creeping faults good news bad news author s chen kh burgmann r abstract 2017 american geophysical union all rights reserved the motion of the earth s tectonic plates drive fault slip some faults slip in sudden movements releasing great amounts of energy during large earthquake ruptures while others slip in steadier movements which release energy more slowly the latter known as creeping faults are believed to be less hazardous but there is mounting evidence that they are more complex than previously thought and can also pose a significant hazard a recent review by harris 2017 documents the earthquake potential of creeping faults in shallow continental fault zones from worldwide data she presents a comprehensive review of prior studies key insights into when where and why fault creep takes place and under which conditions creeping faults may represent high seismic hazard and suggests some directions for future research

results for aseismic creep on the hayward fault using polarization persistent scatterer insar abstract we present new results for shallow aseismic creep on the hayward fault in california using a new dinsar technique this method not only provides for the first time the ability to map the displacement field on both sides of the fault it does so over a much shorter time period than earlier results the results provide a good match in the near field to both the regional continuous gps velocities and data from an alinement network that measures long term creep along the fault the average slip rate for the northern segment of the hayward fault is 4 4 mm yr between 2008 and 2011 slightly less than that estimated for longer time periods suggesting that the slip rate may not be constant if the slip rate along the fault is variable on the decadal or longer scale current estimates of its earthquake potential and the associated hazard associated with the slip rate deficit may need to be revised from previous estimates we demonstrate the potential impact of this method to better define the spatial and temporal complexity of aseismic slip and estimate the accumulated elastic strain along one of the most significant sources of seismic hazard in the san francisco bay area

insar analyses of terrain deformation near the wieliczka salt mine poland european remote sensing satellites ers 1 and ers 2 synthetic aperture radar sar data are used to analyze terrain deformation in the area of wieliczka poland using interferometric techniques terrain deformations in wieliczka are due to i salt mining ii catastrophic suffusion caused by water inflows to the mine and iii landslides in the southern part of the region to discriminate between different deformation regimes differential sar interferometry d insar and persistent scatterers interferometry psi are used a comparison with published information based on leveling data is performed it can be concluded that rapid subsidence caused by catastrophic water inflow cannot be identified with insar techniques however both d insar and psi retrieve information about slow subsidence due to mine convergence these data match with subsidence maps constructed from leveling data a limited amount of coherent scatterers were identified on landslides some scatterers can be related to buildings with clear damage caused by landslide movement

geohazards monitoring in roma from insar and in situ data outcomes of the pangeo project within the pangeo project financed by the european commission under the 7th framework program the geological survey of italy ispra and the urban planning department of the city of roma developed a geodatabase and map of the geological hazards for the territory of roma integrating remotely sensed data psinsar permanent scatterer interferometry synthetic aperture radar and in situ geological information numerous thematic layers maps and inventories of hazards e g landslides sinkholes cavities geological and hydrogeological data added to historical and recent urbanization information were compared to the permanent scatterer ps data from the european remote sensing satellites ers 1 2 1992 2000 and envisat 2002 2005 descending scenes in order to produce a ground stability layer gsl based on the ps data most of the territory appears stable almost 70 of ps velocities are within 1 mm year about 14 of the pss show positive line of sight los velocities measured along the los of the satellite between 1 and 3 mm year and more than 2 exceed 3 mm year more than 11 of pss show negative los velocities between 1 and 3 mm year while about 3 exceed 3 mm year with tens of the pss showing velocities over 20 mm year the gsl is comprised of polygons or multi polygons multipart polygons grouping individual polygons under a single identifier geohazard enclosing areas where geohazards have been pointed out by ps data and or in situ surveys observed instabilities and by polygons enclosing areas potentially affected by geohazards based on the available knowledge of the territory potential instabilities in roma s gsl 18 multi polygons covering ca 600 km2 related to observed instabilities have been outlined where ground movements could be detected through insar data or where landslides and sinkholes are known to have occurred other 13 multi polygons covering nearly 900 km2 concern areas where the potential occurrence of geohazards was inferred by combining geological and or geothematic data potential instabilities the geohazards mapped in roma have been landslides collapsible grounds compressible grounds groundwater abstraction mining man made ground tectonic movements and volcanic inflation deflation the lattermost is the likely cause of the significant uplift observed in the alban hills area however this paper focuses on two more currently impending hazards subsidence and sinkholes in general sinkhole prone areas areas of dense underground cavities are hard to discern from satellite data but can be revealed by ruling out other potential causes of observed ground movement based on in situ data subsiding zones are effectively detected by the available psinsar dataset over a total extent of about 60 km2 mostly overlapping the recent alluvial areas of the tiber and its tributaries pss show a very different behaviour inside and outside the historical centre inside loading by anthropogenic construction and man made ground since ancient times has led to an almost complete consolidation of the recent river deposits marked by modest to absent subsidence in contrast outside subsidence clearly stands out with negative los velocities that although generally within several mm year can locally exceed 25 mm year ps data have provided motion information at both a regional and local scale up to the scale of a single building closer to the sea in the tiber delta area velocities increase especially above recently reclaimed marsh areas rich in peat and organic clays velocities can change significantly over short distances as in the international airport area reflecting the local stratigraphic setting the same occurs in the two subsiding areas located within the alban hills volcanic complex which is generally affected by ground uplift as a whole psinsar ground motion velocities offer a significant contribution to susceptibility and hazard recognition studies in particular such a method provides a fast and effective tool available to local authorities to monitor ground and building behaviour possibly allowing for timely prevention activities especially when coupled with appropriate in situ knowledge

glassy dynamics of landscape evolution soil creeps imperceptibly downhill but also fails catastrophically to create landslides despite the importance of these processes as hazards and in sculpting landscapes there is no agreed upon model that captures the full range of behavior here we examine the granular origins of hillslope soil transport by discrete element method simulations and reanalysis of measurements in natural landscapes we find creep for slopes below a critical gradient where average particle velocity sediment flux increases exponentially with friction coefficient gradient at critical gradient there is a continuous transition to a dense granular flow rheology slow earthflows and landslides thus exhibit glassy dynamics characteristic of a wide range of disordered materials they are described by a two phase flux equation that emerges from grain scale friction alone this glassy model reproduces topographic profiles of natural hillslopes showing its promise for predicting hillslope evolution over geologic timescales

long term monitoring of creep rate along the hayward fault and evidence for a lasting creep response to 1989 loma prieta earthquake we present results from over 30 yr of precise surveys of creep along the hayward fault along most of the fault spatial variability in long term creep rates is well determined by these data and can help constrain 3d models of the depth of the creeping zone however creep at the south end of the fault stopped completely for more than 6 years after the m7 1989 loma prieta earthquake lpeq perhaps delayed by stress drop imposed by this event with a decade of detailed data before lpeq and a decade after it we report that creep response to that event does indeed indicate the expected deficit in creep

