time resolved seismic tomography detects magma intrusions at mount etna the continuous volcanic and seismic activity at mount etna makes this volcano an important laboratory for seismological and geophysical studies we used repeated three dimensional tomography to detect variations in elastic parameters during different volcanic cycles before and during the october 2002 january 2003 flank eruption well defined anomalous low p to s wave velocity ratio volumes were revealed absent during the pre eruptive period the anomalies trace the intrusion of volatile rich 4 weight percent basaltic magma most of which rose up only a few months before the onset of eruption the observed time changes of velocity anomalies suggest that four dimensional tomography provides a basis for more efficient volcano monitoring and short and midterm eruption forecasting of explosive activity

lithospheric p and s wave velocity models of the sicilian area using wam tomography procedure and assessments we present 3 d models of the p and s wave velocity distributions in the crust and uppermost mantle beneath sicily calabria southern italy and surrounding submerged areas obtained by tomographic inversion of traveltimes of regional body waves phases our method combines double difference tomographic inversion with a post processing procedure weighted average model method wam this procedure was applied to a set of models consistent with the experimental data we tested the ability of the wam procedure to mitigate the uncertainty associated with the arbitrary nature of the many input parameters required for each inversion the local reliability and resolution of the obtained models have been assessed through syn thetic tests experimental tests carried out with independent data sets and unconventional tests based on the analysis of the internal consistency of the p and s velocity models the tomo graphic images provide a detailed sketch of p and s wave velocity anomalies these clearly show the shape of the sicilian maghrebian belt beneath sicily and calabrian arc at different depths low vp and vs bodies are imaged beneath stromboli and marsili volcanoes in the southern tyrrhenian whereas high and low seismic velocities alternate beneath the etna giving inferences on the possible depth of the mantle melting feeding the volcano in the upper crust the main sedimentary basins and tectonic features are also well imaged finally tomographic cross sections show the trend of the moho in the study area where its depth ranges between 35 and 40 km beneath the sicilian belt and between 15 and 22 km in the southern tyrrhenian basin and ionian sea

three dimensional seismic tomography from p wave and s wave microearthquake travel times and rock physics characterization of the campi flegrei caldera 1 the campi flegrei cf caldera experiences dramatic ground deformations unsurpassed anywhere in the world the source responsible for this phenomenon is still debated with the aim of exploring the structure of the caldera as well as the role of hydrothermal fluids on velocity changes a multidisciplinary approach dealing with three dimensional delay time tomography and rock physics characterization has been followed selected seismic data were modeled by using a tomographic method based on an accurate finite difference travel time computation which simultaneously inverts p wave and s wave first arrival times for both velocity model parameters and hypocenter locations the retrieved p wave and s wave velocity images as well as the deduced v p v s images were interpreted by using experimental measurements of rock physical properties on cf samples to take into account steam water phase transition mechanisms affecting p wave and s wave velocities also modeling of petrophysical properties for site relevant rocks constrains the role of overpressured fluids on velocity a flat and low v p v s anomaly lies at 4 km depth under the city of pozzuoli earthquakes are located at the top of this anomaly this anomaly implies the presence of fractured overpressured gas bearing formations and excludes the presence of melted rocks at shallow depth a high v p v s anomaly located at 1 km suggests the presence of rocks containing fluids in the liquid phase finally maps of the v p v s product show a high v p v s horseshoe shaped anomaly located at 2 km depth it is consistent with gravity data and well data and might constitute the on land remainder of the caldera rim detected below sea level by tomography using active source seismic data

signature of ongoing brine reinjection on noble gas isotopes and fluid chemistry at las tres virgenes geothermal field mexico abstract a geochemical survey of the las tres virgenes geothermal field ltvgf baja california sur mexico was carried out to determine the origin and evolution of its fluids along with the influence of injection of local brines and inhibitors intended to manage carbonate scaling issues major and minor cations cl br sr o h and noble gas he ne ar kr and xe isotopes were measured in fluids collected from four production wells two injection wells and one fumarole el azufre in 2016 and 2018 variations in the stable isotopes of water d and 18o and halogens 37cl 81br over the years suggest that local brine reinjection might have started to modify the pristine chemistry of the fluids however relevant information on the original geothermal fluids has been preserved the na br and cl br ratios suggest that ltvgf brines are seawater having leached evaporite deposits halite these deposits are absent in the area but were likely present during the miocene prior to the breakup of the gulf of california suggesting that the saline fluid end member at the ltvgf could be several million years old measured 3he 4he ratios r normalized to the atmospheric ratio ra 1 384 10 6 plotted against the 4he 20ne ratios suggest mixing between a mantle fluid with a r ra of 6 19 typical of the sub continental lithospheric mantle and an atmospheric helium component the r ra versus the 132xe 36ar ratio normalized to air suggests mixing between a mantle rich pre production fluid and air the source of air appears to be linked to local gravity controlled flow reinjection which causes the entrapment of air bubbles leading to a fluid supersaturated in atmospheric noble gases this pattern suggests that reinjection fluids are impacting the production area

seismic velocity structures of southern italy from tomographic imaging of the ionian slab and petrological inferences summary in this study we have determined detailed vp and vs seismic velocity models of the ionian lithosphere subducting beneath the tyrrhenian basin and of the surrounding mantle by applying a post processing technique to a large sample of local earthquake tomography studies our seismic velocity models permit us to infer the presence of low velocity anomalies within the slab which we interpret as regions that are partially hydrated by fluids released during the subduction process a petrological interpretation of the velocity anomalies gives new details on the magmatism of the volcanic aeolian arc furthermore our velocity models provideamoredetaileddescriptionoftheboundaryoftheslabanditsconnectionwiththelarge seismically active tindari letojanni strike slip system finally these results allow describing in detail some features of the slab as the presence of lateral and vertical tears in conclusion the obtained models provide some constraints for inferences on mantle circulation and on the geodynamical evolution of the central western mediterranean

kinematics triggers and mechanism of majiagou landslide based on fbg real time monitoring reservoir landslide as one of the most serious geohazards is worldwide distributed to investigate its triggering factors and mechanisms that underlie its propagations a real time monitoring system based on fiber bragg grating fbg technology was designed for the majiagou landslide in the three gorges reservoir tgr region through analyses of inclinometer data it is found that there are two sliding surfaces existed in the majiagou landslide and that the deeper sliding surface is the critical one it accounts for nearly 80 of the deformation of the landslide this information necessitated the recording of the displacement at the deeper sliding surface together with the rainfall water level pore water pressure temperature of the landslide using a real time monitoring system after analyzing the multi parameter data in detail it is found that observed deformation is mainly governed by reservoir water levels while precipitation has some minor effects the reservoir water level is the determining factor of landslide deformation when it exceeds 160 m or lower than 150 m whereas the reservoir water level varies from 150 m to 160 m the fluctuation velocity plays a dominant role the relationship between the variation of seepage field and kinematic evolution of majiagou landslide is recognized the average displacement rate of majiagou landslide is within 0 1 mm day signifying that the landslide is still creeping presently the results are significant with respect to stability evaluation and formulation of early warning plans for the reservoir landslide

application of field geophysics in geomorphology advances and limitations exemplified by case studies abstract during the last decade the use of geophysical techniques has become popular in many geomorphological studies however the correct handling of geophysical instruments and the subsequent processing of the data they yield are difficult tasks furthermore the description and interpretation of geomorphological settings to which they apply can significantly influence the data gathering and subsequent modelling procedure e g achieving a maximum depth of 30 m requires a certain profile length and geophone spacing or a particular frequency of antenna for more than three decades geophysical techniques have been successfully applied for example in permafrost studies however in many cases complex or more heterogeneous subsurface structures could not be adequately interpreted due to limited computer facilities and time consuming calculations as a result of recent technical improvements geophysical techniques have been applied to a wider spectrum of geomorphological and geological settings this paper aims to present some examples of geomorphological studies that demonstrate the powerful integration of geophysical techniques and highlight some of the limitations of these techniques a focus has been given to the three most frequently used techniques in geomorphology to date namely ground penetrating radar seismic refraction and dc resistivity promising applications are reported for a broad range of landforms and environments such as talus slopes block fields landslides complex valley fill deposits karst and loess covered landforms a qualitative assessment highlights suitable landforms and environments the techniques can help to answer yet unsolved questions in geomorphological research regarding for example sediment thickness and internal structures however based on case studies it can be shown that the use of a single geophysical technique or a single interpretation tool is not recommended for many geomorphological surface and subsurface conditions as this may lead to significant errors in interpretation because of changing physical properties of the subsurface material e g sediment water content in many cases only a combination of two or sometimes even three geophysical methods gives sufficient insight to avoid serious misinterpretation a good practice guide has been framed that provides recommendations to enable the successful application of three important geophysical methods in geomorphology and to help users avoid making serious mistakes

rock cities and ruiniform relief forms processes terminology abstract spectacular rock cut landscapes consisting of closely spaced residual rock blocks separated by narrow intersecting corridors are variously termed as rock cities and ruiniform relief the former term has apparently never been formally defined except in the local czech literature whereas the latter was applied in various contexts making the terminology confusing this paper provides a global overview of forms processes and controls behind such rock city ruiniform landscapes and develops geomorphological terminology for such rock cut landscapes including the proposal that rock city becomes a legitimate scientific term rock cities and ruiniform relief are two different types of rock erosional morphology typified by the presence of a street pattern in the former and highly weathered surfaces of rock residuals in the latter although there is some overlap between the two examples of rock cities or ruiniform relief may be found in different lithologies and in a wide range of climates from hyper arid to humid classic localities include northern czechia and adjacent parts of poland and germany australia central sahara and the gran sabana in venezuela lithologies particularly suitable to the development of this type of erosional morphology include mainly sandstones followed by limestones dolomites conglomerates tuffs but igneous rocks such as granites or rhyolites are also known to support this type of relief the combination of sufficient rock strength to support steep rock faces and the presence of discontinuities which preferentially eroded turn to streets and squares in the rock cities appears as the basic prerequisite a wide range of processes are involved in their formation including surface and subsurface weathering mass movements salt tectonics karst processes in both carbonate and silicate rocks piping fluvial erosion and aeolian abrasion despite being spectacular landscapes very few models of long term evolution of rock city and ruiniform relief have been presented in the literature and it is unlikely that any one scenario would apply to all situations rather rock cities are examples of geomorphological convergence

