an automated so 2 camera system for continuous real time monitoring of gas emissions from kīlauea volcano s summit overlook crater abstract so 2 camera systems allow rapid two dimensional imaging of sulfur dioxide so 2 emitted from volcanic vents here we describe the development of an so 2 camera system specifically designed for semi permanent field installation and continuous use the integration of innovative but largely off the shelf components allowed us to assemble a robust and highly customizable instrument capable of continuous long term deployment at k lauea volcano s summit overlook crater recorded imagery is telemetered to the usgs hawaiian volcano observatory hvo where a novel automatic retrieval algorithm derives so 2 column densities and emission rates in real time imagery and corresponding emission rates displayed in the hvo operations center and on the internal observatory website provide hvo staff with useful information for assessing the volcano s current activity the ever growing archive of continuous imagery and high resolution emission rates in combination with continuous data from other monitoring techniques provides insight into shallow volcanic processes occurring at the overlook crater an exemplary dataset from september 2013 is discussed in which a variation in the efficiency of shallow circulation and convection the processes that transport volatile rich magma to the surface of the summit lava lake appears to have caused two distinctly different phases of lake activity and degassing this first successful deployment of an so 2 camera for continuous real time volcano monitoring shows how this versatile technique might soon be adapted and applied to monitor so 2 degassing at other volcanoes around the world

rock slope reliability analysis based on distinct element method and random set theory abstract the random set distinct element method rs dem has been developed and applied in the stability analysis of a rock slope from china in this study the influence of the discontinuity of joints of rock material on the slope stability is considered and the sensitivity analyses for different input parameters have been conducted the uncertainties of the strength parameters of both rock blocks and discontinuity joints are considered in the reliability analysis model in this study the commercial distinct element code udec has been used to model the rock material and the strength reduction method is used to calculate the safety factor of slope

a model for slow motion of natural slopes a new model for describing the slow movement of natural slopes is proposed the geological material in the slope is modeled with a nonhomogeneous bingham constitutive equation this model describes the effect of gravitational consolidation on the material response and allows for a variation of density and yield stress with depth a criterion for shear flow initiation is formulated and the ensuing motion is described velocity profiles for several slip conditions at the interface with the bedrock are given the model is used to predict the observed field behavior of a natural slope villarbeney switzerland key words natural slope incipient shear flow nonhomogeneous bingham law creep flow gravitational consolidation

back analysis of a rock landslide to infer rheological parameters abstract on 30 january 2009 a rock slide involving approximately 0 23 mm 3 of highly jointed gneiss from the local ercinic substratum was recorded in southern italy the landslide occurred after exceptional autumnal rainfalls and involved a quarry whose activity has been documented over the past 10 years by aerial images an engineering geology model of the slope involved in the landslide was developed based on the geomechanical classification of the outcropping rock masses the isrm 2007 indexes ib the block size index and jv the volumetric joint count and the observed geological setting of the slope an equivalent continuum approach was adopted to attribute strength and stiffness parameter values to the different classes of jointed rock masses a simplified evolutionary model of the slope was developed starting from 300 ka i e from the erosional phase following the deposition of the 300 m a s l marine terrace deposits overlaying the gneiss substratum to 30 january 2009 the model took into account the main depositional phases as indicated by the pleistocene marine terrace deposits and the documented stages of quarry activity time dependent stress strain numerical modelling was performed by the fdm software flac 6 0 a visco plastic burger model was used to back analyse the landslide event and to define the values of the rheological parameters for the jointed gneiss the results which were strongly constrained by the geomorphological evidences and by the displacement field observed before and after the landslide demonstrated a combination of i time dependent gravitational slope deformation and ii anthropogenic release due to quarry activity which induced a progressive failure process and an increase in the jointing within the gneissic rock mass located behind the cut wall of the quarry failure was ultimately triggered by intense rainfalls that occurred in the 3 months before the landslide the stress strain numerical modelling demonstrated the reliability of visco plastic rheology for simulating the rock mass creep in this case history viscosity values in the range of 10 19 10 23 pa s were derived

the valpola landslide abstract the large valpola landslide which occurred on july 28 1987 in valtellina central alps italy on the eastern slope of mt zandila is described and analyzed the slide which took place after a period of heavy rainfall involved a slope made up of 34 million cubic meters of fractured igneous rock the rock mass detached between the elevations of 2250 and 1700 m above s l and with the characteristics of a rock avalanche fell approximately 800 m devastating the bottom of the valley over a distance of 4 km and killing 27 people the mass movement was due to the reactivation of a paleoslide triggered by the rise of hydrostatic pressure in the fractured rock mass and by deep erosion along the bed of pola creek in order to mitigate the risks connected with slope instabilities comprehensive surveying and prediction methods are necessary monitoring since july 28 1987 has been very successfull in assisting prediction

remote determination of sif4 in volcanic plumes a new tool for volcano monitoring sif4 is probably a common trace component of fumarole gases on volcanoes arising from interactions between magmatic hf and wall rocks it is not distinguished from hf in conventional analyses a strong absorption band at 1032 cm 1 makes sif4 well suited to remote open path ftir spectroscopic techniques we report the first measurements of sif4 in volcanic gases at etna and vulcano sicily sif4 concentrations were low at etna but higher at vulcano where the so2 sif4 ratio was consistently around 1 7 10 2 1 thermodynamic considerations show that the hf sif4 ratio increases sharply with increasing temperature thus remote measurements of sif4 may offer a qualitative way of constraining fumarole temperatures we use our ftir measurements of hcl sif4 in combination with conventional measurements of hcl hf to infer an hf sif4 ratio for vulcano of 10 1 consistent with gas temperatures in the range 200 450 c

terrestrial laser scanning of rock slope instabilities this manuscript presents a review on the application of a remote sensing technique terrestrial laser scanning tls to a well known topic rock slope characterization and monitoring although the number of publications on the use of tls in rock slope studies has rapidly increased in the last 5 10 years little effort has been made to review the key developments establish a code of best practice and unify future research approaches the acquisition of dense 3d terrain information with high accuracy high data acquisition speed and increasingly efficient post processing workflows is helping to better quantify key parameters of rock slope instabilities across spatial and temporal scales ranging from cubic decimetres to millions of cubic metres and from hours to years respectively key insights into the use of tls in rock slope investigations include a the capability of remotely obtaining the orientation of slope discontinuities which constitutes a great step forward in rock mechanics b the possibility to monitor rock slopes which allows not only the accurate quantification of rockfall rates across wide areas but also the spatio temporal modelling of rock slope deformation with an unprecedented level of detail studying rock slopes using tls presents a series of key challenges from accounting for the fractal character of rock surface to detecting the precursory deformation that may help in the future prediction of rock failures further investigation on the development of new algorithms for point cloud filtering segmentation feature extraction deformation tracking and change detection will significantly improve our understanding on how rock slopes behave and evolve perspectives include the use of new 3d sensing devices and the adaptation of techniques and methods recently developed in other disciplines as robotics and 3d computer vision to rock slope instabilities research

combining digital elevation model analysis and run out modeling to characterize hazard posed by a potentially unstable rock slope at turtle mountain alberta canada abstract turtle mountain in alberta canada has become an important field laboratory for testing different techniques related to the characterization and monitoring of large slope mass movements as the stability of large portions of the eastern face of the mountain is still questionable in order to better quantify the volumes potentially unstable and the most probable failure mechanisms and potential consequences structural analysis and runout modeling were preformed the structural features of the eastern face were investigated using a high resolution digital elevation model hrdem according to displacement datasets and structural observations potential failure mechanisms affecting different portions of the mountain have been assessed the volumes of the different potentially unstable blocks have been calculated using the sloping local base level slbl method based on the volume estimation two and three dimensional dynamic runout analyses have been performed calibration of this analysis is based on the experience from the adjacent frank slide and other similar rock avalanches the results will be used to improve the contingency plans within the hazard area

