bp and during the little ice age times with overall less glacier activity were apparently around 5000 4000 3000 2000 and 1200 cal yr bp it has been proposed that several glacier advances occurred in scandinavia including northern sweden at 8500 7900 7400 7200 6300 6100 5900 5800 5600 5300 5100 4800 4600 4200 3400 3200 3000 2800 2700 2000 1900 1600 1200 1000 and 700 200 cal yr bp glaciers in northern sweden probably reached their greatest little ice age extent between the 17th and the beginning of the 18th centuries evidence for early holocene glacier advances in northern scandinavia however has been questioned by more recent multi disciplinary studies the early to mid holocene glacier episodes in northern sweden may therefore be questioned most norwegian glaciers attained their maximum little ice age extent during the mid 18th century cumulative glacier length variations in southern norway based on marginal moraines dated by lichenometry and historic evidence show an overall retreat from the mid 18th century until the 1930s 40s subsequently most norwegian glaciers retreated significantly maritime outlet glaciers with short frontal time lags 15 20 years continued their retreat to the 1970s and 1980s however maritime glaciers started to advance as a response to higher winter accumulation during the first part of the 1990s after 2000 several of the observed glaciers have retreated remarkably fast annual frontal retreat 100 m mainly due to high summer temperatures the general glacier retreat during the early holocene and the neoglacial advances after 6000 cal yr bp are in line with orbital forcing due to the decrease of northern hemisphere summer solar insolation and the increase in winter insolation in addition regional weather modes such as the north atlantic oscillation nao and the arctic oscillation ao play a significant role with respect to decadal and multi decadal climate variability

the spatial and temporal complexity of the holocene thermal maximum the holocene thermal maximum a period of relatively warm climate between 11 000 and 5 000 years ago1 2 is most clearly recorded in the middle and high latitudes2 3 of the northern hemisphere where it is generally associated with the local orbitally forced summer insolation maximum however proxy based reconstructions have shown that both the timing and magnitude of the warming vary substantially between different regions2 3 4 suggesting the involvement of extra feedbacks and forcings here we simulate the holocene thermal maximum in a coupled global ocean atmosphere vegetation model we find that before 7 000 years ago summers were substantially cooler over regions directly influenced by the presence of the laurentide ice sheet whereas other regions of the northern hemisphere were dominated by orbital forcing our simulations suggest that the cool conditions arose from a combination of the inhibition of labrador sea deep convection by the flux of meltwater from the ice sheet which weakened northward heat transport by the ocean and the high surface albedo of the ice sheet we thus conclude that interglacial climate is highly sensitive to relatively small changes in ice sheet configuration

early to mid holocene forest line and climate dynamics in southern scandes mountains inferred from contrasting megafossil and pollen data the result of 344 radiocarbon dated megafossils is here presented and discussed this study aims at elucidating early to mid holocene forest line and climate dynamics in the southern scandes along

regression models for estimating coseismic landslide displacement newmark s sliding block model is widely used to estimate coseismic slope performance early efforts to develop simple regression models to estimate newmark displacement were based on analysis of the small number of strong motion records then available the current availability of a much larger set of strong motion records dictates that these regression equations be updated regression equations were generated using data derived from a collection of 2270 strong motion records from 30 worldwide earthquakes the regression equations predict newmark displacement in terms of 1 critical acceleration ratio 2 critical acceleration ratio and earthquake magnitude 3 arias intensity and critical acceleration and 4 arias intensity and critical acceleration ratio these equations are well constrained and fit the data well 71 br 2 b88 but they have standard deviations of about 0 5 log units such that the range defined by the mean one standard deviation spans about an order of magnitude these regression models therefore are not recommended for use in site specific design but rather for regional scale seismic landslide hazard mapping or for rapid preliminary screening of sites 2007 elsevier b v all rights reserved

extraordinary floods of 4100 4000 a bp recorded at the late neolithic ruins in the jinghe river gorges middle reach of the yellow river china abstract holocene palaeohydrological investigations were carried out in the middle reach of the jinghe river that drains the central part of the loess plateau a set of palaeoflood slackwater deposits was found interbedded in the holocene loess soil sequence within the cliff riverbanks both the sedimentary criteria and the analytical results show that this sediment was sourced from a suspended sediment load of floodwater the major cultural layer of a late neolithic settlement 4300 4000 a bp occurring at the same site is blanketed by this flood deposit directly slopewash with pottery shards charcoal and burnt earth occurs in between the palaeoflood slackwater deposit beds it indicates that each of the slackwater deposit beds has recorded one individual flood event and that these extraordinary floods occurred when the late neolithic people occupied the riverbank terrace land this pre historical settlement was abandoned after the floods eventually due presumably to repeated inundation by overbank floodwater the flood events were osl dated to between 4100 and 4000 a bp and checked by archaeological dating of the anthropogenic remains retrieved from the sequences peak discharges of the floods were estimated to between 19 500 and 22 000 m3 s 1 which is several times gauged maximum floods during the 4200 4000 a bp climatic event severe droughts were documented in china s monsoonal regions and great floods were known from an ancient legend this study provides a well dated sediment record of pre historical floods which occurred at the transition from the neolithic to the bronze age in the yellow river basin it shows that extraordinary floods were part of the abrupt climatic variability during the 4200 4000 a bp climatic event the highly variable unstable and catastrophic climate typified by both droughts and floods resulted in settlement abandonment and possibly the decline of the highly developed late neolithic civilizations in china s monsoonal regions

