impact of bedrock surface topography on spatial distribution of quaternary sediments and on the flow pattern of late weichselian glaciers on the east european craton russian plain this paper presents the first high quality maps of the bedrock surface topography and the quaternary sediment distribution for the late weichselian glaciation area on the east european craton eec and the reasoning behind the estimated sediment distribution geographic information system gis based three dimensional model of the bedrock surface topography the current digital terrain model dtm and the ice flow pattern of the last glaciation provided the main source data for the analyses and interpretations in the current continental area of the western eec which was covered by the last scandinavian ice sheet sis the bedrock lies overwhelmingly 85 above the contemporary sea level with an average altitude of 54 m above sea level the topography of the bedrock surface is very well reflected in the current topography and an 80 m difference in the ice bed surface altitudes results in the topographic focusing of the ice flow and thus all late weichselian ice streams were accommodated to the depressions in the subglacial surface such depressions are characterised by a thin 10 m layer of sediment with one till bed just 50 m upslope from the bottom of the depressions the thickness of the sediment increases two to threefold and comprises five or more till layers indicating relief enhancement through subsequent glaciations the average calculated thickness of the quaternary deposits in the study area was 49 m and the total volume of sediments was 20 280 km3

the awakening of the dormant mount vettore fault 2016 central italy earthquake mw 6 6 paleoseismic clues on its millennial silences

timing of lateglacial vegetation dynamics and respective palaeoenvironmental conditions in southern estonia evidence from the sediment record of lake nakri this paper investigates a detailed well dated lateglacial floristic colonisation in the eastern baltic area ca 14 000 9000 cal a bp using palynological macrofossil loss on ignition and 14c data during 14 000 13 400 cal a bp primarily treeless pioneer tundra vegetation existed tree birch betula sect albae macro remains and a high tree pollen accumulation rate indicate the presence of forest tundra with birch and possibly pine pinus sylvestris l trees during 13 400 12 850 cal a bp palaeobotanical data indicate that the colonisation and development of forested areas were very rapid arising within a period of less than 50 years thus far there are no indications of conifer macrofossils in estonia to support the presence of coniferous forests in the lateglacial period signs of greenland interstadial 1b cooling during 13 100 cal a bp are distinguishable biostratigraphic evidence indicates that the vegetation was again mostly treeless tundra during the final colder episode of the lateglacial period associated with greenland stadial 1 approximately 12 850 11 650 cal a bp this was followed by onset of the holocene vegetation with the expansion of boreal forests in response to rapid climatic warming copyright 2011 john wiley sons ltd

pleistocene chronostratigraphy in estonia southeastern sector of the scandinavian glaciation abstract pleistocene chronostratigraphy in estonia is based on 29 studied sites sections the dating of which covers a span from approximately 200 ka bp to the pleistocene holocene chronostratigraphic boundary and a local varved clay chronology for eastern estonia which enables tentative correlation of lateglacial lg events to finnish and swedish varve chronologies analysis of existing and unpublished data was used to review the current pleistocene chronostratigraphy and particularly the history of weichselian cold stage in estonia osl ages from fluvial deposits that included the korvekula holsteinian or rongu eemian continental interglacial deposits revealed that the pre weichselian interglacial deposits were glacially dislocated during the weichselian available osl tl and 14 c dates and new 14 c ams ages of mammoth bones indicate ice free conditions between 105 and 68 ka bp and a comparatively mild middle weichselian between 43 and 22 ka bp the lg chronology indicates in general rapid average 110 m yr deglaciation of the territory between ca 14 7 and 12 7 ka bp the duration of the late weichselian glaciation in estonia ranged between 7 3 and 9 3 ka

fault generated mountain fronts in the central apennines central italy geomorphological features and seismotectonic implications the morphotectonic framework of the central apennines is given by faulted blocks bounded by normal faults mostly trending nw se nnw sse and ne sw which cut previous compressive structures such a structural setting is consistent with the lbcal mechanisms of the earthquakes which often occur in this area in this paper three lithologically different normal fault generated mountain fronts are analysed in order to assess the relations between their geomorphic features and active tectonics they border the norcia depression sibillini mts umbria the amatrice ampotosto plateau laga mts lazio and the fucino basin marsica mts abruzzi the norcia depression is bounded by a n20 w trending normal fault to the east and by a parallel antithetic fault to the west the main fault has a 1000 m throw and gives rise to a wide fault escarpment characterized by l sharp slope breaks due to low angle gravity faults 2 important paleolandslides and 3 several fault scarplets on the piedmont belt affecting quaternary deposits the amatrice ampotosto plateau is delimited by the western slope of mt gorzano which runs along a n20 w trending normal fault having a 1500m throw minor parallel faults dislocate quaternary landforms large scale massmovements also occur here e the fucino basin was struck by th e 1915 avezzano earthquake 0 xi mcs which produced extensive surface faulting along two parallel nw trending normal fault escarpments on the eastern border of the basin there is paleoseismrc evidence including buried gravity graben in late glacial gravels and tectonic dip slip striations on holocene calcitic crusts covering bedrock normal fault planes these data suggest that active extensional tectonics plays a major role in the slope morphogenesis of the central apennines and they indicate the importance of geomorphic analysis in seismic zonation of this area

persistent surface snowmelt over antarctica 1987 2006 from 19 35 ghz brightness temperatures 1 persistent melting e g continuing for more than three days or for one consecutive day and night is mapped in antarctica 1987 2006 using night and day time special sensor microwave imager brightness temperatures tb at 19 35 ghz horizontal polarization snowmelt is indicated when tb and relative daily difference exceed threshold values respectively tc and t computed for each pixel and year or when both daytime and nighttime tb exceed tc results from an electromagnetic model suggest that the minimum detectable liquid water content ranges between 0 2 and 0 5 in volume we find that melting areas have been moving inland since 1987 a first time extensive melting 1987 2006 is detected over the transantarctic mountains on january 2005 875 km inland and 2000 m above sea level melting extent and index have been decreasing over antarctica since 1987 although either positive and negative trends are observed from a sub continental scale analysis