displacement fields from point cloud data application of particle imaging velocimetry to landslide geodesy 1 acquiring spatially continuous ground surface displacement fields from terrestrial laser scanners tls will allow better understanding of the physical processes governing landslide motion at detailed spatial and temporal scales problems arise however when estimating continuous displacement fields from tls point clouds because reflecting points from sequential scans of moving ground are not defined uniquely thus repeat tls surveys typically do not track individual reflectors here we implemented the cross correlation based particle image velocimetry piv method to derive a surface deformation field using tls point cloud data we estimated associated errors using the shape of the cross correlation function and tested the method s performance with synthetic displacements applied to a tls point cloud we applied the method to the toe of the episodically active cleveland corral landslide in northern california using tls data acquired in june 2005 january 2007 and january may 2010 estimated displacements ranged from decimeters to several meters and they agreed well with independent measurements at better than 9 root mean squared rms error for each of the time periods the method provided a smooth nearly continuous displacement field that coincides with independently mapped boundaries of the slide and permits further kinematic and mechanical inference for the 2010 data set for instance the piv derived displacement field identified a diffuse zone of displacement that preceded by over a month the development of a new lateral shear zone additionally the upslope and downslope displacement gradients delineated by the dense piv field elucidated the non rigid behavior of the slide

telling a different story the promote role of vegetation in the initiation of shallow landslides during rainfall on the chinese loess plateau abstract vegetation is widely used for controlling landslides around the world however rainfall induced shallow landslides occur frequently on vegetation covered slopes on the chinese loess plateau during the rainy season to probe this phenomenon we conducted on site investigations and measurements in the nanxiaohegou catchment on the loess plateau to explore the effects of soil properties and vegetation on shallow loess landslides most of the loess landslides on vegetation covered slopes were small scale with depths ranging from 0 3 m to 1 0 m corresponding to the topsoil being saturated due to rainfall majority of shallow landslides occurred on herbage covered area which made up 69 of total landslides there are significant differences in soil properties between the upper layer root soil composite and the lower layer loess of the sliding surface our study demonstrated that root plays a leading role in landslide erosion and that the most adverse effect of vegetation on landslides is mainly the increase in soil moisture content in the shallow soil through the root zone creating preferential infiltration flow paths there are remarkable differences in landslide erosion depths and landslide erosion intensities among different vegetation types the landslide erosion depth and landslide erosion intensity increased linearly with increasing main root depth indicating that the vegetation root depth determines the landslide erosion intensity during rainfall therefore the potential implications of vegetation especially the herbage to promote landslide occurrences during rainfall should be given more attention in the future

rate weakening friction characterizes both slow sliding and catastrophic failure of landslides abstract catastrophic landslides cause billions of dollars in damages and claim thousands of lives annually whereas slow moving landslides with negligible inertia dominate sediment transport on many weathered hillslopes surprisingly both failure modes are displayed by nearby landslides and individual landslides in different years subjected to almost identical environmental conditions such observations have motivated the search for mechanisms that can cause slow moving landslides to transition via runaway acceleration to catastrophic failure a similarly diverse range of sliding behavior including earthquakes and slow slip events occurs along tectonic faults our understanding of these phenomena has benefitted from mechanical treatments that rely upon key ingredients that are notably absent from previous landslide descriptions here we describe landslide motion using a rate and state dependent frictional model that incorporates a nonlocal stress balance to account for the elastic response to gradients in slip our idealized one dimensional model reproduces both the displacement patterns observed in slow moving landslides and the acceleration toward failure exhibited by catastrophic events catastrophic failure occurs only when the slip surface is characterized by rate weakening friction and its lateral dimensions exceed a critical nucleation length h h that is shorter for higher effective stresses however landslides that are extensive enough to fall within this regime can nevertheless slide slowly for months or years before catastrophic failure our results suggest that the diversity of slip behavior observed during landslides can be described with a single model adapted from standard fault mechanics treatments

using dinsar airborne lidar and archival air photos to quantify landsliding and sediment transport 1 we demonstrate the ability of coupled remote sensing tools to characterize large slow moving landslides in the eel river catchment northern california from a stack of alos interferograms we identified 5 large 1 km long landslides that exhibited significant activity from february 2007 to february 2008 for the boulder creek earthflow we used orthorectified air photos taken in 1964 and unfiltered airborne lidar flown in 2006 to map the displacement of trees growing on the landslide surface combining those displacement orientations with stacked dinsar data we observed average downslope velocities of 0 65 m yr 1 through the central transport zone of the landslide given landslide depth estimates minimum sediment transport and denudation rates are estimated to be 4100 m3 yr 1 and 1 6 mm yr 1 respectively our results demonstrate the highly erosive role of large slow moving landslides in landscape evolution and suggest that the superposition of dense ephemeral gully networks and rapidly moving zones within the landslide may facilitate delivery of slide mobilized sediment into adjacent fluvial channels

using persistent scatterer interferometry to map and quantify permafrost thaw subsidence a case study of eboling mountain on the qinghai tibet plateau

first delimitation of areas affected by ground deformations in the guadalfeo river valley and granada metropolitan area spain using the dinsar technique abstract a differential interferometric sar dinsar analysis of terrain displacements in the province of granada southern spain is presented here for two different study zones the first zone concerns the guadalfeo river basin where abundant landslides and unstable slopes were previously identified and inventoried on a gis application however no instrumental quantification of landslide activity was available considering morphological criteria and field observations these deep seated landslides were considered to be dormant or moving extremely slowly the second study zone corresponds to the granada metropolitan area where no previous information was available on any vertical movement the analysis was based on ers1 and ers2 images covering the period from 1993 to 2000 by using dinsar we made an initial qualitative assessment of movements on landsliding slopes in the guadalfeo river basin and also vertical land movements in the alluvial quaternary sediments to the west and south of the granada metropolitan area the terrain instability assessment resulting from this research shows maximum annual velocities along the sar line of sight los of 6 mm yr for the tablones landslide and up to 13 mm yr for the albunuelas village where progressive differential settlement processes were established as the origin of the movement in the case of the granada metropolitan area two sites were detected with subsidence affecting two villages santa fe located in the western part of the area with an estimated average velocity of 8 mm yr and otura in the south of the area with maximum velocities of 12 mm yr a description of geological features of the different sites showing los ground displacement is presented with a discussion of the application of the rates to landslide activity assessment found local ground conditions or exploitation of subterranean water in urban areas

