holocene fault scarps near tacoma washington usa airborne laser mapping confirms that holocene active faults traverse the puget sound metropolitan area northwestern continental united states the mapping which detects forest floor relief of as little as 15 cm reveals scarps along geophysical lineaments that separate areas of holocene uplift and subsidence along one such line of scarps we found that a fault warped the ground surface between a d 770 and 1160 this reverse fault which projects through tacoma washington bounds the southern and western sides of the seattle uplift the northern flank of the seattle uplift is bounded by a reverse fault beneath seattle that broke in a d 900 930 observations of tectonic scarps along the tacoma fault demonstrate that active faulting with associated surface rupture and ground motions pose a significant hazard in the puget sound region

objective landslide detection and surface morphology mapping using high resolution airborne laser altimetry a map of extant slope failures is the most basic element of any landslide assessment without an accurate inventory of slope instability it is not possible to analyze the controls on the spatial and temporal patterns of mass movement or the environmental human or geomorphic consequences of slides landslide inventory maps are tedious to compile difficult to make in vegetated terrain using conventional techniques and tend to be subjective in addition most landslide inventories simply outline landslide boundaries and do not offer information about landslide mechanics as manifested by internal deformation features in an alternative approach we constructed accurate high resolution dems from airborne laser altimetry lidar data to characterize a large landslide complex and surrounding terrain near christchurch new zealand one dimensional circular 2 d and spherical 3 d statistics are used to map the local topographic roughness in the dems over a spatial scale of 1 5 to 10 m the bedrock landslide is rougher than adjacent unfailed terrain and any of the statistics can be employed to automatically detect and map the overall slide complex furthermore statistics that include a measure of the local variability of aspect successfully delineate four kinematic units within the gently sloping lower half of the slide features with a minimum size of surface folds that have a wavelength of about 11 to 12 m and amplitude of about 1 m are readily mapped two adjacent earthflows within the landslide complex are distinguished by a contrast in median roughness and texture and continuity of roughness elements the less active of the earthflows has a surface morphology that presumably has been smoothed by surface processes the laplacian operator also accurately maps the kinematic units and the folds and longitudinal levees within and at the margins of the units finally two dimensional power spectra analyses are used to quantify how roughness varies with length scale these results indicate that no dominant length scale of roughness exists for smooth unfailed terrain in contrast zones with different styles of landslide deformation exhibit distinctive spectral peaks that correspond to the scale of deformation features such as the compression folds the topographic based analyses described here may be used to objectively delineate landslide features generate mechanical inferences about landslide behavior and evaluate relatively the recent activity of slides published by elsevier science b v

landslide susceptibility revealed by lidar imagery and historical records seattle washington abstract light detection and ranging lidar data were used to visually map landslides headscarps and denuded slopes in seattle washington four times more landslides were mapped than by previous efforts that used aerial photographs the mapped landforms landslides headscarps and denuded slopes were created by many individual landslides the spatial distribution of mapped landforms and 1308 historical landslides show that historical landslide activity has been concentrated on the mapped landforms and that most of the landslide activity that created the landforms was prehistoric thus the spatial densities of historical landslides on the landforms provide approximations of the landforms relative susceptibilities to future landsliding historical landslide characteristics appear to be closely related to landform type so relative susceptibilities were determined for landslides with various characteristics no strong relations were identified between stratigraphy and landslide occurrence however landslide characteristics and slope morphology appear to be related to stratigraphic conditions human activity is responsible for causing about 80 of historical seattle landslides the distribution of mapped landforms and human caused landslides suggests the probable characteristics of future human caused landslides on each of the landforms the distribution of mapped landforms and historical landslides suggests that erosion of slope toes by surface water has been a necessary condition for causing seattle landslides human activity has largely arrested this erosion which implies that landslide activity will decrease with time as hillsides naturally stabilize however evaluation of glacial age analogs of areas of recent slope toe erosion suggests that landslide activity in seattle will continue for the foreseeable future

from incipient slope instability through slope deformation to catastrophic failure different stages of failure development on the ivasnasen and vollan rock slopes western norway abstract the long term evolution of rock slope failures involves different stages from incipience of slope instability to catastrophic failure through a more or less long lasting slope deformation phase that also involves creeping or sliding topography lithology and structural inheritance are the main intrinsic factors that influence this evolution here we investigate the role of these intrinsic factors on the rock slope failure development of the ivasnasen and vollan rock slopes sunndal valley western norway using a multitechnique approach that includes geomorphologic and structural field mapping kinematic analysis terrestrial cosmogenic nuclide exposure dating topographic reconstruction and deformation quantification ivasnasen is a rock slope failure complex with several past rock slope failures and a present unstable rock slope located on a cataclinal nw facing slope and developed in augen gneiss vollan on the opposite valley side is a deep seated gravitational slope deformation dsgsd affecting the whole mountainside developed in quartzite in the upper part and micaschist in the lower part these different lithologies belong to different nappe complexes that were emplaced and folded into a series of syn and anticlines during the caledonian orogeny these folds lead to different lithologies being exposed in different structural orientations on the opposite valley flanks which in turn leads to different types and evolution of rock slope failures at ivasnasen the 45 55 nw dipping ductile foliation allowed for a fairly simple planar sliding mechanism for the 1 2 million m 3 post glacial rock slope failure failure occurred ca 3 3 ka ago after a short period of prefailure deformation for the present 2 2 million m 3 unstable rock slope at ivasnasen a steepening of the foliation at the toe impedes such a mechanism and up to 10 m of displacement has not lead to a catastrophic failure yet the vollan dsgsd is characterized by a steep major back scarp with its up to 130 m wide graben which opened along the subvertical foliation in the quartzite and a conspicuous array of counter scarps in the micaschist the morphologic features are explained by a flexural toppling mechanism in the micaschist which likely initiated in the lower slope section and propagated retrogressively until reaching the massive quartzite at the back scarp flexural toppling cannot solely explain the total along slope displacement of up to 200 m i e an elongation of 28 creep along a basal shear zone which may have developed in the hinge zone of the flexural toppling combined with shallow valley dipping joints likely accounts for the large elongation implications of this study for the hazard assessment of unstable rock slopes in norway include the relatively rapid development of instabilities in cataclinal slopes and the important insights on long term displacement rates gained from cosmogenic nuclide dating for a better understanding of the evolution of unstable rock slopes

monitoring velocity variations in the crust using earthquake doublets an application to the calaveras fault california we present a technique that greatly improves the precision in measuring temporal variations of crustal velocities using an earthquake doublet or pair of microearthquakes that have nearly identical waveforms and the same hypocenter and magnitude but occur on different dates we compute differences in arrival times between seismograms recorded at the same station in the freqency domain by cross correlation of short windows of signal a moving window analysis of the entire seismograms including the coda gives t the difference in arrival times versus running time along the seismogram the time resolution of the method is an order of magnitude better than the digitization interval the t technique is illustrated with a pair of microearthquakes m 1 7 and 2 0 that occurred before and after the coyote lake california earthquake m 5 9 of august 6 1979 and on the same segment of the calaveras fault that ruptured during the earthquake the coda wave arrivals for some stations are progressively delayed for the second earthquake in the doublet so that its seismogram appears as a stretched version of the earlier event we interpret this systematic variation in t along the coda as a change in the average s velocity in the upper crust in the time interval between the two doublets s wave velocities appear to have decreased by 0 2 in an oblong region 5 10 km in radius at the south end of the aftershock zone

