3 d high speed imaging of volcanic bomb trajectory in basaltic explosive eruptions imaging in general and high speed imaging in particular are important emerging tools for the study of explosive volcanic eruptions however traditional 2 d video observations cannot measure volcanic ejecta motion toward and away from the camera strongly hindering our capability to fully determine crucial hazard related parameters such as explosion directionality and pyroclasts absolute velocity in this paper we use up to three synchronized high speed cameras to reconstruct pyroclasts trajectories in three dimensions classical stereographic techniques are adapted to overcome the difficult observation conditions of active volcanic vents including the large number of overlapping pyroclasts which may change shape in flight variable lighting and clouding conditions and lack of direct access to the target in particular we use a laser rangefinder to measure the geometry of the filming setup and manually track pyroclasts on the videos this method reduces uncertainties to 10 in azimuth and dip angle of the pyroclasts and down to 20 in the absolute velocity estimation we demonstrate the potential of this approach by three examples the development of an explosion at stromboli a bubble burst at halema uma u lava lake and an in flight collision between two bombs at stromboli

quaternary sediments and environments on the continental shelf off northern norway abstract based on lithologic palaeontologic and chronostratigraphic investigations of close to 200 gravity cores from troughs deep banks and shallow banks the following late quaternary environment can be outlined in the weichselian deposition of basal tills was followed by deposition of laminated clay in a sea ice environment later a pebbly pelite was deposited in the troughs at the same time as the banks were iceberg ploughed then 13 000 yrs b p a period with incipient winnowing occurred on the deep banks and deposition of sandy pelite took place in the troughs the holocene commenced with a marked environmental change due to intrusion of atlantic water the fauna changed from arctic to boreal high energy winnowing forming a lag deposit took place on the banks and high accumulation rates in the troughs occurred due to the winnowing and sediment influx from the downwasting continental icesheet during the later part of the holocene the winnowing diminished on the deeper banks on the shallow banks and on the shelf break it still prevails and in the troughs calcareous sandy mud is being deposited the surface sediments comprise three main facies bouldery and pebbly sand sand and sandy mud whose distribution mainly depends on the prevailing bottom current regime the composition of the older quaternary sediments is demonstrated by some selected seismic profiles

late weichselian and holocene sedimentary palaeoenvironment and glacial activity in the high arctic van keulenfjorden spitsbergen high arctic fjords for example van keulenfjorden on spitsbergen provide valuable palaeoenvironmental archives as they typically contain landforms and sediment sequences that document past changes in glacial activity with high temporal resolution van keulenfjorden was covered with a grounded glacier during the last glacial and it was deglaciated between c 11 8 and 11 3 cal ka bp the retreat of the ice front accelerated from approximately 80 to 190 m a during the deglaciation the maximum late holocene glacier extent occurred after surge like advances of the glacier nathorstbreen between 2790 and 2610 cal yr bp i e during a period with the coldest climatic conditions on svalbard this maximum extent was reached approximately 2600 years earlier than inferred for most fjords on svalbard suggesting that surge like glacier advances on svalbard can occur under variable climatic conditions the time interval between the advances of nathorstbreen around 2 7 ka bp was approximately 100 150 years this is comparable to the last and only historically known quiescent phase of nathorstbreen of c 120 years between the late 19th century and the most recent surge from 2003 to 2012