tracking and evolution of complex active landslides by multi temporal airborne lidar data the montaguto landslide southern italy abstract a multi temporal lidar study of an active landslide at montaguto italy is presented four lidar derived digital terrain models acquired on may 2006 july 2009 april 2010 and june 2010 are used the interpretation of selected morphometric parameters surface roughness residual topographic surface and the statistical analysis of the temporal variations of such parameters allowed the reconstruction and tracking of the landslide the landslide boundary monitoring was achieved and zones of uplift and subsidence volumes of removed and or accumulated material and average rates of vertical and horizontal displacement retreat rate of the crown and advancement rate of the toe were estimated deformation structures scarps cracks folds affecting the landslide in different times were also mapped some of such structures represent precursors of impending instability processes or give information on the mechanism of emplacement various types of activity e g rock fall flow and geometry e g channelized flow are recognized and zones whose topographic features change with time due to artificial drainage and earth handling removal work were detected the lidar derived information allows us to decipher the kinematics of the landslide the results provide new insight on the use of airborne lidar in the monitoring strategies of gravity controlled processes

experimental study of shallow mass movements on gully slopes and associated sediment under rainfall on the chinese loess plateau abstract mass movements on gully slopes are the main contributors to gully bank expansion and are the major source of sediment delivered to rivers however they are often overlooked because they are either too small or too time consuming to measure in the field to resolve this challenge a novel topography meter was used to observe shallow mass movements on the gully slopes of the loess plateau under simulated rainfall the experiment showed that the cumulative shallow mass movement volume logarithmically increased with the rainfall amount the critical rainfall for shallow mass movement occurrence was about 28 mm at a rainfall intensity of 50 mm h 1 the results also show that soil water content was a key element controlling the occurrence of the shallow mass movements and the minimal soil water content for permitting shallow mass movements was about 23 1 25 6 for 10 20 cm deep soil shallow mass movement on gully slopes has a significant influence on sediment yield the sediment concentration and sediment transport rate during mass movement failure were on average 3 6 times and 4 0 times higher than that during pre failure events respectively our results have important implications for understanding the connectivity of sediment discharge and mass movements on gully slopes in hilly and gully watersheds

earthquake potential along the northern hayward fault california the hayward fault slips in large earthquakes and by aseismic creep observed along its surface trace dislocation models of the surface deformation adjacent to the hayward fault measured with the global positioning system and interferometric synthetic aperture radar favor creep at 7 millimeters per year to the bottom of the seismogenic zone along a 20 kilometer long northern fault segment microearthquakes with the same waveform repeatedly occur at 4 to 10 kilometer depths and indicate deep creep at 5 to 7 millimeters per year the difference between current creep rates and the long term slip rate of 10 millimeters per year can be reconciled in a mechanical model of a freely slipping northern hayward fault adjacent to the locked 1868 earthquake rupture which broke the southern 40 to 50 kilometers of the fault the potential for a major independent earthquake of the northern hayward fault might be less than previously thought

analysis of the deep seated gravitational slope deformations over mt frascare central italy with geomorphological assessment and dinsar approaches abstract a quantitative and innovative dgsd deep gravitational slope deformation assessment method that used integrated remote sensing was tested in the central apennine mountain range italy the movement rate was calculated for selected test areas using the differential sar interferometry small baseline subset sbas technique the selected test areas were previously identified by interpreting both aerial photos and using 32 ers radar images taken between 1993 and 2000 more than 15 cm of cumulative surface displacement occurred across the podalla dgsd along the satellite line of sight los moreover the displacement time series showed non linear deformation rates which included periods of accelerated movement correlated with strong rainfall the high estimated podalla dgsd activity indicates that this type of study should be conducted to monitor the evolution of this phenomenon in addition the dinsar movement rate can be used to improve mapping and identify dgsds in specific landscapes

a 1 d mechanistic model for the evolution of earthflow prone hillslopes 1 in mountainous terrain deep seated landslides transport large volumes of material on hillslopes exerting a dominant control on erosion rates and landscape form here we develop a mathematical landscape evolution model to explore interactions between deep seated earthflows soil creep and gully processes at the drainage basin scale over geomorphically relevant 10 3 year timescales in the model sediment flux or incision laws for these three geomorphic processes combine to determine the morphology of actively uplifting and eroding steady state topographic profiles we apply the model to three sites one in the gabilan mesa california with no earthflow activity and two along the eel river california with different lithologies and varying levels of historic earthflow activity representative topographic profiles from these sites are consistent with model predictions in which the magnitude of a dimensionless earthflow number based on a non newtonian flow rheology reflects the magnitude of recent earthflow activity on the different hillslopes the model accurately predicts the behavior of earthflow collection and transport zones observed in the field and estimates long term average sediment fluxes that are due to earthflows in agreement with historical rates at our field sites finally our model predicts that steady state hillslope relief in earthflow prone terrain increases nonlinearly with the tectonic uplift rate suggesting that the mean hillslope angle may record uplift rate in earthflow prone landscapes even at high uplift rates where threshold slope processes normally limit further topographic development

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

recent subsidence of the venice lagoon from continuous gps and interferometric synthetic aperture radar 1 coastal regions are increasingly affected by larger storms and rising sea level predicted by global warming models aggravating the situation in the city of venice where tidal induced seasonal flooding coupled with natural and anthropogenic subsidence have been perennial problems in light of accelerated efforts to protect venice from the rise in sea level we assess land subsidence in the venice lagoon over the last decade through a combined analysis of gps position time series from 2001 55 to 2011 00 for four stations installed by the magistrato alle acque di venezia and thousands of observations of insar permanent scatterers using radarsat 1 images from 2003 3 to 2007 85 we determine that the northern lagoon subsides at a rate of 2 3 mm yr whereas the southern lagoon subsides at 3 4 mm yr the city of venice continues to subside at a rate of 1 2 mm yr in contrast to geodetic studies in the last decade of the 20th century suggesting that subsidence has been stabilized the gps results indicate a general eastward tilt in subsidence and that the natural subsidence rate related to the retreat of the adriatic plate subducting beneath the apennines is at least 0 4 0 6 mm yr our combined gps and insar analysis demonstrates high spatial resolution in the vertical direction with a precision of 0 1 0 2 mm yr with respect to a global reference frame continued efforts to secure the city of venice from flooding must also take into account the significant local and regional subsidence rates as well as the expected rise in sea level

use of sentinel 2 images for the detection of precursory motions before landslide failures abstract the sentinel 2 optical satellites provide a global coverage of land surfaces with a 5 day revisit time at the equator we investigate the ability of these freely available optical images to detect precursory motions before rapid landslides a 9 month time series of displacement is derived from sentinel 2 data over a major landslide in the french alps which exhibited a sudden reactivation in june 2016 this analysis reveals a 7 month period of low activity 1 m followed by a sudden acceleration of 3 2 1 2 m in 3 days before the failure of a mass of about 2 to 3 6 106 m3 the location of this precursory motion is consistent with that of the slow motions occurring since 2001 about 1 m year as revealed by aerial photographs and lidar analysis this change in activity over a very short period of time days emphasizes the value of the frequent revisit time of sentinel 2 despite its medium resolution of 10 m we finally simulate the ability of sentinel 2 for detecting these precursory patterns before a rapid landslide occurs based on typical voight s laws for creeping materials characterized by a power law exponent based on this analysis and on global cloud cover maps we compute the probability to detect pre failure motions of landslides using the sentinel 2 constellation this probability is highly heterogeneous at the global scale affected by the revisit time of the satellite and the cloud cover however the main factors controlling this detection ability are the properties of the landslide itself its size and the parameter with almost 100 of detection probability for 1 3 and 0 for 1 8 despite all these limitations probability to detect a motion before a landslide failure often reaches 50 for classical landslide parameters these results open new perspectives for the early warning of large landslide motion from global and open source remote sensing data