imaging the laguna del maule volcanic field central chile using magnetotellurics evidence for crustal melt regions laterally offset from surface vents and lava flows abstract magnetotelluric mt data were collected at the laguna del maule volcanic field ldmvf located in central chile 36 s 70 5 w which has been experiencing unprecedented upward ground deformation since 2007 these data were used to create the first detailed three dimensional electrical resistivity model of the ldmvf and surrounding area the resulting model was spatially complex with several major conductive features imaged at different depths and locations around laguna del maule ldm a near surface conductor c1 0 5 m approximately 100 m beneath the lake is interpreted as a conductive smectite clay cap related to a shallow hydrothermal reservoir at 4 km depth a strong conductor c3 0 3 m is located beneath the western edge of ldm the proximity of c3 to the recent pleistocene to holocene vents in the northwest ldmvf and nearby hot springs suggests that c3 is a hydrous 5 wt h2o rhyolitic partial melt with melt fraction 35 and a free water hydrothermal component c3 dips towards and is connected to a deeper conductor c4 1 m c4 is located to the north of ldm at 8 km depth below surface and is interpreted as a long lived rhyolitic to andesitic magma reservoir with melt fractions less than 35 it is hypothesized that the deeper magma reservoir c4 is providing melt and hydrothermal fluids to the shallower magma reservoir c3 a large conductor directly beneath the ldmvf is not imaged with mt suggesting that any mush volume beneath ldm must be anhydrous 10 km as it moves from the deep magma reservoir c4 to create small ephemeral volumes of eruptible melt c3 it is hypothesized that there may be a north south contrast in physical processes affecting the growth of melt rich zones since major conductors are imaged in the northern ldmvf while no major conductors are detected beneath the southern vents the analysis and interpretation of features directly beneath the lake is complicated by the surface conductor c1 which attenuates low frequency signals the attenuation from c1 does not affect c3 or c4 at 1 km depth directly beneath ldm a weak conductor c2 50 silicic reservoir with 5 wt h2o at 2 to 5 km depth beneath the inflation center is not supported by the mt data however a smaller 10 km3 eruptible volume could go undetected even with relatively high melt fraction 50 the location of large melt regions to the north has important implications for long term volcanic hazards at ldmvf as well as other volcanoes as it raises the possibility that the vent distribution is not always indicative of the location of deeper source regions of melt

late cenozoic tectonism collapse caldera and plateau formation in the central andes abstract the evolution of andean volcanism including the formation of late miocene to recent collapse calderas on the puna plateau is generally interpreted in terms of the kinematic framework of the nazca and south american plates we present evidence that caldera dynamics and associated ignimbrite volcanism are genetically linked to the activity of first order nw se striking zones of left lateral transtension on the local and regional scales consequently ages of collapse calderas indicate activity of these fault zones which initiated at about 10 ma on the puna plateau the onset of such faulting points to a change in the deformation regime from dominantly vertical thickening to orogen parallel stretching upon reaching maximum crustal thickness and critical surface elevation horizontal magma sheets that formed at mid crustal level possibly due to heat advection by volume increase of asthenospheric mantle below thickened crust were tapped by sub vertical faults this accounts well for the observed tectono magmatic phenomena at surface it follows that formation of collapse calderas and eruption of voluminous ignimbrites appear to be related to the mechanical evolution of the andean plateau rather than to changes in the geometry of the wadati benioff zone or plate boundary kinematics

application of lidar and discriminant analysis to determine landscape characteristics for different types of slope failures in heavily vegetated steep terrain horseshoe run watershed west virginia abstract a landslide inventory map was created for horseshoe run watershed west virginia using high resolution topographic data obtained from airborne lidar a total of 152 landslides were remotely mapped and classified as planar slides rotational slumps debris flows debris fans debris slides and active slopes based on morphologic characteristics interpreted from lidar derived shaded relief maps with field verification at several locations seven landscape variables were calculated for the watershed from the high resolution 0 5 m topographic data elevation slope angle slope aspect distance from roads distance from streams plan curvature and profile curvature statistical analyses were conducted to determine the mean and standard deviations for each variable and corresponding slope failure type discriminant analyses were conducted on the different types of failed slopes with a maximum 86 accuracy level to determine which landscape characteristics contribute to each type of landslide results from the discriminant analyses indicate that statistically significant differences exist between the failure classes mapped within the watershed and that slope angle slope aspect and landscape curvature are important variables influencing the type of process the results from this study have important implications for predicting where certain types of slope failures may occur based on landscape characteristics

automated landslide mapping using spectral analysis and high resolution topographic data puget sound lowlands washington and portland hills oregon abstract landslide inventory maps are necessary for assessing landslide hazards and addressing the role slope stability plays in landscape evolution over geologic timescales however landslide inventory maps produced with traditional methods aerial photograph interpretation topographic map analysis and field inspection are often subjective and incomplete the increasing availability of high resolution topographic data acquired via airborne light detection and ranging lidar over broad swaths of terrain invites new automated landslide mapping procedures we present two methods of spectral analysis that utilize lidar derived digital elevation models of the puget sound lowlands washington and the tualatin mountains oregon to quantify and automatically map the topographic signatures of deep seated landslides power spectra produced using the two dimensional discrete fourier transform and the two dimensional continuous wavelet transform identify the characteristic spatial frequencies of deep seated landslide morphologic features such as hummocky topography scarps and displaced blocks of material spatial patterns in the amount of spectral power concentrated in these characteristic frequency bands highlight past slope instabilities and allow the delineation of landslide terrain when calibrated by comparison with detailed independently compiled landslide inventory maps our algorithms correctly classify an average of 82 of the terrain in our five study areas spectral analysis also allows the creation of dominant wavelength maps which prove useful in analyzing meter scale topographic expressions of landslide mechanics past landslide activity and landslide modifying geomorphic processes these results suggest that our automated landslide mapping methods can create accurate landslide maps and serve as effective objective and efficient tools for digital terrain analysis

structural control of volcanism and caldera development in the transtensional taupo volcanic zone new zealand abstract the taupo volcanic zone tvz new zealand comprises several segments with variable components of extension and is characterised by longitudinal segmentation into a central zone dominated by rhyolitic calderas and extremities with only andesitic composite volcanoes modern

the southern andes between 36 and 40 s latitude seismicity and average seismic velocities abstract the project issa 2000 integrated seismological experiment in the southern andes consists of a temporary seismological network and a seismic refraction profile a network of 62 seismological stations was deployed across the southern andes at 38 s three hundred thirty three local seismic events were observed in a 3 month period p and s arrival times of a subset of high quality data were inverted simultaneously for 1 d velocity structure hypocentral coordinates and station delays seismic refraction data along a transect at 39 s provide further constraints on the crustal structure low crustal velocities beneath the forearc may be either due to subducted trench sediments or serpentinized mantle material of the continental lithosphere the continental moho is not clearly observed in this region average velocities of the crust beneath the arc are higher than those beneath the forearc crustal thickness is about 40 km crustal seismicity concentrates in the forearc region along the bio bio and gastre fault zones the area between these two prominent fault zones seems to be nearly devoid of crustal seismicity but shows highest uplift and topography in the forearc region benioff seismicity is observed down to 150 km depth resulting in the first accurate image of the benioff zone in the southern andes a maximum of seismicity at 60 km depth may be caused by dehydration embrittlement