measuring volcanic plume and ash properties from space the remote sensing of volcanic ash plumes from space can provide a warning of an aviation hazard and knowledge on eruption processes and radiative effects in this paper new algorithms are presented to provide volcanic plume properties from measurements by the michelson interferometer for passive atmospheric sounding mipas the advanced along track scanning radiometer aatsr and spinning enhanced visible and infrared imager seviri a challenge of remote sensing is to provide near real time methods to identify and so warn of the presence of volcanic ash to achieve this a singular vector decomposition method has been developed for the mipas instrument on board the environmental satellite envisat this method has been applied to observations of the ash clouds from the eruptions of nabro and the puyehue cordon caulle in 2011 and lead to a more sensitive volcanic signal flag which was capable of tracking changes in the volcanic signal spectra as the plume evolved a second challenge for remote sensing is to identify the ash plume height this is a critical parameter for the initialisation of algorithms that numerically model the evolution and transport of a volcanic plume as mipas is a limb sounder the identification of ash also provides an estimate of height provided the plume is above about 6 km this is complemented by a new algorithm stereo ash plume height retrieval algorithm saphra that identifies plume height using the parallax between images provided by along track scanning radiometer type instruments the algorithm was tested on an image taken at 14 01 gmt on 6 june 2011 of the puyehue cordon caulle eruption plume and gives a height of 11 9 1 4 km which agreed with the value derived from the location of the plume shadow 12 7 1 8 km this plume height was similar to the height observed by mipas 12 1 5 km at 02 56 gmt on 6 june the quantitative use of satellite imagery and the full exploitation of high resolution spectral measurements of ash depends upon knowing the optical properties of the observed ash laboratory measurements of ash from the 1993 eruption of mt aso japan have been used to determine the refractive indices from 1 to 20 m these preliminary measurements have spectral features similar to ash values that have been used to date albeit with slightly different positions and strengths of the absorption bands the refractive indices have been used to retrieve ash properties plume height optical depth and ash effective radius from aatsr and seviri instruments using two versions of oxford ral retrieval of aerosol and cloud orac algorithm for aatsr a new ash cloud type was used in orac for the analysis of the plume from the 2011 eyjafjallajokull eruption for the first 500 km of the plume orac gave values of plume height 2 5 6 5 km optical depth 1 2 5 and effective radius 3 7 m which are in agreement with other observations a weakness of the algorithm occurs when underlying cloud invalidates the

late pleistocene and holocene paleoenvironments of the north pacific coast abstract unlike the north atlantic the north pacific ocean probably remained free of sea ice during the last glacial maximum lgm 22 000 to 17 000 bp following a eustatic low in sea level of ca 120 m at 19 000 bp a marine transgression had flooded the bering and chukchi shelves by 10 000 bp post glacial sea level history varied widely in other parts of the north pacific coastline according to the magnitude and timing of local tectonism and glacio isostatic rebound glaciers covered much of the continental shelf between the alaska peninsula and british columbia during the lgm maximum glacier extent during the lgm was out of phase between southern alaska and southern british columbia with northern glaciers reaching their outer limits earlier between 23 000 and 16 000 bp compared to 15 000 14 000 bp in the south glacier retreat was also time transgressive with glaciers retreating from the continental shelf of southern alaska before 16 000 bp but not until 14 000 13 000 bp in southwestern british columbia major climatic transitions occurred in the north pacific at 24 000 22 000 15 000 13 000 and 11 000 9000 bp rapid climate changes occurred within these intervals including a possible younger dryas episode an interval of climate warmer and drier than today occurred in the early holocene cooler and wetter conditions accompanied widespread neoglaciation beginning in some mountain ranges as early as the middle holocene but reaching full development after 3000 bp

substrate control on distribution of subglacial and glaciomarine seismic facies based on stochastic models of glacial seismic facies deposition on the ross sea continental margin antarctica abstract a quantitative approach was utilized to establish the nature of spatial and temporal variations of glaciomarine and subglacial seismic facies deposition in the ross sea the ross sea is an excellent area to study antarctic ice sheet volume variations because it receives ice sheet drainage from approximately 25 of the continent and it contains subsiding basins to preserve the stratigraphic record of the ice sheet volume fluctuations this region receives most of the influence on deposition from the marine based west antarctic ice sheet which is believed to have been subject to catastrophic surges hollin j t 1962 on the glacial history of antarctica journal of glaciology 4 173 195 the eastern basin in particular has been subsiding creating accommodation space in which to preserve the plio pleistocene record of ice sheet fluctuations evidence from high resolution seismic data in conjunction with dsdp leg 28 drilling results are used to test hypotheses of paleo ice sheet behavior here we present quantitative evidence for a dynamic polar style of glaciation meaning that the ice sheets have had dynamic or large ice volume change not merely in the plio pleistocene but back to the late oligocene high resolution seismic data correlated to dsdp sites 270 273 shows evidence of multiple ice sheet grounding events in central and eastern ross sea strata a recipient of both west and east antarctic ice sheets from the late oligocene until the present we suggest that the west and east antarctic ice sheets are dynamic and have gone through a full spectrum of thermal states temperate through polar since the late oligocene and not necessarily in any particular preferred temporal order statistical analysis of the spatial distribution of seismic facies within seismic cores indicates that tectonic influence on distribution of basal substrate is a significant contributor to spatial variability of subglacial depositional processes and therefore distribution of subglacial facies