slope deformation prior to zhouqu china landslide from insar time series analysis abstract a major landslide in zhouqu china occurred on august 8 2010 and caused widespread damage and over 1700 casualties we study the deformation of the slopes over a time period of about three years prior to the landslide by an enhanced stamps sb technique with 16 ascending alos palsar images in particular the orbit error and stratified troposphere that were not well dealt with in the original stamps sb method have been satisfactorily corrected by a novel phase ramp correction method the deformation in four regions of the study area has been retrieved with a maximum of up to 70 mm yr in the luojiayu sanyanyu valley the slopes where the 2010 giant landslide occurred have been found to be quite unstable before the event deformation exceeding 30 mm yr has been detected in the suoertou slope which is a well known place for an ancient fault zone landslide fast movement larger than 40 mm yr is observed in the xieliupo slope which poses threats of landslide dam and dammed lake to the pai lung river together with another slope deformation detected in the opposite slope in the nanshanqiaotou slope the detected 30 mm yr deformation can be viewed as the prelude of the large landslide occurred in october 2010 more important it is found that the slope deformation time series has strong correlation with the precipitation in the area as well as with the devastating wenchuan earthquake that occurred in may 2008 whose epicenter is about 300 km away from zhouqu

mapping landslide surface displacements with time series sar interferometry by combining persistent and distributed scatterers a case study of jiaju landslide in danba china abstract insar technology provides a powerful tool to detect potentially unstable slopes across wide areas and to monitor surface displacements of a single landslide however conventional time series insar methods such as persistent scatterer interferometry psi and small baseline subset sbas can rarely identify sufficient measurement points mps in mountainous areas due to decorrelations caused by steep terrain and vegetation coverage in this study we developed a new insar approach coherent scatterer insar csi to map landslide surface displacements in the radar line of sight los direction by combining persistent scatterers ps and distributed scatterers ds the key ideas of csi include the employment of the generalized likelihood ratio glr test for the identification of statistically homogeneous pixels shps and the use of the phase linking algorithm to estimate optimal phase for each ds pixel the joint exploitation of ps and ds targets dramatically increases the spatial density of mps which makes the phase unwrapping more reliable to demonstrate the effectiveness of the csi approach we applied it to retrieve the historical displacements of the jiaju landslide in danba county of southwest china using 19 l band alos palsar images 2006 2011 and nine c band envisat asar images 2007 2008 multiple comparisons clearly illustrated the big advantages of csi over psi and sbas in mapping landslide displacements with more details owing to much higher 10 times mp density furthermore the superiority of l band sar data over c band for landslide investigation in rural environments was confirmed quantitative validation of the csi results for palsar data against in situ gps measurements suggested an accuracy of about 10 5 millimeters per year mm year in terms of root mean square error rmse afterwards the spatial temporal characteristics of the jiaju landslide surface displacements were summarized with a new upper boundary for the active northern part delineated particularly the northern part of the landslide moved faster than the southern part exhibiting a maximum los displacement rate of around 120 mm year subsequently the fluvial erosion by the dajinchuan river was identified as the predominant impact factor for the instability of the jiaju landslide finally the major problems and challenges for the application of csi method were discussed and the conclusions were given

morphology structure and kinematics of a rainfall controlled slow moving andean landslide peru the large slow moving landslide of maca is located in the upper colca valley southern peru a region characterized by a well pronounced rainy period and intense and recurrent sustained seismicity the landslide developed in deep lacustrine deposits has recently accelerated threatening the maca village this work aims at understanding the rupture mechanism and the causes of the recent landslide reactivation acceleration we present a multidisciplinary characterization of the maca landslide that includes i geological and morphological mapping in the field ii remote sensing analysis using an historical aerial photograph of 1955 and the pleiades satellite images 2013 iii global positioning system gps including time series of surveys over 13 years and continuous measurements over 14 months iv a geophysical campaign with deep electrical resistivity tomography profiles acquired across the landslide mass our study shows that this 60 mm3 landslide which can be classified as a clay silt compound landslide moved by 15 m between 2001 and 2014 with a large inter annual velocity variation up to a factor of 500 depending on the rainfall intensity we suggest that these dramatic changes in velocity are the result of the combination of a threshold mechanism and the short intense rainy season in peru this study reveals three main driving factors acting at different timescales i over several decades the river course has significantly changed causing the maca landslide reactivation in the 1980s due to the erosion of its toe ii at the year scale a minimum amount of rainfall is required to trigger the motion and this amount controls the landslide velocity iii transient changes in slide velocity may occur anytime due to earthquakes this study particularly highlights the non linear behaviour of the motion with rainfall copyright 2016 john wiley sons ltd

synthetic aperture radar interferometry to measure earth s surface topography and its deformation synthetic aperture radar interferometry insar from earth orbiting spacecraft provides a new tool to map global topography and deformation of the earth s surface radar images taken from slightly different viewing directions allow the construction of digital elevation models of meter scale accuracy these data sets aid in the analysis and interpretation of tectonic and volcanic landscapes if the earth s surface deformed between two radar image acquisitions a map of the surface dis placement with tens of meters resolution and subcentimeter accuracy can be con structed this review gives a basic overview of insar for earth scientists and presents a selection of geologic applications that demonstrate the unique capabilities of insar for mapping the topography and deformation of the earth

analysis of ground deformation detected using the sbas dinsar technique in umbria central italy ground deformation affecting the umbria region central italy in the 9 year period from 1992 to 2000 was investigated through multi temporal differential synthetic aperture radar interferometry dinsar for the purpose the small baseline subset sbas technique was adopted which allows studying the temporal evolution of the detected deformation at two spatial scales a low resolution regional scale and a full resolution local scale for the analysis sar data acquired by the european remote sensing ers 1 2 satellites along ascending and descending orbits were used the detected deformation was analysed to investigate its relevance to geophysical geomorphologic and human induced processes that may result in hazardous conditions to the population of umbria low resolution deformation data were used to i determine the amount of displacement caused by the umbria marche earthquake sequence from september 1997 to april 1998 in the foligno area ii determine the number and percentage of the known landslides that can be monitored by the dinsar technology in the investigated area and iii identify and measure subsidence induced by exploitation of a confined aquifer in the valle umbra results indicate that earthquakes moved through the foligno area westwards up to 3 9 cm and with an uplift reaching 1 7 cm intersection in a gis of the low resolution deformation maps with a detailed landslide inventory map allowed the determination that the portion of landslides that can be monitored by the sbas dinsar technique in umbria ranges from 2 7 to 3 4 and the percentage of the total landslide area ranges from 10 4 to 12 8 in the valle umbra a dependency was found between the time and the amount of detected ground deformation and the record of water withdrawal the full resolution deformation data were used to investigate the movement of the ivancich landslide in the assisi municipality joint analysis of the spatial and the temporal characteristics of the ground displacement allowed the formulation of a hypothesis on the landslide geometry and deformation pattern

