geomorphology and age of the marocche di dro rock avalanches trentino italy abstract the marocche di dro deposits in the lower sarca valley are some of the most distinctive rock avalanche deposits of the alps we use geomorphology and cosmogenic 36 cl exposure dating of boulders to divide the marocche di dro deposits into two rock avalanche bodies the marocca principale to the north and the kas to the south the deposits were previously undated and had been mapped as up to five different events the largest event marocca principale which comprises an estimated 1000 10 6 m 3 of predominantly rotzo formation limestones occurred 5300 860 yr ago the release area is located mainly in the alcove between mt casale and mt granzoline but likely extends all the way to mt brento the kas event took place 1080 160 yr ago with detachment below mt brento the kas debris with an estimated volume of 300 10 6 m 3 buried the southern third of the marocca principale deposit kas presents a barren stark landscape dominated by house sized tovel member rotzo formation boulders bearing distinctive chert lenses both the extreme relief of the rock wall more than 1300 m and the tectonic setting predispose the range front to massive failure for the two events initially translational movement likely quickly evolved into complex failure and massive collapse run out across the valley of several kilometers and run up on the opposite slope of hundreds of meters followed a summary of all dated and large historical landslides in the alps underlines the periods of enhanced slope activity discussed in the literature 10 9 kyr 5 3 kyr and 2 1 kyr the latter especially for the southern alps no deposits of the first temporal cluster are found at marocche di dro the age of marocca principale at 5300 860 yr suggests occurrence during the second period failure may have been related to the shift to wetter colder climate at the transition from the middle to the late holocene nevertheless a seismic trigger cannot be ruled out for the kas rock avalanche at 1080 160 yr ago we implicate the middle adige valley 1046 ce earthquake as trigger its epicentral distance is much closer to the sarca valley in comparison to that of the verona earthquake 1117 ce

paleomagnetic evidence for neogene rotational deformations in the aegean domain new paleomagnetic data are reported from the islands of skyros and lesbos in central aegea and the izmir foca region in western anatolia together with previous results obtained in northwestern greece and with results from northern aegea reported by others authors these data suggest that the lower miocene arc was almost rectilinear trending e w and that the curvature was acquired by opposed rotational deformations at each termination moreover the observed inclinations which are shallower than those expected on the basis of a geocentered dipole field suggest a large northward drift since middle miocene

lateglacial and holocene talus slope development and rockwall retreat on mynydd du uk modification of lateglacial and holocene talus sheets by debris flows and gully incision on mynydd du wales has resulted in a convergence of upper slope form characterised by an upper rectilinear slope gradient of 36 3 and a range of concavities of c 0 1 0 2 in most cases gully incision and accumulation of debris cones have led to an increase in slope concavity evidence for talus erosion reworking and redeposition on the upper slope emphasises secondary reworking processes as well as primary talus accumulation on the upper slope and permits construction of a model of talus development at mynydd du on the basis of talus volume calculation of the first rockwall retreat data set for southern britain suggests that c 7 1 m 84 of overall rockwall retreat 8 5 m took place during the lateglacial and only c 1 4 m 16 occurred during the holocene these figures imply that lateglacial retreat rates ranged from 1 01 to 2 44 m ka 1 with an overall mean rate of 1 23 m ka 1 in contrast holocene rockwall retreat rates range from 0 10 to 0 17 m ka 1 with a mean rate of 0 12 m ka 1 approximately 27 of cliff retreat is attributed to microgelivation while similar to holocene and present day alpine environments these lateglacial retreat rates are one order of magnitude higher than most equivalent values for arctic sites this reflects both alpine style diurnal freeze thaw activity on mynydd du during the younger dryas and paraglacial rock mass instability following deglaciation assuming an exponential decline in rockwall sediment release it is estimated that approximately half the talus had accumulated within c 1 ka of deglaciation at one site paraglacial talus accumulation appears to have contributed significantly to the glacial sediment transport system of a subsequent ice advance present day rates of rockwall retreat and talus accumulation by rockfall are estimated to be 0 014 and 0 022 mm yr 1 m ka 1 respectively similar to values for other british sites and markedly lower than holocene rates of cliff recession due to microgelivation by implication the geomorphic significance of microgelivation may have been greatly underestimated in studies of inland rock slope evolution in temperate mid latitude environments

investigations regarding alpine talus slopes using ground penetrating radar gpr in the bavarian alps germany the applicability of ground penetrating radar gpr for the investigation of loose debris was tested at two sites viererkar and zugspitzplatt a pulseekko 100 gpr system equipped with 25 mhz antennae was utilized the aim of the investigation was to record the base of the debris layer and thereby acquire an estimation of the backweathering rates of the adjacent rockwalls the study areas are situated in the northern alps near the german austrian border the sites are characterized by steep limestone rockwalls and extensive talus accumulations a total of six profiles was surveyed the method is suitable and effective for a quick survey in this dry high ohmic substrate the gpr system was able to deliver information about the subsurface stratigraphy to c 70 m depth the boundary line to the bedrock was discovered depending upon the profile surveyed 5 to 25 m below the surface the base of the debris material sometimes shows no distinct reflection buried features v shaped furrows zones overdeepened by ice action geological structures could be detected arched structures well below the talus bedrock interface can be interpreted as drainage systems in the karstic bedrock a thick scree layer of late glacial age was separated from a thinner layer on the talus surface which was related to the holocene the backweathering rates were fixed by a calculation of talus volume to c 100 mm 103 a during the holocene viererkar and 150 300 mm 103 a zugspitzplatt the detrital formation in north exposed sites is twice as intense as in south exposed sites these results match the rates of recent rockfall in the same area of investigation the calculated backweathering for the late glacial period is 150 730 mm 103 a the magnitude of the calculated rockwall retreat lies well within the range of previous measurements the discrepancy between some weathering rates highlights the fact that recent and past relief formation must be differentiated otherwise recent removal rates may be overestimated copyright 2001 john wiley sons ltd