coseismic reverse and oblique slip surface faulting generated by the 2008 mw 7 9 wenchuan earthquake china the mw 7 9 wenchuan china earthquake ruptured two large thrust faults along the long menshan thrust belt at the eastern margin of the tibetan plateau this earthquake generated a 240 km long surface rupture zone along the beichuan fault and an additional 72 km long surface rupture zone along the pengguan fault maximum vertical and horizontal offsets of 6 5 m and 4 9 m respectively were measured along the beichuan fault a maximum vertical offset of 3 5 m was measured along the pengguan fault coseismic surface ruptures integrated with aftershocks and industry seismic profiles show that two imbricate structures have ruptured simultaneously resulting in the largest continental thrust event ever documented large oblique thrusting observed during this earthquake indicates that crustal shortening is an important process responsible for the high topography in the region as everywhere along the edge of tibetan plateau

lake store finnsjoen a key for understanding lateglacial early holocene vegetation and ice sheet dynamics in the central scandes mountains the lateglacial lg deglaciation and vegetation development in the scandes mountains has been debated for a century here we present new evidence from microfossils radiocarbon dated plant macrofossils and sedimentary ancient dna from laminated sediments in lake store finnsjoen 1260 m a s l at dovre central norway combined with previous results from three other dovre lakes this allows for new interpretations of events during and immediately after the lg deglaciation the finnsjoen sediments present the first uninterrupted record of local vegetation development in the scandes mountains from the late younger dryas yd ca 12 000 cal years bp to the early holocene around 9700 cal years bp the local vegetation in late yd early holocene was extremely sparse with pioneer herbs e g artemisia norvegica beckwithia campanula cf uniflora koenigia oxyria papaver saxifraga spp and dwarf shrubs betula nana salix including salix polaris from 11 300 cal years bp local vegetation rapidly closed with dominant dryas saxifraga spp and silene acaulis from ca 10 700 cal years bp open birch forests with juniper empetrum nigrum and other dwarf shrubs developed pine forests established within the area from 10 300 cal years bp we identified the cold preboreal oscillation pbo not earlier described from pollen data in south norway around 11 400 cal years bp by a regional pollen signal distinct local vegetation changes were not detected until the post pbo warming around 11 300 cal years bp apparently the earlier warming at the yd holocene transition at 11 650 cal years bp was too weak and short lived for vegetation closure at high altitudes at dovre for the first time we demonstrate a regional glacier readvance and local ice cap formations during the yd in the scandes mountains in two of the deep lakes with small catchments yd glaciation blocked sedimentation without removing old sediments and caused a hiatus separating sediments of the ice free lg interstadial lgi from those of the ice free holocene period both regional glaciers and local ice caps caused hiati ice free pre yd conditions at dovre followed by a yd readvance point to a scenario that is intermediate between the maximum ice model postulating a thick glacier during the entire lg and the minimum ice model postulating thin and multi domed early lg ice

environmental responses to the 9 7 and 8 2 cold events at two ecotonal sites in the dovre mountains mid norway abstract we found strong signals of two cooling events around 9700 and 8200 cal yrs bp in lakes store finnsjoen and flafattjonna at dovre mid norway analyses included pollen in both lakes and c n ratio biomarkers e g alkanes and br gdgts and xrf scanning in finnsjoen the positions of these lakes close to ecotones upper forest lines of birch and pine respectively reduced their resilience to cold events causing vegetation regression at both sites the global 8 2 event reflects the collapse of the laurentide ice sheet the 9 7 event with impact restricted to scandinavia and traced by pollen at dovre only reflects the drainage of the baltic ancylus lake more detailed analysis in finnsjoen shows that the events also caused increased allochtonous input k ca increased sedimentation rate and decreased sediment density and aquatic production br gdgt based temperatures indicate gradual cooling through the early holocene in finnsjoen ca 3100 maxima minima couplets in sediment density along the analysed sequence of ca 3100 calibrated years show the presence of varves for the first time in norway impact of the 9 7 and 8 2 events lasted ca 60 and 370 years respectively pine pollen percentages were halved and re established in less than 60 years indicating the reduction of pine pollen production and not vegetative growth during the 9 7 event the local impact of the 8 2 event sensu lato ca 8420 8050 cal yrs bp divides the event into a precursor an erosional phase and a recovery phase at the onset of the erosional phase summer temperatures increased

predictive model and probabilistic assessment of sliding displacement for regional scale seismic landslide hazard estimation in iranpredictive model and probabilistic assessment of sliding displacement