high precision analysis of hydrous rhyolitic glass inclusions in quartz phenocrysts using the electron microprobe and inaa a high precision electron microprobe emp technique has been developed that is capable of analyzing major minor and trace element abundances si ti ai fe mn mg ca na k cl in hydrous rhyolitic glasses the technique was developed to characterize the chemical compositions of rhyolitic glass inclusions in phenocrysts that occur in layers of paleozoic altered volcanic ash the compositions of these inclusions serve as excellent chemical fingerprints of the altered volcanic ash layers for use in stratigraphic correlation the precision and reproducibility of the analyses is sufficientnot only to distinguish one altered volcanic ash layer from another on the basis of inclusion compositions but also to discern differencesin the compositions of different inclusions from the same layer a high precision instrumental neutron activation analytical inaa technique was also developed that is capable of measuring an additional suite oftrace elements e g sc co rb cs sr ba la ce sm eu tb yb lu zr hf ta in rhyolitic glass inclusions in quartz phenocrysts with excellent accuracy and precision after correcting for the presence of the host quartz the abundances of elements measured by the emp technique and the corrected abundances determined using the inaa technique are identical within analytical uncertainty thus demonstrating the internal consistency of the results

the 1989 1990 activity of etna magma mingling and ascent of h2oclsrich basaltic magma evidence from melt inclusions abstract the melt inclusions in olivine phenocrysts from basaltic tephra erupted by etna volcano during the 1989 1990 eruptive period were investigated for major elements cl and s by electron microprobe fluorine by pigme particule induced gamma ray emission and h 2 o by sims the results indicate the ascent of basaltic magmas with different k 2 o concentrations possibly related to different feeding dykes lk basaltic melt inclusions rich in cl s and h 2 o are trapped in olivine fo 84 from the 1990 tephra and represent the early crystallization stage their composition in major elements is quite similar to those of most of the historic and even pre etnean alkali basalts but significantly lower in k 2 o compared with the 1989 1990 lavas only scarce hk basaltic melt inclusions were observed in the outer rim fo 79 6 of reversely zoned olivine phenocrysts and correspond to late crystallization stage at low pressure high sulfur concentration s 0 3 wt is a general characteristic of the etnean basaltic magmas with h 2 o s ratio as high as 7 the volatile abundances of the etna primitive basalts were computed at 1 45 wt for h 2 o 0 17 wt for cl and 0 047 wt for f with a high cl f ratio close to 3 6 the 1989 lava samples with cl at 660 90 ppm and f at 770 30 ppm have suffered a significant cl loss the possible behaviour of the volatile phase as co 2 h 2 o even cl is discussed with h 2 o and chlorine late degassing and an active role of h 2 o during the lava fountaining activity

oblique slip tectonics in an active volcanic chain a case study from the southern andes abstract oblique slip tectonics in the intra arc region of the southern andes accommodates heterogeneous deformation derived from plate convergence during the pliocene and quaternary long term mechanical interaction between andean transverse faults i e nw striking sinistral faults and margin parallel faults i e nne striking faults results in linked transtensional fault damage zones that facilitate structural conditions for the migration and emplacement of geofluids in the upper crust we investigated the architecture of pre eruptive units and the nature of faulting at the tatara san pedro pellado volcanic complex in the southern andes here oblique slip faulting crosscuts miocene folded strata and granitoids our main results suggest that quaternary volcanism and an associated geothermal systems developed on top of an ene oriented structural anisotropy defined by hundreds of faults and dikes interacting in a ca 9 km long and 4 km wide rock volume named the tatara damage zone deformation in this domain is characterized by ene to wnw striking transtensional oblique slip faults flanked by 1 the seismically active ns striking dextral melado fault to the west 2 discrete ns to ene striking dextral splay faults to the east and 3 the sinistral nw striking los condores fault to the north east which is reported for the first time in this work the latter fault represents an excellent example of a long lived andean transverse fault furthermore we suggest that the los condores fault accommodates a margin oblique slip component of bulk transpressional deformation we demonstrate that pliocene quaternary intra arc oblique faulting developed after pre late miocene compressional tectonics and that this oblique faulting constrains the geometry of permeable pathways for the flow emplacement and eruption of quaternary geofluids furthermore we evaluated the stress field for a discrete volcanic complex and provided key elements to better understand the role of andean transverse faults in the spatial organization of quaternary arc volcanism and geothermal systems in the southern andes

collapse at the eastern eiger flank in the swiss alps on 13 june 2006 parts of the eastern flank of the eiger peak in the swiss alps collapsed leading to a major rock fall the unstable spur on this flank is made up of several blocks that move relative to one another instability was initiated by a block at the rear that acted as a wedge and triggered motion of the other blocks landslides are a significant natural hazard in mountainous regions1 and are often triggered by external factors such as earthquakes rainfall permafrost melting or retreat of glaciers2 a large landslide occurred in the swiss alps on 13 july 2006 when portions of an immense rock spur on the eastern flank of the eiger peak3 collapsed here we use field observations and terrestrial laser scanning data to record and quantify the relative motion along the various blocks of rock that form this spur the data show that during the year of observation the blocks moved relative to one another by up to tens of metres along fractures that can be related to pre existing planes of weakness rates of motion and deformation were high throughout july 2006 particularly in the northern part of the spur that partially collapsed on 13 july the rates decreased considerably during the subsequent months although a slight increase was noted in june and july 2007 these observations are consistent with instability of the spur initiated by subsidence of a single block at the rear which acted as a wedge and disintegrated over time owing to loss of lateral confinement

holocene relative sea level changes along the seattle fault at restoration point washington abstract at a marsh on the hanging wall of the seattle fault fossil brackish water diatom and plant seed assemblages show that the marsh lay near sea level between 7500 and 1000 cal yr b p this marsh is uniquely situated for recording environmental changes associated with past earthquakes on the seattle fault since 7500 cal yr b p changes in fossil diatoms and seeds record several rapid environmental changes in the earliest of these brackish conditions changed to freshwater 6900 cal yr b p possibly because of coseismic uplift or beach berm accretion if coseismic uplift produced the freshening 6900 cal yr b p that uplift probably did not exceed 2 m during another event about 1700 cal yr b p brackish plant and diatom assemblages changed rapidly to a tidal flat assemblage because of either tectonic subsidence or berm erosion the site then remained a tideflat until the most recent event when an abrupt shift from tideflat diatoms to freshwater taxa resulted from 7 m of uplift during an earthquake on the seattle fault 1000 cal yr b p regardless of the earlier events no seattle fault earthquake similar to the one 1000 cal yr b p occurred at any other time in the past 7500 years

morphology effusion rates and petrology of postglacial lavas of laguna del maule volcanic field chilean andes and implications for their plumbing system we analyzed the dimensions morphology and petrography of nine postglacial lava flows ranging from andesites to rhyolites located at the laguna del maule volcanic field in the southern andes of chile our data were used in conjunction with theoretical models of magma ascent and lava flow advance to estimate time scales of lava emplacement effusion rates magma chamber volume and conduit dimensions the results indicate that the parameters of these past eruptions correspond to eruptions of months to a few years in duration with peak effusion rates 100m 3 s and were fed by magma chambers of 6 to 30km 3 and conduits of radius 20 to 70m thermobarometric results indicate crystallization pressures between 260 and 450mpa and temperatures of 780 to 1060 degrees c for the analyzed units these results taken together with recent geophysical studies suggest that the most likely scenario in case of an eruption corresponds to a medium size eruption 0 1 1km 3 initial activity would be explosive followed by the extrusion of lava flows that can last several months