a multiscale subpixel mixture analysis applied for melt detection using passive microwave and radar scatterometer image time series of the antarctic peninsula 1999 2009

inversion of field data in fault tectonics to obtain the regional stress iii a new rapid direct inversion method by analytical means summary a new method for determining the reduced stress tensor with four degrees of freedom the orientations of the three principal stress axes as well as the ratio of principal stress differences using fault slip data or focal mechanisms of earthquakes is presented from a computational point of view the inversion of fault slip data is made in a direct way by purely analytical means as a result the determination process is extremely fast and adaptable on small microcomputers from a physical point of view the method aims at simultaneously i minimizing the angles between theoretical shear stress and actual slip vector and ii having relative magnitudes of shear stress large enough to induce slip despite rock cohesion and friction examples of application to actual fault slip data sets with good or poor variety of fault slip orientations are shown the double significance of the basic criterion adopted results in a more realistic solution of the inverse problem than the single minimization of the shear stria angle

climate and surface mass balance of coastal west antarctica resolved by regional climate modelling west antarctic climate and surface mass balance smb records are sparse to fill this gap regional atmospheric climate modelling is useful providing that such models are employed at sufficiently high horizontal resolution and coupled with a snow model here we present the results of a high resolution 5 5 km regional atmospheric climate model racmo2 simulation of coastal west antarctica for the period 1979 2015 we evaluate the results with available in situ weather observations remote sensing estimates of surface melt and smb estimates derived from radar and firn cores moreover results are compared with those from a lower resolution version to assess the added value of the resolution the high resolution model resolves small scale climate variability invoked by topography such as the relatively warm conditions over ice shelf grounding zones and local wind speed accelerations surface melt and smb are well reproduced by racmo2 this dataset will prove useful for picking ice core locations converting elevation changes to mass changes for driving ocean ice sheet and coupled models and for attributing changes in the west antarctic ice sheet and shelves to changes in atmospheric forcing

thirty years of elevation change on antarctic peninsula ice shelves from multimission satellite radar altimetry 1 we use data acquired between 1978 and 2008 by four satellite radar altimeter missions seasat ers 1 ers 2 and envisat to determine multidecadal elevation change rates dhi dt for six major antarctic peninsula ap ice shelves in areas covered by the seasat orbit to 72 16 s regional averaged 30 year trends were negative surface lowering with rates between 0 03 and 0 16 m a 1 surface lowering preceded the start of near continuous radar altimeter operations that began with ers 1 in 1992 the average rate of lowering for the first 14 years of the period was typically smaller than the 30 year average the exception was the southern wilkins ice shelf which experienced negligible lowering between 2000 and 2008 when a series of large calving events began analyses of the continuous ers envisat time series to 81 5 for 1992 2008 reveal a period of strong negative dhi dt on most ice shelves between 1992 and 1995 based on prior studies of regional atmospheric and oceanic conditions we hypothesize that the observed elevation changes on larsen c ice shelf are driven primarily by firn compaction while the western ap ice shelves are responding to changes in both surface mass balance and basal melt rates our time series also show that large changes in dhi dt can occur on interannual time scales reinforcing the importance of long time series altimetry to separate long term trends associated with climate change from interannual to interdecadal natural variability

late pleistocene glacial events in the central apennines italy the study of glacial evidence in the gran sasso massif of the central apennines italy has allowed the last maximum advance and the subsequent stadial phases to be dated and the mean annual temperature and quantity of precipitation in the form of snow to be assessed for a number of periods the glaciers probably reached their maximum extension campo imperatore stade ca 22 60014c yr b p and started to retreat ca 21 000 yr b p leaving behind three recessional moraines after a first interstade fornaca interstade the fontari stade appears to have taken place shortly after 16 000 yr ago ca 15 000 yr ago the glacier started retreating leaving behind four more recessional moraines an interstade venacquaro interstade preceded the mount aquila stade datable at ca 11 000 yr b p a strong correlation is evident between the glacial phases on land and the isotopic variations in cores from the tyrrhenian sea

evaluation of passive microwave melt detection methods on antarctic peninsula ice shelves using time series of sentinel 1 sar abstract passive microwave datasets have been used to quantify the extent and duration of surface melt in greenland and antarctica from 1978 on with daily and near daily intervals these results have important implications for climate analysis and may help evaluate ice shelf stability however the accuracy of passive microwave methods used to detect melt is difficult to quantify especially on the antarctic peninsula here four different melt detection methods are employed including a new formulation of a statistical analysis of brightness temperature time series using a k means clustering algorithm strikingly two of the most widely used passive microwave melt detection methods are found to vary by 48 mean days of melt per year across six different locations on the larsen c wilkins and george vi ice shelves in the absence of ground truth observations time series of sentinel 1 sar observations from 2016 on provide a comparison dataset in topographically flat regions where surface melt is spatially uniform the passive microwave melt detection method based on a k means analysis and the cross polarization gradient ratio method demonstrate the highest agreement and correlation with active radar melt detection methods one issue which has plagued passive microwave analysis is its coarse spatial resolution high resolution sar images are able to demonstrate and quantify the spatial variability of melt within individual passive microwave pixels melt is shown to be suitably uniform in space for passive microwave applications at the study sites on antarctic peninsula ice shelves but not so in other regions of the antarctic peninsula spatial heterogeneity of surface melt on the sub pixel scale is often related to varying surface topography

interactions of earthquakes in central italy over the past 100 yr through coulomb stress changes and implications for seismic hazardsinteractions of earthquakes in central italy over the past 100 yr through coulomb stress changes and implications for seismic hazards