active deformation of a segment of arc the strait of kythira hellenic arc greece abstract a field analysis of late cenozoic faults has been carried out in the southwest hellenic arc on the islands of kythira and antikythira as well as on both sides of the strait in southeast peloponnisos and western crete the previously unknown geological structure of antikythira is briefly described together with accurate bathymetric data obtained using a multi beam echo sounder on submarine fault scarps the results of studies on land lead to a new interpretation of the neotectonic deformation of this segment of the hellenic arc the submersion of the strait is a consequence of extension related to normal faulting the extension rate being faster than in adjacent segments of the arc the direction of extension related to late pliocene quaternary normal faulting is determined from on land information the existence of oblique en echelon normal faults indicates that dextral deformation plays a role within the kythira strait in connection with the opening of the adjacent cretan sea triggered by subduction beneath the hellenic arc the whole pattern of fault systems in southeast peloponnisos as inferred from teledetection and field studies is consistent with the clockwise rotation that has been independently proposed and verified by palaeomagnetic studies the kythira strait thus provides an example of a complex transform extensional deformation and rotation between two major segments of external arc

spatial and temporal variations in rockfall determined from tls measurements in a deglaciated valley switzerland steep u shaped valleys produced by glaciation are commonly eroded by rockfall in this study we investigate modern and long term power law predicted rates of rock wall retreat in a deglaciated valley our emphasis is on the 5 2 km2 calcareous cliffs covering in the lauterbrunnen valley switzerland terrestrial laser scans were collected during nine field campaigns over 18 months to provide a continuous coverage of most of the valley walls results indicate a total of 122 rockfalls with volumes ranging between 0 06 0 01 and 119 34 1 07 m3 different size groups of rockfall events were correlated with environmental factors e g freeze thaw cycles temperature precipitation and seismicity using a linear regression with variable lag times of 0 6 months the highest correlation factor r 0 6 p 0 08 90 significance level is observed for freeze thaw cycles and rockfall events smaller than 1 m3 with a 2 month delay between temperature extremes and rockfall frequency magnitude relationships for rockfall events were calculated to predict less frequent larger rockfall events that did not occur during the observation period a monte carlo analysis was applied to the frequency magnitude relationship to evaluate the sensitivity of results to their stochastic nature an average power law exponent of 1 71 0 09 was calculated using linear regression the calculated exponents are similar to other studies in calcareous rock settings conducted over different observation durations finally we determine an average total eroded volume of 2 0 0 01 0 6 103 m3 yr and a corresponding long term power law predicted cliff retreat rate of 0 39 0 02 0 12mm yr

climate influence on rockfalls in high alpine steep rockwalls the north side of the aiguilles de chamonix mont blanc massif since the end of the little ice age rockfalls fundamentally affect the morphodynamics of high mountain rockwalls and represent a great danger for both people and infrastructures but still are poorly known by comparing old recent and new photographs in addition to geomorphological field data we propose an inventory of the rockfalls that occurred since the end of the little ice age on the north side of the aiguilles de chamonix mont blanc massif ranging in volume from 500 to 65 000 m 3 these 42 rockfalls occurred after 1947 of which 70 during the last two decades with a maximal frequency during the warm summers especially in 2003 average elevation of scars 3130 m a s l close to the lower modelled permafrost limit and the topography e g spurs of the affected rock faces enhancing lateral heat fluxes suggest that a climatically driven permafrost degradation has triggered many of the recent rockfalls in high alpine steep rockwalls

global climate and tectonic controls on the denudation of glaciated mountains abstract significant uncertainty exists concerning the efficiency of alpine glacial erosion relative to fluvial and hillslope processes latitudinal variations in temperature are important for determining the extent of glaciers as are the rates of tectonic uplift that influence the elevation and hence temperatures that glaciers can form the acute sensitivity of glacial erosion to temperature has complicated previous interpretations because temperatures must be cool enough to maintain ice yet warm enough to allow glacial sliding here we quantify the influence of climate and tectonics on glacial landscape evolution with a coupled glacial fluvial and hillslope landscape evolution model that systematically explores variations in rock uplift rate and periodic variations in climate i e glacial interglacial periods over million year time scales emphasis is placed on understanding when a particular climate is either more e g buzzsaw conditions or less erosive than its preglacial landscape results indicate that the erosional efficiency of glaciers varies as a function of latitudinal controlled temperature and rock uplift rate an order of magnitude increase in erosion rates occurs in some scenarios for both localized valley bottom erosion and short term one glacial period durations of glaciation however when averaged over the entire landscape for 2 ma increases in glacial erosion are typically less than double that of the preglacial landscape in some scenarios average glacial erosion rates are less than preglacial rates due to either small inefficient glaciers or extensive cold based glaciation model predictions are compared with a compilation of long term denudation rates from glaciated mountain ranges and indicate models perform well at explaining patterns of glacial erosion efficiency the findings presented here have clear implications for the impact of glaciations on the evolution of landscapes including 1 the climatic window in which glaciers are more erosive compared to pre glacial rates 2 spatial and temporal variations in denudation that can lead to pulses of erosion and 3 predictions of glacial erosional efficiency at different latitudes we conclude that latitudinal and elevation dependent variations in temperature control the efficiency of glacial denudation and explain discrepancies between previous studies

topography based modeling of large rockfalls and application to hazard assessment 1 rockfalls are among the most important natural hazards in mountainous regions similarly to earthquakes and wildfires their sizes follow a power law distribution covering an enormous range of sizes in this paper the presumably first modeling approach that explains this power law distribution quantitatively is presented applied to the european alps the himalayas and the rocky mountains the model suggests that a power law exponent of 1 35 with respect to the detached volume is a universal property of rockfalls beyond reproducing and explaining existing statistical data the model allows an estimate on size and frequency of the largest possible rockfalls in a region which cannot be derived from available rockfall inventories so far