solution weathering rate and origin of karst landforms and caves in the quartzite of auyan tepui gran sabana venezuela abstract the paper reports the results of sio 2 analyses in the aonda cave system located on the auyan tepui one of the widest table mountains of the gran sabana south venezuela characterised by karst landforms developed in siliceous rock chemical analyses underline the very low concentration of sio 2 of the surface water percolation and cave drip waters have a sio 2 concentration of about 1 mg l the mean silica load of the cave stream is 184 mg s mainly derived from surface solution removal in the allogenic recharge area in the aonda cave system the mean sio 2 dissolved load is 40 mg s in part from surface solution 15 and mainly from underground processes 85 the low solubility of sio 2 in slightly acidic water implies the importance of the time factor in the formation of cave systems with the present dissolution rate about 10 ma would be necessary to form the known karst system this estimation can be significant only if we assume that climate has been stable in the last few tens of millions of years furthermore this age can be taken as a minimum estimate while according to the geomorphic evolution of the area the origin of the aonda cave system could be reasonably dated back to at least 20 30 ma that is to the oligocene

monitoring landslide displacements with the geocube wireless network of low cost gps abstract the analysis of landslide hazard requires continuous and high frequency surface displacement monitoring at numerous and geomorphologically relevant locations ground based geodetic methods gnss tacheometry allow very accurate and high frequency temporal observations while remote sensing methods insar terrestrial and satellite photogrammetry lidar allow spatially distributed observations at high spatial resolution a single surface deformation monitoring technique coupling all these capabilities is still missing the geocube system has been designed to partly overcome this pitfall by creating a low cost flexible easy to install and wireless gps receiver dense geocube monitoring networks can be set easily for operational observations furthermore the monitoring of other landslide properties micro seismicity seismic waves or triggering factors meteorology slope hydrology is possible with the capacity of integrating additional sensors to the geocube this work presents the geocube system and the results of a field campaign performed during the summer 2012 at the super sauze landslide southern french alps with a network of wireless low cost gps the objective was to assess the performance of the geocube system in real field monitoring conditions our results document the spatial and temporal evolution of the landslide during a period of 40 days landslide acceleration periods are detected and correlated to rainfall events

seismic activity and stress tensor inversion at las tres virgenes volcanic and geothermal field mexico abstract we analyze local earthquakes occurring between 2003 and 2012 at the las tres virgenes volcanic and geothermal field tvvgf to establish their temporal and spatial distribution and relationships with local and regional fault systems water injection acid stimulation and steam production tests we obtained focal mechanisms and inverted data for the stress tensor to understand the local and regional stress fields we analyzed 423 local earthquakes with magnitudes between 0 1 and 2 9 mc and hypocentral depths from 0 2 to 7 4 km b s l the cutoff depth at 7 4 km possibly delineates the brittle ductile transition zone we identified seven swarms from 1 to 7 swarms 1 december 2009 2 may 2010 3 june july 2010 and 7 december 2012 are strongly correlated with injection processes whereas swarms 5 april 2012 and 6 september 2012 are correlated with local tectonic faults stress inversion showed nw se e w and ne sw extensional orientations s hmin in agreement with the local tectonic stress field while ne sw compressional orientations s hmax are correlated with the regional tectonic stress field

underground erosion and sand removal from a sandstone tableland stolowe mountains sw poland abstract models of geomorphic evolution of tablelands vary as far as the patterns of cliff line degradation and hence scarp retreat are concerned among surface processes rock slope failures from caprock cliffs often induced by preferential seepage from rock faces are emphasized in this paper evidence is provided that mechanical removal of sand from inside the caprock through underground erosion may also play an important role in the long term evolution of cliffed escarpments in sandstone tablelands more than 140 sandy cones and nearly 80 sand sheets emerging from fissures in the sandstone cap were mapped and measured along six cliff sections of variable length in the stolowe mountains tableland in sw poland the density of sandy accumulation forms varies along the cliff length with cones preferentially associated with intact cliffs and sand sheets being more common along degraded cliff sections further redistribution of sand downslope results in widespread sandy covers below cliff lines which extend for a few hundred metres and are 1 3 m thick as demonstrated by electrical resistivity tomography sand removal from caprock accounts for progressive non catastrophic degradation of tableland margins through gradual subsidence of blocky compartments and the development of ruiniform relief behind the cliff lines thus it may be an important component of long term evolution of stepped relief in sedimentary terrains

large scale geomorphological mapping of tors proposal of a key and landform interpretation abstract isolated bedrock outcrops amidst regolith covered slopes often named as tors have been the object of interest in many geomorphological studies usually as a part of long term landscape evolution inquiries however detailed presentation of tor morphology on maps in publications is very uncommon in this paper we propose a new comprehensive method of detailed large scale geomorphic mapping of tors it is tested on selected tor groups located in the sudetes in southwestern poland they are diversified in terms of lithology granite greenstone and sandstone bedrock and morphological features solitary tor rock city cluster of tors rock cliffs etc the method consists of three stages preparation of digital spatial data field mapping and final legend and map design the legend consists of 40 symbols which allows to show tor morphology in considerable detail assisting thereby in the interpretation of controls behind tor formation and evolutionary pathways of different types of tors using detailed maps one can extract information about major vertical joint sets and the patterns of tor decay weathering of rock surfaces in subaerial conditions structure of slope covers and internal morphological differentiation within large clusters of tors the latter being a possible manifestation of certain stages in the development of these landforms

the role of landslides in downslope transport of caprock derived boulders in sedimentary tablelands stolowe mts sw poland abstract escarpment slopes in sedimentary tablelands are often mantled by extensive boulder blankets while lithology shows beyond doubt that caprock is the source of boulders the processes involved in boulder movement and their distribution patterns are rarely examined in this paper we investigate the role of landslides initiated within middle and lower escarpment slopes in redistributing boulder covers on the example of the stolowe mountains in sw poland quartz sandstones form caprock and give rise to precipitous albeit rather low 30 m high at most typically 10 15 m uppermost slope sections and are the source of boulders which occur at distances even 1 km away from the caprock on the nearly flat footslope sedimentary series beneath caprock include fine grained rocks such as mudstones claystone and calcareous sandstones geomorphological mapping and geomorphometric analysis of a high resolution dem allowed us to identify landform patterns interpreted as resulting from landslides both rotational and translational the latter produced distinctive tread and riser topography with risers up to 10 m high results of geophysical prospecting using electrical resistivity tomography ert confirm the presence of allochthonous sandstone derived upper layer that wedges out downslope and indicate resistivity contrasts at depth of 5 15 m interpreted as basal boundaries of landslide material sandstone boulders rafted on top of slid masses and reached very distant footslope settings the primary role of landsliding consists of transporting allochthonous boulders further than would be possible otherwise and accumulating boulders in clusters and linear belts across the slope notably on risers

effect of pore geometry on vp vs from equilibrium geometry to crack seismic wave velocities of melt or aqueous fluid containing systems are studied over a wide range of pore shapes including oblate spheroids tubes cracks and an equilibrium geometry controlled by a dihedral angle the relative role of liquid compressibility and pore geometry on the v p v s velocity ratio is clarified the result clearly indicates that p and s velocity structures determined by seismic tomography can be used to verify whether interfacial energy controlled melt or fluid geometry equilibrium geometry is achieved relationships between the diverse models are clearly established by relating each model to the oblate spheroid model in terms of the equivalent aspect ratio as a function of the aspect ratio a significant effect of pore geometry on d in v s d in v p the ratio of the fractional changes in v s and v p is shown equilibrium geometry of the partially molten rocks characterized by a dihedral angle of 20 40 corresponds to an aspect ratio of 0 1 0 15 the value of d in v s d in v p expected for the texturally equilibrated partially molten rocks is shown to be 1 1 5 which is much smaller than that expected for cracks and dikes with an aspect ratio of 10 2 10 3 in the upper mantle low velocity regions the seismologically obtained value of d in v s d in v p is within this range beneath the bolivian andes 1 1 1 4 but is as high as 2 beneath iceland 1 7 2 3 and beneath northeastern japan 2 0 the former region can be regarded as a region where equilibrium geometry is achieved and the latter regions can be regarded as regions where dikes and veins typical of a system far from the textural equilibrium dominate

image based mapping of surface fissures for the investigation of landslide dynamics abstract the development of surface fissures is an important indicator for understanding and forecasting slope movements landslide investigations therefore frequently include the elaboration and interpretation of maps representing their spatial distribution typically comprising intensive field work and instrumentation it is only recently that aerial photography with sub decimetre spatial resolution is becoming more commonly available and opens a window to analyse such features from a remote sensing perspective while these data are in principle helpful to elaborate maps from image interpretation techniques there is still no image processing technique available to extract efficiently these geomorphological features this work proposes a largely automated technique for the mapping of landslide surface fissures from very high resolution aerial images the processing chain includes the use of filtering algorithms and post processing of the filtered images using object oriented analysis the accuracy of the resulting maps is assessed by comparisons with several expert maps in terms of affected area fissure density and fissure orientation under homogenous illumination conditions true positive rates up to 65 and false positive rates generally below 10 are achieved the resulting fissure maps provide sufficient detail to infer mechanical processes at the slope scale and to prioritize areas for more detailed ground investigations or monitoring

hydrochemical isotopic and hydrogeological conceptual model of the las tres virgenes geothermal field baja california sur mexico abstract based on geological structural hydrochemical and isotopic data a hydrogeological conceptual model for the geothermal reservoir shallow wells and springs at the las tres virgenes geothermal field and its surroundings is proposed the model explains the genesis of different types of thermal and cold groundwater in the nw el azufre valley las tres virgenes and aguajito complex ne reforma complex and s sierra mezquital areas shallow groundwater of sulfate type in the nw zone is explained by the rise of co2 h2s vapor from a shallow magma chamber and the subsequent heating up of a shallow aquifer vertical communication between the reservoir and the surface is facilitated by a series of extensional nw se trending normal faults forming the graben structures of the santa rosalia basin low permeability characteristics of the geological formations of the study area support the hypothesis of a fracture and fault dominated subterranean flow circulation system the na cl hco3 composition of springs in the ne and se zones indicates influence of ascending geothermal fluids facilitated by radial fault systems of the reforma caldera and probably the existence of a shallow magma chamber close to the surface the rising geothermal fluids are mixed up with meteoric water from a shallow aquifer the las tres virgenes and the reforma complex are separated by younger n s trending lateral shearing faults such as the cimarron fault such disposition explains the genesis of different hydrogeological flow regimes on both sides hco3 type surface water from the southern zone between san ignacio and mezquital is of typical meteoric origin with no influence of geothermal fluids due to arid climatic conditions in the study zone recent recharge in the geothermal area seems improbable thus recent interaction between the surface and the geothermal reservoir can be excluded furthermore isotopic and hydrochemical data exclude the presence of marine water from the gulf of california in the deep reservoir both conditions indicate recharge of the reservoir by meteoric water during glacial periods in holocene or pleistocene time or a magmatic origin of the reservoir fluids the slightly positive slope of the 18o d line of geothermal fluids and its intermediate isotopic composition between the surface samples and magmatic andesitic water indicate that magmatic andesitic water contributes approximately 30 to the geothermal fluid composition whereas fossil meteoric water represents the major component 70 the geothermal reservoir is considered to represent a hydrostatic stagnant flow system based on the observed linear correlation between the isotopic composition and the altitude of the surface manifestations the isotopic composition and altitude of the former recharge were determined as 18 o 9 7 and d 67 3 and 350 m a s l respectively this altitude is interpreted as mean average recharge elevation scarcity of permanent rivers low density of springs and domestic wells as well as low precipitation rates reflect restricted distribution of shallow groundwater systems in the study zone these systems are related to isolated local aquifers composed of valley fillings