new insights on the tectonics along the new hebrides subduction zone based on gps results 1 at the new hebrides nh subduction zone ridges born by the subducting australia plate enter the trench and collide with the overriding margin results from gps surveys conducted on both sides of the trench and new bathymetry maps of the nh archipelago bring new light on the complex tectonics of this area convergence vectors present large variations that are not explained by australia pacific a p poles and that define four segments vectors remain mostly perpendicular to the trench and parallel to the earthquake slip vectors slow convergence i e 30 40 mm yr is found at the central segment facing the d entrecasteaux ridge the southern segment moves faster than a p motion predicts 89 to 124 mm yr relatively to a western north fiji basin wnfb reference the northern and southern segments rotate in opposite directions consistently with the extension observed in the troughs east of both segments both rotations combine in central vanuatu into an eastward translation that bulldozes the central segment into the wnfb at 55 mm yr that model suggests that the motion of the central segment forced by the subduction collision of the d entrecasteaux ridge influences the motion of the adjoining segments the new caledonia archipelago is motionless with respect to the rest of the australia plate despite the incipient interaction between the loyalty ridge and the nh margin southeast of the interaction area convergence is partitioned into a 50 mm yr trench normal component accommodated at the trench and a 90 mm yr trench parallel component close to the a p convergence and presumably accommodated by a transform boundary at the rear of the nh arc

megathrust splay faults at the focus of the prince william sound asperity alaska 1 high resolution sparker and crustal scale air gun seismic reflection data coupled with repeat bathymetric surveys document a region of repeated coseismic uplift on the portion of the alaska subduction zone that ruptured in 1964 this area defines the western limit of prince william sound differencing of vintage and modern bathymetric surveys shows that the region of greatest uplift related to the 1964 great alaska earthquake was focused along a series of subparallel faults beneath prince william sound and the adjacent gulf of alaska shelf bathymetric differencing indicates that 12 m of coseismic uplift occurred along two faults that reached the seafloor as submarine terraces on the cape cleare bank southwest of montague island sparker seismic reflection data provide cumulative holocene slip estimates as high as 9 mm yr along a series of splay thrust faults within both the inner wedge and transition zone of the accretionary prism crustal seismic data show that these megathrust splay faults root separately into the subduction zone decollement splay fault divergence from this megathrust correlates with changes in midcrustal seismic velocity and magnetic susceptibility values best explained by duplexing of the subducted yakutat terrane rocks above pacific plate rocks along the trailing edge of the yakutat terrane although each splay fault is capable of independent motion we conclude that the identified splay faults rupture in a similar pattern during successive megathrust earthquakes and that the region of greatest seismic coupling has remained consistent throughout the holocene

seismic stratigraphy of shuswap lake british columbia canada abstract shuswap lake is a glacially overdeepened fiord lake located in the shuswap highlands of southern british columbia canada and consists of two sub basins each nearly 60 km long and up to 3 km wide single channel seismic reflection data collected along 218 km of track line identifies a tripartite infill stratigraphy up to 800 m thick preserved in bedrock basins eroded as much as 298 m below sea level a similar tripartite stratigraphy is exposed in nearby outcrops along the valley of the south thompson river and allows interpretation of age and depositional settings for the infill identified on seismic records in shuswap lake the lowermost seismic stratigraphic sequence sssi up to 407 m thick shows chaotic seismic facies with large scale diffractions and fills axial parts of v shaped bedrock basins outcrop data suggest that this sequence consists of subaqueously deposited ice contact silts sands and gravels deposited in a deep 1 km ice frontal lake during late wisconsin deglaciation ca 10 ka the overlying seismic stratigraphic sequence sssii up to 403 m thick shows continuous high frequency seismic facies that pass down basin into transparent reflection free facies high frequency facies are interpreted as rhythmically deposited silts and sands deposited by underflows varves such facies are well exposed along the south thompson river valley transparent distal facies likely record uninterrupted settling from suspended sediment transported down basin by interflow or overflow plumes and similar deposits are reported as currently forming in nearby kamloops lake a relatively thin deposition of very thick late glacial stratigraphic successions and an absence of older pre late wisconsin strata appears to be a characteristic shared by other narrow glacially overdeepened valleys and basins in central british columbia this may be the result of scour by subglacial meltwaters and sediment focussing during deglaciation of fiord like valleys occupied by deep ice frontal lakes and rapidly retreating ice margins

