geology and structure of the continental margin off northern israel and the adjacent part of the levantine basin abstract the continental margin off northern israel and southern lebanon is characterized by a narrow coastal plain in places it is absent a narrow shelf a narrow slope which is incised by numerous submarine canyons and by a complex topography of the adjacent deep sea levantine platform detailed seismic reflection surveys have revealed the development of the area since the late miocene during the messinian when the level of the mediterranean sea dropped the present continental slope area was exposed eroded and covered by thinly scattered sediments in the deep basin evaporite bearing series accumulated reaching 1 km in thickness about 60 km offshore during the pliocene quaternary the area was covered by a fine clastic sequence up to 1 5 km thick that forms the present continental margin basinward gravitational slumping of these sediments over the messinian evaporites which acted as a lubricant resulted in a complex topography and many shore parallel rootless growth faults along the base of the continental slope and the adjacent deep sea young faults which are exposed in northern israel and extend seaward comprise the most important structural feature of the study area these faults were active during the pliocene and quaternary possibly also during the miocene the major nw trending young yagur carmel fault and e w trending rosh hanniqra fault extend to the base of the continental slope where they converge enclosing the complex western galilee graben the relief of the base of the pliocene quaternary sequence was affected by motions of these faults and of smaller faults inside the graben farther seaward a horst like block is developed along the extension of the carmel fault still farther basinward there is a group of diapiric ridges trending nw to e w they were formed by flowage of messinian evaporites in some cases these ridges seem to be aligned along underlying faults this group of diapirs is unique in the area the diapir ridges are interpreted as expressions of deeply rooted faults

comparison of frequency of occurrence of earthquakes with slip rates from long term seismicity data the cases of gulf of corinth sea of marmara and dead sea fault zone summary in this article through the comparison of knowledge relating to historical earthquakes with the understanding of present day earthquake mechanics and overall gps slip rates in the eastern mediterranean region it has been possible to obtain an idea of how frequently large earthquakes may be expected in some parts of the region it has also been possible to make an assessment from these early events of slip rates over a long period of time for the gulf of corinth in greece the marmara sea in turkey and the dead sea fault system as well as deriving long term magnitude frequency relations for these same regions it has been demonstrated that slip rates calculated from historical data are in general comparable to those calculated from gps measurements and field observations while the size of historical earthquakes and their uncertainty can be quantified this permits a more reliable estimation of the long term hazard the calculation of which is the concern of the engineering seismologist it has also been shown that in most cases large earthquakes are less frequent when they are estimated from long term data sets rather than from the instrumental period making the notion of recurrence time and of hazard assessment questionable this study focuses on some of the few areas in the world for which long term macroseism information exists and which facilitate this kind of analysis

large submarine landslides in the japan trench a new scenario for additional tsunami generation 1 we describe in detail possible large submarine landslides several tens of kilometers in length and width on the trench landward slope of the japan trench on the basis of high resolution topographic surveys and detailed seafloor observations these slides stopped at the toe of the trench slope after initial movement of the toe along a basal decollement or thrust of the trench landward slope wedge during an earthquake the basal frictional condition s might change drastically from static to dynamic thus reducing the frictional strength as a result rapid submarine landsliding push downward on the toe generating large horizontal displacements for tsunamis this hypothesis should explain suitably the relation between large displacement of the thrust fault and tsunami generation by the 2011 tohoku earthquake as well as tsunami generation by the 1896 tohoku earthquake

cold decade ad 1810 1819 caused by tambora 1815 and another 1809 stratospheric volcanic eruption climate records indicate that the decade of ad 1810 1819 including the year without a summer 1816 is probably the coldest during the past 500 years or longer and the cause of the climatic extreme has been attributed primarily to the 1815 cataclysmic tambora eruption in indonesia but the cold temperatures in the early part of the decade and the timing of the tambora eruption call into question the real climatic impact of volcanic eruptions here we present new evidence based on sulfur isotope anomaly 33s a unique indicator of volcanic sulfuric acid produced in the stratosphere and preserved in polar snow and on the precise timing of the volcanic deposition in both polar regions that another large eruption in 1809 of a volcano is also stratospheric and occurred in the tropics the tambora eruption and the undocumented 1809 eruption are together responsible for the unusually cold decade

timing and climate forcing of volcanic eruptions for the past 2 500 years volcanic eruptions contribute to climate variability but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual to decadal temperature variability in the northern hemisphere during the past 2 500 years our results are based on new records of atmospheric aerosol loading developed from high resolution multi parameter measurements from an array of greenland and antarctic ice cores as well as distinctive age markers to constrain chronologies overall cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth century pandemics famines and socioeconomic disruptions in eurasia and mesoamerica while allowing multi millennium quantification of climate response to volcanic forcing

revising midlatitude summer temperatures back to a d 600 based on a wood density network annually resolved and millennium long reconstructions of large scale temperature variability are primarily composed of tree ring width trw chronologies changes in ring width however have recently been shown to bias the ratio between low and high frequency signals to overcome limitations in capturing the full spectrum of past temperature variability we present a network of 15 maximum latewood density mxd chronologies distributed across the northern hemisphere extratropics independent subsets of continental scale records consistently reveal high mxd before 1580 and after 1910 with below average values between these periods reconstructed extratropical summer temperatures reflect not only these long term trends but also distinct cooling pulses after large volcanic eruptions in contrast to trw dominated reconstructions this mxd based record indicates a delayed onset of the little ice age by almost two centuries the reduced memory inherent in mxd is likely responsible for the rapid recovery from volcanic induced cooling in the fourteenth century and the continuation of warmer temperatures until 1600