holocene paleoearthquakes and early late pleistocene slip rate on the sulmona fault central apeninnes italy abstract the 23 km long sulmona normal fault flanks the southwestern slope of the mount morrone range in the central apennines to date the recent activity of this structure is uncertain as the faulting evidence concerns only undated deposits and the fault cannot be associated with any of the strong historical earthquakes m w 6 5 of the region our observation from 1 ma offset slope breccias coupled with new tephrochronological data on faulted early last glacial lacustrine infilling of the sulmona basin implies a vertical slip rate of 0 5 mm yr over both the long term and middle term moreover at the apex of a late pleistocene alluvial fan radiocarbon dating of offset stratigraphy uncovered in four paleoseismological trenches shows that repeated earthquakes resulted in more than 4 m of vertical offset since 9 ka providing again a minimum holocene vertical slip rate of 0 5 mm yr in combination with the results of the trench exposure we define four faulting events in the past 9 ky b p and at least one before then the most recent is constrained by robust radiocarbon dates as the middle of the second century a d the penultimate event was around the middle of the fifth millennium b p whereas the other two events are dated in a time between 8 5 ky to 6 5 ky b p and around 9 ky cal b p the oldest occurred before 9 5 ky b p as well as revealing the unexpected paleoseismic history of the sulmona silent fault our data provide a recurrence time for m w 6 5 earthquakes of 2 4 ky versus an elapsed time of 1 85 ky since the last event the latter matches with an earthquake previously hypothesized through archaeoseismic clues collected from several roman settlements of the sulmona plain all of which were dated to halfway through the second century a d online material table of major element compositions field photos and harker diagrams

integrated near surface geophysics across the active mount marzano fault system southern italy seismogenic hints here we describe an original geophysical multi method approach applied to the mount marzano fault system this is one of the most hazardous seismogenic faults of the apennines irpinia southern italy and it was responsible for the 1980 mw 6 9 earthquake along with many others before we carried out electrical resistivity tomography ert ground penetrating radar gpr measurements and horizontal to vertical spectral ratio hvsr microtremor analysis along several common transects designed across the potential and or certain fault traces the data obtained from these non invasive inexpensive expeditious methods mutually integrate with and complement each other providing a valuable subsurface image of the near surface fault architecture ert depicts the general shallow image of the fault zone and of the fault controlled sedimentary basin with the depth of the buried bedrock cross correlated through ambient noise hvsr results gpr delineates the very shallow geometry of the fault and of the associated deformation coupled with previous paleoseismological studies these data allow the evaluation of some fault parameters and the precise locating of the fault trace to aid future paleoseismological investigations aimed at seismic risk reduction programs

extent and duration of antarctic surface melting the extent and duration of surface melting on the antarctic ice shelves and margins of the antarctic ice sheet are derived from satellite passive microwave data for 1978 87 the occurrence of surface melting in daily maps of t b is indicated by a marked increase in microwave brightness temperature t b which is caused by moisture in the near surface firn t b increases of more than 30 deg above the annual mean t b are chosen to indicate melting most antarctic surface melting occurs during december and january the observed melting is correlated with regional air temperatures but some melt patterns also appear to be related to katabatic wind effects the correlations suggest that the surface melting in antarctica increases about 3 5 10 6 d km 2 per degree of summer temperature increase the surface melt index duration times area of melting calculated for antarctica is 24 10 6 d km 2 averaged over nine summers the observed inter annual and regional variability is large surface melting was most extensive during the 1982 83 summer 36 10 6 d km 2 and least extensive during the 1985 86 summer 15 10 6 d km 2 the data indicate a decline in surface melting over the 9 years but meaningful inferences regarding trends in surface melting are precluded by the large inter annual variability

insignificant change in antarctic snowmelt volume since 1979 1 surface snowmelt is widespread in coastal antarctica satellite based microwave sensors have been observing melt area and duration for over three decades however these observations do not reveal the total volume of meltwater produced on the ice sheet here we present an antarctic melt volume climatology for the period 1979 2010 obtained using a regional climate model equipped with realistic snow physics we find that mean continent wide meltwater volume 1979 2010 amounts to 89 gt y 1 with large interannual variability 41 gt y 1 of this amount 57 gt y 1 64 is produced on the floating ice shelves extending from the grounded ice sheet and 71 gt y 1in west antarctica including the antarctic peninsula we find no statistically significant trend in either continent wide or regional meltwater volume for the 31 year period 1979 2010

antarctic surface and subsurface snow and ice melt fluxes abstract this paper presents modeled surface and subsurface melt fluxes across near coastal antarctica simulations were performed using a physical based energy balance model developed in conjunction with detailed field measurements in a mixed snow and blue ice area of dronning maud land antarctica the model was combined with a satellite derived map of antarctic snow and blue ice areas 10 yr 1991 2000 of antarctic meteorological station data and a high resolution meteorological distribution model to provide daily simulated melt values on a 1 km grid covering antarctica model simulations showed that 11 8 and 21 6 of the antarctic continent experienced surface and subsurface melt respectively in addition the simulations produced 10 yr averaged subsurface meltwater production fluxes of 316 5 and 57 4 km3 yr 1 for snow covered and blue ice areas respectively the corresponding figures for surface melt were 46 0 and 2 0 km3 yr 1 respectively thus demonstrating the dominant role of subsurface ov

summer drivers of atmospheric variability affecting ice shelf thinning in the amundsen sea embayment west antarctica satellite data and a 35 year hindcast of the amundsen sea embayment summer climate using the weather research and forecasting model are used to understand how regional and large scale atmospheric variability affects thinning of ice shelves in this sector of west antarctica by melting from above and below linked to intrusions of warm water caused by anomalous westerlies over the continental shelf edge el nino episodes are associated with an increase in surface melt but do not have a statistically significant impact on westerly winds over the continental shelf edge the location of the amundsen sea low and the polarity of the southern annular mode sam have negligible impact on surface melting although a positive sam and eastward shift of the amundsen sea low cause anomalous westerlies over the continental shelf edge the projected future increase in el nino episodes and positive sam could therefore increase the risk of disintegration of west antarctic ice shelves