model for the origin of the yakutat block an accreting terrane in the northern gulf of alaska a composite oceanic and continental terrane the yakutat block is currently colliding with and accreting to north america in the northern gulf of alaska marine geophysical data indicate that the block has moved with the pacific plate during pliocene and quaternary time but are indeterminant about its previous movement history a model that explains some observed geologic and structural features of the block is that it originated as a result of subduction of the kula farallon spreading center beneath north america in this model the spreading center that formed the basaltic basement of the yakutat block was offset from a spreading center to the south by a left lateral transform fault 400 500 km long subduction of the northern spreading center about 45 m y ago sliced off part of the north america continental margin attached it to the kula plate and initiated northward movement of the composite terrane as the yakutat block during eocene and oligocene time migration of the southern spreading center toward north america truncated the yakutat block on the south and left a fossil fracture zone that is now seen as the transition fault the southern spreading center subducted about 25 m y ago and the yakutat block has since traveled with the pacific plate to southern alaska

submarine valleys in the northeastern gulf of alaska characteristics and probable origin abstract the continental shelf of the northeastern gulf of alaska between prince william sound and cross sound is cut by at least eight major valleys from west to east these are hinchinbrook seavalley egg island trough kayak trough bering trough pamplona troughs yakutat valley alsek valley and yakobi valley evidence common to most of these troughs or valleys indicating that the present morphology is due to glacial processes includes 1 a pre holocene subbottom erosional surface incised into the underlying lithified strata of the shelf 2 u shaped cross sections both at the sea floor and at the pre holocene erosional surface 3 concave longitudinal sections commonly shoaling at the seaward end 4 till like sediments collected from the walls or outer shelf adjacent to the troughs and 5 seismic stratigraphy that can be correlated with bottom samples indicative of glacially derived strata depressions with tens of meters of relief are present on the pre holocene subbottom erosional surface beneath most of these valleys these depressions have been partially filled by a seaward thinning wedge of holocene glacial flour clayey silt that is filling the valleys and blanketing the inner shelf at rates as high as 15 mm yr based on 210 pb measurements although glaciation played a dominant role in the modern morphology of these sea valleys structural features including structurally controlled topographic highs on the shelf e g tarr bank kayak island pamplona spur and fairweather ground influenced the flow directions of the glacial lobes

interlaminated ice proximal glacimarine sediments in muir inlet alaska muir inlet in glacier bay alaska is a glacial fjord receiving a tremendous volume of sediment annually the rate of sediment accumulation is greatest proximal to muir glacier about 9 m yr 1 and decreases away from the glacier the primary sediment sources are meltwater streams discharging at subglacial and ice marginal positions to form overflows interflows and underflows continuous turbidity currents overflows and interflows interact with diurnal tidal currents and their volume and sediment concentration varies diurnally and annually with meltwater discharge these effects produce cyclic deposits of a thin fine grained sand or silt lamina that grades normally to a thicker poorly to very poorly sorted mud lamina this lamina couplet is termed a cyclopel underflows are suggested to occur in this glacimarine environment because of conditions unique to subglacial fluvial systems underflow deposits occur only in proximal positions 0 5 km from glacier face and are coarse grained reverse to normal graded and exhibit an increase in sorting and sand content up layer ice rafted debris identified as particles 177 m is ubiquitous though low 5 by weight and occurs as isolated particles frozen pellets or as lenses that in cores may have a lamina appearance proximally ice rafted debris is difficult to identify because proximal sediment is often as coarse grained deposited sediment may be reworked by tidal currents and sediment gravity flows depositional processes operating in muir inlet produce interlaminated sand silt clay that characterizes sediment proximal to a glacier and fines seaward to mud sediment is classified into one of three sediment types 1 1 type i sediment is very fine grained mean 8 65 7 17 o low in sand 0 1 11 2 and very poorly to poorly sorted it is the dominant sediment type in muir inlet and is transported by plumes and deposited by suspension settling 2 2 type ii sediment is fine to coarse grained mean 6 70 3 12 o low to high in sand 5 1 86 6 and very poorly to moderately sorted it represents reworked sediment proximal plume deposits or coarse grained laminae of cyclopels 3 3 type iii sediment is coarse grained mean 3 89 2 38 o high in sand 58 0 100 0 and poorly to well sorted it is deposited by sediment gravity flows or underflows