focal mechanisms of recent seismicity at campi flegrei italy abstract the present study analysed volcano tectonic earthquakes that occurred in the caldera of campi flegrei italy from 2000 to 2019 to compute source focal mechanisms we used data from a large number of seismic stations to estimate reliable fault plane solutions for 71 events of a maximum duration magnitude md ranging between 0 5 md 2 5 we found that most solutions were of a normal type and were rake angle negative focal mechanisms in 86 of the cases only a few earthquakes occurred on normal dip slip faults the majority occurred on varying degrees of oblique slip only one event had a pure reverse mechanism and it was located far from the caldera centre the spatial distribution of the computed mechanisms exhibited a remarkable mix of fault orientations without any relationship to the location area or source depth the predominance of normal kinematics on high angle and nearly vertical faults and the very shallow source depth exhibited good agreement with the fact that seismicity at campi flegrei occurred during periods of ground uplift in fact ground uplift elongated the shallowest crust thus reducing the normal stress on existing locked faults this facilitated earthquakes particularly those characterised by normal dip slip and strike slip mechanisms in contrast ground subsidence produced a horizontal shortening of the upper crust which increased the normal stress on high angle faults and reduced earthquake occurrence our results indicate that the driving force of the recent volcano tectonic seismicity in the study region is the ongoing ground uplift

slope instability and valley formation in canadian soft clay deposits the purposes of the paper are to examine the deepening of valleys in clay deposits of eastern canada and in particular to look at the changes in the groundwater regime and slope stability conditions during valley formation field observations and laboratory testing indicate that the rate of valley deepening in champlain clay deposits is of the order of only a few millimetres a year owing to the low erodibility of the intact clay the clay banks are however more erodible owing to alteration and fissuration the stratigraphy of eastern canadian clay deposits can be simplified by considering it to be a stratum of low permeabilityconfined between two boundary layers of relatively high permeability which are the till layer at the base and a weathered crust or coarse grained layer at the top as the valley bottom get closer to the bottom till layer the groundwater regime and consequently the stability conditions are modified during the process of valley formation the groundwater regime passes through a

close range terrestrial digital photogrammetry and terrestrial laser scanning for discontinuity characterization on rock cuts this paper reviews the application of close range terrestrial digital photogrammetry and terrestrial laser scanning for discontinuity characterization on rock cuts terrestrial remote sensing techniques are being increasingly used as a complement to traditional scanline and window mapping methods they provide more comprehensive information on rock cuts allow surveying of inaccessible outcrops and increase user safety selected case studies are used to estimate the accuracy of several 3d model registration approaches and the most time effort and cost effective methods are highlighted it is shown that simple registration networks are able to provide adequate measurement of discontinuity orientation for engineering purposes the case studies presented also illustrate the effects of sampling bias and limitations related to discontinuity characterization using remote sensing techniques vertical orientation bias and occlusion can be of particular concern when persistent discontinuities dip at the same angle as the camera scanner line of sight major advantages of the techniques are presented illustrating how terrestrial remote sensing techniques provide rapid spatial measurements of discontinuity location orientation and curvature and are well suited to the quantification of persistence magnitudes greater than 3 m

kinematics of active earthflows revealed by digital image correlation and dem subtraction techniques applied to multi temporal lidar data earthflow type landslides are persistent natural hazards having deep socio economic and environmental consequences they have significantly contributed to the geomorphic evolution of mountainous slopes in europe since the late glacial an understanding of their complex kinematics is crucial to better constrain the processes governing their occurrence and mobility in this work we explored the possibility to quantify displacement vectors on a spatially distributed basis and to quantify volumetric transfer at the slope scale with regard to a large flow type landslide located in the northern apennines of italy for this purpose we applied digital image correlation dic and digital elevation model differencing demod techniques to multi temporal airborne lidar surveys of 2006 2007 and 2009 the dic was applied to greyscale slope gradient maps retrieved after precise co registration of lidar surveys thereby movement patterns over various sectors of the landslide were reconstructed and quantified most notably up to 20 m in the head zone up to 51 m in the lower main track and up to about 27 m at the landslide toe the demod analysis revealed significant mass transfer from the source to the tracks and toe zone with the upper flow tracks acting as temporal storage of large amounts of material the mass balance indicated that significant amounts of advancing landslide debris were eroded by a local stream an integrated analysis of demod and dic results allowed for a discussion of governing processes such as the transition from slide to flow the influence of underlying topography on earthflow mobility and the role of undrained loading as a mechanism of toe zone reactivation in conclusion the successful application of dic and demod to the case study underlines the added value of high resolution dems in the analysis of earthflow kinematics toward a better understanding of their role in the geomorphic evolution of slopes copyright 2012 john wiley sons ltd

lidar derived dem evaluation of deep seated landslides in a steep and rocky region of japan abstract in steep and rocky terrains their rough surfaces make it difficult to create landslide inventories even with detailed maps images produced from airborne lidar data to provide objective clues in locating deep seated landslides the surface textures of a 5 km2 steepland area in japan was investigated using the eigenvalue ratio and slope filters calculated from a very high resolution lidar derived dem the range of filter values was determined for each of a number of surface features mapped in the field and these included cracked bedrock outcrops coarse colluvial deposits gently undulating surfaces and smooth surfaces recently active slides commonly contained patches of ground in which deposition and erosion occurred together near the erosion front or where cracked bedrock outcrops and coarse colluvial deposits coexisted under a gently undulating surface the characteristic eigenvalue and slope filter values representing this sliding process were applied to maps of the dem derived filter values to extract potential sites of recent landslide activity in addition the relationships between the filter values of deep seated landslides at various stages of evolution within the field mapped area were extended to the entire study area to assess the contribution that landslide evolution makes to change in the landscape as a whole while landslide components made up the steepest as well as the gentlest parts of the landscape depending on their evolutionary stage landslides were constantly coarsened and steepened by progressive erosion probably initiated by river bank erosion at the foot of slopes

repeating earthquakes in the yellowstone volcanic field implications for rupture dynamics ground deformation and migration in earthquake swarms abstract we evaluated properties of yellowstone earthquake swarms employing waveform multiplet analysis thirty seven percent of the earthquakes in the yellowstone caldera occur in multiplets and generally intensify in areas undergoing crustal subsidence outside the caldera in the hedgen lake tectonic area the clustering rate is higher up to 75 the yellowstone seismicity follows a succession of two phases of earthquake sequence the first phase is defined between swarms it is characterized by a decay of clustering rate and by foreshock aftershock sequences the second phase is confined to swarms and is characterized by an increase in clustering rate and dominant aftershock sequences this phase reflects tectonic swarms that occur on short segments of optimally oriented faults for example the largest recorded swarm in yellowstone occurred in autumn 1985 on the northwest side of the yellowstone plateau which was initiated as a tectonic source sequence fitting experimental dependence of fluid injection with intrusion migration suggests that the 1985 swarm involved after 10 days hydrothermal fluids flowing outward from the caldera the 2008 2009 yellowstone lake swarm exhibited a high migration rate of 1 km day a decrease in clustering rate without a main shock and appears to be associated with magma injection of 1 to 5 m 3 s in a succession of migrating magma fronts that incrementally solidify and fracture at its brittle edges the 2010 madison plateau earthquake swarm on the west side of the caldera initiated as a tectonic sequence but the expansion of the swarm front was associated with hydrothermal fluid migration

predicting the sliding behavior of rotational landslides based on the tilting measurement of the slope surface abstract the surface displacements of slopes have been considered as a significant indicator in landslide investigations in last several decades while in recent years the tilting of slope surfaces is also being recognized as an important index in landslide monitoring however the slope surface tilting has been rarely examined so far and requires detailed investigations in this paper a series of laboratory tests and a field test were performed to investigate the surface tilting in rotational landslides as well as the correlation between tilt angles and displacements of slope surfaces in the laboratory tests slope models were constructed with different shapes of pre designed slip surfaces and tested under varying test conditions the tilting behavior of the slope surfaces in laboratory tests was measured using tilt sensors embedded into the slopes while the surface displacement was obtained by tracing the movement of marked points set on the slope surfaces near to the tilt sensors the test results revealed a linear relationship between the tilt angles and displacements of slope surfaces in the process of slope failure and this linear relationship was validated by a field test in which the slope failure was triggered by artificial rainfall the test results also indicated that the coefficient of the linear relation is consistent with the value of real distance between the locations of tilt sensors and the centers of slip surfaces an equation that relates the slope surface tilting and displacements was proposed in this study furthermore a method to estimate the geometry of the slip surface was also developed which was deduced from the observation that the path of the sliding masses was parallel to the slip surface according to the results of laboratory tests additionally an acceleration stage of surface tilting was observed in slope failure induced by artificial rainfall which implies that the surface tilting measurement can be used to predict the potential development of a rotational landslide or its reactivation