fast evolving conduits in clay bonded sandstone characterization erosion processes and significance for the origin of sandstone landforms abstract in strelec quarry the czech republic an underground conduit network 300 m long with a volume of 10 4 m 3 and a catchment of 7 km 2 developed over 5 years by groundwater flow in cretaceous marine quartz sandstone similar landforms at natural exposures conduits slot canyons undercuts are stabilized by case hardening and have stopped evolving the quarry offers a unique opportunity to study conduit evolution in sandstone at local to regional scales from the initial stage to maturity and to characterize the erosion processes which may form natural landforms prior to stabilization a new technique was developed to distinguish erodible and non erodible sandstone surfaces based on measurements of relative erodibility drilling resistance ambient and water saturated tensile strength ts at natural and quarry exposures three distinct kinds of surfaces were found 1 erodible sandstone exposed at 60 of surfaces in quarry this sandstone loses as much as 99 of ts when saturated 2 sub vertical fracture surfaces that are non erodible already prior to exposure at ground surface and which keep considerable ts if saturated 3 case hardened surfaces that start to form after exposure in favorable conditions they became non erodible and reach the full ts in just 6 years an increase in the hydraulic gradient from 0 005 to 0 02 triggered conduit evolution based on long term monitoring of water table in 18 wells and inflows to the quarry rapidly evolving major conduits are characterized by a channel gradient of 0 01 a flow velocity 40 cm s and sediment concentration 10 g l flow in openings with a discharge 1 ml s and hydraulic gradient 0 05 exceeds the erosion threshold and initiates piping in the first phase of conduit evolution fast concentrated flow mobilizes erodible sandstone between sets of parallel fractures in the shallow phreatic zone in the second phase the conduit opening mainly expands vertically upward into the vadose zone by mass wasting of undercut sandstone slabs mass wasting is responsible for 90 of mobilized sandstone sides of the mature conduits are protected by non erodible fracture surfaces natural landforms were probably formed very rapidly by overland flow piping and possibly fluidization during or at the end of the glacial periods when sandstone was not yet protected by case hardening

a history of basin inversion scarp retreat and shallow denudation the araripe basin as a keystone for understanding long term landscape evolution in ne brazil at the border between the states of ceara and pernambuco northeast brazil the chapada do araripe is a high plateau 800 1000 m a s l formed by a slab of cenomanian fluvial sandstone this caprock is underlain by lacustrine or marine albian layers and older rift deposits during the cretaceous the araripe basin lay at a palaeoelevation close to sea level through a presentation and discussion of original field and cartographic data we analyse the mechanisms of topographic inversion in this sedimentary basin in relation to local or regional crustal upwarp the contrast between the plateau a weakly dissected structural surface and the surrounding lowlands is explained through a study of the erosional scarps cuesta like landforms and their outliers that fringe the chapada no evidence of local tectonic inversion is found river incision spring sapping landslides and other forms of mass movement are listed as efficient processes of topographic inversion and scarp retreat the rates and patterns of which appear to be controlled by lithological contrasts and conditions of exhumation of the basement geometric relationships with regional stepped surfaces e g the low elevation sertaneja surface exhumed palaeosurfaces and regional drainage systems are analysed our estimation of the amplitude of denudation and topographic inversion 0 6 0 7 km differs significantly from apatite fission track derived estimates reported in recent literature which would imply burial by considerable thicknesses of younger sediments followed by 1 5 km or more of post rift denudation not just in the study area but also in the tucano jatoba basin to the south the exhumation and reworking of surrounding basement surfaces probably began during the early cenozoic as shown to the northwest of the chapada by the presence of widespread laterites of probable palaeogene age a second stage of topographic inversion occurred during the oligocene or later this would correspond to the major stages of river incision partial planation and basin inversion

permanent scatterers for landslide investigations outcomes from the esa slam project within the slam project service for landslide monitoring launched in 2003 by the european space agency esa the permanent scatterers ps technique a multi image interferometric approach coupled with the interpretation of aerial photos and optical satellite images was carried out for landslide investigations the ps analysis was applied at a regional scale as support for landslide inventory mapping and at local scale for the monitoring of single well known slope movements for the integration of the ps measurements within a landslide inventory the arno river basin italy was chosen as test site for the presence of a high number of mass movements to date about 300 areas at high landslide risk and more than 27 000 individual landslides mapped by the institutional authorities about 350 sar images have been interferometrically processed by means of the ps technique with the detection of about 600 000 ps the use of optical images contributed spatial meaning to the point wise information provided by the ps making it easier to identify terrain features related to slope instability and the landslide boundaries here we describe the employed methodology and its impact in the updating of a preexisting landslide inventory 6 8 of the total number of landslides were characterized by ground displacement measurements from the ps 6 1 of already mapped landslides and 0 8 of new unstable areas detected through the ps analysis moreover most of the ps are located in urban areas showing that the proposed methodology is suitable for landslide mapping in areas with a quite high density of urbanization but that over vegetated areas it still suffers from the limitations induced by the current space borne sar missions e g temporal de correlation on the other hand the use of insar for the monitoring of single slow landslides threatening built up areas has provided satisfactory results allowing the measurement of superficial deformations with high accuracy on the landslide sectors characterized by a good radar reflectivity and coherence

escarpment retreat in sedimentary tablelands and cuesta landscapes landforms mechanisms and patterns abstract although the general concept that escarpments in layered rocks retreat through time was offered more than 150 years ago recognizing the exact mechanisms patterns and rates of retreat remains a challenge in this paper we provide the state of the art of the theme of escarpment retreat reviewing both the classic contributions often forgotten but important case studies and the latest research in separate parts of the paper we discuss 1 terminology applied to the geomorphology of escarpments 2 the main assumptions and pathways of long term evolution of escarpments including conceptual models presented so far 3 processes involved in cliff retreat mainly weathering mass movements and erosion 4 the role of spring erosion and fluvial processes leading to fluvial dissection and development of canyons present in many tablelands 5 the possible role of climate change in escarpment evolution 6 rates of escarpment retreat in conclusions we summarize the major advances in our understanding of escarpment evolution of the last two three decades such as the recognition of the key role of emerging groundwater in non uniform escarpment retreat of an important role of silica dissolution and underground removal of dissolved solids increasing appreciation of rock properties in governing the patterns of escarpment retreat the proposal that cliffs do not necessarily retreat via catastrophic rock slope failures but may disintegrate in situ and the first attempts to date escarpment retreat using cosmogenic isotopes finally the remaining gaps and possible research priorities for the future are identified

a global review of solutional weathering forms on quartz sandstones abstract solutional landforms in limestone have been described for over a hundred years but landforms of similar morphology on highly siliceous sandstones and quartzites have also been identified in a wide variety of environments and generally termed pseudokarst these include large bedrock pinnacles and towers caves corridors grikes solution basins and runnels and even silica speleothems quartzites and quartz sandstones have been held to be amongst the most chemically resistant of rocks but the similarity both in morphology and genetic process of many landforms developed from them to features of known solutional origin on limestone has prompted some authors to refer to these quartzose landforms as true karst the most detailed studies of quartzose karst landforms have been in present day tropical regions or areas believed to have been tropical in the geologically recent past this concentration of research in hot wet areas allied with the long held assertion of the insolubility of silica especially quartz has led to a belief that tropical climatic conditions are necessary for karstic solution of these rocks however the existence of quartzose karst landforms in temperate and even sub polar latitudes especially where there is no evidence of prior tropical conditions suggests that the requirement of tropical weathering is no longer tenable the reports of these quartzose solutional landforms are widely scattered through the geomorphological and geological literature but a comprehensive world wide review of the range of solutional landforms on quartzose rocks has not previously been published because of the increasing awareness in this karst type such a summary is sorely overdue

vp structure of mount st helens washington usa imaged with local earthquake tomography we present a new p wave velocity model for mount st helens using local earthquake data recorded by the pacific northwest seismograph stations and cascades volcano observatory since the 18 may 1980 eruption these data were augmented with records from a dense array of 19 temporary stations deployed during the second half of 2005 because the distribution of earthquakes in the study area is concentrated beneath the volcano and within two nearly linear trends we used a graded inversion scheme to compute a coarse grid model that focused on the regional structure followed by a fine grid inversion to improve spatial resolution directly beneath the volcanic edifice the coarse grid model results are largely consistent with earlier geophysical studies of the area we find high velocity anomalies nw and ne of the edifice that correspond with igneous intrusions and a prominent low velocity zone nnw of the edifice that corresponds with the linear zone of high seismicity known as the st helens seismic zone this low velocity zone may continue past mount st helens to the south at depths below 5 km directly beneath the edifice the fine grid model images a low velocity zone between about 2 and 3 5 km below sea level that may correspond to a shallow magma storage zone and although the model resolution is poor below about 6 km we found low velocities that correspond with the aseismic zone between about 5 5 and 8 km that has previously been modeled as the location of a large magma storage volume

factors controlling evolution of karst conduits in sandy limestone and calcareous sandstone turnov area czech republic abstract karst potential is rarely studied in calcareous sandstones and sandy limestones the minimum content of carbonate necessary for the development of conduits is unknown and the mechanisms of the origins of conduits in these rocks are poorly understood this article focuses upon these questions in an important regional aquifer samples of limestones and sandstones were taken from outcrops in vertical profiles and were subjected to a rapid dissolution test with 10 hcl the degree of disintegration of the samples after dissolution of the carbonate was observed in order to estimate which portions of the rock enabled formation of karst conduits carbonate content was measured by calcimetry distribution of calcite cement and other sources of cohesion were studied by scanning electron microscopy tracer tests in the conduits were evaluated calcite is the dominant carbonate mineral and main cementing agent in the jizera fm aquifer mean content 51 however calcite content was found to be a weak predictor of karst potential most of the samples disintegrated completely if the calcite content exceeded 55 on the other hand some rocks with a calcite content up to 70 did not disintegrate due to microcrystalline amorphous silica which bound the quartz grains together and or formed a foam like supporting structure after in situ calcite dissolution the rock in karst prone zones is turned to residuum which consequently is washed out by fast flow 0 01 0 2 m s based on tracer tests microscopic study of cementing agents of the siliciclastic carbonate sediments and dissolution tests are essential for understanding the mechanisms of conduit origin in ghost rock karst