the structure dynamics and chemical composition of noneruptive plumes from mount st helens 1980 1988 abstract from may 1980 to september 1988 more than 1000 fixed wing aircraft flights were made with a correlation spectrometer to measure the sulfur dioxide flux from mount st helens volcano these flights also provided valuable data on the structure and dynamics of noneruptive plumes emanating from mount st helens during 1980 and part of 1981 an infrared spectrometer was also used to measure carbon dioxide emission rates at distances up to 25 km from mount st helens plume widths can range up to 20 km or more with width thickness ratios from 3 to about 30 maximum sulfur dioxide concentrations in these plumes depend on wind speed and are typically under 5 ppm and usually 1 ppm or less close examination of the plume data reveals that the characteristics of quiescent plumes from mount st helens are strongly affected by certain meteorological conditions such as thermal and wind stratification in the troposphere as well as by the topography of the volcano

before the frank slide the frank slide occurred on the east limb of the turtle mountain anticline which was thrust up along the folded and splayed turtle mountain fault easterly dipping paleozoic limestones and dolomi

real time seismic amplitude measurement rsam a volcano monitoring and prediction tool seismicity is one of the most commonly monitored phenomena used to determine the state of a volcano and for the prediction of volcanic eruptions although several real time earthquake detection and data acquisition systems exist few continuously measure seismic amplitude in circumstances where individual events are difficult to recognize or where volcanic tremor is prevalent analog seismic records provide a quick visual overview of activity however continuous rapid quantitative analysis to define the intensity of seismic activity for the purpose of predicing volcanic eruptions is not always possible because of clipping that results from the limited dynamic range of analog recorders at the cascades volcano observatory an inexpensive 8 bit analog to digital system controlled by a laptop computer is used to provide 1 min average amplitude information from eight telemetered seismic stations the absolute voltage level for each station is digitized averaged and appended in near real time to a data file on a multiuser computer system raw realtime seismic amplitude measurement rsam data or transformed rsam data are then plotted on a common time base with other available volcano monitoring information such as tilt changes in earthquake activity associated with dome building episodes weather and instrumental difficulties are recognized as distinct patterns in the rsam data set rsam data for domebuilding episodes gradually develop into exponential increases that terminate just before the time of magma extrusion mount st helens crater earthquakes show up as isolated spikes on amplitude plots for crater seismic stations but seldom for more distant stations weather related noise shows up as low level long term disturbances on all seismic stations regardless of distance from the volcano implemented in mid 1985 the rsam system has proved valuable in providing up to date information on seismic activity for three mount st helens eruptive episodes from 1985 to 1986 may 1985 may 1986 and october 1986 tiltmeter data the only other telemetered geophysical information that was available for the three dome building episodes is compared to rsam data to show that the increase in rsam data was related to the transport of magma to the surface thus if tiltmeter data is not available rsam data can be used to predict future magmatic eruptions at mount st helens we also recognize the limitations of rsam data two examples of rsam data associated with phreatic or shallow phreatomagmatic explosions were not preceded by the same increases in rsam data or changes in tilt associated with the three dome building eruptions

contribution a l analyse de la deformation et de la rupture des grands versants rocheux en terrain cristallophyllien in mountainous regions the study of the stability of rock slopes is of major importance for land management and safety of populations the monitoring of several unstable alpine slopes has shown th

down slope variation in geotechnical parameters and pore fluid control on a large scale alpine landslide abstract a geotechnical investigation has been carried out on a large volume landslide in the stambach valley on the slopes above the town of bad goisern austria undrained loading has been considered as a means of triggering a large volume debris flow the initiation of this landslide has been linked with the collapse of rock pillars from the rock face of zwerchwand onto the head of the flow the concept of pore tensions resulting from stress relief has been used to account for the time delays of up to 10 months between the loading and the reactivation of the debris flow

exhaustion and steady state models for predicting landslide hazards in the canadian rocky mountains abstract the temporal distribution of landslides can be evaluated by steady state and exhaustion models the probability of landsliding remains constant through time in the steady state model but the probability decreases in the exhaustion model as more slopes fail rock sliding down bedding surfaces on overdip slopes exhausts hazardous sites to leave stable dipslope landforms in kananaskis country in the canadian rocky mountains the distribution of rock slides in this area can be better explained by the exhaustion model than by the steady state model

from the source area to the deposit collapse fragmentation and propagation of the frank slide the combination of structural data from the source area and descriptive data from the deposit s carapace as well as remote sensing and statistical analysis allows a better understanding of the collapse fragmentation and propagation processes of the frank slide rock avalanche the in situ observed conservation of the stratigraphic sequence of the turtle mountain anticline s normal limb in the deposit is interpreted as the consequence of the collapse mode involving simple shearing of the mass accompanied by a rotational movement i e a simple shear parallel to the topography and a breakage of the hinge followed by overthrusting of the normal limb on the inverse limb coherence between the block size distributions of the source area and the deposit carapace is interpreted as a demonstration of the primary control of preexisting fracturing on the fragmentation processes remote sensing indexes allow us to uncover a priori hidden morphological features preserved on the surface of the deposit i e longitudinal and compressional features as well as lobes their location on the carapace provides evidence of lateral heterogeneity in the propagation highlighted by three different types of propagation behaviors this comprehensive study not only provides elements that contribute to an understanding of the frank slide rock avalanche but it also provides insight into essential parameters to take into account in further modeling of these types of phenomena

passive infrared remote sensing evidence for large intermittent co2 emissions at popocatepetl volcano mexico abstract passive infrared ftir and correlation spectrometer cospec measurements were conducted at popocatepetl volcano during february 10 to 26 1998 from sites 4 to 17 km distant from the summit volcano behavior was relatively quiet and so 2 flux averaged 1670 1420 t day 51 measurements relatively small for popocatepetl concurrent hcl so 2 and hf so 2 ratios were 0 17 0 01 and 0 031 0 003 respectively about the same as ratios measured from 1994 to 1997 the amount of co 2 in the volcanic plume was quantified using fascode in which atmospheric co 2 is numerically subtracted from the total infrared spectrum to obtain the residual magmatic co 2 surprisingly co 2 so 2 mass ratios rose dramatically to values as high as 140 about 30 times higher than typical values of 2 to 8 measured from 1994 to 1996 these excursions in high co 2 so 2 ratios were short lived lasting no longer than about 0 5 to 3 0 h but co 2 flux occasionally exceeded 100 000 t day we estimate that the average co 2 so 2 ratio for the period was about 23 yielding an average co 2 flux of roughly 38 000 t day chemical and petrographic analyses of lava and pumice erupted during explosions on june 30 1997 and january 1 1998 show conclusively that popocatepetl produces mixed products formed by injection of mafic magma into a more silicic chamber at temperatures and pressures of roughly 1040 c and 5 kbar in addition popocatepetl eruptive products include xenoliths of metamorphosed carbonate rocks containing wollastonite and other calc silicate minerals indicating reaction of magma with cretaceous limestone underlying the volcano using a normal co 2 so 2 ratio of 4 for reference we calculate an average excess co 2 production of 32 000 t day for 17 days this would require assimilation of only 5 10 4 km 3 of limestone an amount easily accessible in the 3 km thick cretaceous section beneath the volcano we also examine two scenarios in which excess co 2 is produced by degassing of subjacent basalt magma but these explanations seem less plausible to us because many other volcanoes are underlain by carbonate sequences short duration bursts of co 2 flux and increased co 2 so 2 ratio might be observed at other sites if simultaneous real time measurements of major gas species are made