crustal seismicity associated to rpid surface uplift at laguna del maule volcanic complex southern volcanic zone of the andes abstract laguna del maule volcanic complex lmvc southern andes of chile has been experiencing large rates ca 30 cm yr of surface uplift as detected since 2008 by satellite geodetic measurements previous works have modeled the source of this deformation as an inflating rectangular sub horizontal sill underlying lmvc at 5 km depth which is supposedly related to an active process of magmatic replenishment of a shallow silicic reservoir however little is known about the tectonic context on which this activity is taking place particularly its relation with crustal seismicity that could help understanding and monitoring the current deformation process here we present the first detailed characterization of the seismic activity taking place at lmvc and integrate it with structural data acquired in the field in order to illuminate the possible connection between the ongoing process of surface uplift and the activation of crustal faults our main finding is the recognition of repetitive volcano tectonic vt seismic swarms that occur periodically between 2011 and 2014 near the sw corner of the sill modeled by insar studies a cross correlation analysis of the waveforms recorded for these vt events allows identifying three different seismic families families f1 and f3 share some common features in the stacked waveform and its locations which markedly differ from those of family f2 swarms belonging to this later family are more energetic and its energy was increasing since 2011 to a peak in january 2013 which coincide with maximum vertical velocities detected by local gps stations this points to a common process relating both phenomena the location of vt seismic swarms roughly coincides with the intersection of a ne sw lineament with a wnw ese lineament the former shows clear field evidences of dextral strike slip that are fully consistent with one nodal plane of focal mechanism for well recorded f2 events the conjugate nodal plane of these focal mechanisms could coincide with the wnw ese lineament for which our field reconnaissance suggests a dominant normal motion events belonging to families f1 and f3 are also dominantly strike slip but with some mixture with thrust and normal components our results in conjunction with results of previous authors suggest a complex mechanical interaction between the arrangement of crustal faults forming the structural framework on which the magmatic plumbing system of lmvc is emplaced and the inflating source at depth

effects of gravel content on shear resistance of gravelly soils abstract shallow landslides in colluvium which generally consists of wide particle gradation in a loose state occur in steep slope terrains to perform stability analyses shear strength parameters that represent soil constituents in situ stress state and shearing mode are needed this experimental study investigates the effects of gravel content on the shearing characteristics of gravelly soils based on the intergrain state concept a series of drained simple shear tests was performed on reconstituted specimens of gap and well graded sands with various gravel content levels the results reveal that 1 the shear strength of gravelly soils depends on the packing condition of dominant particles with the intergrain granular void ratio being a more representative parameter for the soil packing condition than the global void ratio 2 the drained shear strength of loose gravelly sand is dominated by sand matrix properties with the inclusion of gravel content reducing the strength by no more than 20 compared to that of pure sand 3 the strength parameters of sand like gravelly soils can be estimated from the sand matrix with proper reduction

tectonic setting of late archean bimodal volcanism in the michipicoten wawa greenstone belt ontario the tectono stratigraphic relationships depositional environments rock associations and major and trace element compositions of the late archean 2744 2696 ma bimodal basalt rhyolite volcanic rocks of the michipicoten wawa greenstone belt ontario are compatible with an origin along a convergent plate margin that varied laterally from an immature island arc built on oceanic crust to a more mature arc underlain by continental crust this environment is similar to that of the cenozoic taupo kermadec tonga volcanic zone michipicoten basaltic rocks most of which are proximal deposits compositionally similar la yb n 0 63 1 18 to modern oceanic island arc tholeiites are interpreted as having formed along the largely submerged island arc voluminous michipicoten rhyolitic pyroclastic rocks la yb n 4 3 18 7 ybn 5 7 15 9 probably erupted subaerially from the continental arc with distal facies deposited subaqueously on the adjacent oceanic island arc and proximal facies deposited in subaeri

reply to the discussion by olsen and stuedlein on use of terrestrial laser scanning for the characterization of retrogressive landslides in sensitive clay and rotational landslides in river banks appears in canadian geotechnical journal 47 10 1164 1168 in their discussion about aerial laser scanning als and terrestrial laser scanning tls olsen and stuedlein present some issues than we did not address in our paper jaboyedoff et al 2009a our study deals with compact landslide bodies and we had to overcome many related problems such as shadowing vegetation site accessibility and safety issues in contrast olsen and stuedlein deal with linear clean features coastal cliffs which enable a completely different way of working nonetheless their remarks are relevant and they were not addressed in our paper because it was beyond the scope of our study studies on landslide volumes and mechanisms do not in general need a high accuracy while it is crucial for landslide movement monitoring in their discussion olsen and stuedlein give some examples of tls applications in landslide studies in addition to those highlighted in our article most of them relate to coastal erosion and rockfalls in cliffs and only a few relate to landslides for the sake of completeness of the literature overview tls has also been widely used for

review of earth science research using terrestrial laser scanning abstract the application of advanced remote sensing technologies including terrestrial laser scanning tls to the earth sciences has increased rapidly in the last two decades improving the spatial and temporal resolution of data terrestrial laser scanning units have evolved into a common tool in studies of spectral and structural geology seismology natural hazards geomorphology and glaciology special consideration of the advantages and limitations of tls in each of these fields is discussed in depth in the context of important work published in each field the workflow used in a tls survey is crucial to the success of the survey and field specific earth science workflows are therefore also discussed products based on tls data such as triangulated irregular networks tin and digital surface models dsm are commonplace tools throughout the earth sciences and the use of these tools to measure slip distributions fault geometries aeolian transport river bed morphologies and flows and other research problems is expanded on where appropriate the review concludes with a discussion of recent trends in tls instrument development and their potential impact on the use of tls in the earth sciences in the future

active normal faulting diking and doming above the rapidly inflating laguna del maule volcanic field chile imaged with chirp magnetic and focal mechanism data

optimization of lidar scanning and processing for automated structural evaluation of discontinuities in rockmasses terrestrial light detection and ranging lidar can be used for the delineation and evaluation of geomechanically controlled hazards the united states geological survey 1 has adopted the use of lidar through numerous projects as discussed in 2 other examples of the use of lidar surveys for geological data collection include discussion of the process of acquiring digital outcrop models for stratigraphic modelling 3 mapping basalt flow units 4 structural mapping of a large landslide 5 and evaluation of rockfall source and accumulation zones 6 7 in non geologicalbased applications lidar has been used for projects ranging from volumetric analysis in open pit mines 8 to recording and cataloguing archaeological digs in ancient ruins 9 the equipment mobility accuracy and rate of data collection in comparison to conventional surveying and stereophotogrammetric methods have allowed existing surface analysis projects to proceed at unprecedented levels of detail and have promoted new applications the use of terrestrial ground based lidar as a structural analysis and measurement tool has been investigated in detail by kemeny and post 10 feng and roshoff 11 pringle et al 12 slob et al 13 and others once the data is acquired and the primary 3d model is generated as x y z data points with intensity scalars or mapped colourization via photo coupling the analytical process can proceed in a similar fashion to modern photogrammetric techniques such as those applied by haneberg et al 14 both applications can replace traditional field mapping processes including the use of a compass or inclinometer to measure orientation photos and notebooks to keep records and manual data entry further the conventional measurement of