a method for producing digital probabilistic seismic landslide hazard maps abstract the 1994 northridge california earthquake is the first earthquake for which we have all of the data sets needed to conduct a rigorous regional analysis of seismic slope instability these data sets include 1 a comprehensive inventory of triggered landslides 2 about 200 strong motion records of the mainshock 3 1 24 000 scale geologic mapping of the region 4 extensive data on engineering properties of geologic units and 5 high resolution digital elevation models of the topography all of these data sets have been digitized and rasterized at 10 m grid spacing using arc info gis software on a unix computer combining these data sets in a dynamic model based on newmark s permanent deformation sliding block analysis yields estimates of coseismic landslide displacement in each grid cell from the northridge earthquake the modeled displacements are then compared with the digital inventory of landslides triggered by the northridge earthquake to construct a probability curve relating predicted displacement to probability of failure this probability function can be applied to predict and map the spatial variability in failure probability in any ground shaking conditions of interest we anticipate that this mapping procedure will be used to construct seismic landslide hazard maps that will assist in emergency preparedness planning and in making rational decisions regarding development and construction in areas susceptible to seismic slope failure

reconstructing palaeoclimatic variables from fossil pollen using boosted regression trees comparison and synthesis with other quantitative reconstruction methods abstract we test and analyse a new calibration method boosted regression trees brts in palaeoclimatic reconstructions based on fossil pollen assemblages we apply brts to multiple holocene and lateglacial pollen sequences from northern europe and compare their performance with two commonly used calibration methods weighted averaging regression wa and the modern analogue technique mat using these calibration methods and fossil pollen data we present synthetic reconstructions of holocene summer temperature winter temperature and water balance changes in northern europe highly consistent trends are found for summer temperature with a distinct holocene thermal maximum at ca 8000 4000 cal a bp with a mean t jja anomaly of ca 0 7 c at 6 ka compared to 0 5 ka we were unable to reconstruct reliably winter temperature or water balance due to the confounding effects of summer temperature and the great between reconstruction variability we find brts to be a promising tool for quantitative reconstructions from palaeoenvironmental proxy data brts show good performance in cross validations compared with wa and mat can model a variety of taxon response types find relevant predictors and incorporate interactions between predictors and show some robustness with non analogue fossil assemblages

a new approach to calculating holocene winter precipitation by combining glacier equilibrium line altitudes and pine tree limits a case stud from hardangerjokulen central southern norway at hardangerjokulen central southern norway detailed knowledge of the number age and magnitude of holocene glacier fluctuations is used to reconstruct variations in equilibrium line altitude ela for the last 10 000 years present and past elas are based on an accumulation area ratio aar of 0 7 and are adjusted for land uplift a synchronous relationship between advanced glacier positions and the highest pine tree limits pinus sylvestris l is demonstrated for the early to mid holocene in southern scandinavia which indicates that warm summers were compensated for by high winter precipitation based on pine tree limit fluctuations as a measure of mean ablation season temperature holocene variations in winter precipitation at hardangerjokulen have been calculated by substitution in the close exponential relationship between mean ablation season temperature and winter precipitation at the ela of norwegian glaciers setting the winter precipitation during the period ad 1961 1990 at 100 mean values

regional patterns of earthquake triggered landslides and their relation to ground motion 1 we have documented patterns of landsliding associated with large earthquakes on three thrust faults the northridge earthquake in california chi chi earthquake in taiwan and two earthquakes on the ramu markham fault bounding the finisterre mountains of papua new guinea in each case landslide densities are shown to be greatest in the area of strongest ground acceleration and to decay with distance from the epicenter in california and taiwan the density of co seismic landslides is linearly and highly correlated with both the vertical and horizontal components of measured peak ground acceleration based on this observation we derive an expression for the spatial variation of landslide density analogous with regional seismic attenuation laws in its general form this expression applies to our three examples and we determine best fit values for individual cases our findings open a window on the construction of shake maps from geomorphic observations for earthquakes in non instrumented regions

northern hemisphere forcing of climatic cycles in antarctica over the past 360 000 years the milankovitch theory of climate change proposes that glacial interglacial cycles are driven by changes in summer insolation at high northern latitudes the timing of climate change in the southern hemisphere at glacial interglacial transitions which are known as terminations relative to variations in summer insolation in the northern hemisphere is an important test of this hypothesis so far it has only been possible to apply this test to the most recent termination because the dating uncertainty associated with older terminations is too large to allow phase relationships to be determined here we present a new chronology of antarctic climate change over the past 360 000 years that is based on the ratio of oxygen to nitrogen molecules in air trapped in the dome fuji and vostok ice cores this ratio is a proxy for local summer insolation5 and thus allows the chronology to be constructed by orbital tuning without the need to assume a lag between a climate record and an orbital parameter the accuracy of the chronology allows us to examine the phase relationships between climate records from the ice cores and changes in insolation our results indicate that orbital scale antarctic climate change lags northern hemisphere insolation by a few millennia and that the increases in antarctic temperature and atmospheric carbon dioxide concentration during the last four terminations occurred within the rising phase of northern hemisphere summer insolation these results support the milankovitch theory that northern hemisphere summer insolation triggered the last four deglaciations