the nature and formation of cristobalite at the soufriere hills volcano montserrat implications for the petrology and stability of silicic lava domes cristobalite is commonly found in the dome lava of silicic volcanoes but is not a primary magmatic phase its presence indicates that the composition and micro structure of dome lavas evolve during and after emplacement nine temporally and mineralogically diverse dome samples from the soufriere hills volcano shv montserrat are analysed to provide the first detailed assessment of the nature and mode of cristobalite formation in a volcanic dome the dome rocks contain up to 11 wt cristobalite as defined by x ray dif fraction prismatic and platy forms of cristobalite identified by scanning electron microscopy sem are commonly found in pores and fractures suggesting that they have precipitated from a vapour phase feathery crystallites and micro crystals of cristobalite and quartz associated with vol canic glass identified using sem raman are interpreted to have formed by varying amounts of devitrification we dis cussmechanismsof silicatransport and cristobaliteformation and their implications for petrological interpretations and domestability we conclude 1 that silica maybetransported in the vapour phase locally or from one part of the magmatic system to another 2 that the potential for transport of silica into the dome should not be neglected in petrological and geochemical studies because the addition of non magmatic phases may affect whole rock composition and 3 that the extent of cristobalite mineralisation in the dome at shv is sufficient to reduce porosity hence permeability and may impact on the mechanical strength of the dome rock thereby potentially affecting dome stability

recent geomorphologic evolution of a glaciovolcanic active stratovolcano popocatepetl mexico abstract the recent geomorphologic evolution of the statovolcano popocatepetl 19 03 n 98 35 w including the volcanic activity and the evolution of the glacier that still exists on the north face was assessed most of the data were obtained from references in historical sources and aerial photographs dating from 1945 this information was supplemented with data from fieldwork conducted between 1992 and 1995 landform typology shows volcanic and glacial interactions the conclusions affirm that a geomorphologic evolution of the volcano occurred since the maximum glacier advance in the little ice age lia and the formation of a proglacial ramp later fluvioglacial gorges cut into the ramp especially during the 1921 27 eruption once the glacier had shrunk to a small size and was left hanging above the steep slope the streams disappeared and the gorges filled with blocks that fell in snow and ice avalanches

the use of surface monitoring data for the interpretation of landslide movement patterns the tessina landslide is a large seasonally active slope failure located on the southern slopes of mt teverone in the alpago valley of ne italy consisting of a complex system that has developed in tertiary flysch deposits the landslide which first became active in 1960 threatens two villages and is hence subject to detailed monitoring with high quality data being collected using piezometers inclinometers extensometers and through the use of a highly innovative automated electronic distance measurement edm system which surveys the location of a large number of reflector targets once every 6 h these systems form the basis of a warning system that protects the villages but they also provide a very valuable insight into the patterns of movement of the landslide in this paper analysis is presented of the movement of the landslide concentrating on the edm dataset which provides a remarkable record of surface displacement patterns it is proposed that four distinct movement patterns can be established which correspond closely to independently defined morphological assessments of the landslide complex any given block of material transitions through the four phases of movement as it progresses down the landslide with the style of movement being controlled primarily by the groundwater conditions the analysis is augmented with modelling of the landslide undertaken using the itasca flac code the modelling suggests that different landslide patterns are observed for different parts of the landslide primarily as a result of variations in the groundwater conditions the model suggests that when a movement event occurs displacements occur initially at the toe of the landslide then retrogress upslope

remote detection of hcl and so2 in volcanic gas from unzen volcano japan a telescope attached ft ir spectral radiometer was applied for remote measurement of chemical composition of the volcanic gas of unzen volcano japan which started erupting in november 1990 the observations were carried out at the site about 1 3 km away from the gas emitting region of the volcano in march and july 1992 absorption features of so2 vl and hcl were identified and column amounts of so2 and hcl of the volcanic gas plume were estimated using a nonlinear least squares method the so2 hcl ratio was in the range between 0 7 and 1 8 for both march and july observations this is the first remote ground based observation of hcl in volcanic gas

the middle proterozoic mescal paleokarst central arizona u s a karst development silicification and cave deposits abstract a regionally extensive paleokarst developed on the mescal limestone of the middle proterozoic apache group in central arizona prior to deposition of the overlying middle proterozoic troy quartzite and before intrusion of 1 1 ga diabase sills intense weathering of middle proterozoic basalt lavas overlying the mescal released abundant silica that led to widespread silicification of the underlying paleokarst dissolution of the host carbonate allowed insoluble early diagenetic cherts of the mescal to accumulate in their original stratigraphy while the remaining carbonate underwent nearly complete replacement by secondary silica phases silicified collapse breccias cave filling sandstone lenses thinly laminated cave floor siltstone and newly discovered flowstone indicate extensive development of caves and cave deposits during the karst event the geographic distribution of silicification was controlled by adjacent uplift caused by movement along precambrian monoclines cutting across the sierra ancha the mescal paleokarst is one of the best preserved silicified karsts on earth and hosts some of the best preserved cave flowstone from the precambrian

continental paleoclimates from δd and δ18o of secondary silica in paleokarst chert lags approximate continental paleotemperatures can be inferred from oxygen and hydrogen isotopic analyses of authigenic silica that precipitated within chert lags on paleokarst surfaces data for two proterozoic examples suggest continental weathering temperatures that ranged from 30 to 43 c quantitative results appear possible for rocks at least as old as 1 1 ga

dynamics of the bingham canyon rock avalanches utah usa resolved from topographic seismic and infrasound data the 2013 bingham canyon mine rock avalanches represent one of the largest cumulative landslide events in recorded u s history and provide a unique opportunity to test remote analysis techniques for landslide characterization here we combine aerial photogrammetry surveying topographic reconstruction numerical runout modeling and analysis of broadband seismic and infrasound data to extract salient details of the dynamics and evolution of the multi phase landslide event our results reveal a cumulative intact rock source volume of 52 mm3 which mobilized in two main rock avalanche phases separated by 1 5 h we estimate the first rock avalanche had 1 5 2 times greater volume than the second each failure initiated by sliding along a gently dipping 21 highly persistent basal fault before transitioning to a rock avalanche and spilling into the inner pit the trajectory and duration of the two rock avalanches were reconstructed using runout modeling and independent force history inversion of intermediate period 10 50 s seismic data intermediate and shorter period 1 50 s seismic data were sensitive to intervals of mass redirection and constrained finer details of the individual slide dynamics back projecting short period 0 2 1 s seismic energy we located the two rock avalanches within 2 and 4 km of the mine further analysis of infrasound and seismic data revealed that the cumulative event included an additional 11 smaller landslides volumes 104 105 m3 and that a trailing signal following the second rock avalanche may result from an air coupled rayleigh wave our results demonstrate new and refined techniques for detailed remote characterization of the dynamics and evolution of large landslides

the ongoing dome emplacement and destruction cyclic process at popocatepetl volcano central mexico the ongoing eruptive activity of popocatepetl volcano has been characterized by emplacement and subsequent destruction of a succession of lava domes between the onset of the current eruption in 1994 and the time of this submission 38 episodes of lava dome formation and removal have been identified each dome has showed particular features related to the magma extrusion process among other manifestations dome emplacement events have been usually accompanied by relatively low intensity protracted explosions referred to as exhalations after variable times of residence emplacements have ended in partial or total destruction of the domes by strong vulcanian explosions that produced sizeable ash plumes with most of them also ejecting incandescent debris onto the volcano flanks here we present a detailed account for the observed activity related to the domes growth and destruction related seismic monitoring signals and morphological features of the domes based on 19 years of visual observations and image analysis we then discuss a model for the process of dome growth and destruction and its hazard implications