structural applications and discussion of a paleomagnetic post paleozoic data base for the central mediterranean abstract a post paleozoic paleomagnetic data base has been compiled for the central mediterranean with the intention of listing directions at the highest possible level of data combination the value of the entries depends on the number and quality of data available the most reliable data are those based on regionally distributed localities and sites where the age is known to a stage and where tectonic correction has been made these represent a whole tectonic unit in a given period of time the lowest quality directions are those based on few samples and isolated in space and time in the tectonic interpretation of the listed data this variation in quality of data has been taken into consideration indications for cenozoic movements having a fundamental influence on the now observable distribution of the clockwise and counter clockwise rotated paleomagnetic directions were treated first and those for older movements afterwards microplate block and nappe movements were considered as possible mechanisms for the rotation of these the last two mechanisms explained satisfactorily the occasional local deviations from a general pattern other differences however such as those which exist between the northern calcareous alps or the tisza unit and the counter clockwise rotated superunit of the central mediterranean which are large and persisted through a longer period of time are best explained by independent movement of the whole unit

establishment of a continuous gps network across the kephalonia fault zone ionian islands greece abstract we report on the establishment of a continuous gps network across the kephalonia fault zone kfz central ionian islands greece the kfz is an important segment of the boundary zone between the rapidly moving aegean microplate and the apulian platform italy repeated gps measurements carried out between the northern ionian islands and the island of crete have shown rates of crustal motion of the aegean reaching 35 mm a oriented sw relative to southern italy the kfz coincides with a maximum shear strain rate 180 nano strain a and a very high level of seismicity in order to monitor the ongoing deformation across the kfz and correlate the strain accumulation with earthquakes a continuous gps network has been installed operating at a sampling rate of 5 s this paper describes the instrumental set up the data logging strategy and first preliminary results

late pleistocene catchment wide denudation patterns across the european alps abstract we compile detrital 10be concentrations of alpine rivers representing the denudation rates pattern for 375 catchments across the entire european alps using a homogeneized framework we employ state of the art techniques for inverting in situ 10be concentrations into denudation rates from our compilation we find that i while lithologic properties and precipitation runoff do influence erosion mechanisms and rates at the scale of individual catchments and in some specific alpine regions such controls do not directly stand for the entire alps ii as also previously suggested catchment wide denudation rates across the entire european alps closely follow first order alpine topographic metrics at the scale of individual catchments or selected alpine sub regions however in addition to previous local scale studies conducted in the european alps our large scale compilation highlights a functional relationship between catchment wide denudation and mean catchment slope angle catchment wide denudation positively correlates with mean catchment slope up to a threshold angle 25 30 above this threshold any correlation between catchment wide denudation and slope as well as other catchment metrics breaks apart we can reconcile these systematic patterns by proposing a regional erosion model based on diffusive transport laws for catchments located below the slope threshold angle in oversteepened catchments situated above threshold slopes erosion is stochastic in nature as glacial carving likely caused a partial decoupling between hillslope and fluvial domains with complex topographic relationships and sediment connectivity patterns finally we identify a first order positive relationship between modern geodetic rock uplift and catchment wide denudation for the european alps the observed spatial pattern is highly variable and possibly reflects the surface response to deep geodynamic mechanisms prevailing in the different alpine regions we conclude that today s topography and geomorphic features of the entire alps are the result of a millenial scale geomorphic response to past glacial processes and active rock uplift highlighting a link between external and internal drivers for mountain erosion

regional scale controls on the spatial activity of rockfalls turtmann valley swiss alps a multivariate modeling approach abstract in mountain geosystems rockfalls are among the most effective sediment transfer processes reflected in the regional scale distribution of talus slopes however the understanding of the key controlling factors seems to decrease with increasing spatial scale due to emergent and complex system behavior and not least to recent methodological shortcomings in rockfall modeling research in this study we aim i to develop a new approach to identify major regional scale rockfall controls and ii to quantify the relative importance of these controls using a talus slope inventory in the turtmann valley swiss alps we applied for the first time the decision tree based random forest algorithm rf in combination with a principal component logistic regression pclr to evaluate the spatial distribution of rockfall activity this study presents new insights into the discussion on whether periglacial rockfall events are controlled more by topo climatic cryospheric paraglacial or and rock mechanical properties i both models explain the spatial rockfall pattern very well given the high areas under the receiver operating characteristic roc curves of 0 83 highest accuracy was obtained by the rf correctly predicting 88 of the rockfall source areas the rf appears to have a great potential in geomorphic research involving multicollinear data ii the regional permafrost distribution coupled to the bedrock curvature and valley topography was detected to be the primary rockfall control rockfall source areas cluster within a low radiation elevation belt 2900 3300 m a s l consistent with a permafrost probability of 90 the second most important factor is the time since deglaciation reflected by the high abundance of rockfalls along recently deglaciated the study demonstrates the benefit of combined statistical approaches for predicting rockfall activity in deglaciated permafrost affected mountain valleys and highlights the complex interplay between rock mechanical paraglacial and topo climatic controls at the regional scale

without power landslide inventories in the face of climate change projected scenarios of climate change involve general predictions about the likely changes to the magnitude and frequency of landslides particularly as a consequence of altered precipitation and temperature regimes whether such landslide response to contemporary or past climate change may be captured in differing scaling statistics of landslide size distributions and the erosion rates derived thereof remains debated we test this notion with simple monte carlo and bootstrap simulations of statistical models commonly used to characterize empirical landslide size distributions our results show that significant changes to total volumes contained in such inventories may be masked by statistically indistinguishable scaling parameters critically depending on among others the size of the largest of landslides recorded conversely comparable model parameter values may obscure significant i e more than twofold changes to landslide occurrence and thus inferred rates of hillslope denudation and sediment delivery to drainage networks a time series of some of earth s largest mass movements reveals clustering near and partly before the last glacial interglacial transition and a distinct step over from white noise to temporal clustering around this period however elucidating whether this is a distinct signal of first order climate change impact on slope stability or simply coincides with a transition from short term statistical noise to long term steady state conditions remains an important research challenge copyright 2011 john wiley sons ltd