centennial scale climate cooling with a sudden cold event around 8 200 years ago the extent of climate variability during the current interglacial period the holocene is still debated temperature records derived from central greenland ice cores show one significant temperature anomaly between 8 200 and 8 100 years ago which is often attributed to a meltwater outflow into the north atlantic ocean and a slowdown of north atlantic deep water formation this anomaly provides an opportunity to study such processes with relevance to present day freshening of the north atlantic anomalies in climate proxy records from locations around the globe are often correlated with this sharp event in greenland but the anomalies in many of these records span 400 to 600 years start from about 8 600 years ago and form part of a repeating pattern within the holocene more sudden climate changes around 8 200 years ago appear superimposed on this longer term cooling the compounded nature of the signals implies that far field climate anomalies around 8 200 years ago cannot be used in a straightforward manner to assess the impact of a slowdown of north atlantic deep water formation and the geographical extent of the rapid cooling event 8 200 years ago remains to be determined

obtaining suitable logic tree weights for probabilistic earthquake induced landslide hazard analyses abstract in this study an inventory of landslides induced by the 2011 lorca earthquake mw 5 1 has been used in order to develop a new procedure to obtain objective logic tree weights for a probabilistic earthquake induced landslide hazard analysis the 2011 lorca earthquake triggered more than 250 landslides mainly of disrupted type the logic tree was designed having regard to variability of relevant geotechnical parameters involved in the problem and uncertainties associated with the use of several empirical relationships in order to compute newmark displacements for the purpose the resulting hazard maps were compared with this landslide inventory and weights estimated for each branch of the logic tree based on these results the best model for seismic landslide hazard mapping for a moderate earthquake correctly identifies around 72 of landslide areas based on the set of parameters that comprises depth of failure surface specific weight cohesion friction angle and newmark displacement model the corresponding weights were objectively established these weights are reliable enough for the obtaining seismic landslide hazard maps and may be implemented in similar environments characterized by moderate low magnitude earthquakes mw

temperature and precipitation history of the arctic as the planet cooled from peak warmth in the early cenozoic extensive northern hemisphere ice sheets developed by 2 6 ma ago leading to changes in the circulation of both the atmosphere and oceans from not vert similar2 6 to not vert similar1 0 ma ago ice sheets came and went about every 41 ka in pace with cycles in the tilt of earth s axis but for the past 700 ka glacial cycles have been longer lasting not vert similar100 ka separated by brief warm interglaciations when sea level and ice volumes were close to present the cause of the shift from 41 ka to 100 ka glacial cycles is still debated during the penultimate interglaciation not vert similar130 to not vert similar120 ka ago solar energy in summer in the arctic was greater than at any time subsequently as a consequence arctic summers were not vert similar5 c warmer than at present and almost all glaciers melted completely except for the greenland ice sheet and even it was reduced in size substantially from its present extent with the loss of land ice sea level was about 5 m higher than present with the extra melt coming from both greenland and antarctica as well as small glaciers the last glacial maximum lgm peaked not vert similar21 ka ago when mean annual temperatures over parts of the arctic were as much as 20 c lower than at present ice recession was well underway 16 ka ago and most of the northern hemisphere ice sheets had melted by 6 ka ago solar energy reached a summer maximum 9 higher than at present not vert similar11 ka ago and has been decreasing since then primarily in response to the precession of the equinoxes the extra energy elevated early holocene summer temperatures throughout the arctic 1 3 c above 20th century averages enough to completely melt many small glaciers throughout the arctic although the greenland ice sheet was only slightly smaller than at present early holocene summer sea ice limits were substantially smaller than their 20th century average and the flow of atlantic water into the arctic ocean was substantially greater as summer solar energy decreased in the second half of the holocene glaciers re established or advanced sea ice expanded and the flow of warm atlantic water into the arctic ocean diminished late holocene cooling reached its nadir during the little ice age about 1250 1850 ad when sun blocking volcanic eruptions and perhaps other causes added to the orbital cooling allowing most arctic glaciers to reach their maximum holocene extent during the warming of the past century glaciers have receded throughout the arctic terrestrial ecosystems have advanced northward and perennial arctic ocean sea ice has diminished here we review the proxies that allow reconstruction of quaternary climates and the feedbacks that amplify climate change across the arctic we provide an overview of the evolution of climate from the hot house of the early cenozoic through its transition to the ice house of the quaternary with special emphasis on the anomalous warmth of the middle pliocene early quaternary warm times the mid pleistocene transition warm interglaciations of marine isotope stages 11 5e and 1 the stage 3 interstadial and the peak cold of the last glacial maximum

woody vegetation fuel and fire track the melting of the scandinavian ice sheet before 9500 cal yr bp abstract new studies indicate the presence of early holocene ice free areas far north in scandinavia post glacial fire and vegetation were investigated based on sedimentary charcoal and pollen from two small lakes in northern sweden accumulation of organic sediment started around 10 900 and 9200 cal yr bp showing that both lake valleys were ice free extremely early given their northerly location fire events started after 9600 cal yr bp and became less common around the 8 2 ka event woody vegetation provided fuel that contributed to fires the first vegetation in our pollen record consisted of hippophae dryas grasses and sedges subsequently broadleaved trees betula salix increased in abundance and later pinus alnus ferns and lycopodium characterized the vegetation pollen from larix picea and malus were also found the change in vegetation composition was synchronous with the decrease in lake water ph in the region indicating ecosystem scale processes this occurred during a period of net global and regional warming the changes in fire frequency and vegetation appear independent of regional trends in precipitation the reconstructed fire history and vegetation support the scenario of early ice free areas far north in scandinavia during early holocene warming creating favorable conditions for woody plants and wildfires