applying terzaghi s method of slope characterization to the recognition of holocene land slippage abstract during site investigations engineering geologists are expected to recognize landslides both active and dormant those without substantial experience evaluating the evolution of geomorphic features associated with localized mass wasting often mischaracterize site conditions karl terzaghi suggested seven steps in characterizing natural hillslopes including 1 a literature review 2 site reconnaissance 3 a program of subsurface exploration 4 preparation of sketches and diagrams illustrating the essential features 5 preparation of a preliminary geology report 6 observation and mapping of geologic structures exposed during excavation for construction and 7 development of contingency plans for anticipated variations in old landslide features based on our interpretation of terzaghi s original principles we review some of the most common interpretive problems with nomenclature of landslide features describe common mistakes in characterizing old landslides and present technical approaches that often aid in the recognition of old landslide features a wide variance in geological terms exists for describing landslides and various terms have been applied to the same features by workers in different areas which often leads to confusion some of these terms include nomenclature such as slip surfaces alluvial fans colluvium and slope creep active surficial landslides are relatively easy to recognize when they are well exposed although these features tend to become obscured with time anomalous hummocky topography often provide key recognition features of a slope s geomorphic evolution deeper seated bedrock landslides can be more difficult to recognize because their features become increasingly mollified with time these features can often be identified by anomalous geomorphic features such as isolated saddles or anomalous discontinuous benches these features are some of the best locations to excavate borings or exploratory trenches well placed trenches across headscarp grabens can provide more detailed structure of old landslides and are usually a cost effective approach additional subsurface exploration can often be employed to characterize landslides small diameter borings are usually employed for geotechnical investigations but can easily be applied to landslides depending on the mean particle size diameter d50 downhole logging of large diameter holes is the best method to evaluate complex subsurface conditions such as dormant bedrock landslides

mapping fractures with gpr a case study from turtle mountain ground penetratingradargprsurveyswereacquiredof rocks on the highly fractured summit of turtle mountain in canada in 1903 a disastrous rock slide occurred at turtle mountain and it still poses a geologic hazard dips shapes and penetration depths of fractures are important parameters inslope stabilityanalysis determinationoffractureorientation at turtle mountain has been based mostly on areal geologic mapping and most recently on data collected from boreholes the purpose of gpr surveys was to test confirm and extend information about fractures and bedding planes data acquisition was complicated by the rough terrain because slopes are steep and uneven this also complicated analysis of the data measurement of in situ velocity an important value for migration was impossible instead data were migrated with different velocities and data results were chosen that were considered to be reasonable analysis and interpretation of the data resulted in confirmation and extension of the a priori information on orientations of fractures and bedding planes at turtle mountain despite the rough terrain and highly fractured rock mass gpr surveys provide reliable information about the shapes and density of fractures informationimportantforslope stabilityevaluation the most reliable migration results obtained for velocities were considerably less than the standard velocities recorded for limestone the dominant lithofacies at turtle mountain we interpret this observation as an indicator of water within the rock however thorough investigation of thisconclusionremainsaprojectforfuturework

the mechanics of deep seated landslides results are presented of a sequence of laboratory tests undertaken to elucidate the behaviour of deep seated landslides in deep seated failures deformation has been reported at depths of up to 250 m in the movement zone owing to the weight of the overburden and the surrounding stress environment conventional soil mechanics cannot be used to explain effectively associations between the landslip activity and the deformation mechanisms operating within the moving mass a series of experiments has been undertaken on london clay using a high pressure servohydraulically controlled triaxial deformation system to replicate the stresses acting at the base of a large deep seated landslide a number of tests were undertaken the most significant focusing on the transition between ductile and brittle behaviour although sediments usually behave in a brittle manner at low effective stresses common to many geomorphological studies and in a ductile manner at high effective stresses the results presented here identify for the first time in mudrocks a transitional phase of behaviour in which creep like movement will manifest itself at the base of a deep seated landslide as the growth of microcracks the microcracks may eventually coalesce to form a shear surface a consequence of which is likely to be sudden failure the results thus have important implications in the understanding of movement mechanisms in large deep seated failures rates of displacement and how they may change through time 1997 by john wiley sons ltd

the so2 camera a simple fast and cheap method for ground based imaging of so2 in volcanic plumes 1 so2 flux is widely monitored on active volcanoes as it gives a window into the hidden subsurface magma dynamics we present here a new approach to so2 flux monitoring using ultraviolet imaging of the volcanic plume through carefully chosen filters to produce images of so2 column amount the so2 camera heralds a breakthrough in both our ability to measure so2 flux at unprecedented frequencies 2 hz and at unprecedented accuracy thanks to the application of correlation techniques to determine wind speed directly from the images and the ability to measure the whole profile simultaneously in this paper we detail the commercially available pieces required to construct the so2 camera introduce a retrieval scheme to determine so2 amounts from the images and present results from a field campaign in november 2005 on sakurajima volcano japan

modelling stability and surging in accumulation slides abstract an idealized model for certain classes of debris flows and avalanches is developed slopes characterized by a steep feeder segment which loads a flatter accumulation segment will be focused on such slopes have been observed to exhibit episodic surging motions the simplified model allows considerable insight into the behavior of such slides an approximate stability criterion is derived explaining the surging motions it is shown that in general one cannot predict the onset of surging due to the inability to precisely characterize the interaction between the feeder and accumulation slopes other results include an approximate analysis for the mean acceleration which may occur during surging

the deep seated slope deformation at encampadana andorra representation of morphologic features by numerical modelling abstract the present study is intended to improve some aspects referring to the general understanding of deep seated gravitational slope deformations dsgsd by the description of field data from the encampadana slope in andorra and using a simplified numerical modelling the site investigation of the encampadana dsgsd revealed two major morphologic features a prominent graben close to the summit and counterscarps at different altitudes of the slope the geological data showed that the slope is affected by an antiform consisting of hard resistant rocks in its outer parts and a more ductile material in its inner part subsequently called core currently available information does not allow the appraisal of the failure mechanism affecting the slope in order to improve the knowledge of both the pattern of the slope deformation and the influence of the different geologic structural and geomorphologic features 2d finite element modelling has been carried out simulating the joint pattern of the rock slope by interface elements the encampadana slope is located at a river valley that was subjected to erosion by pleistocene glaciers plus the subsequent decompression of the valley walls after their retreat these stages were implemented into the model to account for the evolving stress history during modelling focus was set on the effect of three different factors 1 geological discontinuities 2 glacier erosion and 3 a ductile core in the slope consisting of black carbonaceous shales the calculations showed that a staged approach for simulating the stress history of the site was very appropriate although the presence of tectonic stresses was not incorporated the results indicated that the discontinuity set and the glacier erosion generate an opening of the joints some toppling effects and the development of counterscarps moreover the incorporation of a ductile core produced a graben like structure all these features are consistent with the morphology observed in the field in conclusion the numerical modelling indicates that some realistic results representing the general deformation of the slope and the observed field features can be achieved even with very limited input data

space and ground based measurements of sulphur dioxide emissions from turrialba volcano costa rica remotely sensed measurements of sulphur dioxide so2 emitted by turrialba volcano costa rica are reported for the period september 2009 january 2011 these measurements were obtained using images from advanced spaceborne thermal emission and reflexion radiometer ozone monitoring instrument and a ground based uv camera these three very different instruments provide flux measurements in good agreement with each other which demonstrate that they can be integrated for monitoring so2 fluxes fluxes from turrialba increased fourfold in january 2010 following a phreatic explosion that formed a degassing vent in the w crater of turrialba since then the so2 flux has remained high 30 50 kg s but seems to be showing a slowly decreasing trend we interpret this evolution as the start of open vent degassing from a recently intruded magma body the opening of the degassing vent decreased the confining pressure of the magma body and allowed the gases to bypass the hydrothermal system