holocene rockwall retreat in svalbard a triple rate evolution volumetric calculations of slope deposits direct measurements of rockwall retreat and chronological control based on lichenometry provide a wide range of rockwall retreat rates in svalbard 0 1580 mm ka 1 that appears consistent with previous evaluations from other arctic areas in northwest and central spitsbergen 79 n a triple rate rockwall retreat is suggested for the last two millennia very slow biogenic flaking 2 mm ka 1 moderate retreat due to frost shattering 100 ka 1 and rapid retreat associated with post glacial stress relaxation c 1000 mm ka 1 examination of the distribution of various processes indicates that the holocene retreat of most rockwalls has not exceeded one or two metres bedrock conditions appear to be the main control on retreat rates the massiveness of igneous and metamorphic outcrops widespread in arctic shield areas largely accounts for the slowness of rockwall retreat which on these lithologies is primarily due to chemical and biological processes more rapid rates are usually associated with stress relaxation following glacial surges or with local frost susceptibility of bedrock often where faulting has induced high joint density at such sites rockwall retreat rates are of the same order of magnitude as those reported from alpine areas 1000 3000 mm ka 1 where both bedrock weakening due to tectonic stresses and the greater height of steep rockwalls account for the more rapid rockwall retreat rate 1997 by john wiley sons ltd

statistical analysis of rockfall volume distributions implications for rockfall dynamics we analyze the volume distribution of natural rockfalls on different geological settings i e calcareous cliffs in the french alps grenoble area and granite yosemite cliffs california sierra and different volume ranges i e regional and worldwide catalogs contrary to previous studies that included several types of landslides we restrict our analysis to rockfall sources which originated on subvertical cliffs for the three data sets we find that the rockfall volumes follow a power law distribution with a similar exponent value within error bars this power law distribution was also proposed for rockfall volumes that occurred along road cuts all these results argue for a recurrent power law distribution of rockfall volumes on subvertical cliffs for a large range of rockfall sizes 102 1010 m3 regardless of the geological settings and of the preexisting geometry of fracture patterns that are drastically different on the three studied areas the power law distribution for rockfall volumes could emerge from two types of processes first the observed power law distribution of rockfall volumes is similar to the one reported for both fragmentation experiments and fragmentation models this argues for the geometry of rock mass fragment sizes to possibly control the rockfall volumes this way neither cascade nor avalanche processes would influence the rockfall volume distribution second without any requirement of scale invariant quenched heterogeneity patterns the rock mass dynamics can arise from avalanche processes driven by fluctuations of the rock mass properties e g cohesion or friction angle this model may also explain the power law distribution reported for landslides involving unconsolidated materials we find that the exponent values of rockfall volume on subvertical cliffs 0 5 0 2 is significantly smaller than the 1 2 0 3 value reported for mixed landslide types this change of exponents can be driven by the material strength which controls the in situ topographic slope values as simulated in numerical models of landslides densmore et al 1998 champel et al 2002 index terms 5104 physical properties of rocks fracture and flow 1815 hydrology erosion and sedimentation 8122 tectonophysics dynamics gravity and tectonics

significance of rockfall magnitude and carbonate dissolution for rock slope erosion and geomorphic work on alpine limestone cliffs reintal german alps abstract the proportional contribution of low mid and high magnitude rock slope failure orchestrates rock slope erosion and rockfall hazard in alpine and arctic environments in this study we compare sediment yield geomorphic work and rock wall retreat of carbonate dissolution and five different magnitudes of rock slope failure in the steep alpine reintal trough valley we combine a four year rockfall collector measurement of 140 mg of fragmental rockfall a 20th century scientific record of mid magnitude rockfall as well as carbon dating and a historical record of 15th to 19th century rock avalanche activity the total rockfall sediment yield of 8 6 3 4 10 3 m 3 year 1 is dominated by high magnitude rock avalanches 10 6 m 3 62 and low magnitude debris falls 3 18 while mid magnitude boulder block and cliff falls are less important the magnitude signal contradicts studies on siliceous rocks where mid magnitude rockfall dominates rock slope erosion the geomorphic work released in the 17 3 km 2 large catchment by rockfalls 123 47 w km 2 i e 0 38 0 15 mm year 1 and solute transport 34 18 w km 2 i e 0 05 0 03 mm year 1 exceeds previously published alpine values by one to multiple orders of magnitude we hypothesise that the magnitude signal of enhanced small and high magnitude rockfall is characteristic for carbonate cliffs the elevated porosity related susceptibility to fragmentation and persistent carbonate dissolution along potential sliding planes are likely to favour both low and high magnitude rock slope failures here we show how the magnitude signal of rock slope failure influences rock wall retreat geomorphic work rockfall deposition and sediment connectivity

paleomagnetic results from mio pliocene marine sedimentary series in crete abstract paleomagnetic measurements have been conducted on mio pliocene marine sedimentary series from crete in order to detect any eventual rotation of this island the results obtained from 14 stable sites of tortonian age 7 m y yield a paleomagnetic pole not significantly different from either the european or the african ones showing that crete has not undergone any significant rotation since that epoch