global characterization of the holocene thermal maximum we analyze the global variations in the timing and magnitude of the holocene thermal maximum htm and their dependence on various forcings in transient simulations covering the last 9000 years 9 ka performed with a global atmosphere ocean vegetation model in these experiments we consider the influence of variations in orbital parameters and atmospheric greenhouse gases and the early holocene deglaciation of the laurentide ice sheet lis considering the lis deglaciation we quantify separately the impacts of the background melt water fluxes and the changes in topography and surface albedo in the analysis we focus on the intensity of the maximum temperature deviation relative to the preindustrial level its timing in the holocene and the seasonal expression in the model the warmest htm conditions are found at high latitudes in both hemispheres reaching 5 c above the preindustrial level while the smallest htm signal is seen over tropical oceans less than 0 5 c this latitudinal contrast is mostly related to the nature of the orbitally forced insolation forcing which is also largest at high latitudes and further enhanced by the polar amplification the holocene timing of the htm is earliest before 8 ka bp in regions not affected by the remnant lis particularly nw north america e asia n africa n south america the middle east ne siberia and australia compared to the early holocene insolation maximum the htm was delayed by 2 3 ka over ne north america and regions directly downwind from the lis a similar delay is simulated over the southern ocean while an intermediate lag of about 1 ka is found over most other continents and oceans the seasonal timing of the htm over continents generally occurs in the same month as the maximum insolation anomaly whereas over oceans the htm is delayed by 2 3 months exceptions are the oceans covered by sea ice and north africa were additional feedbacks results in a different seasonal timing the simulated timing and magnitude of the htm are generally consistent with global proxy evidence with some notable exceptions in the mediterranean region sw north america and eastern eurasia 2012 elsevier ltd

holocene thermal maximum in the western arctic 0 180 w the spatio temporal pattern of peak holocene warmth holocene thermal maximum htm is traced over 140 sites across the western hemisphere of the arctic 0 180 w north of 60 n paleoclimate inferences based on a wide variety of proxy indicators provide clear evidence for warmer than present conditions at 120 of these sites at the 16 terrestrial sites where quantitative estimates have been obtained local htm temperatures primarily summer estimates were on average 1 6 0 8 c higher than present approximate average of the 20th century but the warming was time transgressive across the western arctic as the precession driven summer insolation anomaly peaked 12 10 ka thousands of calendar years ago warming was concentrated in northwest north america while cool conditions lingered in the northeast alaska and northwest canada experienced the htm between ca 11 and 9 ka about 4000 yr prior to the htm in northeast canada the delayed warming in quebec and labrador was linked to the residual laurentide ice sheet which chilled the region through its impact on surface energy balance and ocean circulation the lingering ice also attests to the inherent asymmetry of atmospheric and oceanic circulation that predisposes the region to glaciation and modulates the pattern of climatic change the spatial asymmetry of warming during the htm resembles the pattern of warming observed in the arctic over the last several decades although the two warmings are described at different temporal scales and the htm was additionally affected by the residual laurentide ice the similarities suggest there might be a preferred mode of variability in the atmospheric circulation that generates a recurrent pattern of warming under positive radiative forcing unlike the htm however future warming will not be counterbalanced by the cooling effect of a residual north american ice sheet

the lateglacial and early holocene vegetation and environment in the dovre mountains central norway as signalled in two lateglacial nunatak lakes abstract by using heavy coring equipment in two high altitudinal lakes 1253 and 1316 m a s l at dovre central norway 1 1 5 m of unsorted coarsely minerogenic sediments were retrieved below the holocene organic sediments the minerogenic sequence contained well preserved pollen and chironomid remains revealing new and detailed palaeoenvironmental knowledge of the mountains in central norway during the last 5 6000 years of the lateglacial lg period however the lg chronology is based on biostratigraphical correlations and not on 14c dates due to low organic content in the minerogenic sediments the emerging lg nunataks probably indicating a thin and multi domed scandinavian ice sheet was rapidly inhabited by immigrating species which could explain the present centric distributions of certain arctic alpine plants the lg vegetation development included a pre interstadial dominated by mineral soil pioneers an interstadial dominated by shrubs and dwarf shrubs and the younger dryas cold period with recurring dominance of pioneers pollen and stomata of pinus and picea indicate their local lg presence at dovre lg climate oscillations are indicated by pollen stratigraphy and for the later part of lg also by chironomids these oscillations could correspond to heinrich event 1 gi 1d gi 1b and the younger dryas cold events the lg interstadial reached july mean temperatures of more than 7 8 c similar to the present chironomids colonized the lake already during the onset of the interstadial albeit at very low richness and abundances starting from yd there are sufficient chironomid head capsules to perform a temperature reconstruction the holocene warming of about 2 c initiated a vegetation closure from snow beds and dwarf shrub tundra to shrubs and forests birch forests established about 10 ka cal bp slightly earlier than pine forests alnus expanded ca 9 2 ka cal bp and a thinning of the local forests occurred from ca 7 ka cal bp two short lasting climate deteriorations found in the pollen record and the chironomid record may represent the preboreal oscillation and the 8 2 event the holocene thermal maximum is indicated around ca 7 8 7 3 ka cal bp showing a chironomid inferred july mean of at least 11 c this is ca 3 c warmer than today