use of terrestrial laser scanning for the characterization of retrogressive landslides in sensitive clay and rotational landslides in river banks for more than 10 years digital elevation models dem produced by light detection and ranging lidar technology have provided new tools for geomorphologic studies and especially for landslide stu

rapid uplift in laguna del maule volcanic field of the andean southern volcanic zone chile 2007 2012 the laguna del maule ldm volcanic field in chile is an exceptional example of postglacial rhyolitic volcanism in the southern volcanic zone of the andes by interferometric analysis of synthetic aperture radar sar images acquired between 2007 and 2012 we measure exceptionally rapid deformation the maximum vertical velocity exceeds 280 mm yr 1 although the rate of deformation was negligible from 2003 january to 2004 february it accelerated some time before 2007 january statistical testing rejects with 95 per cent confidence four hypotheses of artefacts caused by tropospheric gradients ionospheric effects orbital errors or topographic relief respectively the high rate of deformation is confirmed by daily estimates of position during several months in 2012 as measured by analysis of signals transmitted by the global positioning system gps and received on the ground at three stations around the reservoir forming the ldm the fastest moving gps station mau2 has a velocity vector of 180 4 46 2 280 4 mm yr 1 for the northward eastward and upward components respectively with respect to the stable interior of the south america plate the observed deformation cannot be explained by changes in the gravitational load caused by variations in the water level in the reservoir for the most recent observation time interval spanning 44 d in early 2012 the model that best fits the insar observations involves an inflating sill at a depth of 5 2 0 3 km with length 9 0 0 3 km width 5 3 0 4 km dip 20 3 from horizontal and strike 14 5 clockwise from north assuming a rectangular dislocation in a half space with uniform elastic properties during this time interval the estimated rate of tensile opening is 1 1 0 04 m yr 1 such that the rate of volume increase in the modelled sill is 51 5 million m 3 yr 1 or 1 6 0 2 m 3 s 1 from 2004 january to 2012 april the total increase in volume was at least 0 15 km 3 over the 5 2 yr interval observed by insar the inflating region includes most of the 16 km by 14 km ring of rhyolitic domes and coulees the similarity of high silica rhyolite compositions on opposite sides of the ring and the concentration of rhyolitic eruptions since 20 ka suggest that processes within a large silicic magma chamber are responsible for the current deformation

integrating magnetotelluric and seismic images of silicic magma systems a case study from the laguna del maule volcanic field central chile

3d gravity inversion and thermodynamic modelling reveal properties of shallow silicic magma reservoir beneath laguna del maule chile abstract active large volume silicic magma systems are potentially the most hazardous form of volcanism on earth knowledge of the location size and physical properties of silicic magma reservoirs is therefore important for providing context in which to accurately interpret monitoring data and make informed hazard assessments accordingly we present the first geophysical image of the laguna del maule volcanic field magmatic system using a novel 3d inversion of gravity data constrained by thermodynamic modelling the joint analysis of gravity and thermodynamic data allows for a rich interpretation of the magma system and highlights the importance of considering the full thermodynamic effects on melt density when interpreting gravity models of active magmatic systems we image a 30 km 3 low density volatile rich magma reservoir at around 2 km depth containing at least 85 melt hosted within a broader 115 km 3 body interpreted as wholly or partially crystallised 70 crystal cumulate mush our model suggests a magmatic system with shallow crystal poor magma overlying deeper crystal rich magma even though a large density contrast 600 kg m 3 with the surrounding crust exists the lithostatic load is 50 greater than the magma buoyancy force suggesting buoyancy alone is insufficient to trigger an eruption the reservoir is adjacent to the inferred extension of the troncoso fault and overlies the location of an intruding sill driving present day deformation the reservoir is in close proximity to the 2 0 km 3 nieblas rln eruption at 2 3 ka which we calculate tapped approximately 7 of the magma reservoir however we suggest that the present day magma system is not large enough to have fed all post glacial eruptions and that the location or size of the system may have migrated or varied over time with each eruption tapping only a small aliquot of the available magma the presence of a shallow reservoir of volatile rich near liquidus magma in close proximity to regional scale faulting has important implications for volcano monitoring and hazard mitigation

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

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

application of a long range terrestrial laser scanner to a detailed rockfall study at vall de nuria eastern pyrenees spain abstract in this study we show the application of a long range terrestrial laser scanner tls to a detailed rockfall study in a test zone at vall de nuria located in the eastern pyrenees data acquisition was carried out using tls ilris3d the new generation of reflector less laser scanners with a high range accuracy and velocity of measurements eight scans were performed at 3 stations to acquire coordinates of almost 4 million points the results from the acquired data are a high accuracy digital elevation model dem and the reconstruction of the joint geometry the former is used for inventory of rockfalls and for more accurate rockfall simulation trajectories and velocities the latter allows us to model the geometry and volume of the source area in recent rockfalls our findings suggest that tls technology could be a tool of reference in rockfall studies in the near future

field observations and numerical models of a pleistocene holocene feeder dyke swarm associated with a fissure complex to the east of the tatara san pedro pellado complex southern volcanic zone chile abstract magma is transported through the lithosphere as dykes which during periods of unrest may feed eruptions at the surface the propagation path of dykes is influenced by the crustal stress field and can be disturbed by crustal heterogeneities such as contrasting rock units or faults moreover as dykes propagate they themselves influence the surrounding stress field through processes of stress transfer crustal deformation and seismic failure the result is the formation of arrested dykes as well as contrasting strike and dip angles and dyke segmentation here we study the mechanisms of dyke injection and the role played in modifying the stress field and potential propagation paths of later dyke injections to do this we combine field data from an eroded and well exposed shallow feeder dyke swarm with a suite of two dimensional fem numerical models we mapped 35 dyke segments over a 1 km long dyke swarm exposed 5 km to the east of pellado volcano in the tatara san pedro pellado tspp volcanic complex southern volcanic zone of the andes detailed mapping of the swarm elucidates two preferential strike orientations one n80 e and the other n60 e our numerical models simulate both the tspp volcanic complex and the studied dyke swarm as zones of either magmatic excess pressure or as a rigid inclusion the crustal segment hosting the volcanic complex and dykes is modelled using an elastic domain subjected to regional compression in select model cases model outputs provide the stress and strain fields resulting from the different geometries and applied boundary loads the model results indicate that individual dyke injections can locally rotate the principal stresses such as to influence the range of orientations over which later dykes will form the orientation of 1 at the dyke tip ranges over 60 30 either side of the dyke tip indicating that the strike orientation of later dykes will fall within this range the effect of adding a bulk regional compression is to locally increase the magnitude of favorably oriented tensile stresses in the bedrock but to reduce the range of 1 orientations to 40 20 this implies that under a far field transpressive stress regime as is common in andean settings regional dyke swarms will tend to maintain their strike orientation parallel to the regional bulk stress these results should be accounted for when studying periods of volcanic unrest in order to discern the location and orientation of potential fissure eruptions in active volcanic areas such as the southern volcanic zone of the andes