surface air temperature variability reconstructed with tree rings for the gulf of alaska over the past 1200 years a 1200 year long tree ring width record from living and subfossil mountain hemlock wood is used to reconstruct february through august temperatures for the gulf of alaska providing a record of past climate variability for the northeast pacific sector that captures interannual to centennial timescales the moderate elevation at the tree ring sites has allowed these trees to retain their temperature signal without evidence of the so called divergence effect or underestimation of tree ring inferred temperature trends which is observed at many northern latitude forest locations this divergence free reconstruction reveals centennial trends that include a warm interval centered on ad 950 for coastal alaska that occurs around the time of the medieval warm period a warming that is only rivaled by recent decades spectral analysis of this reconstruction supports the centennial pacing identified as a 170 220 year cadence consistent with solar variability on the decadal to bidecadal scale the reconstructi

volcano induced regime shifts in millennial tree ring chronologies from northeastern north america the cooling effect on the earth s climate system of sulfate aerosols injected into the stratosphere by large volcanic eruptions remains a topic of debate while some simulation and field data show that these effects are short term less than about 10 years other evidence suggests that large and successive eruptions can lead to the onset of cooling episodes that can persist over several decades when sustained by consequent sea ice ocean feedbacks here we present a new network of millennial tree ring chronologies suitable for temperature reconstructions from northeastern north america where no similar records are available and we show that during the last millennium persistent shifts toward lower average temperatures in this region coincide with series of large eruptions

1300 years of climatic history for western central asia inferred from tree rings more than 200 000 ring width measurements from 384 trees were obtained for 20 individual sites ranging from the lower to upper local timber lines in the northwest karakorum of pakistan and the southern tien shan of kirghizia samples were obtained predominantly from juniper species juniperus and were analysed to reconstruct regional climatic variation patterns in western central asia since ad 618 site distri bution represents diverse ecological conditions e g combinations of temperature and moisture stress within the karakorum and tien shan mountains permitting both intra montane and inter montane comparisons of chronologies three different types of chronologies ree ecting interannual decadal and centennial scale ring width variations were calculated a statistic skeleton plotting technique was used to identify ring width pointer years interannual a 101 year kernel e lter was used to identify decadal scale variations and for a subset of long lived trees the mean ring width of the entire single series was used to identify centennial trends after extracting and calibrating each of these three distinct wavelengths in ring width variation the results were combined into a comprehensive reconstruction ree ecting primarily temperature e uctuations in western central asia since ad 618 the nature and the temporally changing strength of the climatic signals of this reconstruction are discussed in detail a maximum latewood density record of pinus tienschanica from central tien shan was used as a predictor series to calibrate and validate tree ring width variation in so doing we link our results to the circumpolar maximum latewood density network briffa et al 1998a 1998b schweingruber and briffa 1996

last millennium climate and its variability in ccsm4 abstractan overview of a simulation referred to as the last millennium lm simulation of the community climate system model version 4 ccsm4 is presented the ccsm4 lm simulation reproduces many large scale climate patterns suggested by historical and proxy data records with northern hemisphere nh and southern hemisphere sh surface temperatures cooling to the early 1800s common era by 0 5 c nh and 0 3 c sh followed by warming to the present high latitudes of both hemispheres show polar amplification of the cooling from the medieval climate anomaly mca to the little ice age lia associated with sea ice increases the lm simulation does not reproduce la nina like cooling in the eastern pacific ocean during the mca relative to the lia as has been suggested by proxy reconstructions still dry medieval conditions over the southwestern and central united states are simulated in agreement with proxy indicators for these regions strong global cooling is associated with large volcanic erup

what have we learnt from palaeoclimate simulations there has been a gradual evolution in the way that palaeoclimate modelling and palaeoenvironmental data are used together to understand how the earth system works from an initial and largely descriptive phase through explicit hypothesis testing to diagnosis of underlying mechanisms analyses of past climate states are now regarded as integral to the evaluation of climate models and have become part of the toolkit used to assess the likely realism of future projections palaeoclimate assessment has demonstrated that changes in large scale features of climate that are governed by the energy and water balance show consistent responses to changes in forcing in different climate states and these consistent responses are reproduced by climate models however state of the art models are still largely unable to reproduce observed changes in climate at a regional scale reliably while palaeoclimate analyses of state of the art climate models suggest an urgent need for model improvement much work is also needed on extending and improving palaeoclimate reconstructions and quantifying and reducing both numerical and interpretative uncertainties

volcanic forcing of climate over the past 1500 years an improved ice core based index for climate models 1 understanding natural causes of climate change is vital to evaluate the relative impacts of human pollution and land surface modification on climate we have investigated one of the most important natural causes of climate change volcanic eruptions by using 54 ice core records from both the arctic and antarctica our recently collected suite of ice core data more than double the number of cores ever used before reduces errors inherent in reconstructions based on a single or small number of cores which enables us to obtain much higher accuracy in both detection of events and quantification of the radiative effects we extracted volcanic deposition signals from each ice core record by applying a high pass loess filter to the time series and examining peaks that exceed twice the 31 year running median absolute deviation we then studied the spatial pattern of volcanic sulfate deposition on greenland and antarctica and combined this knowledge with a new understanding of stratospheric transport of volcanic aerosols to produce a forcing data set as a function of month latitude and altitude for the past 1500 years we estimated the uncertainties associated with the choice of volcanic signal extraction criteria ice core sulfate deposition to stratospheric loading calibration factor and the season for the eruptions without a recorded month we forced an energy balance climate model with this new volcanic forcing data set together with solar and anthropogenic forcing to simulate the large scale temperature response the results agree well with instrumental observations for the past 150 years and with proxy records for the entire period through better characterization of the natural causes of climate change this new data set will lead to improved prediction of anthropogenic impacts on climate the new data set of stratospheric sulfate injections from volcanic eruptions for the past 1500 years as a function of latitude altitude and month is available for download in a format suitable for forcing general circulation models of the climate system