landform characterization using geophysics recent advances applications and emerging tools abstract this paper presents an overview of the strengths and limitations of existing and emerging geophysical tools for landform studies the objectives are to discuss recent technical developments and to provide a review of relevant recent literature with a focus on propagating field methods with terrestrial applications for various methods in this category including ground penetrating radar gpr electrical resistivity er seismics and electromagnetic em induction the technical backgrounds are introduced followed by section on novel developments relevant to landform characterization for several decades gpr has been popular for characterization of the shallow subsurface and in particular sedimentary systems novel developments in gpr include the use of multi offset systems to improve signal to noise ratios and data collection efficiency amongst others and the increased use of 3d data multi electrode er systems have become popular in recent years as they allow for relatively fast and detailed mapping novel developments include time lapse monitoring of dynamic processes as well as the use of capacitively coupled systems for fast non invasive surveys em induction methods are especially popular for fast mapping of spatial variation but can also be used to obtain information on the vertical variation in subsurface electrical conductivity in recent years several examples of the use of plane wave em for characterization of landforms have been published seismic methods for landform characterization include seismic reflection and refraction techniques and the use of surface waves a recent development is the use of passive sensing approaches the use of multiple geophysical methods which can benefit from the sensitivity to different subsurface parameters is becoming more common strategies for coupled and joint inversion of complementary datasets will once more widely available benefit the geophysical study of landforms three cases studies are presented on the use of electrical and gpr methods for characterization of landforms in the range of meters to 100 s of meters in dimension in a study of polygonal patterned ground in the saginaw lowlands michigan usa electrical resistivity tomography was used to characterize differences in subsurface texture and water content associated with polygon swale topography also a sand filled thermokarst feature was identified using electrical resistivity data the second example is on the use of constant spread traversing cst for characterization of large scale glaciotectonic deformation in the ludington ridge michigan multiple cst surveys parallel to an 60 m high cliff where broad 100 m synclines and narrow clay rich anticlines are visible illustrated that at least one of the narrow structures extended inland a third case study discusses internal structures of an eolian dune on a coastal spit in new zealand both 35 and 200 mhz gpr data which clearly identified a paleosol and internal sedimentary structures of the dune were used to improve understanding of the development of the dune which may shed light on paleo wind directions

an updated global review of solutional weathering processes and forms in quartz sandstones and quartzites abstract quartz is considered one of the less soluble minerals of the earth s crust and thus hardly affected by chemical weathering despite this for more than forty years it is clear that the formation of caves and peculiar solutional weathering dominated landforms in quartz rich lithologies is common and shares several similarities to the well known karstic ones in carbonate rocks in the last thirty years great strides have been made in furthering our knowledge of the distribution of these forms around the world and the geochemical processes involved these studies have clearly shown that solutional weathering is a fundamental process acting through intergranular dissolution of quartz increasing the rock porosity and decreasing the rock strength to erosion this process has been described in the concepts of arenization and phantomization and the widespread evidences of the fundamental role of quartz solution in landform genesis has even developed to the extent of several geomorphologists reassessing the definition of the term karst and its application to these peculiar lithologies nonetheless the process is complicated by several factors related both to environmental conditions water chemistry and availability as well as to the compositional and textural characters of the lithology presence of clays iron hydroxides carbonate cement etc all these aspects have to be taken carefully in consideration in order to understand if solution is a dominant or accessory process in the landscape evolution in this review the state of knowledge on the relevant chemical processes weathering mechanisms and speleogenesisk involved in the surface and underground karstification and clear examples of quartz solution and solutional landforms from different world locations are outlined and discussed

field measurement and failure forecast during the remediation of a failed cut slope a large number of deep cuts are formed during the construction of expressways in mountainous areas inadequate interpretation of ground conditions is a major contributing factor to the failure of cut slopes this study focuses on the hongyan landslide along the s26 expressway due to lack of an adequate pre construction investigation a landslide was triggered by small scale excavation at the toe part of the slope the potential slip surface was incorrectly located consequently two rows of stabilizing piles were not long enough to reach stable rocks to overcome the mistake two additional rows of piles were installed during construction both slope deformation and the stress of reinforced bars in piles were monitored for safety considerations a verhulst model based failure forecast was also utilized to insure the stability of the slope during remedial works reviewing this landslide reveals a number of lessons first sufficient geological investigation and careful interpretation of ground conditions are mandatory prior to the design of a cut slope second systematic field monitoring is strongly recommended especially when the geology of the slope is complex and it is difficult to determine failure patterns third the failure forecast can serve as a supplementary measure to insure the safety of workers and slopes last it always takes some time for stabilizing piles to mobilize

waning miocene subduction and arc volcanism in baja california the san luis gonzaga volcanic field abstract subduction of the guadalupe magdalena microplate beneath baja california ended in the middle miocene and the last volcanic events in the frontal arc extinguished along the present day eastern margin of the baja california peninsula the san luis gonzaga area in the north central gulf coast contains one of the younger arc related volcanic centers in northern baja california the volcanic succession contains three sequences the basal sequence group 1 is composed of stratified pyroclastic deposits up to 500 m thick and subordinate lava flows the near vent facies crop out in tilted fault blocks along the present shoreline whereas the distal facies are exposed across 12 km toward the west and includes epiclastic deposits and at least three ash flow tuffs this sequence is internally concordant and overlies smooth paleosurface developed on granitic basement and pinches out across the gulf escarpment the potrero andesite group 2 is a series of dacite to basaltic andesite lava flows from a shield volcano located 15 km west of today s coastline similar source vents also occurs further south of the san luis gonzaga area a sequence of dacite domes group 3 intrudes the near vent facies of group 1 and contains subordinate volcanic breccia and minor lava flows that overlie group 1 sequence cross cutting relationships and the abundance of volcanic breccia associated with the domes suggest that these domes were emplaced as semi rigid intrusions spines with low explosive activity the san luis gonzaga volcanic suite ranges in composition from basaltic andesite to dacite with predominant plagioclase and pyroxene and variable amounts of hornblende trace element patterns indicate calc alkaline to mildly alkaline magmas with high ba and low nb contents incompatible element ratios and mineralogical characteristics suggest different magma batches and or different amount of crustal assimilation for the three sequences that produced contrasting eruptive styles a pink dacitic tuff that lies in the upper portion of group 1 yielded an 40 ar 39 ar age of 17 2 0 3 ma the most precise of three ages from the andesitic sheet flows of group 2 is 15 4 0 5 ma the dacite domes of group 3 represent the end of miocene arc activity but they are strongly altered and no reliable ages were obtained these data fall within the range of isotopic ages reported for arc lavas 21 to 16 ma from the discontinuous series of isolated volcanic fields in northern baja california this contrasts with the continuous and more voluminous arc volcanism in southern baja california that started earlier 25 ma and ended later 11 ma these space time patterns of arc volcanism reflect the geometry of the subducted farallon slab and the history of its breakup as the rivera triple junction migrated to the south

pre pliocene extension around the gulf of california and the transfer of baja california to the pacific plate late miocene 12 5 ma extension around the edges of the gulf of california has been alternatively attributed to basin and range extension back arc extension or development of the pacific north america plate boundary this extension was ene directed and similar in structural style to extension in the basin and range province timing constraints permit nearly synchronous onset of this deformation in a belt extending sse from northernmost baja california to the mouth of the gulf where this extensional faulting continued through pliocene time to the present synchronous with motion on the modern transform plate boundary in the gulf of california no change in direction of extension can be resolved revised constraints on pacific north america plate motion support the development of this late miocene extension as a component of pacific north america displacement that could not be accommodated by strike slip displacement along the existing plate boundary west of the baja california peninsula this scenario implies that transfer of baja california from the north america plate to the pacific plate was a gradual process beginning about 12 10 ma when motion of the pacific plate relative to north america was partitioned into separate regimes of strike slip and dip slip displacement on opposite sides of baja california

deformation mechanisms and evolution of a pile reinforced landslide under long term reservoir operation abstract stabilizing piles are widely used for reinforcing landslides in the three gorges reservoir area china due to reservoir operations long term water level fluctuations wlfs may cause instability or failure of the reservoir landslide and piles system rlps this study experimentally investigated the deformation characteristics and mechanisms of the rlps under long term wlfs the results showed that long term wlfs led to loading and unloading cycles and consequently a weakening of the slope stability where retrogressive failure and system instability were observed retrogressive failure at the slope toe was caused by topographical variation and physical and mechanical deterioration which may be a result of the long term wlfs system instability was accompanied by a stress release process above the new slip surface and was determined to be dependent on the geological structure of the rlps based on this investigation the evolution model of the pile reinforced landslide under long term wlfs was proposed even though the rlps was adversely affected by the long term wlfs it maintained a relatively steady state due to the reinforcement of the piles effective pile installation changed the development of the reservoir landslides and prevented the entire slip surface from reaching a critical state thus a catastrophic consequence was avoided except for the local failure through physical modeling this study experimentally provided a deeper understanding of the deformation mechanisms and evolution of the rlps influenced by the long term wlfs

using tdr cables and gps for landslide monitoring in high mountain area time domain reflectometry tdr is performed as a complement to the monitoring methods in subsurface deformation in slope together with the global positioning system gps to monitor ground deformation of high altitude landslides in li shan four tdr cables were installed in drill holes near the monitoring stations in the landslide area according to the recorded tdr waveforms there were shear and tensile zones under the b 5 b 9 c 1 and c 2 stations a comparison of the tdr waveforms with the monitored data and boring log revealed that the subsurface sliding occurred between layers of colluvium and strongly weathered slate three gps receivers were installed to measure ground displacement in the landslide area the results from the gps were compared with the surface extensometers data on site the two initial baseline lengths were 451 188 10 and 908 212 4 mm respectively the optimal data reduction achieved used a 3 h session with moving average for each hour s gps data the standard deviation values of the gps were 2 16 and 2 44 mm respectively on site the results of tdr and gps measurements showed their applicability in the deformation monitoring of high mountain landslides