tectonic evolution of the ne palmyride mountain belt syria the bishri crustal block investigation of the bishri block centrally positioned amid the diverse tectonic and structural zones of syria reveals details of the intraplate phanerozoic development of the northern arabian platform the bishri block is a broad ne plunging inverted basin located at the ne portion of the palmyride mountain belt where the mountains intersect the euphrates fault system well and seismic data show that subsidence and sedimentation in the bishri area was generally continuous from carboniferous to paleocene time with the bishri block part of the extensive palmyride sinjar trough major bounding faults and a rift type environment are documented in the permo triassic jurassic and cretaceous the present bishri structural and topographic high has been formed through transpressive structural inversion since the mid miocene high angle mesozoic bounding normal faults now have net reverse offsets with a significant dextral strike slip component east of the bishri block towards the euphrates fault system nnw sse striking normal faults exhibit less reverse movement this deformation history correlates with the opening and closing of the nearby neotethys ocean that has driven the evolution of intracontinental syria

on the applicability of available regression models for estimating newmark displacements for low to moderate magnitude earthquakes the case of the betic cordillera s spain abstract newmark displacement estimation is generally computed using empirical models these models are estimated from large datasets that mainly comprise moderate to high magnitude events mw 6 0 in this work we study the performance of several of these models to study moderate to low magnitude scenarios for this purpose data from the betic cordillera s spain with magnitudes ranging from mw 3 5 to 6 3 were used to compare with model predictions the results show that errors in the estimates depend on the magnitude of events or on the yielding acceleration considered to estimate the displacement the availability of an appropriate range of data magnitude and yielding acceleration when defining the regression model may overcome the differences due to specific characteristics of the seismotectonic context of the area where data derives from the results also show that performance of models including several ground motion predictors is better than those based on a single parameter regardless of the combination these predictors furthermore regression models with polynomial forms present a better performance than other functions based on the logarithm of these predictors finally new specific models for the betic cordillera are proposed especially suitable for low magnitude events

insights into pollen source area transport and deposition from modern pollen accumulation rates in lake sediments abstract pollen accumulation rates par from late quaternary deposits can provide direct estimates of past plant abundance they are influenced by lake internal processes and therefore rarely used in between site comparisons although few studies from fennoscandia have applied them successfully this study aims to explore how pars from selected lakes from northeast germany reflect differences in plant abundance as a step towards quantitative vegetation reconstructions from pars short sediment cores were collected from 18 lakes of which 16 could be dated by 210pb pars were estimated for the youngest sediment representing approximately two years before sampling in 2009 and samples dated to around 1993 forest inventory data for the two time slices were obtained for 15 km around the sites and standing volume sv was estimated as a measure of above ground biomass pars were compared to the total sv within increasing areas around the lakes as well as to distance weighted sv using the prentice sugita model of pollen dispersal and deposition both assessments of the vegetation data yielded strong linear relationships with pars already over distances of tens of metres to a few kilometres documenting the importance of the local vegetation this indicates the importance of the often neglected trunk space component of pollen transport for small lakes results from the small number of large lakes suggest that these sites receive a larger absolute input of pollen from regional sources these observations indicate that small lakes may be somewhat sheltered from pollen transported above the canopy we demonstrate that pars of the major tree taxa obtained from lake sediments are linear related to the lake surrounding biomass this confirms that par can be used to infer past changes in plant biomass although absolute pollen deposition may also be determined by net primary productivity of the biomass

holocene paleoenvironmental records from nikolay lake lena river delta arctic russia radiocarbon dated pollen rhizopod chironomid and total organic carbon toc records from nikolay lake 73 20 n 124 12 e and a pollen record from a nearby peat sequence are used for a detailed environmental reconstruction of the holocene in the lena delta area shrubby alnus fruticosa and betula exilis tundra existed during 10 300 4800 cal yr bp and gradually disappeared after that time climate reconstructions based on the pollen and chironomid records suggest that the climate during ca 10 300 9200 cal yr bp was up to 2 3 c warmer than the present day pollen based reconstructions show that the climate was relatively warm during 9200 6000 cal yr bp and rather unstable between ca 5800 3700 cal yr bp both the qualitative interpretation of pollen data and the results of quantitative reconstruction indicate that climate and vegetation became similar to modern day conditions after ca 3600 cal yr bp the chironomid based temperature reconstruction suggests a relatively warm period between ca 2300 and 1400 cal yr bp which corresponds to the slightly warmer climate conditions reconstructed from the pollen modern chironomid and rhizopod assemblages were established after ca 1400 cal yr bp