late quaternary fluvial terraces of the romagna and marche apennines italy climatic lithologic and tectonic controls on terrace genesis in an active orogen abstract we synthesize a new fluvial terrace chronostratigraphy of the bidente and musone rivers cast within a broader european framework which forms the basis of a terrace genesis and river incision model for the northern apennines italy our model supported by terrace long profiles correlation to po foreland sediments 15 new radiocarbon dates and published numeric and relative stratigraphic ages highlights how drainage basin substrate drives concurrent formation of strath terraces in the bidente basin and fill terraces in the musone basin quaternary climate change paces the formative geomorphic processes through unsteady discharges of water and sediment in the weathering limited setting represented by the bidente basin siliciclastic detritus carves broad strath surfaces during glacial climates that are preserved as terraces as the river incises during the transition to an interglacial climate in contrast the transport limited and carbonate detritus dominated musone basin sees valleys deeply buried by aggradation during glacial climates followed by river incision during the transition to an interglacial climate incision of these rivers over the past 1 million years has been both unsteady and non uniform these and all po adriatic draining rivers are proximal to a base level defined by mean sea level and have little room for increasing their longitudinal profile concavities through incision particularly in their lower reaches despite periodic glacio eustatic drawdowns as a result the observed incision is best explained by rock uplift associated with active local fault or fold growth embedded in the actively thickening and uplifting apennine foreland

strong surface melting preceded collapse of antarctic peninsula ice shelf 1 during the austral summer of 2001 02 melting at the surface of larsen ice shelf in the antarctic peninsula was three times greater than the average of five previous summers this exceptional melt event lasted for three months and was followed by the collapse of larsen b ice shelf during which 3 200 km2 of ice shelf surface was lost the strong melting was caused by a persistent atmospheric circulation anomaly which depleted sea ice concentrations in front of larsen ice shelf and transported warm air to the ice shelf throughout the 2001 02 summer this supports the theory that large meltwater fluxes accelerate the retreat of antarctic peninsula ice shelves

foehn winds link climate driven warming to ice shelf evolution in antarctica rapid warming of the antarctic peninsula over the past several decades has led to extensive surface melting on its eastern side and the disintegration of the prince gustav larsen a and larsen b ice shelves the warming trend has been attributed to strengthening of circumpolar westerlies resulting from a positive trend in the southern annular mode sam which is thought to promote more frequent warm dry downsloping foehn winds along the lee or eastern side of the peninsula we examined variability in foehn frequency and its relationship to temperature and patterns of synoptic scale circulation using a multidecadal meteorological record from the argentine station matienzo located between the larsen a and b embayments this record was further augmented with a network of six weather stations installed under the u s nsf larsen ice shelf system antarctica project significant warming was observed in all seasons at matienzo with the largest seasonal increase occurring in austral winter 3 71 c between 1962 1972 and 1999 2010 frequency and duration of foehn events were found to strongly influence regional temperature variability over hourly to seasonal time scales surface temperature and foehn winds were also sensitive to climate variability with both variables exhibiting strong positive correlations with the sam index concomitant positive trends in foehn frequency temperature and sam are present during austral summer with sustained foehn events consistently associated with surface melting across the ice sheet and ice shelves these observations support the notion that increased foehn frequency played a critical role in precipitating the collapse of the larsen b ice shelf

middle and late pleistocene glaciations in the campo felice basin central apennines italy the present paper refers to research conducted in the tectonic karst depression of campo felice in the central apennines italy in which glacial alluvial and lacustrine sediments have been preserved stratigraphic interpretations of sediments underlying the campo felice plain are based on evidence obtained from nine continuous core boreholes the boreholes reach a depth of 120 m and provide evidence of five sedimentation cycles separated by erosion surfaces each cycle is interpreted as an initial response to a mainly warm stage characterized by low energy alluvial and colluvial deposition pedogenesis and limited episodes of marsh formation in turn a mainly cold stage follows during which a lake formed and glaciers developed and expanded leading to deposition of glacial and fluvioglacial deposits the chronological framework is established by eleven accelerator mass spectrometer 14c ages and three 39ar 40ar ages on leucites from interbedded tephra layers these age determinations indicate five glacial advances that respectively occurred during marine oxygen isotope stages 2 3 4 6 10 and 14

new paleoseismic data from the irpinia fault a different seismogenic perspective for southern apennines italy abstract the irpinia fault i e mount marzano fault system mmfs was responsible for the devastating 1980 earthquake mw 6 9 that caused the longest surface faulting ever observed in italy 30 km early paleoseismological studies have revealed a 2 kyr recurrence time for 1980 like characteristic earthquakes on this fault system during the holocene however this appears to clash with both the catastrophic historical seismicity and high gps derived strain rate of the area to explain this apparent discrepancy we investigated the mmfs through a multidisciplinary approach first on the basis of recent archives and archaeological research we reassessed the historical seismicity of the area analysing the highest intensity distribution of the major earthquakes of the upper ofanto valley with respect to the mmfs hanging wall then we carried out a step by step survey along the entire 43 km long fault system through both high precision topographic levelling along the compound fault scarp and geostructural analyses finally we excavated trenches and pits across different fault segments to explore the recent paleoseismological history of the structure based on the combined results that we have obtained we propose a different point of view concerning the seismogenic behaviour of the mmfs from the holocene to the present at the end fault parameters have been compared with those of all the apennines active faults and cross checked with the newest gps results in peninsular italy providing some relevant observation of the relationships between seismogenesis and geodetic deformation

interannual variations of snowmelt and refreeze timing on southeast alaskan icefields u s a twice daily satellite observations from the special sensor microwave imager ssm i indicate melt onset and refreeze on southeast alaskan icefields melt and refreeze are based on 37 ghz vertically polarized brightness temperatures t b and diurnal amplitude variations dav two types of melt regime have different summer characteristics onset is characterized by increasing average daily t b and a switch from low to high amplitude dav melt timing calibrated using juneau icefield temperatures correlates well with nearby stream hydrographs some pixels maintain high t b throughout the melt season and return to low amplitude dav after melt onset refreeze on these pixels is identified by decrease in t b and accompanying high amplitude dav other pixels maintain high dav throughout the summer indicating nocturnal refrecze fall refreeze is determined by the end of high amplitude dav interannual variability in melt timing and ablation season length is high melt onset and refreeze timing show a regional tendency toward earlier glacier melt onset and longer ablation seasons from 1988 98