differential neotectonic rotations in anatolia and the tauride arc palaeomagnetic investigation of the erenlerdaǧ volcanic complex and isparta volcanic district south central turkey abstract in the anatolian sector of the alpine himalayan collisional belt a palaeotectonic phase of terrane accretion has been succeeded by a neotectonic phase of intracontinental deformation as the afro arabian plate has continued to impinge differentially into the accreted collage the resulting tectonic escape has during the last few million years extruded and rotated blocks in a southwesterly direction this paper reports a palaeomagnetic investigation of the erenlerda volcanic complex and isparta alkaline volcanic district undertaken to extend analysis of crustal rotation into the southwestern part of the anatolian region and investigate the interaction with the isparta angle and the extensional province of western turkey the erenlerda volcanism comprises three phases of volcanism the oldest sille volcanics 11 7 11 4 ma yield a mean d 150 i 52 rotated anticlockwise during early stages of crustal thickening and deformation before a later miocene episode c 10 9 8 9 ma d 183 i 47 and a mio pliocene episode d 179 i 51 the latter two episodes indicate that no significant rotation has resulted during the neotectonic crustal extrusion in this southwestern sector of anatolia further to the west within the isparta angle a 4 7 4 0 ma alkaline episode yields a mean of d 186 i 53 rotated slightly clockwise the pattern of palaeomagnetic declinations across anatolia shows rotations that are strongly anticlockwise in the east near the arabian pincer and diminish towards the west to become zero or slightly clockwise at the western extremity of the collage the timing of rotation also appears to become younger towards the south crustal deformation has therefore been distributed and the net effect of terrane extrusion to the west and south has been to expand the curvature of the tauride arc and by inference the cyprian arc where good age control exists in cappadocia and the sivas basin rotations are found to be concentrated within the last few million years and are up to an order higher than rates deduced from global positioning system the palaeomagnetic data imply that the neotectonic deformation following collision initially produced crustal thickening resulting in uplift of the anatolian plateau and was only subsequently accommodated by major differential block rotation during tectonic escape

landslides as a geomorphological proxy for climate change a record from the dolomites northern italy abstract this study investigates the relationships between climate changes and hillslope evolution in the dolomites eastern alps italy during the late quaternary with particular attention paid to landslide processes the basic premise is that modifications in landslide frequency may be interpreted as changes in the hydrological conditions of slopes which are in turn controlled by climate after the statistical analysis of a data set composed of 73 conventional radiocarbon ages obtained from 24 landslides four periods of enhanced landsliding have been identified i from 10 700 to 8400 cal bp between younger dryas and the preboreal ii from 8200 to 6900 cal bp during the older atlantic iii from 5800 to 4500 cal bp between atlantic and subboreal and iv from 4000 to 2100 cal bp between subboreal and subatlantic these periods have been compared with different lateglacial and holocene paleoclimatic records to check the correspondence between periods of enhanced landslide activity and cold and humid spells recognized at different spatial scales as the records show in the study areas slope instability processes can be considered geomorphological indicators of climatic changes and to a certain extent reliable proxies of environmental evolution

carbonate and silicate biomineralization in a hypersaline microbial mat mesaieed sabkha qatar roles of bacteria extracellular polymeric substances and viruses in a modern peritidal microbial mat from qatar both biomediated carbonates and mg rich clay minerals palygorskite were identified the mat ca 5 cm thick shows a clear lamination reflecting different microbial communities the initial precipitates within the top millimetres of the mat are composed of ca mg si al s amorphous nanoparticles few tens of nanometres that replace the ultrastructure of extracellular polymeric substances the extracellular polymeric substances are enriched in the same cations and act as a substrate for mineral nucleation successively crystallites of palygorskite fibres associated with carbonate nanocrystals develop commonly surrounding bacterial bodies micron sized crystals of low mg calcite are the most common precipitates together with subordinate aragonite very high mg calcite dolomite and ankerite pyrite nanocrystals and framboids are present in the deeper layers of the mat calcite crystallites form conical structures circular to triangular hexagonal in cross section evolving to crystals with rhombohedral terminations some crystallite bundles develop into dumb bell and stellate forms spheroidal organo mineral structures are also common within the mat nanospheres a few tens of nanometres in diameter occur attached to coccoid bacteria and within their cells these are interpreted as permineralized viruses and could be significant as nuclei for crystallite crystal precipitation microspheres 1 to 10 m in diameter result from intracellular permineralization within bacteria or the mineralization of the bacteria themselves carbonates and clay minerals are commonly aggregated to form peloids tens of microns in size surrounded by residual organic matter magnesium silicate and carbonate precipitation are likely to have been driven by ph saturation index redox changes within the mat related to microenvironmental chemical changes induced by the microbes extracellular polymeric substances viruses and their degradation

paleomagnetic evidence for an inverse rotation history of western anatolia during the exhumation of menderes core complex abstract within the aegean extensional system the izmir balikesir transfer zone ibtz is a crucial element in the late cenozoic evolution of western anatolia since it accommodates the differential deformation between the cycladic and the menderes metamorphic core complexes here we determine the rotational history of western anatolia using new paleomagnetic data from 87 sites in miocene volcano sedimentary rocks to better understand the role of the ibtz our results reveal two discrete and opposite major rotational phases during the miocene the first phase is derived from early miocene volcanic sedimentary and granitic rocks and is controlled by detachment and strike slip faults it is characterized by an average net 23 6 clockwise cw rotation within the ibtz since the early miocene our new data from the menderes part on the other hand show an average 23 10 counter clockwise ccw rotation the data from the cycladic part show no significant net rotation since the early miocene the second phase is derived from middle late miocene volcanic and sedimentary rocks and is controlled by high angle normal and strike slip faults the rotations from this phase show a very consistent pattern of 22 11 ccw within the ibtz while now the menderes part shows an average cw rotation of 25 14 our paleomagnetic results hence document a major change and inversion of rotation between the early and late miocene the ibtz region experienced a large 45 cw rotation while during the same time interval the menderes part outside the zone experienced a similar 48 ccw rotation after that the ibtz became narrower and the sense of rotation inverted to ccw 23 10 since the late miocene while in the menderes part it inverted to cw 25 14 since the late miocene our new results do therefore fit the hypotheses of two stage extension scenario rather than a one single phase of extension we also conclude that the observed rotations are not directly related to major detachment faulting but to the change in extensional regime of western anatolia the focal mechanism solutions of recent seismic events corroborate that the ibtz is still active and transfers west anatolian extensional strain into the south aegean sea