boundary effect on the hydraulic characteristics of gravelly soil slopes in physical model tests abstract the stability of a residual gravelly soil slope during heavy rainfall is closely related to the seepage field which is directly affected by the seepage boundaries of the slope to examine the boundary effect a novel model flume that can implement permeable and impermeable boundary conditions was designed with this flume hydraulic model tests of a gravelly soil slope considering those two seepage boundaries were carried out the results show that distinct spatial morphology of seepage fields is reflected by the hydraulic characteristics of the slope models with different seepage boundaries the slope with permeable boundaries generally exhibits a larger average infiltration rate as well as a relatively smaller moving speed of wetting front in the lower part compared to the slope with impermeable boundaries the residual moisture content in the deep lower part of the slope with permeable boundaries is 6 6 cm3 cm3 smaller than that of the slope with impermeable boundaries nevertheless the maximum pore water pressure in the middle part of the slope with permeable boundaries is 1 2 kpa higher than that in the corresponding part of the slope with impermeable boundaries it is noted that regional pore water pressures in the shallow lower and shallow middle parts of the slope with impermeable boundaries exhibit large fluctuations with an amplitude over 0 5 kpa the seepage field in the slope with permeable boundaries presents a multi dimensional development which may lead to a local failure of the slope the results are of great significance in studying the similarity of seepage boundary condition in the field of similarity theory on landslide model tests and provide an experimental basis for establishing rainfall induced landslide theory

comment on sandstone caves on venezuelan tepuis return to pseudokarst by r aubrecht t lanczos m gregor j schlogl b smida p liscak ch brewer carias l vlcek geomorphology 132 2011 351 365 in the recent work of aubrecht et al 2011 the presence of unlithified or poorly lithified beds of sands in the quartz sandstone stratigraphic succession is proposed as a key factor for speleogenesis in the venezuelan tepuis in this comment we observe that in the cited work the geologic history of the region in terms of sedimentation environment diagenesis and low grade burial metamorphism has not been considered furthermore the peculiar pillar flow columns that aubrecht et al describe as a proof of the unlithification are lacking in many other different cave systems in the same area four critical points are discussed the burial metamorphism of the mataui formation the significance of the schmidt hammer measurements the cave morphologies and the role of sio2 dissolution finally we suggest that weathering in its wider significance is probably the triggering process in speleogenesis and there is no need to invoke a differential diagenesis of the sandstone beds

subduction control on the curie isotherm around the pacific north america plate boundary in northwestern mexico gulf of california preliminary results abstract spectral analysis of namag magnetic data enabled us to estimate depths to the curie isotherm along the pacific north america plate boundary the estimated depths for the gulf of california and southern baja california peninsula correlate quite well with the depths to the moho available from previous studies based on receiver function and seismic refraction in northernmost baja california and southwestern usa no correlation is observed between depths to the curie isotherm and depths to the mantle obtained from receiver function analysis depths to the curie isotherm are shallower along the coastal plains of sonora and sinaloa differences between receiver function based mantle depths and curie depths are equally large however there is more consistency with depths established by seismic refraction studies four zones with shallow curie isotherm are identified in southern gulf of california gs1 gs2 gs3 and gs4 gs1 is located at the gulf of california mouth the alarcon rise is located between gs1 and gs2 pescaderos basin is located northwest of gs2 gs3 stretches from the carmen basin to the farallon basin gs4 extends from tiburon island up to northern guaymas basin northernmost shallow curie depth zone gn1 comprises upper and lower delfin basins as well as the consag and wagner basins a northern prolongation also covers pinacate volcanic center the southern shallow curie isotherm zones are associated with lithospheric asthenospheric material upwelling zones gn1 also includes a convective component related to the younger magmatism of the pinacate volcanic field deeper curie depths are found at southern baja california peninsula interpreted as associated with thicker continental or stretched crust it is possible that the crust is underlain or underplated by magnetic oceanic crust as suggested by satellite magnetic anomalies centered at the magdalena shelf a contrasting pattern features northern baja california deep curie zones to the west contrasting with relative shallower curie isotherm areas to the east the prolongation towards the peninsula of the extinct shirley transform fracture zone roughly separates the two domains observed along the peninsula and suggests that the curie isotherm along the peninsula is controlled by differences subduction of the guadalupe and magdalena microplates major differences pointed out between northern and southern gulf of california might indicate that subduction also played a key role at the beginning of the opening of the gulf of california however currently the curie pattern is controlled by the rifting processes shallow curie zones correlating quite well with the rift basins and the lithosphere asthenosphere upwelling material

do microplates in subduction zones leave a geological record active microplate boundaries in ocean continent subduction zones may induce deformation of the overlying plate and spatial or geochemical variations in the volcanic arc we discuss two modern cases the first is the south gorda juan de fuca plate boundary in the cascadia subduction zone where there is little or no effect on the overriding plate and the oceanic plate takes up much of the deformation the second case is the cocos rivera plate boundary in the middle america trench where the overlying colima graben contains substantial deformation in a zone extending from the trench to the volcanic arc and the sub duction related volcanism is spatially and geochemically complex we apply these observations to boundaries of the arguello monterey guadalupe and magdalena microplates which existed in the subduction zone west of baja california at various times from 20 to 12 5 ma the past positions of these boundaries relative to baja california are constrained by global plate reconstructions closure of the gulf of california and an estimate of extension in the mexican basin and range province existing regional mapping and our additional reconnaissance mapping show that paleocene to eocene fluvial and marine sedimentary rocks south of ensenada along the western baja california peninsula and eastward to the mid miocene volcanic arc are undeformed limited available data reveal no major spatial or geochemical variations in the mid miocene volcanic arc that might correlate with the past positions of the microplate boundaries thus these microplate boundaries had little to no effect on the overriding continental plate the nature of guadalupe and magdalena interactions with north america may have been closer to the south gorda juan de fuca example with possible internal deformation of the microplates the monterey and arguello microplates may have behaved like the modern explorer plate with largely strike slip motion relative to north america during their last stages of existence tectonic patterns similar to these examples may be expected from other plate boundaries where a plate is fragmenting as it enters a subduction zone e g the aluk plate in the trench beneath west antarctica in early tertiary time whether these microplates subsequently become attached to the overriding continental plate or to a larger oceanic plate and whether this causes deformation in the region of the former subduction zone may depend on the velocities of the nearby major plates and the relative orientations of the microplate boundaries

scarp retreat and slope development near picton new south wales australia summary slope profiles measured on a ridge extending out from a plateau capped with gently dipping sandstone fall into an evolutionary sequence controls on slope form in the area are the sandstone caprock the processes operating on the slopes themselves and the activity of the channel at the base of the slope as the slopes become older mean slope angles decline from about 18 degrees to about 8 degrees and maximum slope angles decline from 43 to 21 degrees modal slope angles of 6 8 10 12 22 24 and 28 30 degrees appear to be related both to the processes occurring on the slopes and to the strength of the regolith materials a five stage sequence of slope evolution is postulated in which the younger slopes undergo parallel retreat whilst slopes of increasing age first undergo slope replacement and later slope decline soil profile characteristics and a radiocarbon date show that the regolith on the older hillslopes is much older than the adjacent valley fill materials hillslope development is affected much more by incision at the base than by removal or accumulation of debris

mechanism and failure process of qianjiangping landslide in the three gorges reservoir china the qianjiangping landslide is a large planar rock slide which occurred in july 14 2003 shortly after the water level reached 135 m in the three gorges reservoir china the landslide destroyed 4 factories and 129 houses took 24 lives and made 1 200 people homeless field investigation shows that the contributing factors for the landslide are the geological structure of the slope the previous surface of rupture the water level rise and continuous rainfall in order to reveal the mechanism and failure process of the landslide numerical simulation was conducted on qianjiangping slope before sliding based on the characteristics and the engineering conditions of the landslide the topography and the geological profiles of qianjiangping slope before sliding is reconstructed the seepage field of qianjiangping slope before sliding was simulated with the geostudio software the results show that ground water table rises and bends to the slope during the rise of water level and the slope surface becomes partially saturated within the period of continuous rainfall using the ground water table obtained above the failure process of qianjiangping slope is simulated with the flac3d software the results demonstrate that the shear strain increment displacement and shear failure area of the slope increased greatly after the water level rose and continuous rained and the landslide was triggered by the combined effect both of water level rise and continuous rainfall the development of shear strain increment displacement and shear failure area of the slope shows that the landslide was retrogressive in the lower part of the slope and progressive in the upper part of the slope

strain distribution based geometric models for characterizing the deformation of a sliding zone abstract distributed optical fiber sensing technology was used to establish a deformation monitoring system for the majiagou landslide in the three gorges reservoir area china the monitoring methods were introduced the strain distribution of the optical sensing cables can be utilized to accurately detect the position of the sliding zone and to reveal the movement of the landslide which was verified by comparisons with gps and inclinometer data it was found that the strain distributions of the optical sensing cable in the sliding zone were different in order to reasonably explain the shear deformation of the sliding zone based on the strain distribution and its changes three geometric models reflecting the spatial relationship between the sliding zone and the optical cable were proposed the results indicate that the strain distributions depend on the angle between the optical sensing cable and the sliding zone the position of the main slip surface within the sliding zone as well as the shear deformation of the sliding zone the correctness of the geometric models is verified by the monitored strain distribution of the sensing cable the proposed geometric models can be used to precisely describe the deformation of the sliding zone and reveal the evolutionary stage of the landslide

behavior and analysis of stabilizing piles installed in a cut slope during heavy rainfall abstract in this study the behavior of stabilizing piles installed in a cut slope is investigated using a field measurement system and analyzed considering the infiltration depth of environmental rainfall two cut slopes located on an express highway construction site in donghae korea were selected for this study landslides with some tension cracks were found in the upper part of these cut slopes during the cutting process as the primary method of slope enforcement four rows of stabilizing piles were created and a series of field monitoring systems was installed to measure the movements of the stabilizing piles and the slope according to the field monitoring results the deflection of the stabilizing piles and the deformation of the slope were significantly affected by heavy rainfall lumb s theory 1975 was used to calculate the depth of the wetting front for the case in which the rainfall intensity is equivalent to the coefficient of permeability of the soil a slope stability analysis was performed and the calculated depth of the wetting front and the measured groundwater level were considered in this analysis the behavior of the stabilizing piles was calculated by the slopile program ver 3 0 which was used to analyze and design the slope and the piles the expected deflections of the piles obtained from the analysis are similar to measured deflections therefore the rainfall intensity can be used to calculate the depth of the wetting front and this analysis technique very effectively calculates the slope stability and the behavior of stabilizing piles