modeling the microwave emission of bubbly ice applications to blue ice and superimposed ice in the antarctic and arctic passive microwave remote sensing is extensively used in polar regions to study the cryosphere to better understand the measured signal above continental ice covered areas our objective is to estimate the microwave emission of bubbly ice surfaces using a physically based multilayer electromagnetic model i e the dense media radiative transfer multilayer model dmrt ml this model accounts for ice layers with variable amounts of bubbles each layer is fully described by its temperature density thickness and air bubble radius simulations are performed using in situ data from two distinct sites one in antarctica on a coastal blue ice area near the cap prud homme cph station in adelie land and the other on the barnes ice cap bic located on baffin island in the arctic on this ice cap superimposed ice with seasonal snow cover about 1 m thick was observed in both cases several ice parameters were measured or estimated and the others were optimized results of the dmrt ml simulations are compared with in situ surface based radiometer sbr measurements at 11 19 and 37 ghz at both horizontal and vertical polarizations results show that dmrt ml is able to reproduce the microwave emission of different ice types with good accuracy when accounting for ice bubbles final hbox rmse 7 37 hbox k and 8 42 k for cph and bic respectively compared with rmse ranging from 15 k to 40 k without bubbles comparisons between sbr measurements and satellite data for the bic also show good agreement hbox rmse 4 1 hbox k for 19 and 37 ghz both polarizations

the air content of larsen ice shelf 1 the air content of glacial firn determines the effect and attribution of observed changes in ice surface elevation but is currently measurable only using labor intensive ground based techniques here a novel method is presented for using radar sounding measurements to decompose the total thickness of floating ice shelves into thicknesses of solid ice and firn air or firn water the method is applied to a 1997 98 airborne survey of larsen ice shelf revealing large spatial gradients in air content that are consistent with existing measurements and local meteorology the gradients appear to be governed by meltwater induced firn densification we find sufficient air in larsen c ice shelf for increased densification to account for its previously observed surface lowering and the rate of lowering superficially agrees with published trends in melting this does not preclude a contribution to the lowering from oceanic basal melting but a modern repeat of the survey could conclusively distinguish atmosphere led from ocean led change the technique also holds promise for the calibration of firn density models derivation of ice thickness from surface elevation measurements and calculation of the sea level contribution of changes in grounded ice discharge

surface faulting in norcia central italy a paleoseismological perspective we carried out paleoseismological analyses in norcia one of the oldest town of central italy four trenches were dug in late pleistocene holocene deposits across an unmapped antithetic splay of the norcia fault system the investigated fault runs through the recent settlement of the town brushing against the middle age city walls we found evidence of repeated surface ruptures in the past 20 ky the last one dated to a period fitting with the 1703 ad catastrophic earthquake m 6 8 our data i show definitively the late pleistocene holocene activity of the norcia fault system ii strengthen the historical accounts describing surface ruptures during the 1703 event in norcia iii cast light on the seismogenic behavior of the 70 km long fault system between l aquila and norcia central italy and iv predict the occurrence of normal surface faulting inside the municipality of norcia during future mz6 earthquakes d 2005 elsevier b v all rights reserved

carbon isotope systematics of the cambrian vendian aquifer system in the northern baltic basin implications to the age and evolution of groundwater groundwater in the cambrian vendian aquifer system has a strongly depleted stable isotope composition 18o values of about 22 and a low radiocarbon concentration which suggests that the water is of glacial origin from the last ice age the aim of this paper was to elucidate the timing of infiltration of glacial waters and to understand the geochemical evolution of this groundwater the composition of the dissolved inorganic c dic in cambrian vendian groundwater is influenced by complex reactions and isotope exchange processes between water organic materials and rock matrix the 13c composition of dissolved inorganic c in cambrian vendian water also indicates a bacterial modification of the isotope system the corrected radiocarbon ages of groundwater are between 14 000 and 27 000 radiocarbon years which is coeval with the advance of the weichselian glacier in the area

the esr age of portlandia arctica shells from glacial deposits of central latvia an answer to a controversy on the age and genesis of their enclosing sediments abstract the occurrence of portlandia arctica shells in glacigenic sediments of central latvia had created a controversy in many publications about 1 their age ranging from the holsteinian to the late weichselian and 2 the genesis of their enclosing sediments glacial glaciomarine or marine our reinvestigation of the main object of controversy the licupe site leads to a conclusion that the sedimentary package of diamictons clays and sands containing portlandia arctica shells and marine microfossils is a large glacial raft that had been transported and deposited by the riga lobe during the weichselian the electron spin resonance esr ages on five sets of portlandia arctica shells from the licupe and daugmales tom ni sites range from 86 0 6 8 to 105 0 9 2 ka bp these esr age determinations and the cool climate indicators of the associated microflora and microfauna suggest that their source sediments probably in the gulf of riga are marine clays of early weichselian age probably correlative to the brorup interstadial in central latvia portlandia arctica shells and their enclosing clay occur resedimented or translocated in glacial deposits during weichselian glacial advances

a reappraisal of the 1599 earthquake in cascia italian central apennines hypothesis on the seismogenic source abstract in this study we investigate a little known earthquake that struck cascia and its environs central italian apennines in 1599 causing 50 casualties and the destruction and abandonment of several settlements as in current seismic catalogues the characterization of this event is based on the anonymous account of a single source we conducted research using public and private archives and libraries that allow recovering many unpublished contemporary accounts of the earthquake this information permitted a more detailed evaluation of the macroseismic effects and a doubling of the number of intensity datapoints resulting in a more robust earthquake epicentral parameters next we conducted a geological field survey within the newly defined mesoseismic area aimed at finding possible evidence of active tectonics likely faults with indications of recent movements and with an attitude fitting both the 1599 highest intensity distribution and the regional stress field we found evidence for holocene surface faulting along the cascia and mount alvagnano faults that we consider responsible for the 1599 earthquake and possibly also for a twin event in 1979 and the much stronger norcia earthquake in 1703