structural analysis of turtle mountain alberta using digital elevation model toward a progressive failure abstract in 1903 the eastern slope of turtle mountain alberta was affected by a 30 m m 3 rockslide named frank slide that resulted in more than 70 casualties assuming that the main discontinuity sets including bedding control part of the slope morphology the structural features of turtle mountain were investigated using a digital elevation model dem using new landscape analysis techniques we have identified three main joint and fault sets these results are in agreement with those sets identified through field observations landscape analysis techniques using a dem confirm and refine the most recent geology model of the frank slide the rockslide was initiated along bedding and a fault at the base of the slope and propagated up slope by a regressive process following a surface composed of pre existing discontinuities the dem analysis also permits the identification of important geological structures along the 1903 slide scar based on the so called sloping local base level slbl an estimation was made of the present unstable volumes in the main scar delimited by the cracks and around the south area of the scar south peak the slbl is a method permitting a geometric interpretation of the failure surface based on a dem finally we propose a failure mechanism permitting the progressive failure of the rock mass that considers gentle dipping wedges 30 the prisms or wedges defined by two discontinuity sets permit the creation of a failure surface by progressive failure such structures are more commonly observed in recent rockslides this method is efficient and is recommended as a preliminary analysis prior to field investigation

detection and spatial prediction of rockfalls by means of terrestrial laser scanner monitoring abstract a rock face affected by small rockfalls has been monitored using a ground based remote sensing apparatus terrestrial laser scanner tls the pilot study area corresponds to the main scarp of the 1881 puigcercos landslide pallars jussa catalonia spain four datasets of the slope were acquired from september 2007 to july 2008 in an ongoing project the geomorphological evolution of the rock face in terms of volume and frequency of rockfall was studied by the comparison of sequential datasets in addition to the detection of past events this study deals with the spatial prediction of rockfalls through the detection of pre failure deformation as a precursory indicator the high resolution and accuracy and the maximum range of the tls offer interesting prospects for both spatial location and prediction of rockfall

a gravitational spreading origin for the socompa debris avalanche abstract socompa volcano arguably provides the world s best exposed example of a sector collapse derived debris avalanche deposit new observations lead us to re interpret the origin of the sector collapse we show that it was triggered by failure of active thrust anticlines in sediments and ignimbrites underlying the volcano the thrust anticlines were a result of gravitational spreading of substrata under the volcano load about 80 of the resulting avalanche deposit is composed of substrata formerly residing under the volcano and in the anticlines the collapse scar can be traced up to 5 km from the edifice truncating two spreading related anticlines which collapsed in the event outcrops near the volcano preserve evidence of edifice material being carried along on top of mobilised substrata on the north side of the scar the avalanche motion was initially at right angles to the failure edge structural relations indicate that immediately prior to collapse the substrata disintegrated became effectively liquidised and were ejected from beneath the edifice catastrophic mobilisation of substrata probably resulted from breakdown of ignimbrite clasts and cement it may have occurred through progressive rock fracture by high shear strain during spreading material ejected from under socompa formed a layer on which volcanic edifice debris was transported this interpretation of events explains the puzzling observation that avalanche units with the lowest gravitational potential energy moved the furthest it can also account for avalanche motion normal to the collapse scar walls ignimbrites and other rock types probably capable of similar behaviour underlie many other volcanoes identification of spreading at other sites could therefore be a first step towards assessment of the potential for this style of catastrophic sector collapse

continuous measurements of sif 4 and so 2 by thermal emission spectroscopy insight from a 6 month survey at the popocatepetl volcano abstract the processes linked with the emplacement and growth destruction of a lava dome are of prime importance to understand the stability of such extrusions and assess the associated risks for local populations during the last couple of decades ground and space based spectroscopic techniques have been developed to monitor such processes from a safe distance such approaches significantly improved our knowledge about the relationship between the chemical composition of the volcanic gas plumes and both the deep and shallow volcanic processes leading to the different types of explosive activity the potential of the ground based thermal emission fourier transform infrared spectroscopy ftir remained under exploited due to the difficulty to properly handle the radiative transfer phenomena despite the drawbacks in the complex analytical requirements this method enables to continuously monitor day and night with a high temporal resolution 1 meas 3 min relevant gas species such as so 2 and sif 4 in the volcanic plumes previous studies have related the temporal variations of the sif 4 so 2 ratio in volcanic plumes to the onset of vulcanian explosions this study reports a 6 month so 2 sif 4 and sif 4 so 2 time series from january to june 2015 of the popocatepetl s gas plume obtained from ftir thermal emission spectroscopic measurements the infrared spectra were analyzed using the sfit4 radiative transfer and inverse model which we have adapted for this application we obtained highly variable sif 4 so 2 ratios with a mean value of 3 6 10 4 with the highest values around 3 10 3 measured during the final phase of a lava dome growth february march 2015 the rapid sif 4 so 2 variations were more carefully explored and compared for the first time with the seismic activity a remarkable coincidence between sharp sif 4 so 2 rises and the seismic events are evidenced here

temporal behavior of deep seated gravitational slope deformations a review abstract deep seated gravitational slope deformations dsgsds are slow moving hillslope scale mass movements featuring characteristic landforms such as double crested ridges and upslope facing scarps that occur in diverse landscapes throughout the world although these deformations have been studied since the 1960s significant insights to the rates of dsgsds have only been gained within the last two decades owing to progress in geochronology remote sensing and instrumental monitoring absolute age and monitoring data indicate that dsgsd movements are observable over long term 102 years and short term future research directions include constraining the lifespan of dsgsds with absolute age dating and precise high resolution monitoring of spatio temporal displacement across dsgsd bodies it is of great importance to include absolute time scales in the numerical models of dsgsds furthermore combining remote sensing techniques such as synthetic aperture radar interferometry with high resolution lidar scanning and near surface geophysics offers a promising toolkit for collecting very detailed and accurate data on the short term deformation rates of dsgsds

image based correction of the light dilution effect for so2 camera measurements abstract ultraviolet so 2 cameras are increasingly used in volcanology because of their ability to remotely measure the 2d distribution of so 2 in volcanic plumes at a high frequency however light dilution i e the scattering of ambient photons within the instrument s field of view fov on air parcels located between the plume and the instrument induces a systematic underestimation of the measurements whose magnitude increases with distance so 2 content atmospheric pressure and turbidity here we describe a robust and straightforward method to quantify and correct this effect we retrieve atmospheric scattering coefficients based on the contrast attenuation between the sky and the increasingly distant slope of the volcanic edifice we illustrate our method with a case study at etna volcano where difference between corrected and uncorrected emission rates amounts to 40 to 80 and investigate the temporal variations of the scattering coefficient during 1 h of measurements on etna we validate the correction method at popocatepetl volcano by performing measurements of the same plume at different distances from the volcano finally we reported the atmospheric scattering coefficients for several volcanoes at different latitudes and altitudes

pre eruptive inflation caused by gas accumulation insight from detailed gas flux variation at sakurajima volcano japan sulfur dioxide so2 emission rate observations were made at sakurajima volcano japan to quantify the relationship between the so2 emission rate and inflation prior to vulcanian explosions the explosions associated with precursory inflation events were preceded by decreases in so2 emission rates by 10 60 min the amounts of accumulated gas were calculated using time series of so2 emission rate the amounts of accumulated so2 and increases in strain records before the explosions showed a positive correlation the volume increase of a deformation source calculated using the strain records was of the comparable order of magnitude as the volume of the accumulated volcanic gas the results suggest that the inflations before the explosions were caused by the gas accumulation