an integrated geochemical and palynological study of human impacts soil erosion and storminess from southern greenland since c ad 1000 abstract an integrated pollen analytical and geochemical study is presented from qinngua kangilleq southwest greenland this site was formerly one of the largest farms in the eastern settlement of norse greenland the study is the first to determine what link if any exists between norse landnam early settlement vegetation change soil erosion climate change and peat geochemistry the data suggest that fluxes in lithogenic elements supplied to a peat column by terrestrial sources and atmospheric deposition were coupled to the pattern of local norse settlement beginning cal ad 1020 a severe phase of soil erosion is indicated which is coincident with the landnam horizon this may represent proxy evidence for the stripping of turf for the construction of turf and stone buildings at the farm radiocarbon dates suggest the presence of a hiatus in the sediment column spanning cal ad 1380 1950 following the recommencement of sediment accumulation the geochemical data indicate a critical change in site conditions which may be consistent with the well known change in northern hemisphere atmospheric circulation that started between c ad 1400 and 1420 bromine br and chlorine cl concentrations are demonstrably higher in the sediments dating to the 20th century relative to the pre 15th century deposits rising halogen concentrations at qinngua appear to be correlated with increased levels of na sea salt sodium precipitation in the gisp2 ice core which earlier studies have interpreted as indicative of increased north atlantic storminess

density distribution of landslides triggered by the 2008 wenchuan earthquake and their relationships to peak ground acceleration the distribution of landslides induced by the 2008 m w 7 9 wenchuan earthquake was investigated following the method of meunier et al 2007 to examine the relationships to peak ground acceleration pga results suggest that landslide densities are quantifiably related to pga thresholds of pgacr for landslide failure are graphic 1 for average horizontal pga and graphic 2 for average vertical pga as with other earthquakes the distribution of the wenchuan earthquake triggered landslides can be described by two equations based on area and source densities respectively the similar damping factors of 20 in these two equations suggest that both density distribution patterns of landslides reflect the dissipation of seismic energy landslide derived pga equations were then produced for the hanging wall region of the earthquake affected area the results indicate that it should be possible to produce an earthquake shake map from the distribution of earthquake triggered landslides in an area where there are few or no seismic instruments but many landslides 1 embed inline graphic 1 gif 2 embed inline graphic 2 gif

timing equilibrium line altitudes and climatic implications of two early holocene glacier readvances during the erdalen event at jostedalsbreen western norway following the younger dryas the e rst evidence of glacial activity in southern norway in response to climatic change occurred during the early holocene when terminal moraines from the erdalen event formed beyond the position of later little ice age moraines in front of present outlet glaciers on both sides of the jostedalsbreen ice cap sets of pre little ice age marginal moraines have been morphostratigraphicallycorre lated with the erdalen event the lithostratigraphyin a peat bog at hellemyrane in jostedalen western norway provides e rm evidence for a two phase erdalen event associated with two glacier readvances of nigardsbreen at the preboreal boreal transition radiocarbon dates from the peat bog give age estimates for the two phases the e rst erdalen event readvance took place between 10 100 and 10 050 cal bp while the second occurred close to 9700 cal bp the lowering of the equilibrium linealtitude ela during these readvances is estimated using the little ice age ratio lr approach to be about 230 m and 215 m respectively the e rst readvance is attributed to an increase in winter precipitation while the second readvance may have been primarily caused by a marked drop in summer temperature which reactivated already existing ice masses

reconstruction of holocene precipitation patterns in europe using pollen and lake level data abstract lake level data can be used to refine palaeoclimate reconstructions based on pollen data this approach is illustrated for the european holocene estimates of p pet precipitation minus potential evapotranspiration were first inferred from modern pollen analogues the pollen based estimates were then compared with the status of lakes within a 5 radius analogues with p pet anomalies inconsistent with the lake level changes were rejected the constrained sets of analogues were used to estimate continental scale patterns of annual mean temperature and annual precipitation at 3000 yr intervals estimated temperature anomalies differed only slightly from the unconstrained reconstructions estimated precipitation anomalies however showed improved spatial coherence and increased regional contrast and were occasionally reversed in sign the effect of the constraint was to impose a rational selection among almost equally similar modern pollen analogues with similar temperatures but widely varying moisture regimes the resulting maps showed clear spatially coherent patterns of change in precipitation as well as temperature suitable for comparison with climate model results further improvement of these maps will become possible as a more extensive coverage of lake level data is obtained

dynamic analysis of a slope failure from the 6 august 1979 coyote lake california earthquake abstract the coyote lake california earthquake of 6 august 1979 m l 5 7 provided a rare opportunity to perform a dynamic numerical analysis of a seismically induced slope failure using actual strong motion records the earthquake displaced a preexisting slump on the northeast shore of lake anderson and formed a fissure 20 m long offsets of 9 mm vertically and 18 mm horizontally were measured across the fissure the slump is 9 km northwest of the located epicenter but within 100 m of the mapped trace of the calaveras fault two strong motion records were written in the vicinity of the slump coyote creek 5 km to the southeast and gilroy 6 15 km to the southeast these records combined with field measurements of the slope estimates of the material properties and a dynamic numerical model based on the newmark analysis of seismic slope stability to calculate a predicted displacement for the landslide a displacement of 27 mm calculated using the n50 e component of the gilroy 6 record is in excellent agreement with the displacement measured in the field 21 mm however displacements of only 0 12 mm calculated using the 250 component of the coyote creek strong motion record reflect significant local variations in seismic shaking intensity because strong motion records and slope failures rarely coincide this landslide provides an important test case for our understanding of the dynamics of seismically induced landslides as well as a warning that local seismologic variations need to be considered in any design applications