climate response to the samalas volcanic eruption in 1257 revealed by proxy records the eruption of samalas in indonesia in 1257 ranks among the largest sulfur rich eruptions of the common era with sulfur deposition in ice cores reaching twice the volume of the tambora eruption in 1815 sedimentological analyses of deposits confirm the exceptional size of the event which had both an eruption magnitude and a volcanic explosivity index of 7 during the samalas eruption more than 40 km 3 of dense magma was expelled and the eruption column is estimated to have reached altitudes of 43 km however the climatic response to the samalas event is debated since climate model simulations generally predict a stronger and more prolonged surface air cooling of northern hemisphere summers than inferred from tree ring based temperature reconstructions here we draw on historical archives ice core data and tree ring records to reconstruct the spatial and temporal climate response to the samalas eruption we find that 1258 and 1259 experienced some of the coldest northern hemisphere summers of the past millennium however cooling across the northern hemisphere was spatially heterogeneous western europe siberia and japan experienced strong cooling coinciding with warmer than average conditions over alaska and northern canada we suggest that in north america volcanic radiative forcing was modulated by a positive phase of the el nino southern oscillation contemporary records attest to severe famines in england and japan but these began prior to the eruption we conclude that the samalas eruption aggravated existing crises but did not trigger the famines

century scale temperature variability and onset of industrial era warming in the eastern tibetan plateau to improve our understanding of climate variability in the tibetan plateau tp and its sensitivity to external forcings recent temperature changes need to be placed in a long term historical context here we present two tree ring based temperature reconstructions a 1003 year 1000 2002 ce annual temperature reconstruction for the northeastern tp netp based on seven series and a 522 year 1489 2010 ce summer june july august temperature reconstruction for the southeastern tp setp based on 11 series our reconstructions show six centuries of generally warm netp temperatures 1000 1586 ce followed by a transition to cooler temperatures 1587 1887 ce for netp and 1588 1930 ce for setp the transition from the medieval climate anomaly to the little ice age thus happened in the 1580s in netp and setp which is about 150 years later than in larger scale e g asia and the northern hemisphere temperature reconstructions we found that tp temperature variability especially in setp was influenced by the atlantic multi decadal oscillation and that the twentieth century was the warmest on record in netp and setp our reconstructions and climate model simulations both show industrial era warming trends the onset of which happened earlier in netp 1812 ce compared to setp 1887 ce and other temperature reconstructions for western china east asia asia and the northern hemisphere the early netp onset of industrial era warming can likely be explained by netp s faster warming rate and by local feedback factors i e ice snow cover albedo comparisons between climate model simulations and our reconstructions reveal that cooler tp temperatures from 1600 to 1800 ce might be related to land use and land cover change

challenges and perspectives for large scale temperature reconstructions of the past two millennia knowledge of the temperature variability during the last one to two millennia is important for providing a perspective to present day climate excursions for assessing the sensitivity of the climate to different forcings and for providing a test bed for climate models since systematic instrumental temperature records only extend back to the nineteenth century such knowledge mainly relies on climate sensitive proxy data here we critically assess some of the many challenges related to large scale multiproxy temperature reconstructions we begin with a review of available large scale temperature reconstructions focusing on the differences in low frequency variability and the response to natural forcings such as major volcanic eruptions and changes in total solar irradiance then we discuss different proxy selection strategies review previously used reconstruction methods and discuss their ability to reconstruct the amplitude of the low frequency variability to shed additional light on the challenges of large scale reconstructions we investigate the spatial and temporal correlation structures in the observed temperature field and discuss the implications of these correlation structures regarding the required number and positions of proxies we demonstrate how the unavoidable uncertainty related to noisy proxies will show up as bias and variance in the reconstruction and that the partition between these forms of errors depends on the reconstruction method pseudo proxy experiments are conducted to further discuss the influence of noise and the requirements regarding the geographical location and number of proxies necessary for reliably reconstructing the low frequency variability we conclude with recommendations for future large scale temperature reconstructions

european summer temperature response to annually dated volcanic eruptions over the past nine centuries the drop in temperature following large volcanic eruptions has been identified as an important component of natural climate variability however due to the limited number of large eruptions that occurred during the period of instrumen tal observations the precise amplitude of post volcanic cooling is not well constrained here we present new evidence on summer temperature cooling over europe in years following volcanic eruptions we compile and analyze an updated net work of tree ring maximum latewood density chronologies spanning the past nine centuries and compare cooling sig natures in this network with exceptionally long instru mental station records and state of the art general circu lation models results indicate post volcanic june august cooling is strongest in northern europe 2 years after an eruption 0 52 0 05 c whereas in central europe the temperature response is smaller and occurs 1 year after an eruption 0 18 0 07 c we validate these estimates by comparisonwith the shorter instrumental network and evaluate the statistical significance of post volcanic summer tempera ture cooling in the context of natural climate variability over the past nine centuries finding no significant post volcanic temperature cooling lasting longer than 2 years our results question the ability of large eruptions to initiate long term temperature changes through feedback mechanisms in the climate system we discuss the implications of these findings with respect to the response seen in general circulation models and emphasize the importance of considering well documented annually dated eruptions when assessing the