geodetically accurate insar data processor we present a new interferometric synthetic aperture radar insar processing approach that capitalizes on the precise orbit tracking that is available with modern radar satellites our method uses an accurate orbit information along with motion compensation techniques to propagate the radar echoes to positions along a noninertial virtual orbit frame in which the location and focusing equations are particularly simple so that images are focused without requiring autofocus techniques and are computed efficiently motion compensation requires two additional focus correction phase terms that are implemented in the frequency domain if the images from an interferometric pair or stack are all computed along the same reference orbit flat earth topographic correction is not needed and image coregistration is simplified obviating many difficulties that are often encountered in insar processing we process several data sets collected by the alos palsar instrument and find that the geodetic accuracy of the radar images is 10 20 m with up to 20 m of additional image distortion needed to align 100 km 100 km scenes with reference digital elevation models we validated the accuracy by using both known radar corner reflector locations and by the registration of the interferograms with digital maps the topography corrected interferograms are free from all geometric phase terms and they clearly show the geophysical observables of crustal deformation atmospheric phase and ionospheric phase

topographic signatures and a general transport law for deep seated landslides in a landscape evolution model a fundamental goal of studying earth surface processes is to disentangle the complex web of interactions among baselevel tectonics climate and rock properties that generate characteristic landforms mechanistic geomorphic transport laws can quantitatively address this goal but no widely accepted law for landslides exists here we propose a transport law for deep seated landslides in weathered bedrock and demonstrate its utility using a two dimensional numerical landscape evolution model informed by study areas in the waipaoa catchment new zealand and the eel river catchment california we define a non dimensional landslide number which is the ratio of the horizontal landslide flux to the vertical tectonic flux that characterizes three distinct landscape types one is dominated by stochastic landsliding whereby discrete landslide events episodically erode material at rates exceeding the long term uplift rate another is characterized by steady landsliding in which the landslide flux at any location remains constant through time and is greatest at the steepest locations in the catchment the third is not significantly affected by landsliding in both the stochastic landsliding and steady landsliding regimes increases in the non dimensional landslide number systematically reduce catchment relief and widen valley spacing producing long low angle hillslopes despite high uplift rates the stochastic landsliding regime captures the frequent observation that deep seated landslides produce large sediment fluxes from small areal extents while being active only a fraction of the time we suggest that this model is adaptable to a wide range of geologic settings and is useful for interpreting climate driven changes in landslide behavior

a last glacial and deglacial pollen record from the northern south china sea new insight into coastal shelf paleoenvironment this study presents a marine palynological record of the asian summer monsoon and sea level change in the last glacial maximum lgm and the deglacial period in the northern south china sea scs a fossil core std 235 855 cm in length and 273 surface sediment samples from the northern scs were pollen analysed to reconstruct the paleoenvironment of the continental shelf during the last glacial period results from fossil pollen show that the main pollen source region fundamentally changed from the lgm to the deglacial period as sea level rapidly rose the modern marine surface samples show that pollen concentrations in the estuary of the pearl river are extremely high and modern pollen assemblages are in good agreement with the regional vegetation however wind transport becomes more important in the deeper ocean as the percentages of pinus a taxon with very high pollen production and dispersal capacity is highest in these sediments which otherwise have very low pollen concentrations the concentration of total pollen between surface and fossil pollen samples is compared in order to determine the possible vegetation sources areas for the marine core pollen concentration as high as 100 grains g at the lgm suggested that the paleo shoreline was located within 80 km of the core consequently pollen would mostly have derived from the exposed continental shelf in the northern scs by contrast pollen concentrations were very low due to a much greater transport distance 318 km at present core std 235 under higher sea levels and windblown pollen played a more important role because of the limitation of riverine input into the deep ocean during this highstand period such alternation of pollen flux and source distance should be repeated during all glacial interglacial cycles reflecting closely sea level and climate dynamics according to fossil pollen assemblages from core std 235 we conclude that wetland and or grassland communities with sparse subtropical trees dominated most of the exposed shelf during the lgm rather than forest that characterizes the region today the existence of a predominantly open landscape on the exposed continental shelf suggests lower precipitation during the lgm which in turn indicates a weaker asian summer monsoon this finding is supported by other records from the okinawa trough and the east china sea suggesting that a weaker summer monsoon was a key characteristic of the lgm in east asia

sediment yield spatial characteristics and the long term evolution of active earthflows determined from airborne lidar and historical aerial photographs eel river california in mountainous landscapes with weak fine grained rocks earthflows can dominate erosion and landscape evolution by supplying sediment to channels and controlling hillslope morphology to estimate the contribution of earthflows to regional sediment budgets and identify patterns of landslide activity earthflow movement needs to be quantified over significant spatial and temporal scales presently there is a paucity of data that can be used to predict earthflow behavior beyond the seasonal scale or over spatially extensive study areas across 226 km 2 of rapidly eroding franciscan complex rocks of the eel river catchment northern california we used a combination of lidar light detection and ranging and orthorectified historical aerial photographs to objectively map earthflow movement between 1944 and 2006 by tracking the displacement of trees growing on earthflow surfaces we find that 7 3 of the study area experienced movement over this 62 yr interval preferentially in sheared argillaceous lithology this movement is distributed across 122 earthflow features that have intricate elongate planform shapes a preferred south southwesterly aspect and a mean longitudinal slope of 31 the distribution of mapped earthflow areas is well approximated by a lognormal distribution with a median size of 36 500 m 2 approximately 6 of the study area is composed of earthflows that connect to major channels these flows generated an average sediment yield of 19 000 t km 2 yr 1 rock erosion rate of 7 6 mm yr over the 62 yr study period equating to a regional yield of 1100 t km 2 yr 1 0 45 mm yr if distributed across the study area as such a small fraction of the landscape can account for half of the regional denudation rate estimated from suspended sediment records 2200 t km 2 yr 1 or 0 9 mm yr we propose a conceptual model for long term earthflow evolution wherein earthflows experience intermittent activity and long periods of dormancy when limited by the availability of readily mobilized sediment on upper slopes ultimately high order river channels and ephemeral gully networks may serve to destabilize hillslopes controlling the evolution of earthflow prone terrain