contribution of deep seated bedrock landslides to erosion of a glaciated basin in southern alaska landslides represent a key component of catchment scale denudation though their relative contribution to the erosion of glaciated basins is not well known bedrock landslide contribution was investigated on the surface of one of eleven glaciers on a glaciated ridge in the chugach st elias range of southern alaska where the debris from four major landslides is easily distinguished from moraines and other supraglacial material a series of aerial and satellite photos from 1972 to 2000 and field observations in 2001 and 2002 indicate that three of four landslides have fallen onto the surface of the glacier since about 1978 the landslides which originated from the steeply dipping 60 70 bedrock walls were deposited onto the glacier in the ablation zone and are currently being transported downstream supraglacially individual glacial valleys with topographic relief of 400 m are cut into highgrade metamorphic rock characterized by a steep north dipping foliation and fractured by numerous large joints measurements of landslide area and average thickness obtained from high resolution survey data indicate a total landslide volume of 2 3 10 5 m 3 this volume suggests a basin averaged erosion rate from landslides of 0 48 mm a 1 an overall basin scale erosion rate of 0 7 to 1 7 mm a 1 can be inferred but depends on the percentage of the totalbasin sediment yield contributed by supraglacial sources a mean rockwall retreat rate of 6 7 mm a 1 is calculated and is considerably higher than published rates which range from 0 04 to 4 0 mm a 1 controls on landslide generation include seismicity freeze thaw processes topography rock strength and debuttressing it is likely all of these factors contribute to failure although the primary controls for the landslides in this study are thought to be rock strength and topography the absence of landslides on ten of the eleven glaciers on this ridge is attributed to landslide magnitude frequency relationships and short temporal scale of this study large volume bedrock landslides 100 000 m 3 may have low frequency occurring less than once in a 55 year time frame copyright 2005 john wiley sons ltd

early holocene 8 6 ka rock avalanche deposits obernberg valley eastern alps landform interpretation and kinematics of rapid mass movement in the obernberg valley the eastern alps landforms recently interpreted as moraines are re interpreted as rock avalanche deposits the catastrophic slope failure involved an initial rock volume of about 45 million m with a runout of 7 2 km over a total vertical distance of 1330 m fahrboschung 10 36cl surface exposure dating of boulders of the avalanche mass indicates an event age of 8 6 0 6 ka a 14c age of 7785 190 cal yr bp of a palaeosoil within an alluvial fan downlapping the rock avalanche is consistent with the event age the distal 2 km of the rock avalanche deposit is characterized by a highly regular array of transverse ridges that were previously interpreted as terminal moraines of late glacial jigsaw puzzle structure of gravel to boulder size clasts in the ridges and a matrix of cataclastic gouge indicate a rock avalanche origin for a wide altitude range the avalanche deposit is preserved and the event age of mass wasting precludes both runout over glacial ice and subsequent glacial overprint the regularly arrayed transverse ridges thus were formed during freezing of the rock avalanche deposits

strong proximal earthquakes revealed by cosmogenic 3he dating of prehistoric rockfalls christchurch new zealand the 2011 rupture of previously undetected blind faults beneath christchurch new zealand in moment magnitude m w 6 2 and 6 0 earthquakes triggered major rockfalls that caused fatalities and infrastructure damage here we use field geospatial seismologic numerical modeling and cosmogenic 3 he data to provide first evidence for prehistoric rockfall ca 8 6 ka and a possible preceding event ca 14 13 ka at a site where extensive rockfall occurred in the christchurch earthquakes the long 7 1 k y time intervals between successive rockfall events and the high peak ground velocity thresholds required for rockfall initiation at this site 20 30 cm s preclude earthquakes from major identified seismic sources including the plate boundary alpine fault as likely rockfall triggering sources rockfalls were probably triggered by strong paleoearthquakes sourced from active faults proximal i e 10 20 km to christchurch including the sources of the 2011 christchurch earthquakes and or other currently unidentified faults given the inherent incompleteness of seismic source catalogues and challenges in obtaining earthquake chronologies for blind faults high scientific priority should be given to the search for and analysis of geologic records of strong earthquake shaking near populated areas

ionian sea western greece its structural outline deduced from drilling and geophysical data abstract this paper outlines the preliminary structural results obtained by the compilation of geological drilling and geophysical data in western greece most external geotectonic zones of the hellenides are included in the geological setting of the marine and insular domain of western greece ionian pre apulian and apulian zones the gavrovo and pindus zones make a restricted contribution to the marine geological framework continental shelf of southwest peloponesus besides the geographical setting of the geotectonic units their general tectonic characteristics allow the following remarks to be made the main tectonic events younger than eocene are well marked in both ionian and pre apulian zones the detrital sequence shows a fast pinch out towards the apulian platform where the plio quaternary clastic layers overlap what are probably late mesozoic or early tertiary limestones taking into consideration general tectonic features we can distinguish a northern area and a southern one separated by a fault trending 30 n located on the western margin of kephallinia lefkas islands 1 a in the northern area we observe a strong tangential tectonism decreasing towards the apulian platform with transitional characteristics on the pre apulian zone paxos where asymmetrical folding occurs 2 b in the southern area from lefkas kephallinia islands to the s w cape of peloponesus the tangential tectomism is well masked by strong vertical faulting attributed to young plio quaternary deformations the fast subsidence induces huge diapiric structures in the ionian zone salt walls originating from triassic layers intersect a thick pleistocene sequence