reassessing the evidence for tree growth and inferred temperature change during the common era in yamalia northwest siberia the development of research into the history of tree growth and inferred summer temperature changes in yamalia spanning the last 2000 years is reviewed one focus is the evolving production of tree ring width trw and tree ring maximum latewood density mxd larch larix sibirica chronologies incorporating different applications of regional curve standardisation rcs another focus is the comparison of independent data representing past tree growth in adjacent yamalia areas yamal and polar urals and the examination of the evidence for common growth behaviour at different timescales the sample data we use are far more numerous and cover a longer time span at yamal compared to the polar urals but yamal has only trw while there are both trw and mxd for the polar urals we use more data sub fossil and from living trees than in previous dendroclimatic studies in this region we develop a new trw chronology for yamal more than 2000 years long and running up to 2005 for the polar urals we develop new trw and mxd chronologies that show good agreement at short 15 years and medium 15e100 years timescales demonstrating the validity of attempts to reconcile the evidence of longer timescale information that they provide we use a conservative application of the rcs approach two curve signal free rcs guarding against the possibility of modern sample bias a possible inflation of recent chronology values arising out of inadvertent selection of mostly relatively fast growing trees in recent centuries we also transform tree indices to have a normal distribution to remove the positive chronology skew often apparent in rcs trw chronologies this also reduces the apparent magnitude of 20th century tree growth levels thereis generallygoodagreement between all chronologies as regardsthe major featuresof the decadal to centennial variability low tree growth periods for which the inferred summer temperatures are approximately 2 5 c below the 1961e90 reference are apparent in the 15 year smoothed reconstructions

five millennia of paleotemperature from tree rings in the great basin usa the instrumental temperature record is of insufficient length to fully express the natural variability of past temperature high elevation tree ring widths from great basin bristlecone pine pinus longaeva are a par ticularly useful proxy to infer temperatures prior to the instrumental record in that the tree rings are annually dated and extend for millennia from ring width measurements integrated with past treeline elevation data we infer dec adal to millennial scale temperature variability over the past 4 500 years for the great basin usa we find that twentieth century treeline advances are greater than in at least 4 000 years there is also evidence for substantial volcanic forcing of climate in the preindustrial record and considerable covariation between high elevation tree ring widths and temperature estimates from an atmosphere ocean general circulation model over much of the last millennium a long term temperature decline of 1 1 c since the mid holocene underlies substantial volcanic forcing of climate in the preindustrial record

a 1000 year record of temperature and precipitation in the sierra nevada abstract tree ring data from subalpine conifers in the southern sierra nevada were used to reconstruct temperature and precipitation back to a d 800 tree growth of foxtail pine pinus balfouriana and western juniper juniperus occidentalis ssp australis is influenced by nonlinear interactions between summer temperature and winter precipitation reconstruction of the separate histories of temperature and precipitation is feasible by explicitly modeling species and site differences in climatic response using response surfaces the summer temperature reconstruction shows fluctuations on centennial and longer time scales including a period with temperatures exceeding late 20th century values from ca 1100 to 1375 a d corresponding to the medieval warm period identified in other proxy data sources and a period of cold temperatures from ca 1450 to 1850 corresponding to the little ice age precipitation variation is dominated by shorter period decadal scale oscillations the long term record presented here indicates that the 20th century is anomalous with respect to precipitation variation a tabulation of 20 and 50 yr means indicates that precipitation equaling or exceeding 20th century levels occurred infrequently in the 1000 yr record

sub milankovitch solar forcing of past climates mid and late holocene perspectives a comparison was performed of solar activity and terrestrial temperature records both derived from tree rings i e without dating uncertainties with identification of detailed and highly quantified time and timescale dependent characteristics of solar forcing on climate through the current interglacial in the context of oceanic variability the tree ring derived temperature record from high latitudes of europe lapland exhibits persistent annual to millennial scale variations with multidecadal to multicentennial periodicities reminiscent of the sun9s periodicities at millennial scales cool temperatures coincided with large scale glacial maxima moreover millennial and bimillennial modes of climate variability were correlative with variations in sunspot numbers on similar scales with near century and near zero lags respectively although they were subtle in amplitude the sub milankovitch scale changes in the reception of the sun9s energy could thus suffice to noticeably modulate interglacial climate variations the relative significance of timescale dependent sun climate linkages has likely varied during the mid and late holocene times respectively thus the warmer and cooler paleotemperatures during the medieval climate anomaly and little ice age were better explained by solar variations on a millennial rather than bimillennial scale the observed variations may have occurred in association with internal climate amplification likely thermohaline circulation and el nino southern oscillation activity the near centennial delay in climate in responding to sunspots indicates that the sun9s influence on climate arising from the current episode of high sunspot numbers may not yet have manifested itself fully in climate trends if neglected in climate models this lag could cause an underestimation of twenty first century warming trends

landslide generated tsunamis geotechnical considerations landslide induced tsunamis are particularly dangerous because the warning time is very short in the coastal area therefore it is critical to identify the potential for coastal landslides involving large masses of material almost invariably such large landslides will occur in material susceptible to liquefaction particularly during earthquakes this paper discusses characteristics of such materials how they may be identified and offers suggestions for estimating the potential for large deformations