active movement of the cascade landslide complex in washington from a coherence based insar time series method abstract we used interferometric synthetic aperture radar insar data from the alos 1 satellite to investigate the active movement of landslides along the columbia river gorge from 2007 2011 to increase the spatial extent of the deformation signal we developed a coherence based small baseline subset sbas method and derived the time series of the landslide movement we find no significant movement on the previously mapped washougal sakamania oregon shore and wind mountain landslides however we document the slow movement of the redbluff landslide which is part of the cascade landslide complex the insar data reveal up to approximately 25 cm of line of sight displacement over the 4 year observation period the redbluff landslide is seasonally activated with accelerated movement observed during the early winter of each year the amplitude of the seasonal signal is variable from year to year with the greatest movement observed in early winter of 2009 and 2011 to assess the triggering mechanisms we compared the displacement time series data with local precipitation data the deformation correlated well with precipitation implying the slow movement is controlled by rainfall that infiltrates to the base of the slide

the portuguese bend landslide abstract the portuguese bend landslide in coastal southern california is an active slow moving mass of blocks and debris that extends from the shoreline to moderate altitudes along part of the southerly margin of the palos verdes hills these hills form a peninsula that is underlain by cenozoic sedimentary and volcanic rocks draped anticlinally over a core of mesozoic schist in the southerly parts of the peninsula inherently weak units in the altamira shale member of the miocene monterey formation dip seaward in general concordance with the ground surface ground failure has been widespread in this area it evidently began in mid to late pleistocene time and it has continued intermittently to the present the portuguese bend landslide represents a reactivation of movement of the eastern part of a complex of prehistoric landslides occupying an area of approximately two square miles this latest episode of movement began in 1956 presumably in response to placement of fill during a road construction project the active slide subsequently was enlarged by sequential failure of adjoining blocks of ground and by september 1969 about 54 500 000 metric tons of debris was slowly moving downslope in an area of approximately 104 ha movement has been continuous since recent failure began in 1956 although the velocity of the active slide decreased markedly after that year between 1962 and 1972 the velocity fluctuated only slightly about an average value of about 1 cm per day the active slide is an irregular prism roughly triangular in plan view the southern side of the triangle trends approximately 1100 m east west along a stretch of shoreline that essentially coincides with the toe of the slide the other two sides of the triangle trend northeast and northwest from the ends of the toe and meet about 1200 m north of the shoreline the thickness of the moving mass differs considerably from one place to another reflecting both topographic irregularities and major undulations in the underlying surface of movement the maximum thickness is approximately 75 m movement is occurring along a distinct basal failure surface the eastern part of the slide is underlain by bedrock and is bordered by bedrock with a general structure that limits further deep seated propagation of failure to the east and northeast in contrast the western part of the slide is underlain and bordered by extensive ancient landslide deposits that are marginally stable further encroachment of the active slide westward and northwestward into these materials was viewed as a distinct possibility at the time the dissertation was prepared and has occurred since then continued movement of the portuguese bend landslide since 1956 has been due to four main factors a rise in the water table during the period 1957 1968 has been documented in the northwestern part of the moving mass and is attributable mainly to infiltration of surface runoff entering numerous open fissures that cut the surface of the slide the toe of the active slide daylights along the shoreline and is subjected to storm wave erosion so that any natural build up of resisting forces is prevented in this area the redistribution of mass as the slide has moved along an undulatory failure surface has been responsible for local fluctuations in the driving and resisting forces finally smoothing of irregularities in the failure surface by the moving slide mass must have decreased some of the forces resisting movement

ground motion phenomena in caltanissetta italy investigated by insar and geological data integration abstract urban areas are frequently affected by ground instabilities of various origins the location of urban zones affected by ground instability phenomena is crucially important for hazard mitigation policies satellite based interferometric synthetic aperture radar insar has demonstrated its remarkable capability to detect and quantify ground and building motion in urban areas especially since the development of advanced differential interferometric sar techniques a dinsar in fact the high density of reflectors like buildings and infrastructures in urban areas improves the quality of the insar signal allowing sub centimetric displacements to be reliably detected the a dinsar techniques allow urban zones affected by ground deformation to be located and mapped but clearly they are not able to point out the causes of the instability phenomena these can only be highlighted by an integrated analysis of multidisciplinary data like geological geotechnical sar interferometric and historical data the overlay of these data which is possible within a geographic information system gis is a useful tool to identify ground motion phenomena affecting urban zones in this study we apply this kind of approach to caltanissetta a provincial capital in sicily italy where local damage has been detected the reconstruction of the local near surface geology shows the presence of zones affected by local natural hazard factors essentially due to the local presence of soils with poor mechanical properties or swelling soils high topographic gradients and steep slopes on loose soils processing 17 asar envisat sar images covering the time interval october 2002 december 2005 by means of an a dinsar procedure the caltanissetta deformation map has been realized it shows that most of the city is stable with the exception of three zones situated in the northwestern northeastern and southern parts of the city respectively two of them characterized by high topographic gradients and steep slopes on sandy soils are affected by subsidence ground motion an uplift motion is recognized in the other zone characterized by the local presence of expansible clays geotechnical swelling tests carried out on them have shown a swelling behavior on site surveys have highlighted the presence of damage in the zones affected by ground motion

dynamics of slow moving landslides from permanent scatterer analysis high resolution interferometric synthetic aperture radar insar permanent scatterer data allow us to resolve the rates and variations in the rates of slow moving landslides satellite to ground distances range changes on landslides increase at rates of 5 to 7 millimeters per year indicating average downslope sliding velocities from 27 to 38 millimeters per year time series analysis shows that displacement occurs mainly during the high precipitation season during the 1997 1998 el nino event rates of range change increased to as much as 11 millimeters per year the observed nonlinear relationship of creep and precipitation rates suggests that increased pore fluid pressures within the shallow subsurface may initiate and accelerate these features changes in the slope of a hill resulting from increases in the pore pressure and lithostatic stress gradients may then lead to landslides

application of multi temporal differential interferometry to slope instability detection in urban peri urban areas abstract we present two case studies regarding the application of synthetic aperture radar sar persistent scatterers interferometry psi techniques to landslide prone slopes situated in the municipal territories of caramanico terme and volturino italy the analysis of satellite sar data with psi techniques poses often problems on sites where due to the scarcity of human artefacts and the presence of vegetation cover density of coherent points ps is low 2 moreover the steep and rough topography typical of landslide prone areas hamper the interferometric pre processing making more difficult the joint estimation of displacements and of dem errors under these conditions the significance of temporal interferometric phase trends can be uncertain and conservative assumptions necessary to ensure low false detection probabilities need to be coupled with innovative processing strategies to increase the detection efficiency of ps objects here the spinua stable point interferometry over un urbanised areas processing technique is applied together with an alternative ps candidate psc selection procedure based on the use of pixels classified as urban the cases of caramanico and volturino are representative respectively of harsh and favourable conditions for psi applications the results from caramanico show clusters of ps exhibiting similar line of sight los deformation behaviour in the period 1995 2000 the locations of moving ps often coincide with distressed buildings and appear consistent with the areal distribution of recent and past landslide activity the temporal displacement trends however are characterised by very low annual average velocities from 3 to 7 mm y and it is uncertain to what extent the ps data reflect true slope movements local deformations e g settlement of engineering structures or both thanks to the more favourable conditions the application of the standard spinua approach in the volturino area was sufficient to obtain suitable densities of ps as well as spatially and temporally consistent displacement results for a period 1992 2000 in particular a group of moving ps was identified in a peri urban area known for the past and recent slope stability problems the slowly moving ps from 3 to 5 mm y fall in a location that unlike the remaining part of the town is characterised by the presence of many distressed buildings and structures although the site information confirms the reliability of ps data in the absence of ground monitoring and detailed records of landslide movements it is difficult to identify the main mechanism of the detected deformations in general in geologically and topographically complex urban peri urban settings the significance of very low velocity psi surface displacements should always be considered together with in situ geotechnical controls and ground monitoring data