map view restoration of aegean west anatolian accretion and extension since the eocene 1 the aegean region greece western turkey is one of the best studied continental extensional provinces here we provide the first detailed kinematic restoration of the aegean region since 35 ma the region consists of stacked upper crustal slices nappes that reflect a complex paleogeography these were decoupled from the subducting african adriatic lithospheric slab especially since 25 ma extensional detachments cut the nappe stack and exhumed its metamorphosed portions in metamorphic core complexes we reconstruct up to 400 km of trench perpendicular ne sw extension in two stages from 25 to 15 ma the aegean forearc rotated clockwise relative to the moesian platform around euler poles in northern greece accommodated by extensional detachments in the north and an inferred transfer fault se of the menderes massif the majority of extension occurred after 15 ma up to 290 km by opposite rotations of the western and eastern parts of the region simultaneously the aegean region underwent up to 650 km of post 25 ma trench parallel extension leading to dramatic crustal thinning on crete we restore a detachment configuration with the mid cycladic lineament representing a detachment that accommodated trench parallel extension in the central aegean region finally we demonstrate that the sakarya zone and cretaceous ophiolites of turkey cannot be traced far into the aegean region and are likely bounded by a pre 35 ma n s fault zone this fault became reactivated since 25 ma as an extensional detachment located west of lesbos island the paleogeographic units south of the izmir ankara sava suture however can be correlated from greece to turkey

tertiary geodynamical evolution of northwestern greece paleomagnetic results abstract paleomagnetic results have been obtained from 29 sites sampled in lower to upper oligocene flysch sections of the ionian zone in northwestern greece they indicate a clockwise rotation of about 45 of the entire region a comparison with previously published results relative to both younger and older formations shows that this rotation has occurred in two phases of comparable amplitude one during middle miocene and the other during pliocene and quaternary separated by a period of at least 7 ma during which no significant rotation has occurred no major rotation has occurred during the entire paleocene and eocene stages this large measured rotation implies a horizontal displacement of at least 100 km in epirus possible mechanisms involving a rotation of the nappe sheets rotation of the basement or a combination of the two are discussed the two phases of paleomagnetic rotation can be correlated with the tertiary and quaternary calc alkaline volcanic activity in the aegean sea a palinspastic reconstruction shows that the orientation of the major structures now striking n155 was almost east west in the middle miocene at the epoch of their formation

arctic rockwall retreat rates estimated using laboratory calibrated ert measurements of talus cones in longyeardalen svalbard holocene rockwall retreat rates quantify integral values of rock slope erosion and talus cone evolution here we investigate holocene rockwall retreat of exposed arctic sandstone cliffs in longyear

palaeomagnetic evidence from pelagic limestones for clockwise rotation of the ionian zone western greece abstract on the basis of a pilot study of all the major carbonate lithologies in the ionian zone of western greece the upper part of the upper senonian to upper eocene microbreccious limestones formation was selected as the most suitable facies for a detailed regional palaeomagnetic study the 51 sites sampled are situated on flanks of anticlines or monoclines which post date the acquisition of the characteristic remanent magnetization the regional folding occurred during post late eocene emplacement of nappe sheets which had undergone decollement on triassic evaporitic horizons the palaeomagnetic directions after correction for deviations of local fold axis orientation have a regional significance after this correction the mean palaeodeclination is about 35 e relative to the geographic pole with respect to the early tertiary african pole position these palaeodeclinations indicate an apparent 38 clockwise rotation of the nappe sheets the palaeoinclinations support a palaeogeographic model locating the carbonate sediments of the ionian zone on the northeastern margin of the adriatic promontory of the african plate the total rotation implied by the palaeodeclination data is possibly due to a combination of two different mechanisms 1 1 rotation of the nappe sheets during overthrust and emplacement during the main mid miocene compressional phase of deformation 2 2 rotation of the ionian zone basement and nappes associated with extension in the aegean basin during the last 13 m y

magnitude frequency relation for rockfall scars using a terrestrial laser scanner abstract the analysis of the three dimensional rockfall scar geometry provides clues for the understanding of the failure mechanisms acting on cliffs of the conditioning factors and on the frequency of the events in this paper a supervised step by step methodology is presented for establishing the statistical magnitude frequency relation of rockfall scar volumes using a point cloud from terrestrial laser scanner tls data the methodology includes a procedure for identifying discontinuity surfaces calculating the areas of those which are exposed and the height of rockfall scars in the estimation of the rockfall scar volume a key issue is the consideration of the minimum spacing of the discontinuity sets to differentiate between step path surfaces and undulated ones having obtained the distributions of both the basal area and height of the scar across the slope the volume of the rockfall scars is calculated stochastically by multiplication of these two parameters by means of a monte carlo simulation both distributions of the basal area and of the rockfall scar volume are found to be power law with the exponent b ranging from 0 9 to 1 2 the relation obtained might be used as a first approach of rockfall magnitude frequency curves in large cliffs

mid holocene cluster of large scale landslides revealed in the southwestern alps by 36cl dating insight on an alpine scale landslide activity abstract although it is generally assumed that the internal structure of a slope e g lithology and rock mass properties inherited faults and heterogeneities etc is preponderant for the progressive development of large scale landslides the ability to identify triggering factors responsible for final slope failures such as glacial debuttressing seismic activities or climatic changes especially when considering landslide cluster at an orogen scale is still debated highlighting in this study the spatial and temporal concordant clustering of deep seated slope failures in the external southwestern alps we discuss and review the possible causes for such wide spread slope instabilities at both local and larger alpine scale high resolution field mapping coupled with electrical resistivity tomography first allows establishing an inventory of large landslides in the southwestern alps determining their structural model precising their depth limit 100 200 m as well as the involved rock volumes 10 7 m 3 we show that they developed in the same geostructural context of thick mudstone layers overlain by faulted limestone and followed a block spread model of deformation that could evolve in rock collapse events cosmic ray exposure dating cre using both 36 cl and 10 be in coexisting limestone and chert respectively has been carried out from the main scarps of six deep seated landslides dsl and leads to landslide failure cre ages ranging from 3 7 to 4 7 ka they highlighted i mainly single and fast ruptures and ii a possible concomitant initiation with a main peak of activity between 3 3 and 5 1 ka centered at ca 4 2 ka because this region was not affected by historical glaciations events landslide triggering by glacial unloading can be excluded the presented data combined with field observations preferentially suggest that these failures were climatically driven and were most likely controlled by high pressure changes in the karstic medium in effect the chronicle of failure ages is concomitant to a well known climatic pulse the 4 2 ka climate event characterized by intense hydrological perturbations associated to the heaviest rainfall period of the entire holocene despite requiring further investigations and discussions the dating of numerous events across the entire alps during the middle holocene period suggests a potential synchronous triggering of several large scale gravitational failures induced by the mid holocene climatic transition