did a submarine landslide contribute to the 2011 tohoku tsunami many studies have modeled the tohoku tsunami of march 11 2011 as being due entirely to slip on an earthquake fault but the following discrepancies suggest that further research is warranted 1 published models of tsunami propagation and coastal impact underpredict the observed runup heights of up to 40 m measured along the coast of the sanriku district in the northeast part of honshu island 2 published models cannot reproduce the timing and high frequency content of tsunami waves recorded at three nearshore buoys off sanriku nor the timing and dispersion properties of the waveforms at offshore dart buoy 21418 3 the rupture centroids obtained by tsunami inversions are biased about 60 km nne of that obtained by the global cmt project based on an analysis of seismic and geodetic data together with recorded tsunami waveforms we propose that while the primary source of the tsunami was the vertical displacement of the seafloor due to the earthquake an additional tsunami source is also required we infer the location of the proposed additional source based on an analysis of the travel times of higher frequency tsunami waves observed at nearshore buoys we further propose that the most likely additional tsunami source was a submarine mass failure smf i e a submarine landslide a comparison of pre and post tsunami bathymetric surveys reveals tens of meters of vertical seafloor movement at the proposed smf location and a slope stability analysis confirms that the horizontal acceleration from the earthquake was sufficient to trigger an smf forward modeling of the tsunami generated by a combination of the earthquake and the smf reproduces the recorded on near and offshore tsunami observations well particularly the high frequency component of the tsunami waves off sanriku which were not well simulated by previous models the conclusion that a significant part of the 2011 tohoku tsunami was generated by an smf source has important implications for estimates of tsunami hazard in the tohoku region as well as in other tectonically similar regions

estimates of volcanic induced cooling in the northern hemisphere over the past 1 500 years explosive volcanism can alter global climate and hence trigger economic political and demographic change1 2 the climatic impact of the largest volcanic events has been assessed in numerous modelling studies and tree ring based hemispheric temperature reconstructions3 4 5 6 however volcanic surface cooling derived from climate model simulations is systematically much stronger than the cooling seen in tree ring based proxies suggesting that the proxies underestimate cooling7 8 and or the modelled forcing is unrealistically high9 here we present summer temperature reconstructions for the northern hemisphere from tree ring width and maximum latewood density over the past 1 500 years we also simulate the climate effects of two large eruptions in ad 1257 and 1815 using a climate model that accounts explicitly for self limiting aerosol microphysical processes3 10 our tree ring reconstructions show greater cooling than reconstructions with lower spatial coverage and based on tree ring width alone whereas our simulations show less cooling than previous simulations relying on poorly constrained eruption seasons and excluding nonlinear aerosol microphysics our tree ring reconstructions and climate simulations are in agreement with a mean northern hemisphere extra tropical summer cooling over land of 0 8 to 1 3 c for these eruptions this reconciliation of proxy and model evidence paves the way to improved assessment of the role of both past and future volcanism in climate forcing

underestimation of volcanic cooling in tree ring based reconstructions of hemispheric temperatures a large volcanic eruption in ad 1258 1259 is expected to have caused substantial climate cooling but evidence for this effect is absent from tree ring based temperature reconstructions numerical modelling of tree growth shows that the lack of cooling is probably an artefact caused by low sensitivity to cooling in trees growing near the treeline

last millennium northern hemisphere summer temperatures from tree rings part i the long term context abstract large scale millennial length northern hemisphere nh temperature reconstructions have been progressively improved over the last 20 years as new datasets have been developed this paper and its companion part ii anchukaitis et al in prep details the latest tree ring tr based nh land air temperature reconstruction from a temporal and spatial perspective this work is the first product of a consortium called n trend n orthern hemisphere tre e ring n etwork d evelopment which brings together dendroclimatologists to identify a collective strategy for improving large scale summer temperature reconstructions the new reconstruction n trend2015 utilises 54 records a significant expansion compared with previous tr studies and yields an improved reconstruction with stronger statistical calibration metrics n trend2015 is relatively insensitive to the compositing method and spatial weighting used and validation metrics indicate that the new record portrays reasonable coherence with large scale summer temperatures and is robust at all time scales from 918 to 2004 where at least 3 tr records exist from each major continental mass n trend2015 indicates a longer and warmer medieval period 900 1170 than portrayed by previous tr nh reconstructions and by the cmip5 model ensemble but with better overall agreement between records for the last 600 years future dendroclimatic projects should focus on developing new long records from data sparse regions such as north america and eastern eurasia as well as ensuring the measurement of parameters related to latewood density to complement ring width records which can improve local based calibration substantially

temperature covariance in tree ring reconstructions and model simulations over the past millennium spatial covariance in the simulated temperature evolution over the past millennium has been reported to exceed that of multiproxy based reconstructions here we use tree ring based temperature reco

the landslide generated tsunami of november 3 1994 in skagway harbor alaska a case study we examine the origin and behavior of the catastrophic tsunami that impacted skagway harbor at the head of taiya inlet alaska on november 3 1994 geomorphologic and tide gauge data combined with numerical simulation of the event reveal that the tsunami was generated by an underwater landslide formed during the collapse of a cruise ship dock undergoing construction use of a fine grid model for skagway harbor and a coarse grid model for taiya inlet enables us to explain many of the eyewitness accounts and to reproduce the dominant oscillations in the tide gauge record including the persistent 1 h 3 min oscillation in skagway harbor the occurrence of the landslide is linked to critical overloading of the slope materials at a time of extreme low tide