active normal fault control on landscape and rock slope failure in northern norway structural geomorphic and interferometric synthetic aperture radar insar surface displacement data show that uplift of the northernmost onshore scandinavian passive margin is associated with active normal faulting and anomalous clusters of landslides regional scale normal faults separate alpine footwall ranges with impressive range front scarps from more gentle hanging wall topography in the lyngen region rockslides sackung features i e deep seated slope gravitational deformation and active faults cluster inside an 1000 km 2 area of hanging wall subsidence parallel to an 30 km long faceted range front scarp from postglacial to recent time rockslides have been released along the main range front and other propagating scarps both in the footwall range and in structurally controlled glacially oversteepened valleys of the hanging wall the active rockslides moving at rates of 10 mm yr show a variety of relationships to the controlling structures reflecting tectonic as well as gravitational faulting recent and present day landscape evolution and large volume rockslide distribution in scandinavia should be viewed from the perspective of tectonic processes involving active normal faults

in situ geophysical and hydro geochemical monitoring to infer landslide dynamics pegairolles de l escalette landslide france the pegairolles de l escalette landslide is located in the central part of the languedoc region southern france it corresponds to a deep seated landslide 50 m of thickness with extremely slow slip displacement 3 4 mm year in this area the current landslide activity is associated with intense precipitation events 300 500 mm in a few days and the related dissolution of triassic evaporite layers at depth considering a relatively simple geological context and a landslide mainly controlled by slope hydrogeology this site constitutes a natural observatory to study the impact of large rain events on slope kinematics this work is based on complete and original instrumentation deployed in two nearby boreholes since 2012 the landslide is investigated down to 65 m depth by two in situ permanent observatories for geophysical electrical resistivity and deformation metric sensor spacing daily and seasonal data acquisition and hydrogeochemical monitoring pressure ph temperature electrical conductivity fluid sampling 4 depths monthly data acquisition the data recorded during the five years of investigations help us to characterize the active slip zones in the underground as well as the seasonal dynamics of the different hydrogeological units within the slope we also observe a heavy rainfall event characterized by both electrical resistivity and geochemical changes down hole which suggest different time responses of the system to the meteorological solicitations these first results point out the relevance of the downhole monitoring to progress towards a better understanding of internal landslide processes in relation to climate forcing

southern california earthquake center geologic vertical motion database the southern california earthquake center geologic vertical motion database vmdb integrates disparate sources of geologic uplift and subsidence data at 104 to 106 year time scales into a single resource for investigations of crustal deformation in southern california over 1800 vertical deformation rate data points in southern california and northern baja california populate the database four mature data sets are now represented marine terraces incised river terraces thermochronologic ages and stratigraphic surfaces an innovative architecture and interface of the vmdb exposes distinct data sets and reference frames permitting user exploration of this complex data set and allowing user control over the assumptions applied to convert geologic and geochronologic information into absolute uplift rates online exploration and download tools are available through all common web browsers allowing the distribution of vertical motion results as html tables tab delimited gis compatible text files or via a map interface through the google maps web service the vmdb represents a mature product for research of fault activity and elastic deformation of southern california

investigating landslides with space borne synthetic aperture radar sar interferometry abstract this paper is addressed to readers without advanced knowledge of remote sensing it illustrates some current and potential uses of satellite synthetic aperture radar interferometry insar for landslide assessment data acquired by sar systems can provide 3d terrain models and be used to assist in regional scale investigations e g aimed at evaluation of susceptibility of slopes to failure under favourable environmental conditions the innovative permanent scatterers ps technique which overcomes several limitations of conventional sar differential interferometry dinsar applications in landslide studies is suitable for monitoring slope deformations with millimetric precision the ps technique combines the wide area coverage typical of satellite imagery with the capability of providing displacement data relative to individual image pixels with the currently available radar satellites however only very slow ground surface displacements can be reliably detected and measured the presented case study of a landslide from the liechtenstein alps indicates that the most attractive and reliable contribution provided by this remote sensing technique lies in the possibility of i wide area qualitative distinction between stable and unstable areas and ii qualitative relative hazard zonation of large slow landslides based on the identification of segments characterised by different movement rates since only the radar line of sight projection of the displacements can be detected a quantitative exploitation of the ps data is possible only where sufficient ground truth is available in site specific or single landslide investigations the ps data can represent a very useful complementary data source with respect to the information acquired through ground based observations and in situ surveying however the difficulties associated with the feasibility assessments of the applicability of sar data to local scale problems as well as with the interpretation of ps results require a close collaboration between landslide experts and specialists in advanced processing of radar satellite data the interpretation of the exact geotechnical significance of small radar sensed ground surface deformations is challenging especially where ground truth is lacking although any ground deformation is potentially of interest to an engineering geologist detection of movements in both vertical and horizontal directions is needed in the case of landslides to evaluate slope failure mechanisms with their high radar viewing angles however the current space borne systems can detect only a fraction of the horizontal component of movement it is expected that the upcoming sar dedicated missions with new sensors and different acquisition geometries combined with the rapid developments in the field of advanced radar data processing will allow a full 3d reconstruction of deformation data and help to further reduce the current limitations of the ps and similar dinsar approaches

gravity induced stresses near topography of small slope topographic modification of gravity induced near surface stresses results in significant departures from a lithostatic state a perturbation scheme provides approximate analytical solutions for plane strain of an elastic half space with an irregularly shaped free surface of small characteristic slope e the leading order effect of the topography is equivalent to that of a distributed normal load on a plane boundary and the correction at order e is due to a distributed shear traction on a plane boundary in the near surface region these two effects contribute at the same order to departures from the lithostatic stress field the contribution of the shearing has been neglected in most previous analyses we present explicit solutions for several particular geometries a symmetric ridge or valley an adjacent ridge and valley a shelf and a sharp crested ridge notable features include 1 for a sufficiently steep ridge the horizontal normal stress is compressive at the crest and decreases possibly becoming tensile with depth 2 large horizontal tension is induced in a valley bottom at greater depth these effects vanish and the stresses approach lithostatic similar analysis is applied to a half space under a far field tectonic compression or tension the result shows that the leading order effect of topography is equivalent to a distributed shear traction on a plane surface regional horizontal compression can be significantly reduced or even change to tension in the neighborhood of a topographic high