why did the 1756 tjellefonna rockslide occur a back analysis of the largest historic rockslide in norway abstract on 22 february 1756 the largest historically recorded rockslide in norway took place at tjelle in the langfjord western norway the rockslide created three displacement waves of up to 50 m in height that caused 32 casualties and destroyed most houses and boats along the shores of the langfjord the trigger and contributing factors leading to the tjellefonna rockslide are largely unknown and even seismic triggering has previously been suggested this study provides a thorough back analysis of the tjellefonna rockslide using detailed geomorphological engineering geological and tectonic field mapping in combination with topographic reconstructions bathymetry analysis volume estimations and numerical slope stability analysis the back scarp and eastern flank of the tjellefonna scar form several tens of meter high rock walls while the basal failure surface and other parts of the scar are covered by rock avalanche debris that extend from the back scarp down to the bottom of the langfjord the rockslide occurred in granodioritic gneisses with variably developed metamorphic foliation that is folded and strike parallel to the fjord two prominent fault zones are present in close proximity to the tjellefonna scar one is steeply se dipping tjelle fault while the other one is sub horizontal to shallow se dipping ritlehamran fault both fault zones are linked to the more trondelag fault complex with one of its branches forming the langfjord lineament and probably also the faults at tjellefonna additionally there are four persistent joint sets that together with the metamorphic foliation and the tjelle fault define the back scarp of the rockslide and give a fracturing of the rock mass corresponding to a geological strength index gsi of 45 55 the gsi decreases significantly to 10 20 in the fault zones which form distinct weakness zones in the rock slope volume estimates based on a reconstruction of the ante rockslide topography range from 9 3 to 10 4 million m 3 which is lower than previous volume estimates 12 15 million m 3 large portions of the failed rock mass remained on land and only approximately 3 9 million m 3 entered the fjord the observed discontinuities in the rock mass at tjellefonna do not allow for a simple kinematic failure mechanism due to the lack of moderately se dipping structures the basal failure surface was most likely not composed of a single structure but of a complex interplay of fault zones metamorphic foliation joints and broken rock bridges numerical slope stability modelling highlights that weak fault zones are essential for the development of the failure surface over a long time this progressive failure was likely aided by low to medium magnitude earthquakes that are frequent in the region numerical slope stability modelling and historical accounts suggest however that heavy long lasting rainfall was the triggering factor for the 1756 tjellefonna rockslide rather than an earthquake

evidence for 2 0 ga continental microbial mats in a paleodesert setting abstract early evolved microbial communities characterized the initial biological invasion of precambrian continental landscapes in modern arid settings microbial mats and biological soil crusts are well developed and stabilize sediment the paleoproterozoic makgabeng formation in south africa is one of the oldest and best preserved dryland systems on earth six types of microbial mat related structures are now recognized within these depositional systems this paper presents three newly discovered structures that include tufted microbial mat biological soil crusts and gas escape features in addition to three previously documented structures that include roll up features sand cracks and wrinkled features these discoveries demonstrate that microbial communities were well established and inhabited diverse continental settings by 2 0 ga approximately 200 million years after the onset of the great oxidation event

trends in oolite dolomitization across the neoproterozoic cambrian boundary a case study from death valley california abstract changes in dolomite fabric within the neoproterozoic cambrian stratigraphic succession in death valley california preserve evidence for a first order biogeochemical change in early diagenetic environments through the neoproterozoic cambrian transition oolite forms the primary focus of the study so that the general paleoenvironmental setting and presumed susceptibility to early diagenesis and fluid flow can be kept relatively constant across geologic time two key generalizations can be made 1 late neoproterozoic dolomitization in death valley occurred very early in the paragenetic sequence was volumetrically significant and preserved fine detail of the original aragonite or calcite precursor and 2 early cambrian dolomitization in death valley occurred late in the paragenetic sequence with burial was commonly incomplete and obliterated details of the calcite or aragonite precursor early diagenetic dolomitization of any kind was absent the dolomitization fabrics in death valley parallel the presumed pattern of seawater mg ca with respect to mimetic dolomitization in the paleozoic low mg ca little no mimetic dolomitization and cenozoic higher mg ca more common mimetic dolomitization however the volume of neoproterozoic mimetic dolomitization is immense compared to the cenozoic examples we speculate that a fundamental shift in the early diagenetic environment occurred in late neoproterozoic time perhaps in association with secular variation in the sulfate concentration of seawater and the advent and proliferation of penetrative bioturbation that destroyed sediment capping microbial mats an oscillatory trend in the fabric and volume of dolomite through the phanerozoic has been suggested but the termination of volumetrically significant mimetic dolomitization across the neoproterozoic cambrian transition a critical time in earth history for many reasons dwarfs the oscillatory trends noted in the phanerozoic

remote sensing of volcanoes and volcanic processes integrating observation and modelling introduction volcanoes are often remote and have footprints that may extend across many hundreds or thousands of square kilometres they are generally inaccessible during eruption and may continue to be inaccessible for extended periods of time after eruption while their products can be scattered or dispersed over regional or global scales consequently since direct measurement can only provide us with part of the picture of many volcanic processes remote sensing is now playing an increasingly important role in advancing understanding of the science underlying volcanic behaviour on this planet and beyond e g mouginis mark et al 2000 sparks et al 2012 satellite airborne and ground based remote sensing are increasingly vital tools for monitoring active or potentially active volcanoes and assessing their likely real time or time averaged impact fig 1 at the same time the synoptic scale surveys that are often well suited to remote sensing techniques allow us to address questions about the fundamental processes that control volcano behaviour in a way that is not necessarily possible from individual case studies new research is often driven by technological advancements in the development of novel sensors or launching of new platforms meaning that the space agencies are increasingly involved in identifying scientific questions and priorities e g ferruci et al 2012 multiple and complementary data streams are increasingly being used both to monitor active volcanoes and advance volcanological science the key geophysical parameters that comprise monitoring data streams typically include the categories of i seismicity ii surface deformation iii thermal measurements and iv gas flux and composition data as major components while measurements of seismicity remain the domain of ground based seismometers remote sensing techniques have made major contributions in each of the others this special publication volume is concerned with the use of remote sensing at volcanoes it is split into three parts roughly arranged from the subsurface to the surface and then further afield as volcanic products are injected and dispersed into the atmosphere the papers span a range of applications of remote sensing techniques to monitor and understand a surface deformation b surface thermal anomalies and c gas fluxes as well as tracking ash and gas plumes from eruptions to gain insights into the extent of a volcano s impacts volcanology is driven in part by the operational concerns surrounding volcano monitoring and hazard and crisis management but the goal of volcanological science is at its heart to understand the processes that underlie volcanic activity this special publication is also concerned with how we go from observations to this deeper understanding including the progress that can be made by integrating observations and modelling while this volume focuses mainly on satellite based remote sensing integrating datasets from different platforms is also of vital importance and so papers on airborne remote sensing and measurement from both manned and unmanned aircraft are also included

stratigraphic investigations of carbon isotope anomalies and neoproterozoic ice ages in death valley california an unusual richness of biogeochemical events is recorded in neoproterozoic cambrian strata of the death valley region california united states eight negative carbon isotope d13c excursions are found in carbonate units between 1 08 ga and the precambrian cambrian boundary four of these excursions occur in carbonates that contain textural features similar to those found globally in postglacial cap carbonates including one or more of the following laminite with rollup structures apparent tube rocks seafloor precipitates and sheet crack cements however only two of these units the sourdough limestone member of the kingston peak formation and the noonday dolomite rest directly upon glacial strata the basal beck spring dolomite and the rainstorm member of the johnnie formation each contain negative excursions and cap carbonate like lithofacies but do not rest on known glacial deposits if the negative d13c excursions are assumed to record depositional processes two equally interesting hypotheses are possible 1 the death valley succession records four glacial pulses in neoproterozoic time but glacial units are not preserved at two stratigraphic levels 2 alternatively other global oceanographic processes can cause negative excursions and cap carbonate like facies in addition to or independent of glaciation

the frank slide a reexamination of the failure mechanism the frank slide involving an estimated 30 million m3 of rock occurred in 1903 on the east face of turtle mountain southwestern alberta canada it resulted in the loss of approximately 70 lives