uav based remote sensing of the super sauze landslide evaluation and results unmanned aerial vehicles uavs equipped with digital compact cameras can be used to map landslides quickly and at a high ground resolution images taken by a radio controlled mini quad rotor uav of the super sauze france landslide have been used to produce a high resolution ortho mosaic of the entire landslide and digital terrain models dtms of several regions the uav capability for imaging fissures and displacements on the landslide surface has been evaluated and the subsequent image processing approaches for suitably georectifying the data have been assessed for super sauze horizontal displacements of 7 to 55 m between a high resolution airborne ortho photo of may 2007 and a uav based ortho mosaic of october 2008 have been measured fixed areas of persistent deformation have been identified producing fissures of different distributions and orientations comparable to glacial crevasses and relating directly to the bedrock topography the uav has demonstrated its capability for producing valuable landslide data but improvements are required to reduce data processing time for the efficient generation of ortho mosaics based on photogrammetric dtms in order to minimise georeferencing errors

a thermomechanical model for saturated clays a thermomechanical model for saturated clays is proposed within the framework of recent extensions of the cam clay model the results of some tests found in the literature are analyzed and the main features of the thermomechanical behaviour of clays are identified the effect of the overconsolidation ratio ocr on the volume change of a soil expansion contraction submitted to heating is well established using experimental data obtained for selected soils by various authors however existing models need to be modified to correctly model this feature for this reason a new volumetric thermal plastic mechanism is developed that allows for the prediction of plastic strains at higher ocr values the overconsolidation effect observed when heating a normally consolidated soil is also modelled particular attention is paid to the coupling and hardening phenomena related to the combined effects of stress and temperature a qualitative validation is made by examining the response of the model under a given th

in situ monitoring platform and preliminary analysis of monitoring data of majiagou landslide with stabilizing piles abstract reservoir landslide evolution is a complex multi fields dynamic process which involves the interaction of the seepage field stress field displacement field and temperature field after installing the stabilizing structure into landslide the landslide and stabilizing structure will establish the landslide stabilization system and lead to a more complex multi fields evolution process under the reservoir operation to study this complex problem this paper designs and establishes a comprehensive in situ multi fields information monitoring platform which has been installed on majiagou landslide in three gorges reservoir area the multi fields information monitoring platform has four components the landslide stabilization system the in situ multi field monitoring system the data transmission and receiving system and the database management system the landslide stabilization system includes majiagou landslide and two experimental reinforced concrete piles the in situ monitoring system consists of landslide surface deformation monitoring system experimental piles monitoring system and boreholes monitoring system the landslide surface deformation monitoring system includes gps stations and fiber lines the experimental pile monitoring system consists of earth pressure cells around piles stress and strain gauges on steel bars and strain and temperature fiber sensors in piles the borehole monitoring system includes boreholes with inclinometers water pressure and water level gauges fiber sensors therefore the in situ monitoring system can monitor the seepage stress displacement and temperature fields in the landslide as well as the force and deformation in the experimental piles currently the data transmission and management system is under construction and will be finished soon current monitoring results show that the landslide moves along three slip surfaces and the deformation of the experimental piles is influenced by reservoir operation this platform can provide multi fields data for scholars to study the evolution of landslide stabilization system

differential single frequency gps monitoring of the la valette landslide french alps abstract recently global positioning system gps surveying techniques have been increasingly employed to monitor landslide movement here we present an application of gps to monitor the la valette landslide located in the ubaye valley in the southern french alps this complex landslide is composed by an upper rotational part a central part with generally translational movement and a lower part which occasionally transforms into mud flows during intense rainfall events displacement rates average a few centimeters per month with velocity peaks of some centimeters per day during periods of strong activity gps data presented in this study were acquired with two single frequency gps receivers magellan connected to multipath resistant antennas the data were processed with the magellan software mstar nine points have been set in the studied area seven of them in the moving area one in a stable area near the landslide and one on the facing slope which is used as reference point for each observation one gps receiver is placed on the reference point for the whole day and the second one is placed on each monitored point for 1 h sessions the distance between the base and monitored point ranges from 480 to 1660 m eight survey campaigns were made between october 2000 and october 2002 to follow the evolution of the surface displacements the maximum cumulative 3 d displacement observed in the area was about 21 m during the period in the center part of the landslide corresponding to an average rate of movement of about 3 cm day the accuracy achieved during the gps measurements has been evaluated to be about 2 4 cm in e w direction about 11 cm in n s direction and about 7 4 cm in elevation in the worst case the gps results have been compared with traditional surveying techniques edm carried out on the same site by rtm service restauration des terrains en montagne the velocities obtained by the two methods are similar the advantage of the gps technique is the collection of data for the three spatial coordinates x y z of each point which allow to calculate the 3 d displacement vector these measurements have been combined with sar interferometric data in order to analyse the temporal evolution of the different landslide sectors

boulder aprons indicate long term gradual and non catastrophic evolution of cliffed escarpments stolowe mts poland abstract caprock crowned escarpments are characteristic geomorphic features of the sandstone tableland of the stolowe mountains sw poland their mid and lower slopes truncate weaker sedimentary formations but are littered with sandstone boulders of various size often more than 5 m long which form nearly continuous aprons a model of escarpment retreat by rock fall has been widely accepted in literature but in the stolowe mountains it has never been tested against field evidence in addition no rock fall events except one minor fall in 1921 have been recorded in historical times in this paper we erected five hypotheses of how escarpments may have evolved through time to result in widespread boulder presence on the slopes mapping boulder extent and slope morphology run out distance simulations using conefall software and rock strength determinations using the schmidt hammer carried out on boulders along eight representative slope profiles provide data about characteristics of the boulder covers systematic decrease in intact rock strength with an increasing distance from the sandstone cliffs suggests that the boulder aprons are diachronic and record long term retreat of escarpments there exists no conclusive evidence of widespread boulder downslope movement although in a few localities shallow landslides have rafted boulders far away from the cliff lines modelling exercise shows that the actual extent of boulders is 2 3 times bigger than suggested by conefall predictions these findings coupled with observations along the cliff lines themselves lead us to propose a model of free face in situ disintegration as the most likely hypothesis to explain block detachment and release from rock faces as cliff lines recede and the slope surface below is lowered remnant boulders occupy a position increasingly further away from escarpment rims but experience little actual movement this model complements the existing models of tableland evolution which tend to emphasize catastrophic mass movement processes on cliffed escarpments

slab tearing following ridge trench collision evidence from miocene volcanism in baja california mexico abstract neogene magmatic activity in central baja california underwent a major change at ca 12 5 ma when the pacific farallon active oceanic ridge collided with the trench east of vizcaino peninsula the calc alkaline magmatism which built the comondu volcanic arc vanished and was replaced by unusual volcanic associations which were erupted within six late miocene to quaternary volcanic fields jaraguay san borja san ignacio santa rosalia santa clara la purisima delineating a 600 km array along the baja california peninsula new fieldwork k ar datings and geochemical analyses on jaraguay and san borja lavas combined with previous data allow us to show that these associations include 1 adakites emplaced between 12 5 and 8 2 ma in the santa clara santa rosalia and jaraguay volcanic fields 2 niobium enriched basalts neb in santa clara and santa rosalia 11 2 to 7 4 ma 3 tholeiitic basalts and basaltic andesites 11 3 to 7 2 ma displaying a very weak subduction imprint in la purisima and san ignacio 4 alkali trachybasalts in mesas san carlos and santa catarina northwest of jaraguay 9 3 to 7 5 ma and finally 5 basalts and associated magnesian basaltic andesites and andesites locally referred to as bajaites the latter lavas display very specific geochemical characteristics including very high sr and ba contents they were emplaced in all the above mentioned volcanic fields between 14 6 and 5 3 ma the origin of these late miocene volcanics has been considered linked either to the opening of an asthenospheric window through which they ascended tholeiites and alkali trachybasalts or to the melting of its edges due to thermal erosion adakites and the subsequent reaction between adakitic melts and the supraslab mantle neb and bajaites however the identification of the remnants of the pacific farallon fossil ridge south of vizcaino peninsula indicates that active ridge subduction was not responsible for the opening of the asthenospheric window we propose that the emplacement of slab window related volcanic rocks between 13 and 7 ma from ca 25 n to 30 n was due to a process of slab tearing which started when the active ridge collided with the trench east of vizcaino peninsula the oldest part of the downgoing plate sunk into the mantle leading to the opening of a tear in the slab which likely started from the southern limit of the already existing southern california slab window it propagated parallel to the trench over about 600 km and developed into an asthenospheric window

centrifuge model test on the retrogressive landslide subjected to reservoir water level fluctuation abstract geological disasters have occurred frequently in the three gorges reservoir area therefore the stability and failure mode research on riverside landslides has become increasingly important taking the toe of liangshuijing landslide as a case study and combining the geological conditions of the three gorges reservoir area a centrifuge slope model is constructed in addition the fluctuation of the water level is simulated in the centrifuge model test based on the digital photography laser displacement sensors lds pore pressure transducers ppt and earth pressure sensors e multi physical data are obtained finally numerical simulation is carried out to analyze the stability and deformation characteristics of the slope model the results indicate that 1 at the water level rise stage the model is dominated by the vertical displacement and the horizontal displacement is much larger than the vertical displacement at the drainage stage 2 cracks first appear at the toe of the slope and extend to the middle and rear of the model gradually then deformation occurs in the middle platform of the slope 3 at the water level rise stage the factor of safety increases rapidly when the reservoir water level remains stable the stability of the slope decreases slowly and at the drainage stage the factor of safety decreases first and then increases 4 there is a significant positive linear correlation between the decline rate of the safety factor and the drainage rate over a certain test range and the stability of the landslides on the reservoir banks would become worse gradually during the long term cyclic operation of the three gorges reservoir

response of a landslide to reservoir impoundment in model tests abstract landslides are often induced or activated by reservoir impoundment within the reservoir area in this paper a physical model test was conducted and compared with another published test to investigate the deformation characteristics and failure behavior of a colluvial landslide for conditions with and without reservoir impoundment the laboratory landslide model represented the lower part of a landslide in the three gorges reservoir area a thrust load was applied to represent the upper part of the landslide the thrust load surface deformation pore water pressure and soil pressure were recorded during the experiments the results show that the effect of the reservoir impoundment reduces the time to failure of the landslide and the load causing the failure as expected when water submerged the lower part of the landslide the shearing resistance was reduced the slip surfaces and failure behavior of the landslide under the two conditions are different the entire landslide mass slid along the contact between the colluvium and the bedrock under reservoir impoundment however without a reservoir the landslide slides partially along this contact and multiple slip surfaces through the colluvium