active salt tectonics in the needles district canyonlands utah as detected by interferometric synthetic aperture radar and point target analysis 1992 2002 1 the needles district in canyonlands national park utah is known for its well exposed array of extensional faults which are thought to be produced by gravity driven extension and downward flexure of a thin sandstone plate into the colorado river canyon in response to dissolution and flow of underlying evaporites halite and gypsum owing to a lack of precise geodetic data however it remains uncertain if and to what extent those extensional faults are currently deforming in this study we use synthetic aperture radar sar data to search for ongoing decadal ground displacements by applying both a stacking interferometric sar insar analysis and interferometric point target analysis ipta our results show that most of the needles district is indeed undergoing deformation now at a maximum rate of 2 3 mm year away from the satellite looking roughly westward with an incidence angle of about 20 also we identify a localized region along the riverbank that is uplifting at a rate of 2 3 mm year we estimate the measurement precision to be better than 0 8 mm year except along the riverbank where the errors are probably higher than this by analyzing residual signals and carrying out a signal recovery experiment using synthetic two dimensional correlated noise the deforming region is almost totally bounded by the colorado river canyon to the west and north a rapidly subsiding east west trending graben to the south and a relatively sharp to very diffuse deformation gradient to the east we observe deformation patterns that were previously undetected these include an area in the southwestern part of the deforming region that is deforming at higher rates than anywhere else in the needles but that has little surface extensional faulting rates of deformation are lower but still clearly significant further north in a region of spectacularly exposed fault blocks that have been previously studied in considerable detail

geochemical evidence for the paleoproterozoic arc back arc basin association and its importance in understanding the evolution of the central indian tectonic zone abstract the central indian tectonic zone citz is considered to be one sector in a series of paleoproterozoic orogens that stitched together the supercontinent columbia the paleoproterozoic mahakoshal belt forms the foundation of the citz metabasalts and metaclastic rocks of the mahakoshal belt have been studied for major elements and trace elements including the rare earth elements ree metabasalts of the lower saleemanabad formation are grouped into two types however both types of metabasalt depict a back arc basalt character by showing enrichments in large ion lithophile elements liles like k rb cs and ba and light rare earth elements lrees but show depletions in high field strength elements hfses like nb ta y and ti and hree heavy rare earth elements in comparison to the n morb this is further supported by some key elemental ratios like ba nb nb ta la nb eu eu nb nb and ree patterns the geochemistry of the metaclastic rocks of the lower saleemanabad middle parsoi and upper dudhmaniya formations of the mahakoshal belt show an arc signature rather than the cratonic signature in the bundlekhand ttg and n morb normalised diagrams the arc signature calc alkaline series of metaclastic rocks is further supported by various tectonic discrimination diagrams the overall study indicates that the mahakoshal belt was formed as a back arc rift basin very close to continental arcs on the hinterland of the bundelkhand craton at the initial stage of subduction as a result of trench rollback followed by thermal relaxation and basin inversion the sediment supply started from the continental arcs lying south of the mahakoshal basin furthermore the present study strengthens the mechanism of subduction related outgrowth of columbia along its continental margins and implies that the citz is a major precambrian crustal boundary that began as a mahakoshal back arc rift by northward subduction

controls on the seasonal deformation of slow moving landslides article history precipitation drives seasonal velocity changes in slow moving landslides by increasing pore water pressure and reducing the effective normal stress along basal shear zones this pressure change is often modeled as a pore water pressure wave that diffuses through the landslide body such that the minimum time required for landslides to respond to rainfall should vary as the square of landslide depth which often approximates the saturated thickness and inversely with hydraulic diffusivity here we assess this model with new observations from the landslide prone eel river catchment northern california using satellite radar interferometry insar time series precipitation data and high resolution topographic data from airborne lidar we quantify the seasonal dynamics of 10 slow moving landslides which share the same lithologic tectonic and mediterranean climate conditions these slope failures have areas ranging from 0 16 to 3 1 km 2

observation and modelling of the saint etienne de tinee landslide using sar interferometry abstract six different interferograms of the la clapiere landslide were derived from ers 1 sar images during the period aug 20 sept 4 1991 the coherence of the associated images is shown to remain significant over most of the surface of the landslide during the two weeks of the survey the interferograms are remarkably similar and indicate steady state displacements over at least 12 days the displacement field derived from the interferograms is shown to be characterized by a non uniform displacement gradient from top to bottom and reveals a significantly faster motion of the western part of the landslide the amplitude of the motion deduced from interferometry is shown to be in good agreement with ground measurements finally sar interferometry is shown to be able to evidence small scale instabilities which may not be observed with discrete ground measurements

a combination of space and terrestrial geodetic techniques to monitor land subsidence case study the southeastern po plain italy 1 the southeastern po plain is affected by high natural and anthropogenic subsidence the area is well suited to test the application of an observational strategy which combines different techniques to extract information on the spatial and temporal variability of the subsidence the simultaneous availability at a few stations of several geodetic observation techniques such as global positioning system gps gravity and interferometric synthetic aperture radar insar allows for validation of the individual time series the combination takes advantage of the complementary strengths of each technique by overcoming the limitations inherent in each single technique alone the combination of velocities derived from the gps and gravity data further complemented by the results of the insar permanent scatterers technique allows us to monitor continuously in space and time vertical crustal movements this high density information is of major importance for understanding the processes responsible for the observed deformation here long term trends were derived enabling us to map the behavior of subsidence even exceeding 20 mm yr with high spatial resolution in the southeastern po plain the uplifting behavior of the apennines chain bordering the po plain is identified together with a narrow zone separating the contrasting vertical crustal movements

sar monitoring of progressive and seasonal ground deformation using the permanent scatterers technique spaceborne differential radar interferometry has proven a remarkable potential for mapping ground deformation phenomena e g urban subsidence volcano dynamics coseismic and postseismic displacements along faults as well as slope instability however a full operational capability has not been achieved yet due to atmospheric disturbances and phase decorrelation phenomena these drawbacks can often be at least partially overcome by carrying out measurements on a subset of image pixels corresponding to natural or artificial stable reflectors permanent scatterers ps and exploiting long temporal series of interferometric data this approach allows one to push the measurement precision very close to its theoretical limit in the order of spl sim 1 mm for c band european remote sensing ers like sensors in this paper the detection of both time uniform and seasonal deformation phenomena is addressed and a first assessment of the precision achievable by means of the ps technique is discussed results highlighting deformation phenomena occurring in two test sites in california are reported fremont in the southern bay area and san jose in the santa clara valley