summer temperatures in the canadian rockies during the last millennium a revised record we present a significant update to a millennial summer temperature reconstruction 1073 1983 that was originally published in 1997 utilising new tree ring data predominantly picea engelmannii the reconstruction is not only better replicated but has been extended 950 1994 and is now more regionally representative calibration and verification statistics were improved with the new model explaining 53 of may august maximum temperature variation compared to the original 39 of april august mean temperatures the maximum latewood density data which are weighted more strongly in the regression model than ringwidth were processed using regional curve standardisation to capture potential centennial to millennial scale variability the reconstruction shows warm intervals comparable to twentieth century values for the first half of the eleventh century the late 1300s and early 1400s the bulk of the record however is below the 1901 1980 normals with prolonged cool periods from 1200 to 1350 and from 1450 to the late 19th century the most extreme cool period is observed to be in the 1690s these reconstructed cool periods compare well with known regional records of glacier advances between 1150 and the 1300s possibly in the early 1500s early 1700s and 1800s evidence is also presented of the influence of solar activity and volcanic events on summer temperature in the canadian rockies over the last 1 000 years although this reconstruction is regional in scope it compares well at multi decadal to centennial scales with northern hemisphere temperature proxies and at millennial scales with reconstructions that were also processed to capture longer timescale variability this coherence suggests that this series is globally important for the assessment of natural temperature variability over the last 1 000 years

the tsunami earthquake of 1932 june 22 in manzanillo mexico seismological study and tsunami simulations summary we conduct a detailed seismological study of the large colima mexico earthquake of 1932 june 3 and of its aftershocks of june 18 and 22 the latter event iii generated a tsunami more devastating than that of the main shock despite much smaller seismic magnitudes thus qualifying as a so called tsunami earthquake relocation based on published arrival times shows that event iii took place up dip of the main shock the analysis of the spectral amplitude of mantle surface waves yields low frequency moments of 24 5 2 and 4 times 1027 dyn cm respectively with event iii featuring a moment growing with period which expresses the source slowness characteristic of tsunami earthquakes this is confirmed by a deficient energy to moment ratio as derived from high frequency p waves recorded at pasadena near field hydrodynamic simulations show that the effects of the main shock s tsunami are well modelled by a standard seismic source whereas the stronger tsunami from event iii can be modelled by rupture along a splay fault in a mechanically deficient material all our results then fit the model for tsunami earthquake aftershocks proposed for the kuril islands by fukao in 1979

temperature sensitive tien shan tree ring chronologies show multi centennial growth trends two millennia length juniper ring width chronologies processed to preserve multi centennial growth trends are presented for the alai range of the western tien shan in kirghizia the chronologies average the information from seven near timberline sampling sites and likely reflect summer temperature variation for comparison chronologies are also built using standard dendrochronological techniques we briefly discuss some qualities of these inter decadal records and show the low frequency components removed by the standardization process include a long term negative trend in the first half of the last millennium and a long term positive trend since about ad 1800 the multi centennial scale alai range chronologies where these trends are retained are both systematically biased but in an opposite sense in their low frequency domains nevertheless they represent the best constraints and estimates of long term summer temperature variation and reflect the medieval warm period the little ice age and a period of warming since about the middle of the nineteenth century

potential tsunamigenic submarine landslides in active margins abstract a review of modern historical and submarine landslides from the geological record shows that landslides in active continental margins can generate tsunamis the tsunamis may damage coastal and seabed infrastructure and so represent an important element of marine geohazards research due to their potentially significant impacts on society the primary trigger mechanism of tsunamis in this type of setting was thought to be earthquake activity however there are also a number of alternative hypotheses regarding the likely initiation mechanism including the generation of submarine landslides in this paper we briefly review the geological features and trigger mechanisms of tsunamigenic submarine landslides on active margins large tsunamigenic submarine landslides appear to occur mostly on margins characterized by non accretion these observations have implications for tsunami warning systems as the japanese system does not consider the scenario of tsunami excitation by submarine landslides

empirical constraints on magnitude distance relationships for seismically induced submarine tsunamigenic landslides abstract seismically induced submarine landslide tsunamis here called silts attract growing attention due to their unique setting damage potential and short warning time a question of key importance especially for tsunami early warning is how far can an earthquake trigger a tsunamigenic slump here we investigate the relationships between earthquake magnitude and the maximal distance between the seismogenic fault and the tsunamigenic slumps rf and between the earthquake epicenter and the slump re and propose empirical constraints on these magnitude distance m d relations the 49 identified silts are spread in various seismotectonic and bathymetric settings in different seas around the globe we found that the maximal distance of the tsunamigenic submarine landslide from the parent earthquake grows with the magnitude and is bounded by an envelope constrained by mw as low as 4 9 for several kilometers the 1968 liguria coast italy and as far as 250 km for mw 7 7 the 1819 rann of kachchh india higher earthquake magnitudes also produce silts seemingly distances lower than 250 km however it is suspected that the available data is limited and unable to reflect the true nature of silt s generation generalized empirical relations between the earthquake magnitude mw and the maximal distance from the seismogenic fault to its generated silt rf in km are log rf 1 17 0 49 mw r2 0 78 the empirical distance between the earthquake epicenter and the corresponding tsunamigenic slump re in km is log re 0 87 0 45 mw r2 0 83 although many earthquakes within the m d bounding envelope did not produce tsunamis the successful events still enable the delineation of the m d zone vulnerable to tsunami generation which in turn can be applied to tsunami early warning procedures this is particularly important for near coast inland earthquakes as their tsunamigenic potential might be overlooked