lateglacial and early holocene palaeoclimatic reconstruction based on glacier fluctuations and equilibrium line altitudes at northern folgefonna hardanger western norway northern folgefonna c 23 km 2 is a nearly circular maritime ice cap located on the folgefonna peninsula in hardanger western norway by combining the position of marginal mor aines with ams radiocarbon dated glacier meltwater induced sediments in proglacial lakes draining northern folgefonna a continuous high resolution record of variations in glacier size and equili brium line altitudes elas during the lateglacial and early holocene has been obtained after the termination of the younger dryas c 11 500 cal yr bp a short lived 100 150 years climatically induced glacier readvance termed the jondal event 1 occurred within the preboreal oscillation pbo c 11 100 cal yr bp bracketed to 10 550 10 450 cal yr bp a second glacier readvance is named the jondal event 2 a third readvance occurred about 10 000 cal yr bp and corresponds with the erdalen event 1 recorded at jostedalsbreen an exponential relationship between mean solid winter precipitation and ablation season temperature at the ela of norwegian glaciers is used to reconstruct former variations in winter precipitation based on the corresponding ela and an indepen dent proxy for summer temperature compared to the present the younger dryas was much colder and drier the jondal event 1 pbo was colder and somewhat drier and the jondal event 2 was much wetter the erdalen event 1 started as rather dry and terminated as somewhat wetter varia tions in glacier magnitude elas and corresponding palaeoclimatic reconstructions at northern folge fonna suggest that low altitude cirque glaciers lowest altitude of marginal moraines 290 m in the area existed for the last time during the younger dryas these low altitude cirque glaciers of sug gested younger dryas age do not fit into the previous reconstructions of the younger dryas ice sheet in hardanger copyright 2005 john wiley sons ltd

holocene treeline history and climate change across northern eurasia radiocarbon dated macrofossils are used to document holocene treeline history across northern russia including siberia boreal forest development in this region commenced by 10 000 yr b p over most of russia forest advanced to or near the current arctic coastline between 9000 and 7000 yr b p and retreated to its present position by between 4000 and 3000 yr b p forest establishment and retreat was roughly synchronous across most of northern russia treeline advance on the kola peninsula however appears to have occurred later than in other regions during the period of maximum forest extension the mean july temperatures along the northern coastline of russia may have been 2 5 to 7 0 c warmer than modern the development of forest and expansion of treeline likely reflects a number of complimentary environmental conditions including heightened summer insolation the demise of eurasian ice sheets reduced sea ice cover greater continentality with eustatically lower sea level and extreme arctic penetration of warm north atlantic waters the late holocene retreat of eurasian treeline coincides with declining summer insolation cooling arctic waters and neoglaciation

holocene tree line and climate change on the queen charlotte islands canada palynological study of two subalpine ponds on the queen charlotte islands reveals changes in tree line and climate during the holocene the findings agree with previous reconstructions from nearby louise pond on the queen charlotte islands that suggest a warmer than present climate and higher than present tree lines in the early holocene ca 9600 660014c yr b p basal ages at sc1 pond and shangri la bog indicate that the basins did not hold permanent water before 720014c yr b p consistent with a warmer and drier early holocene previously inferred from louise pond pollen and plant macrofossils indicate the initial establishment of subalpine conditions by 6090 9014c yr b p similar to the 5790 13014c yr b p age for cooling inferred from louise pond conditions similar to present were established at sc1 pond by 3460 10014c yr b p confirming the previous estimate of 340014c yr b p at louise pond this 340014c yr b p vegetation shift on the queen charlotte islands corresponds with the beginning of the tiedemann glacial advance in the south coastal mountains of british columbia ca 330014c yr b p the peyto and robson glacial advances between 3300 and 280014c yr b p in the rocky mountains and climatic cooling inferred from palynological studies throughout southern british columbia northern washington and southeast alaska these findings confirm that changes in regional climate influenced changes in vegetation in coastal british columbia

holocene glacier fluctuations of flatebreen and winter precipitation changes in the jostedalsbreen region western norvay based on glaciolacustrine sediment records the history of holocene glacier variations of flatebreen an independent glacier close to the sw part of the jostedalsbreen ice cap has been reconstructed from lacustrine sediments in the proglacial lake jarbuvatnet the sedimentary succession shows evidence of three maini episodes of holocene glacier expansion the first is recorded in the basal part of the core up to 370 cm according to the age depth relationship in the sediment core based on 12 ams radiocarbon dates this glacier expansion episode terminated about 10200 cal yr bp the second major glacier phase lasted from 8400 to 8100 cal yr bp while the third was initiated around 4000 cal yr bp and has continued up to the present at 43 cm in the core the medium silt content increases significantly accompanied by a minor increase in the sand content this textural change is interpreted as the first time that the tenninus of flatebreen extended inlto an upstream lake at 1083 m a s l the age model suggests that this event took place around