snowmelt on the greenland ice sheet as derived from passive microwave satellite data abstract the melt extent of the snow on the greenland ice sheet is of considerable importance to the ice sheet s mass and energy balance as well as arctic and global climates by comparing passive microwave satellite data to field observations variations in melt extent have been detected by establishing melt thresholds in the cross polarized gradient ratio xpgr the xpgr defined as the normalized difference between the 19 ghz horizontal channel and the 37 ghz vertical channel of the special sensor microwave imager ssm i exploits the different effects of snow wetness on different frequencies and polarizations and establishes a distinct melt signal using this xpgr melt signal seasonal and interannual variations in snowmelt extent of the ice sheet are studied the melt is found to be most extensive on the western side of the ice sheet and peaks in late july moreover there is a notable increasing trend in melt area between the years 1979 and 1991 of 4 4 per year which came to an abrupt halt in 1

offset components and fault block motion during the 2016 central italy earthquake mw 6 6 monte vettore fault system abstract we performed structural analyses on exhumed fault planes in carbonate rock of the monte vettore fault system central italian apennines slip on these faults was responsible in 2016 for a mw 6 6 earthquake accompanied by 30 km long surface rupture we focused on scratches a peculiar coseismic abrasion feature that is rarely described and analysed in structural geology mainly because of its ephemeral nature most of scratches disappear after just a few months we surveyed coseismic scratches and slip vectors of coseismic surface ruptures that coupled with conventional striae analysis provide interesting clues to the kinematic behavior of the hanging wall during the 2016 mainshock first we investigated whether or not scratches could be considered as kinematic indicators and if they could really add information to results of striae analysis to this end we compared the statistical analysis of scratches with those obtained from conventional fault surface structural elements or inferred from other geological seismological and geodetical data results show that the movement of the hanging wall of the monte vettore fault system during the october 30 2016 mainshock can be traced back to two components the first major component is kinematically linked to deep tectonic deformation the second minor component is related to passive slip deformation induced by the complexity of reciprocal motion between hanging wall and footwall

antarctic surface melting dynamics enhanced perspectives from radar scatterometer data 1 antarctic ice sheet surface melting can regionally influence ice shelf stability mass balance and glacier dynamics in addition to modulating near surface physical and chemical properties over wide areas here we investigate variability in surface melting from 1999 to 2009 using radar backscatter time series from the seawinds scatterometer aboard the quikscat satellite these daily continent wide observations are explored in concert with in situ meteorological records to validate a threshold based melt detection method radar backscatter decreases during melting are significantly correlated with in situ positive degree days as well as meltwater production determined from energy balance modeling at neumayer station east antarctica these results support the use of scatterometer data as a diagnostic indicator of melt intensity i e the relative liquid water production during melting greater spatial and temporal melting detected relative to previous passive microwave based studies is attributed to a higher sensitivity of the scatterometer instrument continental melt intensity variability can be explained in part by the dynamics of the southern annular mode and the southern oscillation index and extreme melting events across the ross ice shelf region may be associated with el nino conditions furthermore we find that the antarctic peninsula accounts for only 20 of antarctic melt extent but greater than 50 of the total antarctic melt intensity over most areas annual melt duration and intensity are proportional however regional and localized distinctions exist where the melt intensity metric provides greater insight into melting dynamics than previously obtainable with other remote sensing techniques

holocene paleoseismology of the norcia fault system central italy abstract we investigated the late quaternary activity of the norcia fault system one of the most hazardous seismogenic structures of italy responsible over the centuries for nucleating several mw 6 earthquakes possibly up to mw 6 9 as on 14th january 1703 this fault is located only 10 km away from the mount vettore fault system which was responsible for the deadly mw 6 6 central italy earthquake in 2016 using evidence gathered from ten paleoseismological trenches we reconstructed the history of the strongest earthquakes sourced by the norcia faults during the past 4 ky and in previous time windows back to 20 ka in particular we found indications of the historical 1703 and 99 bce events as well as a previously unknown one in the bronze age we also obtained a robust estimate of the slip rate for the post last glacial maximum period 1 0 2 mm yr and a rough 1 8 ky recurrence time for mw 6 9 events during the late holocene

twenty years of paleoseismology in italy abstract italy has one of the most complete and historically extensive seismic catalogues in the world due to a unique and uninterrupted flow of written sources that have narrated its seismic history since about the end of the iron age seismic hazard studies have therefore always been mainly based upon this huge mass of data nevertheless the italian catalogue probably lacks many m 6 5 events the seismogenetic structures responsible for which are characterized by recurrence times that are longer than the time span covered by our historical sources for these reasons and as in other countries earthquake data that in italy have been derived from paleoseismological studies should finally become a necessary ingredient in seismic risk assessment indeed over the past 20 years some hundred trenches have been excavated supplying reliable and conclusive data on the recent activities of many faults through to many robust datings of surface fault events these studies have provided the ages of several unknown or poorly known m 6 5 earthquakes here we summarize the state of the art of paleoseismology in italy and present a first catalogue of 56 paleoearthquakes pci that occurred mainly in the past 6 kyr the pci integrates the historical instrumental seismic catalogue and extends it beyond the recurrence time of the seismogenetic faults 2000 1000 yr we feel confident that the use of the pci will enhance future probabilistic seismic hazard assessment and thus contribute to more reliable seismic risk mitigation programs