spatial patterns of old deep seated landslides a case study in the northern ethiopian highlands abstract during the last decade slope failures were reported in a 500 km2 study area in the geba werei catchment northern ethiopia a region where landslides were not considered an important hazard before field observations however revealed that many of the failures were actually reactivations of old deep seated landslides after land use changes therefore this study was conducted 1 to explore the importance of environmental factors controlling landslide occurrence and 2 to estimate future landslide susceptibility a landslide inventory map of the study area derived from aerial photograph interpretation and field checks shows the location of 57 landslides and six zones with multiple landslides mainly complex slides and debris flows in total 14 8 of the area is affected by an old landslide for the landslide susceptibility modelling weights of evidence wofe was applied and five different models were produced after comparison of the models and spatial validation using receiver operating characteristic curves and kappa values a model combining data on elevation hillslope gradient aspect geology and distance to faults was selected this model confirmed our hypothesis that deep seated landslides are located on hillslopes with a moderate slope gradient i e 5 13 the depletion areas are expected on and along the border of plateaus where weathered basalts rich in smectite clays are found and the landslide debris is expected to accumulate on the amba aradam sandstone and upper antalo limestone as future landslides are believed to occur on inherently unstable hillslopes similar to those where deep seated landslides occurred the classified landslide susceptibility map allows delineating zones where human interventions decreasing slope stability might cause slope failures the results obtained demonstrate that the applied methodology could be used in similar areas where information on the location of landslides is essential for present day hazard analysis

local magnitude coda magnitude and radiated energy of volcanic tectonic earthquakes from october 2010 to december 2011 at sinabung volcano indonesia in august 2010 sinabung volcano began erupting after more than a thousand years of dormancy following several weeks of phreatic eruptions the eruptions ceased and sinabung entered what became an inter eruptive period of dominantly seismic unrest while standard equations for understanding the size of an earthquake local magnitude ml coda magnitude mc and seismic energy release er have long been developed it is best practice to fine tune these relations for a given region and period of study to more accurately describe seismicity and to directly compare it with other volcanic systems more accurate descriptions of magnitudes and energy release are vital to accurate volcanic eruption forecasting and evaluation of seismic and volcanic risk in this study we use high frequency volcano tectonic vt earthquakes recorded on a temporary three component network installed between october 2010 and december 2011 in the region around sinabung volcano to better constrain the seismic parameters of and better understand this previously unstudied volcano we determine region specific formulas for ml mc and er as follows mathrm m mathrm l log 10 a 1 1252 log 10 r 0 0280 r 2 5427 kern0 5em mathrm m mathrm c 0 7764 log 10 t coda 0 0676 r 0 7185 kern0 5em mathrm and kern0 5em log 10 left mathrm e mathrm r right 1 5720 mathrm m mathrm l 11 5258 where a r and tcoda are maximum amplitude on a wood anderson seismogram hypocentral distance km and the coda duration s respectively constants in the ml equation have physically interpretable meanings the constant for the geometrical spreading term log10r term equals one for perfect spherical spreading of the waveform our value is greater than one and thus suggests that wavefronts spread at a slightly different rate than for simple spherical spreading the constant for the attenuation term r term is consistent with locally mapped attenuative deposits limestones and tuffs and previous 3d tomographic results our mc equation differs from a previous study likely because different data in a different time period were used earthquake hypocenters are consistent with those located in previous tomographic studies and we interpret the earthquakes in this study as distal vt earthquakes induced by continued magmatic intrusion at sinabung over the period of october 2010 december 2011

volatile contents of obsidian clasts in tephra from the taupo volcanic zone new zealand implications to eruptive processes obsidian clasts in 6500 20 000 year old rhyolitic tephra deposits from the taupo volcanic zone new zealand contain variable h2o 0 2 2 5 wt and ci 0 12 0 18 wt contents these are elevated compared to degassed obsidian from rhyolitic domes 0 1 wt h2o2 0 1 wt cl which quenched at the surface major and trace element compositions of obsidian from tephra deposits suggest that they are co genetic with associated pumice the clear glassy appearance of the obsidian their high h2o release temperatures and 18o of 7 show that the water is magmatic and was not absorbed into the obsidian after tephra deposition based on analysis of melt inclusions recent primary taupo volcanic zone rhyolitic magmas contain 4 3 wt h2o and 0 18 wt cl the obsidian in the tephra deposits therefore represents partially degassed quenched primary magma water and cl contents correlate in the obsidian suggesting that the magmatic cl partitioned into a h2o rich fluid phase during eruptive degassing the partitioning of cl between the water rich vapor phase and the residual magma can be modelled as open system rayleigh fractionation using a pre eruptive h2o content of 4 3 wt and burnham s 1979 water solubility model the pressure and depth of initial vesiculation of the taupo magma is calculated to occur at about 0 9 kbar or 3 5 km depth initial fragmentation assumed to occur at a vapor melt ratio of 3 1 began at 0 1 kbar or 500 m depth obsidian in most tephra deposits contains less than 1 wt h2o and are calculated to have formed at 0 1 kbar or 500 m depth therefore some obsidian in these tephra deposits may have formed from fragmented magma the variable water contents of obsidian fragments in a single deposit indicates that quenching occurred over a range of depths this and the strong alignment of microphenocrysts in obsidian suggests that fragmented magma was welded onto the conduit walls during eruption cooled to form obsidian then incorporated into the tephra the 2000 year old hatepe phreatoplinian tephra contains many obsidian fragments with 2 wt h2o the meteoric water which caused this eruption to be phreatomagmatic may have caused obsidian to quench at unusually great depths resulting in higher h2o contents

viscoelastic relaxation a mechanism to explain the decennial large surface displacements at the laguna del maule silicic volcanic complex abstract silicic systems generate the most explosive eruptions on earth in contrast to basaltic systems they can accumulate large volumes of magma without systematically erupting confronting the classical interpretation that a volcano inflates when a magmatic intrusion occurs understanding the mechanisms of volcanic inflation and unrest is thus one of the most important challenges in volcanic risk assessment laguna del maule ldm in the southern volcanic zone svz of chile is one of the most active holocene silicic complexes in the world and it has been inflating since 2007 accumulating 2 m of uplift without erupting several geophysical and geochemical studies conclude that a large crystal rich reservoir would be residing beneath ldm in consistency with other multi disciplinary studies showing that such crystal rich reservoirs mush zones can be maintained beneath silicic volcanoes fed by mafic magma recharge from below nevertheless the mechanical state of such reservoirs remains unclear here we characterize for the first time the mechanical properties of such a mush reservoir able to promote large surface displacements such as those measured at ldm using a 3d finite element method we simulate a recharge of magma at the base of a crystal rich reservoir by assuming an overpressurized source surrounded by a large viscoelastic shell inversion results show that this model fits the observed temporal and spatial evolution of ground displacements measured with insar data and gnss data between 2007 and 2017 we interpret the temporal behavior of ground displacement at ldm as resulting from two contributions a magma recharge occurred within the first 4 yr of the active inflation followed by the viscous response of the large viscoelastic shell set to a viscosity of 10 17 pa s compared to a purely elastic solution our model suggests that up to 50 of the accumulated surface displacement during the ten year period can be explained by this viscous response and predicts ongoing displacements 50 yr after the onset of inflation this model agrees with geophysical and geochemical observations and offers a simple explanation of the temporal evolution of surface displacements it further allows to reconsider the mechanical behavior of large partially crystallized domains in the upper crust such significant transient stress transfer over large viscoelastic areas should thus be accounted for in other studies of silicic volcanic complexes

evolution of unrest at laguna del maule volcanic field chile from insar and gps measurements 2003 to 2014 the laguna del maule ldm volcanic field in the southern volcanic zone of the chilean andes exhibits a large volume of rhyolitic material erupted during postglacial times 20 2 ka since 2007 ldm has experienced an unrest episode characterized by high rates of deformation analysis of new gps and interferometric synthetic aperture radar insar data reveals uplift rates greater than 190 mm yr between january 2013 and november 2014 the geodetic data are modeled as an inflating sill at depth the results are used to calculate the temporal evolution of the vertical displacement the best time function for modeling the insar data set is a double exponential model with rates increasing from 2007 through 2010 and decreasing slowly since 2010 we hypothesize that magma intruding into an existing silicic magma reservoir is driving the surface deformation modeling historical uplift at yellowstone long valley and three sisters volcanic fields suggests a common temporal evolution of vertical displacement rates