climatic controls on frost cracking and implications for the evolution of bedrock landscapes 1 in mountainous landscapes the role of periglacial processes in producing sediment is poorly defined despite evidence of abundant talus slopes ice growth in rock has long been recognized as an efficient erosion mechanism but the effects have not been readily applied to landscape evolution in response to tectonic and climatic forcing here we quantify how and where ice driven mechanical erosion occurs in cold bedrock dominated landscapes using a simple one dimensional numerical heat flow model in our model ice grows by water migration to colder regions in shallow rock by the reduction in chemical potential associated with intermolecular forces between ice and mineral surfaces a process called segregation ice growth the depth and intensity of frost cracking is primarily dependent on mean annual temperature mat with positive mat sites characterized by intense cracking in the top meter of the rock mass and a maximum frost penetration of 4 m in contrast negative mat areas have less intense cracking that primarily occurs at depths between 50 and 800 cm we compare the depth and intensity of frost cracking predicted by our model with measures of the intensity of frost processes determined in three studies the first measured the timing of rockfall in the canadian rockies niagara escarpment and japanese alps the second analyzed scree deposits in the southern alps new zealand and the third documented rockfall frequency in utah these natural examples show that rockfalls tend to nucleate at elevations that coincide with zones of intense frost cracking predicted by our model as such climatic variations associated with interglacial glacial cycles may impart a significant influence on the denudation of mountainous landscapes

palaeomagnetism and magnetic properties of the cappadocian ignimbrite succession central turkey and neogene tectonics of the anatolian collage abstract the cappadocian ignimbrite succession of central southern anatolia comprises at least nine major and two minor calc alkaline rhyolitic sheets emplaced at 1 2 ma intervals between 11 2 and 1 1 ma it records the last phase of neotethyan subduction during final emplacement of the tauride orogen in southern turkey this study reports magnetostratigraphy and describes associated rock magnetic properties remanence resides in ti poor titanomagnetites haematisation is locally produced by post emplacement oxidation but does not contribute significantly to the palaeomagnetic signature although secondary processes within the ignimbrite sheets have produced composite isothermal remanent magnetisation spectra and variable intensities of magnetisation weak anisotropy of magnetic susceptibility describes tensors with maximum axes close to bedding and minimum axes perpendicular to this plane directions of kmax with weak imbrication mostly suggest flow away from centres of eruption located by gravity and remote sensing older ignimbrites upper and lower goreme akdag zelve from the cardak centre are all of normal polarity later ignimbrites partly erupted from the derinkuyu centre comprise the sarimaden r cemilkoy r tahar r kizilkaya r incesu n and valibaba sofular r ignimbrites the overall reversed group mean is d i 174 51 n 10 units r 9 84 95 6 6 k 55 and all magnetisation directions from the upper goreme 9 0 ma onwards are rotated anticlockwise with respect to eurasian and african palaeofields this sense of rotation characterises most of central anatolia and averages 9 5 in this sector the rotation rate from 8 to 1 ma bp was 1 25 ma but it appears to have accelerated during the latter part of the quaternary to about an order higher than rates determined from gps rotation has resulted from extrusion of fault blocks during tectonic escape of the anatolian collage to the southwest and followed crustal thickening as the afro arabia plate has continued to impinge differentially into eurasia cenozoic magnetic inclinations are systematically shallower across anatolia than inclinations expected from the geocentric dipole model and the apparent polar wander of bordering major plates only part of this difference 400 km can be accommodated by northward movement and crustal thickening in central anatolia since mid miocene times shallow inclinations observed in the aegean region extend into turkey they are observed in young volcanics and appear to reflect a regional geomagnetic anomaly the pattern of neotectonic declinations across anatolia shows rotations that are strongly anticlockwise rotated in the east near the arabian pincer but diminish towards the west to become zero or slightly clockwise at the western extremity of the collage rotations also seem to become generally younger towards the south crustal deformation has therefore been distributed and the net effect of terrane extrusion to the west and south has been to expand the curvature of the tauride arc and by inference the cyprus arc

modeling cliff erosion using negative power law scaling of rockfalls we model cliff erosion using an approach based upon the negative power law scaling properties of rockfall magnitude frequency distributions these are derived from an extensive high resolution rockfall inventory for a series of sea cliffs near staithes north yorkshire a comparison between observed volumetric erosion and that produced by the model yields a statistically significant correlation however we note that the temporal resolution of the inventory can have an influence on results our data indicate that monthly inventories are capable of producing magnitude frequency relations that model erosion in good correlation with observed events however for months that experience high magnitude events seasonal inventories are more appropriate furthermore increasing the return period between surveys has the effect of increasing the superimposition of rockfall events thereby reducing the slope of the power law giving an incorrect picture of the scaling properties of rockfalls at this site applying observed variations in the negative power law scaling parameters to a probabilistic simulation model of cliff retreat provides a new means of assessing the most likely erosional scenarios and indicates that the current dataset may not be indicative of long term cliff evolution this may provide a quantitative means of establishing an appropriate time window for characterizing rockfall erosion over decadal time scales