assessment and development of snowmelt retrieval algorithms over antarctica from k band spaceborne brightness temperature 1979 2008 abstract results from several previously published algorithms for wet snow detection in antarctica from k band spaceborne brightness temperature are compared and evaluated vs estimates of wet snow conditions from ground measurements in addition a new physically driven algorithm in which the detectable liquid water content is assumed constant is proposed and assessed all algorithms are also evaluated by analyzing their results during collapses of ice shelves two algorithms are selected for deriving updated trends of melting index mi the number of melting days times the area subject to melting between 1979 and 2008 over the whole antarctica and at sub continental scales in the first algorithm wet snow is identified when brightness temperature exceeds the mean of winter brightness temperature plus 30 k and the second is the new model based approach described here both negative and positive mi trends are obtained depending on the algorithm used a high number of melting days up to 100 days are detected over the wilkins ice shelf the peninsula and the george vi ice shelf over east antarctica the west and amery ice shelves are subject to melting for a maximum of approximately 50 days positive trends of number of melting days are detected over most of the west antarctica with peak values up to 1 2 days year over the larsen c ice shelf 1 8 days year over the george vi ice shelf and 0 55 days year over the wilkins ice shelf area the correlation between mi values and december january dj averaged air surface temperature over selected locations show values ranging between 0 8 and 0 4 results suggest that a 1 c increase in the monthly averaged dj air surface temperature corresponds to an average mi increase of approximately 2 106 km2 day

palaeoseismology of the l aquila faults central italy 2009 mw 6 3 earthquake implications for active fault linkage summary urgent urban planning problems related to the 2009 april mw 6 3 l aquila earthquake prompted immediate excavation of palaeoseismological trenches across the active faults bordering the aterno river valley namely the mt marine mt pettino and paganica faults cross cutting correlations amongst existing and new trenches that were strengthened by radiocarbon ages and archaeological constraints show unambiguously that these three investigated structures have been active since the last glacial maximum period as seen by the metric offset that affected the whole slope alluvial sedimentary succession up to the historical deposits moreover in agreement with both 18th century accounts and previous palaeoseismological data we can affirm now that these faults were responsible for the catastrophic 1703 february 2 earthquake mw 6 7 the data indicate that the paganica san demetrio fault system has ruptured in the past both together with the conterminous mt pettino mt marine fault system along more than 30 km and causing an mw 6 7 earthquake and on its own along ca 19 km as in the recent 2009 event and in the similar 1461 ad event this behaviour of the l aquila faults has important implications in terms of seismic hazard assessment while it also casts new light on the ongoing fault linkage processes amongst these l aquila faults

antarctic ice sheet loss driven by basal melting of ice shelves accurate prediction of global sea level rise requires that we understand the cause of recent widespread and intensifying glacier acceleration along antarctic ice sheet coastal margins atmospheric and oceanic forcing have the potential to reduce the thickness and extent of floating ice shelves potentially limiting their ability to buttress the flow of grounded tributary glaciers indeed recent ice shelf collapse led to retreat and acceleration of several glaciers on the antarctic peninsula but the extent and magnitude of ice shelf thickness change the underlying causes of such change and its link to glacier flow rate are so poorly understood that its future impact on the ice sheets cannot yet be predicted here we use satellite laser altimetry and modelling of the surface firn layer to reveal the circum antarctic pattern of ice shelf thinning through increased basal melt we deduce that this increased melt is the primary control of antarctic ice sheet loss through a reduction in buttressing of the adjacent ice sheet leading to accelerated glacier flow the highest thinning rates occur where warm water at depth can access thick ice shelves via submarine troughs crossing the continental shelf wind forcing could explain the dominant patterns of both basal melting and the surface melting and collapse of antarctic ice shelves through ocean upwelling in the amundsen and bellingshausen seas and atmospheric warming on the antarctic peninsula this implies that climate forcing through changing winds influences antarctic ice sheet mass balance and hence global sea level on annual to decadal timescales

22 kyr long record of surface faulting along the source of the 30 october 2016 earthquake central apennines italy from integrated paleoseismic data sets

complete seismic release of tectonic strain and earthquake recurrence in the apennines italy here i compare estimates of tectonic strain rates from dense global positioning system measurements with the seismicity released in the last 500 years in the apennines italy the rates of seismic moment accumulation from geodesy and of historical seismic release by earthquakes agree within the uncertainties ruling out significant aseismic deformation within the considered 400 km long section of the apennines this balance yields an average recurrence interval of 30 75 years for mw 6 5 events without requiring a future earthquake larger than those observed historically mw 7 a minimum estimate of unreleased strain allows mw 6 5 and mw 6 9 events to be released in 35 and 10 of the central southern apennines respectively the definition of the seismic potential for smaller events is more uncertain and their occurrence remains a significant threat throughout the apennines

strain monitoring of active faults in the central apennines italy during the period 2002 2017 abstract we present the results of 3 d monitoring of strain along active faults outcropping in the central apennines where recent and historical strong earthquakes occurred using tm 71 extensometers during the period 2002 2017 we discuss the fault slip development as well as kinematics particularly in the light of local recent seismicity the recorded fault slip corresponds to the minimum and maximum principal stress with a sw ne orientation and slightly dipping to sw moreover the detected fault slip is non linear and affected by remarkable transient periods of acceleration which lasted up to several months the recorded accelerations were induced by alternation of extensional reverse and horizontal displacement due to switching extensional and compressional stress strain state and coincide with periods of major seismic events that recently affected the central apennines this phenomenon is being investigated in the case of the moderate l aquila 2009 and norcia 2016 earthquakes the recorded fault slips can be characterized as pre seismic