tomographic inversion of local earthquake data from the hengill grensdalur central volcano complex iceland parameters is generally low however a quantitative analysis of resolution provides an unambiguous assessment of well resolved volumes within the better resolved regions of the model the averaging volumes are 1 2 km and 2 4 km in vertical and horizontal extent respectively results of tomographic inversion image three distinct bodies of anomalously high velocity two of these extend from near the surface to a depth of about 3 km these high velocity volumes are located directly beneath the surface expressions of the extinct grensdalur volcano and the extinct husmuli basalt shield the third high velocity structure occurs in the depth range of 3 4 km but does not extend to the surface these three high velocity bodies are interpreted to be solidified magmatic intrusions relatively low velocities underlay limited portions of the trace of the present accretionary axis and a low velocity body is imaged in the roots of the active hengill volcano the volume of lower velocities located beneath the surface expression of the hengill volcano is interpreted to be a region of partial melt

seismic tomography of the crust underneath the etna volcano sicily abstract a new tomographic inversion of the velocity structure and hypocenter parameters has been carried out in the etna area using a remarkably larger seismic dataset than used in the previous investigations the obtained v p and v p v s space distributions allow us to detail the already known structural features and to find new velocity anomalies a major aseismic high velocity body is recognized in the upper 10 km beneath the central crater area and the southeastern flank of the volcano interpreted as high strength magmatic rocks such as cumulites dike structures etc a high level of seismic activity and low v p values are found immediately to the west and the east of the high velocity body suggesting the presence of highly fractured weakness zones which also taking into account the local distribution of seismogenic stress can be supposed to include paths for magma rising and stationing clear evidence is also found of a shallow aseismic low velocity zone beneath the volcano s southwestern flank corresponding to the volume where previous investigators hypothesized the presence of a magma chamber on the grounds of geodetic data and seismic b value mapping

lithological discontinuities in podzols developed from sandstone cover beds in the stolowe mountains poland abstract podzols developed within so called cover beds were examined on a slope built of cretaceous sandstones in sw poland their typical feature is an easily recognizable stratification of regolith evidenced in the dichotomy of soil texture and dense subsoil heterogeneity of soil profiles is manifested in vertically differentiated sequence 1 dense skeletal and massive layer comprising usually bs and bc horizons sometimes bhs bh horizons with strong platy structure is overlain by 2 the uppermost relatively young layer consisting of loose sandy material bearing single coarse fragments of a less weathered sandstone hosting ae e and partially bh horizons this remarkable layering of slope sediments caused a distinctive lithological discontinuity at the boundary of e and b horizons evidenced by the differences in i rock fragments content ii degree of rock clast weathering iii distribution of highly resistant minerals and iv fluctuation of silt and sand fractions within profiles lithological discontinuity influences both the lateral podzolization and the thickness and depth of albic and spodic horizons along the slope catena regarding the temporal order the lowermost layer was influenced by periglacial conditions at before the boreal presumably as the surface layer high score of pollen grains the age of surficial sandy layer based on pollen record could be established at subatlantic and correlated with forest cutting and intensive surface erosion charcoal dating 960 30 cal bp neither layers that originated from the eolian processes were distinguished nor any admixture of allochthonous material was found therefore typical middle and upper periglacial cover beds are not present in this sequence in any case podzols that were formed from the slope sediments in the stolowe mountains are polygenetic and of the holocene age

contribution to the theory of scarpland development from observations in central queensland australia abstract theories of scarpland geomorphology developed over the past century have been characterized by divergent conceptual frameworks and have been hindered by language barriers here we review the main theories and assess them with reference to field evidence from central queensland this region provides exceptional scope for such an assessment because of the detailed k ar chronology available for basalt that is draped extensively over scarps and valleys the basalt provides the key to deciphering the pattern and rate of denudation erosion began in the late mesozoic and was greatly advanced when volcanism occurred during the middle cenozoic postbasaltic erosion has been dominated by the incision of the basaltic caprock and by the lengthening of canyons rather than by scarp retreat canyons have extended headward by 1 2 km m yr widened by 150 250 m m yr and deepened by 6 25 m m yr while scarps between canyons have retreated by only 18 130 m m yr canyon cutting both on the scarp front and on t

geochemistry of surface and subsurface waters in quartz sandstones significance for the geomorphic evolution of tepui table mountains gran sabana venezuela summary in situ measurements of discharge ph electric conductivity ec temperature and sio2 content have been carried out during five expeditions in the last 20 years on the summit plateaus inside caves and along the rivers of the surrounding lowlands of three tepui massifs in venezuela auyan roraima and chimanta additionally detailed chemical analyses were performed on waters sampled in a newly discovered extensive quartz sandstone cave system on the auyan tepui rock samples of the quartz sandstone bedrock from different locations have been analysed to obtain their chemical composition with a wavelength dispersive x ray fluorescence spectrometer these data show that the majority of silica present in surface and subsurface water comes from dissolution of quartz and only in minor amount from hydrolysis of other silicate minerals probably the presence of a hardened crust of iron hydroxides limits the dissolution of silica on the top surface of tepuis dissolution in the subsurface instead is more significant and causes in the long term the arenisation of the quartz sandstone and its subsequent removal by mechanical erosion on the other hand waters flowing on the arkosic rock outcropping on the lowland below the tepuis obtain their high dissolved silica content mainly from hydrolysis of silicates the morphological evolution of these table mountains appears thus to be controlled mainly by the underground weathering of the quartz sandstone with the opening of deep fractures grietas and the collapse of large underground horizontal cave systems scarp retreat instead seems to be related to the higher weathering rate of the more arkosic formations underlying the quartz sandstones

structural and lithological guidance on speleogenesis in quartz sandstone evidence of the arenisation process a detailed petrographic structural and morphometric investigation of different types of caves carved in the quartz sandstones of the tepui table mountains in venezuela has allowed identification of the main speleogenetic factors guiding cave pattern development and the formation of particular features commonly found in these caves such as funnel shaped pillars pendants and floor bumps samples of fresh and weathered quartz sandstone of the mataui formation roraima supergroup were characterised through wds dispersive x ray chemical analyses picnometer measurements edax analyses sem and thin section microscopy in all the caves two compositionally different strata were identified almost pure quartz sandstones with content of silica over 95 and high primary porosity around 4 and phyllosilicate rich quartz sandstone with contents of aluminium over 10 and low primary porosity lower than 0 5 phyllosilicates are mainly pyrophyllite and kaolinite sem images on weathered samples showed clear evidence of dissolution on quartz grains to different degrees of development depending on the alteration state of the samples grain boundary dissolution increases the rock porosity and gradually releases the quartz grains suggesting that arenisation is a widespread and effective weathering process in these caves the primary porosity and the degree of fracturing of the quartz sandstone beds are the main factors controlling the intensity and distribution of the arenisation process weathering along iron hydroxide or silt layers which represent inception horizons or a strata bounded fracture network predisposes the formation of horizontal caves in specific stratigraphic positions the loose sands produced by arenisation are removed by piping processes gradually creating anastomosing open fracture systems and forming braided mazes geometric networks or main conduit patterns depending on the local lithological and structural guidance on the weathering process this study demonstrates that all the typical morphologies documented in these quartz sandstone caves can be explained as a result of arenisation which is guided by layers with particular petrographic characteristics primary porosity content of phyllosilicates and iron hydroxides and different degrees of fracturing strata bounded fractures or continuous dilational joints

phreatic drainage conduits within quartz sandstone evidence from the jurassic precipice sandstone carnarvon range queensland australia abstract discrete underground drainage conduits in quartz sandstones are far less common than in limestones this paper provides field evidence from the quartzose precipice sandstone in the carnarvon range of south central queensland australia for tubular underground drainage networks similar in many ways to limestone conduits diameters range from less than 1 or 2 cm to over 1 5 m most display a near circular to oval cross section that seems to suggest phreatic or epiphreatic development and the internal surfaces of many are case hardened by secondary silica deposits a number of the region s perennial springs appear to be fed by such tubes the dominant vertical jointing of the quartz sandstone and relatively high permeability of the sandstone are important controls on tube formation solutional weathering of the sandstone is widespread and is followed by the removal of loosened sand grains by flowing underground water the process of arenisation tube development would appear to have been happening for a very long time and may still be occurring a model for tube network formation is proposed these findings highlight our potentially poor understanding of groundwater flow within some quartz sandstones and may have important groundwater management implications

model tests of the evolutionary process and failure mechanism of a pile reinforced landslide under two different reservoir conditions abstract anti slide piles are widely used for stabilizing landslides and a large number of landslide piles systems were constituted in reservoir areas how these landslide piles systems evolve under reservoir effects is vital for the safe operation of dams in this study two reservoir conditions namely condition of static water level and water level fluctuations were considered for detailly exploring the influence of static and dynamic water pressure on a landslide piles system in physical model tests the pore water pressure surface deformation and photographs of visual observations were obtained for comparatively analyzing the deformation characteristic and failure mechanism of landslide piles models under the two conditions the results show that the soil deformation and failure around the piles were similar in the two tests due to the same pile arrangements however retrogressive deformation and two soil collapses occurred in the landslide front area under water level fluctuations instead of slight deformation and shallow erosion under the static water level the outward hydrodynamic pressure caused by reservoir drawdowns was the primary reason for the soil collapses in the landslide front area the progressively intensified deformation around the piles which indirectly decreased the soil stability in the landslide front area was the secondary cause for the collapses the majiagou landslide piles system in the field was identified as in the early period of the uniform deformation stage at present based on the field observations monitoring data and the test results under water level fluctuations

propagation of p and s waves in magmas with different crystal contents insights into the crystallinity of magmatic reservoirs abstract increasing amount of crystals tends to reduce the mobility of magmas and modifies its elastic characteristics e g caricchi l et al 2007 non newtonian rheology of crystal bearing magmas and implications for magma ascent dynamics earth and planetary science letters 264 402 419 bagdassarov n dingwell d b and webb s l 1994 viscoelasticity of crystal and bubble bearing rhyolite melts physics of the earth and planetary interior 83 83 99 to quantify the effect of crystals on the elastic properties of magmas the propagation speed of shear and compressional waves have been measured at pressure and temperatures relevant for natural magmatic reservoirs the measurements have been performed in aggregates at variable particle fractions 0 0 7 the measurements were carried out at 200 mpa confining pressure and temperatures between 300 k and 1273 k i e across the glass transition temperature tg from glass to melt the specimens were mixtures of a haplogranitic melt containing 5 25 wt h2o and variable amounts of sub spherical alumina particles additional experiments were carried out on a sample containing both crystals and air bubbles the temperature derivatives of the shear dvs dt and compressional wave dvp dt velocities for pure glass and samples with a crystal fraction of 0 5 are different below and above the glass transition temperature for a crystal fraction 0 7 only dvp dt changed above the tg in the presence of gas bubbles vp and vs decrease constantly with increasing temperature the bubble bearing material yields a lower bulk modulus relative to its shear modulus the propagation velocities of compressional and shear waves increase non linearly with increasing crystal fraction with a prominent raise in the range 0 5