structural and geomorphological features of landslides in the bhutan himalaya derived from terrestrial laser scanning abstract this study presents data on landslides affecting the main west east transport corridor in the himalaya of eastern bhutan close to the main central thrust the study focuses on the extraction of structural and geometrical information from terrestrial laser scanning tls data utilising a case study landslide the namling landslide analyses of the tls data allow extraction of slide geometry discontinuity orientations and identification of the mode of failure the tls results are compared to a traditional engineering geological survey and prove to yield considerable added value and should form the basis of new approaches to geomorphological studies and site assessment macro scale geomorphological reconnaissance findings are outlined and interpreted within a conceptual model of the evolution of landslide features here termed hierarchical landsliding it is concluded that the nam ling landslide is indicative of deeper seated deformation and is not purely a function of road construction

characterization of landslide ground surface kinematics from terrestrial laser scanning and strain field computation assessment and mitigation of the risk induced by landslide activation need an appropriate phenomenon investigation to obtain useful information about the failure processes the first step is the complete kinematics characterization of the landslide ground surface by evaluating the involved displacement and deformation patterns a dense displacement field can be obtained from comparison of a series of multi temporal observations performed by means of terrestrial laser scanning subsequently the strain field can be computed from displacement vectors in this paper a modified least square technique is employed to compute the strain on the nodes of a regular grid 2d approach or on the points of a digital terrain model 3d approach such a computation takes into account the displacements their spatial distribution as well as the measurement and modelling errors a scale factor is introduced in order to emphasize the contributions of the experimental points on the basis of their distance from each computation point and to recognize possible scale depending behaviours this method has been implemented in matlab and applied on two landslides located in the northeastern italian alps lamosano and perarolo di cadore the experiments show that different kinematics can be recognized and the presence and influence of eventual discontinuities can be revealed

earthquake classification location and error analysis in a volcanic environment implications for the magmatic system of the 1989 1990 eruptions at redoubt volcano alaska abstract determination of the precise locations of seismic events associated with the 1989 1990 eruptions of redoubt volcano posed a number of problems including poorly known crustal velocities a sparse station distribution and an abundance of events with emergent phase onsets in addition the high relief of the volcano could not be incorporated into the hypoellipse earthquake location algorithm this algorithm was modified to allow hypocenters to be located above the elevation of the seismic stations the velocity model was calibrated on the basis of a posteruptive seismic survey in which four chemical explosions were recorded by eight stations of the permanent network supplemented with 20 temporary seismographs deployed on and around the volcanic edifice the model consists of a stack of homogeneous horizontal layers setting the top of the model at the summit allows events to be located anywhere within the volcanic edifice detailed analysis of hypocentral errors shows that the long period lp events constituting the vigorous 23 hour swarm that preceded the initial eruption on december 14 could have originated from a point 1 4 km below the crater floor a similar analysis of lp events in the swarm preceding the major eruption on january 2 shows they also could have originated from a point the location of which is shifted 0 8 km northwest and 0 7 km deeper than the source of the initial swarm we suggest this shift in lp activity reflects a northward jump in the pathway for magmatic gases caused by the sealing of the initial pathway by magma extrusion during the last half of december volcano tectonic vt earthquakes did not occur until after the initial 23 hour long swarm they began slowly just below the lp source and their rate of occurrence increased after the eruption of 01 52 ast on december 15 when they shifted to depths of 6 to 10 km after january 2 the vt activity migrated gradually northward this migration suggests northward propagating withdrawal of magma from a plexus of dikes and or sills located in the 6 to 10 km depth range precise relocations of selected events prior to january 2 clearly resolve a narrow steeply dipping pencil shaped concentration of activity in the depth range of 1 7 km which illuminates the conduit along which magma was transported to the surface a third event type named hybrid which blends the characteristics of both vt and lp events originates just below the lp source and may reflect brittle failure along a zone intersecting a fluid filled crack the distribution of hybrid events is elongated 0 2 0 4 km in an east west direction this distribution may offer constraints on the orientation and size of the fluid filled crack inferred to be the source of the lp events

application of a new in situ 3d laser scanner to study the scale effect on the rock joint surface roughness application of a new in situ 3d laser scanner to study the scale effect on the rock joint surface roughness

earthquake locations and three dimensional crustal structure in the coyote lake area central california previous work on the simultaneous inversion method has been improved and extended to incorporate iterative solution for earthquake locations and laterally heterogeneous structure approximate ray tracing and parameter separation are important elements of the improved method application of the method to p wave arrival time data recorded by stations of the u s geological survey central california network yields a three dimensional model for the velocity structure of the upper crust in an area encompassing the rupture zone of the coyote lake earthquake of august 1979 very strong correlations between the velocity model and the geology and gravity and magnetic anomalies are observed improved estimates of the locations of earthquakes in the study area are also determined the relocation of explosions indicates epicentral accuracies of the order of a kilometer or better based on the revised hypocentral locations it is concluded that the san andreas fault is vertical in this area with no actual offset between the epicenters and the fault trace in contrast the calaveras has two or more active fault surfaces one nearly vertical and another dipping 75 to the northeast

bluff response to wave action abstract the unconsolidated materials forming the bluffs along the coasts of the great lakes are subject to active wave erosion which results in losses in millions of dollars annually due to property damage and reduction in property values an understanding of the mechanics of bluff recession and the long term trends in the evolution of coastal bluffs is required for an evaluation of engineering and management solutions for the problems created by retreating coastal bluffs bluff retreat is usually analyzed and measured from airphotos however since airphotos are taken at discrete points in time they are not capable of providing a full account of bluff retreat mechanisms field investigations coupled with analytical methods can enable investigators to identify patterns of bluff retreat these patterns subsequently incorporated into slope evolution models shed light on data obtained over long periods from airphotos the present paper explains recession rates and bluff profile changes as measured from airphotos with the help of bluff evolution models already established for the bluffs forming the great lakes shorelines

characterizing the primary material sources and dominant erosional processes for post fire debris flow initiation in a headwater basin using multi temporal terrestrial laser scanning data abstract wildfire dramatically alters the hydrologic response of a watershed such that even modest rainstorms can produce hazardous debris flows relative to shallow landslides the primary sources of material and dominant erosional processes that contribute to post fire debris flow initiation are poorly constrained improving our understanding of how and where material is eroded from a watershed during a post fire debris flow requires 1 precise measurements of topographic change to calculate volumetric measurements of erosion and deposition and 2 the identification of relevant morphometrically defined process domains to spatially constrain these measurements of erosion and deposition in this study we combine the morphometric analysis of a steep small 0 01 km 2 headwater drainage basin with measurements of topographic change using high resolution 2 5 cm multi temporal terrestrial laser scanning data made before and after a post fire debris flow the results of the morphometric analysis are used to define four process domains hillslope divergent hillslope convergent transitional and channelized incision we determine that hillslope divergent and hillslope convergent process domains represent the primary sources of material over the period of analysis in the study basin from these results we conclude that raindrop impact induced erosion ravel surface wash and rilling are the primary erosional processes contributing to post fire debris flow initiation in the small steep headwater basin further work is needed to determine 1 how these results vary with increasing drainage basin size 2 how these data might scale upward for use with coarser resolution measurements of topography and 3 how these results change with evolving sediment supply conditions and vegetation recovery