measurement of in situ stress in weak rocks at mont terri rock laboratory switzerland in situ stress measurements in weak rocks such as clay shales that respond strongly to environmental changes are particularly difficult an extensive in situ stress measurement program has been conducted at the mont terri rock laboratory in northwestern switzerland hydraulic fracturing undercoring around a 600 mm diameter borehole using csiro triaxial strain cells and the borehole slotter were used to establish the state of stress for the opalinus clay at this location conflicting orientations and magnitudes resulted from the measurement programs three dimensional elastic modelling was used in conjunction with tunnel and borehole observations to establish the most likely stress tensor a stress measurement program using a borehole deformation gauge is currently underway to check the stress tensor resulting from the observational modelling

the tonian beck spring dolomite marine dolomitization in a shallow anoxic sea abstract the reason for the abundance of dolomite lithologies in earth s early geological record compared to modern environments remains contentious this study provides new insight into this precambrian dolomite problem by revisiting one of the most controversial dolomite localities the beck spring dolomite of death valley usa consistent with some previous studies petrographic evidence indicates that although the beck spring dolomite now consists almost entirely of dolomite it was originally precipitated largely as aragonite and high mg calcite depositional constituents microbialites and ooids were likely originally aragonitic and early marine length fast cements now dolomite are suggested to have precipitated as high mg calcite then replaced syntaxially by dolomite based on petrographic and geochemical evidence we suggest that marine dolomitization was the dominant synsedimentary diagenetic process in the unit and for the most part involved syntaxial and mimetic replacement further a length slow fibrous dolomite generation was precipitated during the later stages of marine diagenesis as a primary marine dolomite cement this is indicated by the length slow crystallographic structure of the cement and from its preserved geochemical and cathodoluminescence growth zonation this new evidence for tonian marine dolomite precipitation reinforces the idea of precambrian marine environmental conditions including the chemical composition of seawater promoting dolomite formation at this time the trace metal geochemical composition of well preserved marine components especially dolomite marine cements reveals information about redox conditions in this tonian shallow seawater in terms of rare earth element geochemistry the beck spring dolomite has no significant ce anomaly and a ubiquitous positive eu anomaly consistent with widespread oceanic anoxia during deposition furthermore the relatively low levels of iron and chalcophile elements co cu pb and zn in marine components compared to other neoproterozoic carbonates suggest euxinic conditions both anoxic and sulphidic prevailed during deposition of the beck spring dolomite

stable isotope variations in the neoproterozoic beck spring dolomite and mesoproterozoic mescal limestone paleokarst implications for life on land in the precambrian proterozoic karst events lowered 13c values by as much as 11 for the 800 ma beck spring dolomite california and as much as 8 5 for the 1 1 ga mescal limestone central arizona relative to the originally deposited carbonate the 13c changes are attributed to input of 13c depleted organic co2 derived from photosynthetic organisms that colonized the ancient land surface the large isotopic shift and its presence at two separate localities suggest that proterozoic karst surfaces were colonized by significant photosynthetic communities with phytomasses possibly approaching those of today

structural characterization of turtle mountain anticline alberta canada and impact on rock slope failure abstract this paper proposes a structural investigation of the turtle mountain anticline alberta canada to better understand the role of the different tectonic features on the development of both local and large scale rock slope instabilities occurring in turtle mountain the study area is investigated by combining remote methods with detailed field surveys in particular the benefit of terrestrial laser scanning for ductile and brittle tectonic structure interpretations is illustrated the proposed tectonic interpretation allows the characterization of the fracturing pattern the fold geometry and the role of these tectonic features in rock slope instability development ten discontinuity sets are identified in the study area their local variations permitting the differentiation of the study zone into 20 homogenous structural domains the anticline is described as an eastern verging fold that displays considerable geometry differences along its axis and developed by both flexural slip and tangential longitudinal strain folding mechanisms moreover the origins of the discontinuity sets are determined according to the tectonic phases affecting the region pre folding folding post folding the localization and interpretation of kinematics of the different instabilities revealed the importance of considering the discrete brittle planes of weakness which largely control the kinematic release of the local instabilities and also the rock mass damage induced by large tectonic structures fold hinge thrust

fragmentation energy in rock avalanches fragmentation is one of the mechanisms involved in rock avalanches quantifying the associated energy dur ing a rock avalanche can help to assess the influence of fragmentation on post failure mass movements in this paper in situ block size distributions of the intact rock mass and the debris deposits are presented and analyzed for nine rock avalanches five in the canadian rocky mountains and four in the european alps degrees of fragmentation are esti mated from these data two methods are examined to assess fragmentation energy one based on the comminution the ory and one on the blasting energy used in the mining industry the results show that for the studied rock avalanches there is a relationship between the reduction in diameter ratio rr d50 d50 where d50 and d50 are the mean diameter of the intact rock mass and the mean diameter of the debris respectively and the potential energy per unit volume normalized with respect to the point load strength of rock hg c where is the unit weight of the material hg is the vertical distance between the centres of gravity of the mass at the start and end positions and c is the point load strength for the cases studied fragmentation energy calculations average 20 of the potential energy an empirical relationship between rr and hg c has been established and is used in the definition of a disintegration index id this index seems to reflect the physics of the disintegration process since it accounts for the fact that the reduction in diameter ratio is a function of the dissipated energy and the strength of the rock these factors have long been known to affect fragmentation but have never been presented in a coherent manner for rock avalanches

distribution of gravitational slope deformation and deep seated landslides controlled by thrust faults in the shimanto accretionary complex abstract the cretaceous shimanto accretionary complex is a typical accretionary complex uplifted without significant deformation after accretion and in which many rain induced deep seated landslides dls have occurred we undertook a thorough geological and geomorphological investigation of the middle kii peninsula where many rain induced dls occurred in 1889 and 2011 during intense and prolonged rainfall associated with typhoons geomorphological investigations using 1 m digital terrain models dtms obtained from airborne light detection and ranging lidar before and after the 2011 typhoon allowed us to examine the microtopography e g small scarps and linear depressions and to locate deep seated gravitational slope deformations dgsds and dls low angle thrust faults with 1 m thick incohesive fault rocks were found to be aligned subparallel to each other with spacings of a few kilometers and control the distribution of dls and dgsds when a thrust fault forms a cataclinal slope river incision removes the overburden and undercuts and destabilizes the slope this process causes gravitational deformation which forms downhill facing scarps and linear depressions at higher elevations on the slope tephrochronology applied to the deposits in the dgsd induced depressions revealed that such deformation began at least 30 000 50 000 years ago and is ongoing when a high angle fault strikes along the line of maximum slope it separates a volume of the rock mass from the juxtaposing slope and facilitates gravitational slope deformation and ultimately catastrophic failure a rock mass on a thrust fault that forms a downslope plunging syncline can also be gravitationally deformed and fail a crush zone of a large scale thrust fault is a continuous weak layer that also forms a barrier to groundwater flow thus leading to a rapid increase in pore pressure during rainstorms potentially triggering catastrophic slope failure accretionary complexes which typically contain thrust faults with incohesive fault rocks thus provide a location for dgsds and dls

gas composition of popocatepetl volcano between 2007 and 2008 ftir spectroscopic measurements of an explosive event and during quiescent degassing abstract on december 1 2007 the solar absorption infrared spectra of the popocatepetl volcanic plume was recorded during an eruptive event and complementarily on november 17 2008 the passive quiescent degassing was measured from the same site a portable ftir spectrometer with a scanning mirror for fast tracking of the sun provided the flexibility quality and simplicity needed for field deployment slant columns of the gases so 2 hcl hf and sif 4 were retrieved and strong differences could be observed when comparing gas ratios in both time periods during the explosive eruption the so 2 hcl ratio was three times greater and the hf hcl ratio was slightly smaller than during passive degassing while the ratios among so 2 hcl hf and sif 4 describe the chemical composition of the volcanic gas mixture the sif 4 hf ratio provides information about the equilibrium temperatures of the stored gases which in this study were calculated at 150 and 185 c for the explosive and quiescent degassing episodes respectively we conclude that cooling of lava domes in the crater precedes vulcanian explosions as suggested by schaaf et al 2005 based on so 2 flux grutter et al 2008 and measurements and data from the november 2008 event the average fluxes for hcl hf sif 4 and f through quiescent degassing are estimated to be 204 22 7 9 8 and 31 7 tons day respectively these values are similar to those reported by love et al 1998 more than 10 yrs ago