investigation of the norcia basin central italy through ambient vibration measurements and geological surveys abstract during the 2016 2017 a seismic sequence struck the central italy involving four regions umbria marche abruzzo and lazio and causing important damages and victims in inhabited areas such as norcia and amatrice towns the strongest event of the seismic sequence was a mw 6 5 event with epicenter at about 5 km far from the norcia area which is an intermontane basin prone to ground motion amplification the historical town of norcia and the surrounding hamlets were recently investigated by the microzonation activity but information on the geometry and velocity are still partial considering the entire basin indeed past studies aimed at reconstructing the elastic and geometrical properties focusing mainly on the northern part of the basin specifically in this paper we integrated seismic and geological data to get a better knowledge of the properties of the quaternary norcia basin a geological survey was carried out to provide a geological map and three geological cross sections we analyzed new seismic ambient vibrations data collected by single seismic stations to infer the distribution of resonant frequency f0 for the entire basin we used passive arrays of seismic stations to better define the velocity profiles of the area in the northern part of the basin two 2d arrays with elliptical like shapes were deployed showing strong discrepancies of the elastic soil properties in proximity of norcia town we found shear wave velocities of the near surface profile of about 300 400 and 500 800 m s in presence of lacustrine and alluvial fan deposits respectively further the values of f0 are abruptly varying from 0 5 hz in the sw sector of norcia village up to 2 hz in its ne sector ambient vibration data reveal less pronounced variation of f0 in the southern part of the basin with resonant values that are almost in the range 1 1 3 hz in the southern sector a 1d array was arranged along a 5 km line and was analyzed by means of seismic noise cross correlation analysis suggesting the presence of a deeper seismic contrast the integration of geophysical and geological results has allowed to infer insights on the subsurface geometry of the basin

the last deglaciation of the southeastern sector of the scandinavian ice sheet the scandinavian ice sheet sis was an important component of the global ice sheet system during the last glaciation but the timing of its growth to or retreat from its maximum extent remains poorly known we used 115 cosmogenic beryllium 10 ages and 70 radiocarbon ages to constrain the timing of three substantial ice margin fluctuations of the sis between 25 000 and 12 000 years before the present the age of initial deglaciation indicates that the sis may have contributed to an abrupt rise in global sea level subsequent ice margin fluctuations identify opposite mass balance responses to north atlantic climate change indicating differing ice sheet sensitivities to mean climate state

when and how did the continental ice retreat from estonia abstract the territory of estonia was freed from the continental ice in gotiglacial time which was charaterized by high activity of the glacial streams and lobes and a highly variable glacial morphogenesis glaciers left behind different landforms and deposits up to 200 m thick glacial accumulation was concentrated in the interlobate subglacial uplands during the course of the thinning of the ice sheet the movement and dynamics of its individual lobes was controlled by the underlying subglacial topography the deglaciation history has been dated using 14 c varve chronology palynology electron spin resonance esr thermoluminescence tl optically stimulated luminescence and the 10 be methods the majority of the radiocarbon dates obtained from submorainic and intermorainic sequences are younger than would be expected the obtained osl and cosmogenic beryllium dates are extremely heterogenous and cannot be readily used to improve the existing stratigraphical charts for the late glacial period in varve years estonia became ice free at about 14 000 12 600 years ago

correlation of swedish glacial varves with the greenland grip oxygen isotope record a mean varve thickness curve has been constructed for a part of the swedish varve chronology from the northwestern baltic proper the mean varve thickness curve has been correlated with the delta 1

surface rupturing paleoearthquakes in the kurai fault zone gorny altai russia trenching and geophysical evidence abstract the kurai fault zone kfz is one of the most hazardous seismogenic structures in the gorny altai russia the kfz have generated five paleoearthquakes with mw 6 6 7 6 and esi 2007 shaking intensities of viii to xi the ultimate event presumably in the second half of the 18th century was preceded by four paleoearthquakes approximately 1 3 3 2 5 8 and 6 3 ka ago the morphology of fault scarps trenching results deformation features in neogene sediments as well as electric resistivity surveys reveal reverse slip mechanisms all earthquakes were sourced by south dipping backthrusts with respect to the main north dipping reverse and thrust faults along which the kurai range is stepping over the two basins the backthrusting maintains the growth of forebergs in front of the kurai range narrow basins limited by reverse faults separate forebergs from the chuya and kurai basins joint interpretation of geological including trenching and geophysical ert and gpr data reveals the resistivity structure of the area with seismogenic faults traceable to depths of 40 50 m the kfz model with the reconstructed relationships between the intramontane basins and the flanking mountains as well as the structural control of large earthquakes makes good reference for other worldwide regions of current and past seismicity in compressional settings assessment of probable magnitudes and recurrence of earthquakes within the kfz is of special importance in view of the future deployment of the gas pipeline from russia to china

ice flow pattern and extent of the last scandinavian ice sheet southeast of the baltic sea a review of scientific literature geological maps and available previous digital data on ice marginal positions glacial landforms and sediment distribution are utilised to reconstruct ice streams and lobes and the maximum lgm and subsequent recessional ice marginal positions of the scandinavian ice sheet sis southeast of the baltic sea this paper presents preliminary results of the ongoing research that aims to build a geographic information system gis based model on the extent and timing of the last sis in the area between its maximum extent and the baltic sea digitized subglacial bedforms ice marginal and other glacial landforms and features from published sources are compared and validated against digital elevation model dem this has allowed specifying revising and questioning the location of the lgm and to interpret and correlate the post lgm ice streams with marginal positions morphological evidence demonstrates that large ice streams of between 100 and 300 km lengths were in operation ca 2 3 ka after the lgm and formed the middle and north lithuanian end moraines ice streams from the onega and white sea basins had high lateral slopes and clearly channelled flow while the ice streams that drained the ice sheet through the ladoga ilmen depression and in the eastern baltic usually had a fan shaped flow pattern and morphologically unclear lateral slopes in elevated areas and highlands that are located between ice streams a crossing of lineated bedforms is common one set of the crossing lineations on zemaitia eastern kursa vidzeme haanja latgale and sudoma highlands that are 200 350 km inside of the lgm margin has northwest southeast orientation that in general conforms to the direction of ice flow during the lgm and baltija phases it is expected that the presented compilation will stimulate discussions and scrutiny of earlier published data and generate ideas for future investigations