continental scale temperature variability during the past two millennia past global climate changes had strong regional expression to elucidate their spatio temporal pattern we reconstructed past temperatures for seven continental scale regions during the past one to two millennia the most coherent feature in nearly all of the regional temperature reconstructions is a long term cooling trend which ended late in the nineteenth century at multi decadal to centennial scales temperature variability shows distinctly different regional patterns with more similarity within each hemisphere than between them there were no globally synchronous multi decadal warm or cold intervals that define a worldwide medieval warm period or little ice age but all reconstructions show generally cold conditions between ad 1580 and 1880 punctuated in some regions by warm decades during the eighteenth century the transition to these colder conditions occurred earlier in the arctic europe and asia than in north america or the southern hemisphere regions recent warming reversed the long term cooling during the period ad 1971 2000 the area weighted average reconstructed temperature was higher than any other time in nearly 1 400 years

volcanic cooling signal in tree ring temperature records for the past millennium the authors acknowledge the national science foundation for funding much of the research presented herein rw s scottish work is currently funded through the uk leverhulme trust and natural environment research council nerc projects relic reconstructing 8000 years of environmental and landscape change in the cairngorms f 00 268 bg and scot2k reconstructing 2000 years of scottish climate from tree rings ne k003097 1

environmental effects from five historical earthquakes in southern apennines italy and macroseismic intensity assessment contribution to inqua eee scale project abstract this paper aims at substantiating the basic postulate of the recent earthquake environmental effects eee scale proposed by the international union for quaternary research inqua that primary and secondary environmental effects of earthquakes provide invaluable information on the earthquake size and intensity field complementing but also independently testing the results of the traditional damage based macroseismic scales the eee scale is applied to five disastrous earthquakes which occurred in southern italy since the end of the xvii century for each considered earthquake the available macroseismic data have been reviewed and integrated through an updated interpretation of the original texts the cataloguing and analysis of the seismically induced environmental effects has provided a a more detailed picture of the macroseismic fields b the chance to test the scaling of the eee scale with the mcs and msk macroseismic scales confirming its good fit with the msk mm c i0 estimates based on eee scale in good agreement with i0 assessments derived from mcs msk scales d further constrains for the new version of the eee scale e useful data for seismic zonation these results have confirmed once more the essential role of eees in the process of seismic hazard assessment and risk reduction

effect of scaling and regression on reconstructed temperature amplitude for the past millennium 1 examination of large scale millennial long temperature reconstructions reveals a wide range of datasets and methods used for calibration proxy time series are commonly calibrated against overlapping instrumental records representing different seasons northern hemisphere latitudinal bands and including or excluding sea surface temperature data methodological differences include using scaling or regression the calibration time period and smoothing data before calibration we find that these various approaches alone can result in differences in the reconstructed temperature amplitude of about 0 5 c this magnitude is equivalent to the mean annual temperature change for the northern hemisphere reported in the last ipcc report for the 1000 1998 period a more precise assessment of absolute reconstructed temperature amplitudes is necessary to help quantify the relative influences of forcing mechanisms in climate models

discrepancies between the modeled and proxy reconstructed response to volcanic forcing over the past millennium implications and possible mechanisms 1 we show that a systematic discrepancy between model simulations and proxy reconstructions of hemispheric temperature changes over the past millennium appears to arise from a small number of radiatively large volcanic eruptions past work has shown that accounting for this mismatch alone appears to reconcile inconsistencies between the overall amplitude of simulated and proxy reconstructed temperature changes we provide empirical support for the previously posited hypothesis that this discrepancy may arise from threshold growth effects in tree line proximal trees that limit their response to large volcanic cooling events such threshold responses could lead to an absence of growth rings as many as six accumulated years over the past eight centuries for some fraction of tree line proximal trees leading to a potential misalignment of volcanic cooling events in trees from climatically distinct regions and a further attenuation and smearing of the volcanic cooling signal since the high frequency component of nearly all proxy reconstructions of past hemispheric temperature change is derived from tree ring data this bias would likely impact nearly all such reconstructions we show here that the discrepancy may have led to an underestimation bias in past studies attempting to infer equilibrium climate sensitivity from proxy temperature reconstructions of the past millennium

1738 years of mongolian temperature variability inferred from a tree ring width chronology of siberian pine 1738 years ad 262 1999 of temperature variability are inferred from tree ring widths of siberian pine at solongotyn davaa sol dav a timberline 2420 m site in mongolia this chronology can account for 33 of the temperature variance from 1882 1993 the warmest conditions over the past millennium are during the 20th century the 1999 ring width has the highest index value over the past millennium both warmer and colder intervals are inferred during the medieval warm epoch the most severe cold occurred in the 19th century unusual cold and frost in ad 536 545 coincide with extremes in other proxies and historical accounts confirming a widespread catastrophic event trends resemble those of other eurasian paleoseries and hemispheric scale reconstructions over the past millennium more chronologies such as sol dav are essential to improve coverage in the uncertain earlier centuries of these reconstructions and their estimates of natural variability relative to recent anthropogenic change