monitoring rapid head scarp movement in an alpine rockslide abstract the aresawa rockslide in the japanese alps which partially collapsed in may 2004 produced a number of new tension cracks in the head area this paper discusses the dynamics of the rock slope and controls on the surface velocity based on the results of on site monitoring of the surface movement and meteorological parameters air and ground surface temperatures precipitation and snow depth the rock mass deformation progressed at ca 60 cm yr 1 mainly along a slip plane dipping downslope at ca 50 the surface velocity of the slipping rock mass showed a significant seasonal variation in response to the water infiltration the velocity was small 1 mm day 1 in winter subzero air temperatures and a heat insulating snow cover and resulting growth of seasonal frost prevent water infiltration into the bedrock and contribute to the rock slope stability most of the movement in this period is attributed to gravitational deformation originating from the overburden pressure in contrast the surface velocity increased up to 10 mm day 1 during snow melting and snow free periods snowmelt and rainfalls promote water infiltration into the bedrock destabilizing the rock slope and accelerating the rock slip such a rapid movement is attributed to water induced sliding superimposed on gravitational deformation

trends in the aggregated rate of pre eruptive volcano tectonic seismicity at kilauea volcano hawaii accelerating rates of volcano tectonic vt earthquakes are commonly observed during volcanic unrest understanding the repeatability of their behaviour is essential to evaluating their potential to forecast eruptions quantitative eruption forecasts have focused on changes in precursors over intervals of weeks or less previous studies at basaltic volcanoes in frequent eruption such as kilauea in hawaii and piton de la fournaise on reunion suggest that vt earthquake rates tend to follow a power law acceleration with time about 2 weeks before eruption but that this trend is often obscured by random fluctuations or noise in vt earthquake rate these previous studies used a stacking procedure in which precursory sequences for several eruptions are combined to enhance the signal from an underlying acceleration in vt earthquake rate such analyses assume a common precursory trend for all eruptions this assumption is tested here for the 57 eruptions and intrusions recorded at kilauea between 1959 and 1984 applying rigorous criteria for selecting data e g maximum depth restricting magnitudes to be greater than the completeness magnitude 2 1 we find a much less pronounced increase in the aggregate rate of earthquakes than previously reported the stacked trend is also strongly controlled by the behaviour of one particular pre eruptive sequence in contrast a robust signal emerges among stacked vt earthquake rates for a subset of the eruptions and intrusions the results are consistent with two different precursory styles at kilauea 1 a small proportion of eruptions and intrusions that are preceded by accelerating rates of vt earthquakes over intervals of weeks to months and 2 a much larger number of eruptions that show no consistent increase until a few hours beforehand the results also confirm the importance of testing precursory trends against data that have been filtered according to simple constraints on the spatial distribution and completeness magnitude of the vt earthquakes

slope tectonics a short introduction geomorphology structuralgeologyandengineeringgeology allow description of the main character istics of a slope in distinct ways that can be com bined to provide a complementary view of theoperative slope processes the subjects presentedin this special publication include slope mor phology and evolution mechanical behaviour ofthe material modes of failure and collapse in u ence of lithology and structural features and therole played by controlling factors this slope tec tonics volume comprises a series of very differentcontributions that attempt to underline a multidisci plinary approach thatshould form the framework ofslope instability studies slope tectonics is adopted in this volume tomeandeformationthatisinducedorfullycontrolledbytheslopemorphologyandthatgeneratesfeaturesthatcanbecomparedtotectonicfeatures thestress eld in a slope is the result of gravity topographyand the geological setting created by an ensembleof geodynamic processes active tectonics alsocalled neotectonics generates a stress eld thatcancontrolslopeprocesses astrongfeedbackexist ingbetween geological history tectonics lithology geomorphological evolution and topography as a consequence a list of factors and theirrela tive in uence can be presented 1 fabric induced by a local stress eld within aslope discontinuities and local faults with cata clastic bands of variable thickness folds fig 1 associated predominantlywith brittle structures complex failure paths stepped or multi surface localfailures rockbridgefailuresorexten sional failures graben like or pseudo graben like subsidence due to weak or soluble mate rials causing complex sliding topplingphenomena 2 reactivation of pre existing faults disconti nuities joints foliations or rock anisotropies surfaces characterized by residual or lowerthan peak strength formation of composite failure surfaces 3 regional tectonic movements inducing newslope morphologies uplift major fault movement pull apart zones folding the boundary between classical tectonics andslope deformations especially at a large scale hasalways been indistinct as emphasized by antoine 1988 schultz ela 2001 in his paper antoinediscussed mechanisms like diverticulation def ined by lugeon 1943 and badoux 1963 wherepart of pre alpine nappes were reversed in geo metry by huge landslides inverting the stratigraphy antoine 1988 a remarkable geometrical analogyexists between basin extensional tectonics wer nicke 1981 and certain landslide spreading inclays voight 1973 varnes 1978 hutchinson1988 this is despite the fact that wernicke shypothesis demonstrated that basin and rangeregions were not produced by huge landslides butby low angle faulting induced by geodynamic pro cesses regional extension has produced changesin topography and as a consequence signi cantgravity induced deformations therefore we suggest that the term slope tec tonics is justi ed and must be recognized as animportant component in slope deformation slopeinstability implies movements driven by gravitythat can produce irreversible deformations in thepast slopes were viewed as privileged erosionzones de la noe de margerie 1888 strahler1950 whereas few erosion processes were attribu ted to landslides young 1972 since the work ofsimonett 1967 and hovius et al 1997 the link

development of an ultra violet digital camera for volcanic so2 imaging abstract in an effort to improve monitoring of passive volcano degassing we have constructed and tested a digital camera for quantifying the sulfur dioxide so 2 content of volcanic plumes the camera utilizes a bandpass filter to collect photons in the ultra violet uv region where so 2 selectively absorbs uv light so 2 is quantified by imaging calibration cells of known so 2 concentrations images of volcanic so 2 plumes were collected at four active volcanoes with persistent passive degassing villarrica located in chile and santiaguito fuego and pacaya located in guatemala images were collected from distances ranging between 4 and 28 km away with acceptable detection up to approximately 16 km camera set up time in the field ranges from 5 10 min and temporal resolution of up to 6 images per minute is possible which combined with the camera s field of view makes a continuous so 2 dataset attainable variable in plume concentrations can be observed and accurate plume speeds or rise rates can readily be determined by tracing individual portions of the plume within sequential images initial fluxes computed from camera images require a correction for the effects of environmental light scattered into the field of view at fuego volcano simultaneous measurements of corrected so 2 fluxes with the camera and a correlation spectrometer cospec agreed within 25 experiments at the other sites were equally encouraging and demonstrated the camera s ability to detect so 2 under variable background meteorological and environmental conditions this early work has shown great success in imaging so 2 plumes and offers promise for volcano monitoring due to its rapid deployment and data processing capabilities relatively low cost and improved interpretation afforded by synoptic coverage from a range of distances

life on land in the precambrian microfossils have been discovered in cavity fill and replacement silica that occurs between chert breccia clasts in 1200 million year old paleokarst at the top of the mescal limestone central arizona and in 800 million year old paleokarst at the top of the beck spring dolomite southeastern california microbial communities on precambrian g550 million years ago land may have been extensive enough to affect weathering erosion sedimentation and geochemical processes