recent movement of the late pleistocene shoushan slump southwestern taiwan based on landform surveys this study aims to investigate and to analyze the recent complex mass movements of shoushan in kaohsiung city southwestern taiwan by the short term global positioning system gps survey and the comparison of elevation data from different sources landform change is derived from difference of 5 m digital elevation models dems i e the dems of difference dod which are abstracted from 1 5000 scale contour maps dating to 1978 and 1998 the spatial distribution of elevation change within the study area is visualized and delineated by the threshold value of 2 5 m which is resulted from the error level of contour maps the gps survey of benchmarks is deployed to infer the short term surface movement in the study area and to argue with the results of dod analysis to ensure the reliability of gps field measurements a 6 h static surveying procedure is applied to each benchmark with the reference gps station being positioned in a tectonically stable location close to the study area based on the gps survey results and the dod analysis the study identifies the development of several secondary slumps on the main body of the huge slump the secondary slumps are characterized by relatively slow movements with diverse directions

landslide monitoring by using ground based sar interferometry an example of application to the tessina landslide in italy abstract an innovative technique based on radar interferometry and implemented using ground based instrumentation has been applied for monitoring the tessina landslide italy belluno the technique has allowed us to derive multitemporal surface deformation maps of the entire depletion zone of the landslide with a high spatial resolution and accuracy the portable device used in this application is known as linear sar lisa and it is able to provide measurements at 17 ghz with a synthetic aperture of up to 2 8 m the results have been validated by comparing the recorded pixel displacements with independent measurements carried out by a motorized theodolite and electronic distance meter edm on two benchmarks

patterns of movement in reactivated landslides abstract the primary aim of this research was to study the relationship between landslide motion and its causes with reference to large slow moving reactivated translational rock slides surface displacements of the 22 106 m3 utiku landslide in central north island new zealand were measured using continuous gps cgps for three years the nature of the movement of such slides has often been difficult to determine because of poor temporal and spatial monitoring resolutions after removal of tectonic plate motion the temporal pattern of the landslide s surface motion could be understood to arise from irregular episodes of faster up to 21 mm day and slower up to 26 mm yr post failure landslide displacement and seasonal cyclic displacements of about 20 mm yr 10 mm per half year in alternating directions intervals of faster motion gave rise to displacements of between 10 and 120 mm per event faster displacement was associated mostly with basal sliding mechanism 1 involving deformation within a thin clay seam as recorded by borehole inclinometer surveys slower surface displacement involved permanent internal deformation of the larger landslide mass consisting of plastic deformation within the landslide body and or slip along existing internal planes of weakness and slip on the slide base mechanism 2 it accounted for up to 26 mm yr of displacement at a mean angle of about 49 from the horizontal indicating that the slide mass was thinning as it moved down slope seasonal cyclic displacements were synchronous with changes in pore pressure suggesting that it is a shrink swell process mechanism 3 associated with wetting and recharge of groundwater during the wetter winter months leading to a downslope movement and soil shrinkage leading to upslope rebounds during the dryer summer months the brief periods of faster displacement were triggered by seasonal peaks in pore pressure linked to long periods 12 to 20 weeks of increased precipitation and lowered evapotranspiration faster displacement however was not arrested by lowering pore pressure or by any other monitored factor similarly periods of slower displacement did not correlate with pore pressure changes or with any other monitored factor this study has shown that the annual movement pattern of a reactivated landslide is a combination of these processes that generate a complex overall movement record the field measurements showed real variability arising from variations in rainfall and pore pressure which were overprinted with measurement noise that may mask some other processes

distributed acquisition characterization and process analysis of multi field information in slopes the slope is a multiphase composite system including solid liquid and gas phases slope stability changes under the actions of stress temperature and seepage slopes will be very prone to landslide if in an unstable state in this paper considering the contributions of different fields to the landslide the distributed acquisition characterization and stability analysis of multi field information from slopes was studied systematically using distributed fiber optic sensing dfos technology a sensing system based on dfos was designed and developed for multi field information monitoring including stress temperature seepage and deformation the corresponding methods for data processing identification and methods for characterization description are also proposed on this basis the evolution of the slope is analyzed finally monitoring results of the dfos system from the majiagou landslide are shown as a case study for verification

geohazards in the three gorges reservoir area china lessons learned from decades of research abstract the impoundment of the 660 km long reservoir behind the huge three gorges dam the world s largest hydropower station increased regional seismicity and reactivated severe geohazards before the reservoir filling was initiated in 2003 the region had approximately two earthquakes per year with magnitudes between 3 0 and 4 9 after the full impoundment in 2008 approximately 14 earthquakes per year occurred with magnitudes between 3 0 and 5 4 in addition hundreds of landslides were reactivated and are now in a state of intermittent creep many landslides exhibit step like annual pattern of displacement in response to quasi regular variations in seasonal rainfall and reservoir level additional problems include rock avalanches impulse waves and debris flows the seriousness of these events motivated numerous studies that resulted in 1 better insight into the behavior and evolution mechanism of geohazards in the three gorges reservoir area tgra 2 implementation of monitoring and early warning systems of geohazards and 3 design and construction of preventive countermeasures including lattice anchors stabilizing piles rock bolts drainage canals and tunnels and huge revetments this paper reviews the hydro geologic setting of tgra geohazards examines their occurrence and evolution in the past few decades offers insight learned from extensive research on tgra geohazards and suggests topics for future research to address the remaining challenges

eruptive chronology and tectonic context of the late pleistocene tres virgenes volcanic complex baja california sur mexico abstract based on a detailed geological map and stratigraphy aided by new 230th 238u and 206p 238u age determinations we established the eruptive chronology of the tres virgenes volcanic complex tvvc the complex consists of three northeast southwest aligned stratovolcanoes which from older to younger are el viejo el azufre and la virgen and associated cinder cones and domes the alignment was fed from fissures that mark the southern trace of the left lateral cimarron fault the tvvc was built upon the basement rocks of the peninsular ranges batholith 99 ma the santa lucia formation 21 6 ma the esperanza basalt 7 6 ma and the 1 1 ma ignimbrite of el aguajito caldera the tvvc began its formation at ca 300 ka mainly with dacitic lava flows and domes that formed el viejo volcano 4 2 km3 at around 173 ka activity migrated to the southwest to build el azufre volcano 3 8 km3 with the emission of dacitic lavas and several phases of dome construction and destruction with the generation of pyroclastic density currents el azufre s activity ended 128 ka with the extrusion of the summit dome at about 112 ka volcanism migrated 4 2 km to the southwest to begin the construction of la virgen volcano through the emission of andesitic and dacitic lavas that built the largest cone of the complex until 22 ka 31 2 km3 this volcano was built upon several stages of cone construction with the emission of lava flows and peripheral dacitic domes and cinder cones between 128 and 112 ka six cinder cones vented along the cimarron fault between the la virgen and el azufre volcanoes by assuming a constant emission of magma the total volume of the tvvc 39 km3 was erupted at an average rate of 0 13 km3 kyr of this volume effusive eruptions dominated the evolution of the complex 89 of which 62 are dacites and 38 andesites the tvvc rocks have compositions of 50 67 wt in silica and low medium k 0 5 2 5 wt k2o trace element signatures of the tvvc rocks sr y 2 km within the peninsular ranges batholith as confirmed by geobarometry aeromagnetic data and the drill holes of the geothermal field today the tres virgenes geothermal field generates 10 mw of electricity although future exploration of several nearby areas may increase such capacity

imaging of the magmatic system feeding las tres virgenes geothermal field baja california sur mexico using enhanced seismic tomography abstract the las tres virgenes volcanic field baja california sur mexico hosts one of the five active geothermal power plants operating in mexico the volcanic system is considered still active and has been extensively studied during and after the development of the geothermal activities however the volumes and locations of the magmatic sources as well as the size of the geothermal reservoir are still poorly known in this work we use the records of 177 local earthquakes recorded in 2012 by a temporary local seismic network to characterize compressional vp and shear vs wave seismic velocities of the volcanic system from the surface down to 8 10 km of depth we applied the enhanced seismic tomography method which incorporates the double difference tomography and the post processing weighted average method results describe for the first time that the magmatic source reaches at least 4 5 km of depth beneath la virgen volcano feeding a widespread reservoir confined in the first 2 3 km of depth which is much larger than the currently exploited region

optimising uav topographic surveys processed with structure from motion ground control quality quantity and bundle adjustment structure from motion sfm algorithms greatly facilitate the production of detailed topographic models from photographs collected using unmanned aerial vehicles uavs however the survey quality achieved in published geomorphological studies is highly variable and sufficient processing details are never provided to understand fully the causes of variability to address this we show how survey quality and consistency can be improved through a deeper consideration of the underlying photogrammetric methods we demonstrate the sensitivity of digital elevation models dems to processing settings that have not been discussed in the geomorphological literature yet are a critical part of survey georeferencing and are responsible for balancing the contributions of tie and control points we provide a monte carlo approach to enable geomorphologists to 1 carefully consider sources of survey error and hence increase the accuracy of sfm based dems and 2 minimise the associated field effort by robust determination of suitable lower density deployments of ground control by identifying appropriate processing settings and highlighting photogrammetric issues such as over parameterisation during camera self calibration processing artefacts are reduced and the spatial variability of error minimised we demonstrate such dem improvements with a commonly used sfm based software photoscan which we augment with semi automated and automated identification of ground control points gcps in images and apply to two contrasting case studies an erosion gully survey taroudant morocco and an active landslide survey super sauze france in the gully survey refined processing settings eliminated step like artefacts of up to 50 mm in amplitude and overall dem variability with gcp selection improved from 37 to 16 mm in the much more challenging landslide case study our processing halved planimetric error to 0 1 m effectively doubling the frequency at which changes in landslide velocity could be detected in both case studies the monte carlo approach provided a robust demonstration that field effort could by substantially reduced by only deploying approximately half the number of gcps with minimal effect on the survey quality to reduce processing artefacts and promote confidence in sfm based geomorphological surveys published results should include processing details which include the image residuals for both tie points and gcps and ensure that these are considered appropriately within the workflow