a 1052 year tree ring proxy for alpine summer temperatures a june august alpine temperature proxy series is developed back to ad 951 using 1 527 ring width measurements from living trees and relict wood the reconstruction is composed of larch data from four alpine valleys in switzerland and pine data from the western austrian alps these regions are situated in high elevation alpine environments where a spatially homogenous summer temperature signal exists in an attempt to capture the full frequency range of summer temperatures over the past millennium from inter annual to multi centennial scales the regional curve standardization technique is applied to the ring width measurements correlations of 0 65 and 0 86 after decadal smoothing with high elevation meteorological stations since 1864 indicate an optimal response of the rcs chronology to june august mean temperatures the proxy record reveals warm conditions from before ad 1000 into the thirteenth century followed by a prolonged cool period reaching minimum values in the 1820s and a warming trend into the twentieth century this latter trend and the higher frequency variations compare well with the actual high elevation temperature record the new central alpine proxy suggests that summer temperatures during the last decade are unprecedented over the past millennium it also reveals significant similarities at inter decadal to multi centennial frequencies with large scale temperature reconstructions however deviating during certain periods from h h lamb s european north atlantic temperature history

summer temperature variations in the european alps a d 755 2004 abstract annually resolved summer temperatures for the european alps are described the reconstruction covers the a d 755 2004 period and is based on 180 recent and historic larch larix decidua mill density series the regional curve standardization method was applied to preserve interannual to multicentennial variations in this high elevation proxy dataset instrumental measurements from high low elevation grid boxes back to 1818 1760 reveal strongest growth response to current year june september mean temperatures the reconstruction correlates at 0 7 with high elevation temperatures back to 1818 with a greater signal in the higher frequency domain r 0 8 low elevation instrumental data back to 1760 agree with the reconstruction s interannual variation although a decoupling between warmer instrumental and cooler proxy data before 1840 is noted this offset is larger than during any period of overlap with more recent high elevation instrumental data even though the proxy time series

influence of volcanic eruptions on the climate of the asian monsoon region 1 several state of the art general circulation models gcms predict that large volcanic eruptions should result in anomalous dry conditions throughout much of monsoon asia here we use long and well validated proxy reconstructions of asian droughts and pluvials to detect the influence of volcanic radiative forcing on the hydroclimate of the region since the late medieval period superposed epoch analysis reveals significantly wetter conditions over mainland southeast asia in the year of an eruption with drier conditions in central asia our proxy and model comparison suggests that gcms may not yet capture all of the important ocean atmosphere dynamics responsible for the influence of explosive volcanism on the climate of asia

northern hemisphere temperature anomalies during the 1450s period of ambiguous volcanic forcing ice core based estimates of past volcanic eruptions are the main forcing of the last millennium climate model simulations understanding the timing and magnitude of eruptions is thus critical for assessing the dynamics of the earth s climate system uncertainty associated with a major event in the 1450s originally attributed to the south pacific kuwae eruption in 1452 and recently shifted to 1458 fundamentally alters model simulations their comparison with proxy based climate reconstructions and any subsequent historical interpretation here we compile a northern hemisphere tree ring network of 25 maximum latewood density chronologies extending back over the past 650 years to analyze the 1450s temperature deviations statistically robust warm season temperature reconstructions from 20 of these records reveal a spatially coherent and exceptional cooling in 1453 summer cooling ranged from 0 4 c in the swiss alps to 6 9 c in the polar urals russia and was generally stronger across the eurasian high latitudes and northwestern north america year 1453 also marks the onset of a 15 year cold period during which network mean temperatures ranged from 2 5 c in 1453 to 0 5 c in 1468 in contrast the years 1459 1 0 c and 1460 0 4 c were not exceptionally cold in the contemporary context these findings suggest either that the original dating pointing to a major eruption in 1452 and large scale cooling in 1453 was correct or that the eruption left no substantial climatic fingerprint in northern hemisphere temperature proxies the latter appears less likely as sulfate aerosol deposits associated with the 1450s event are found in ice cores of both hemispheres

sources of the large a d 1202 and 1759 near east earthquakes the sources of the may 1202 and november 1759 m 7 5 near east earthquakes remain controversial because their macroseismal areas coincide straddling subparallel active faults in the lebanese restraining bend paleoseismic trenching in the yammouneh basin yields unambiguous evidence both for slip on the yammou neh fault in the twelfth thirteenth centuries and for the lack of a posterior event this conclusion is supported by comparing the freshest visible fault scarps which imply more recent slip on the r chaiya serghaya system than on the yammouneh fault our results suggest that the recurrence of an a d 1202 type earthquake might be due this century as part of a sequence similar to that of a d 1033 1202 possibly heralded by the occurrence of the 1995 mw 7 3 aqaba earthquake the seismic behavior of the levant fault might thus be characterized by millennial periods of quiescence separated by clusters of large earthquakes

compound soil horizons with mixed calcic and argillic properties examples from the northern great basin usa abstract palaeosols between deposits of the last two deep lake cycles in the northern great basin have multiple carbonate engulfed horizons and compound calcic and argillic properties at depth they are difficult to explain pedogenetically because they bifurcate in places especially in basin centres where they are separated by sediments of a minor lake expansion of probable early wisconsinan age one sequence of processes can account for all phenomena two cycles of colluviation and synchronous admixture of loess particles were each succeeded by the formation of an argillic over a calcic horizon carbonate enrichment resulting from the later period of soil formation affected the buried older soil this led to welding of the two soils and the formation of a compound horizon carrying the argillic properties of the first and the calcic properties of the second pedogenic phase steady aeolian influx to the same soil surface the commonly invoked mechanism cannot explain the bifurcated palaeosols and is not needed to explain the welded ones