seismic stratigraphic evidence for glacial expanse during glacial maxima in the yakutat bay region gulf of alaska 1 modern shelf bathymetry bordering the gulf of alaska exhibits shelf crossing sea valleys that suggest focused pathways for ice flow during glacial conditions using an integrated seismic data set between the present yakutat and alsek sea valleys we investigate the glacial stratigraphic record in order to improve our understanding of the regional glacial system during maximum glacial conditions our investigations reveal four glacial unconformities of which the latter two are overlain by sediment packages hundreds of meters thick we suggest that these unconformities are indicative of ice advance phases during the little ice age lia the last glacial maxima lgm and two pre lgm advances with glacial retreat sequences preserved from the youngest two the advances were dominated by ice expanse from the malaspina glacial system and alsek river districts rather than the hubbard glacial system and only show distinctive morainal bank development near the shelf edge and near the mouth of or within modern bays fjords or river valleys this observation strongly supports rapid and continuous retreat from glacial maxima conditions during climatic warming all except the inferred lia sequence transgress the shelf and exhibit concentrated erosion in overdeepened troughs analogous to cross shelf troughs similar to those observed on other high latitude glaciated shelves the two alaskan troughs discussed here may be end member examples of high sediment flux systems due to the temperate glacial setting combined with an actively exhuming orogen

plate boundary localization slip rates and rupture segmentation of the queen charlotte fault based on submarine tectonic geomorphology abstract linking fault behavior over many earthquake cycles to individual earthquake behavior is a primary goal in tectonic geomorphology particularly across an entire plate boundary here we examine the 1150 km long right lateral queen charlotte fairweather fault system using comprehensive multibeam bathymetry data acquired along the queen charlotte fault qcf offshore southeastern alaska and western british columbia fine scale analysis of tectonic geomorphology allowed us to identify and reconstruct 184 strike slip piercing points over a 630 km stretch of the qcf age constraints from glacial recession and offshore sedimentation patterns yield a consistent slip rate of 50 57 mm yr since 17 12 ka the fastest rate for a continent ocean strike slip fault on earth these slip rates equal or exceed estimates of pacific north america pa na relative motion from global plate reconstructions indicating that pa na motion is highly localized the qcf cuts the seafloor along a narrow and unusually straight trace for its entire length and multiple fault traces are observed only at local step overs the geometry and behavior of the qcf over many earthquake cycles is simple and typical of mature faults with relatively homogeneous stress fields since the qcf is the primary pa na plate boundary we used the trace of the qcf to define the small circle path for relative plate motion and computed the associated euler pole predicted along strike obliquity variations based on the new pole agree with observed tectonic geomorphology and suggest that previous global plate reconstructions overestimated the degree of oblique convergence along the qcf we also find that subtle long wavelength 75 150 km bends and discrete step overs appear to define the endpoints of m 7 earthquakes suggesting that obliquity and resultant fault geometry may control rupture segmentation and asperity development lastly the agreement between predicted obliquity and tectonic geomorphology along the entire length of qcf compelled a reevaluation of regional tectonic models in the north the eastern yakatat terrane appears to be translating northwest with the pacific plate and slip transferred from the qcf to the fairweather fault results in 20 mm yr of convergence along the southern st elias mountains in the south we predict a reduced rate of convergence along the qcf west of haida gwaii 5 6 mm yr of shortening on average relative to previous studies our results support a model for transpression and strike slip partitioning along the edge of a hot and weak pacific plate leading to crustal thickening and growth of the queen charlotte terrace to the west of haida gwaii

observations on delta forming processes in a fjord head delta british columbia canada abstract the bella coola delta is a laterally confined steep fronted fjord head delta in north bentinck arm in the pacific coast mountains of british columbia the principal controls on sedimentation are 1 the high sediment yield and bedload dominance of the bella coola river which reflect climatic conditions and high drainage basin relief 2 river mouth processes which are controlled by tidal stage and delta morphology and 3 delta front deformational processes which are related primarily to oversteepening in the upper delta front wave processes are of limited significance the large tidal range 3 9 m mean range 5 9 m large range changes the location of distributary outlets at high tide and high discharge frictional forces dominate and the effluent disperses as a plane jet over the delta plain at low tide and high discharge inertial frictional and buoyant forces are important and the effluent disperses over saline basin water subaqueous landslides and debris flows have produced a series of erosional chutes on the delta front

ultra rapid landscape response and sediment yield following glacier retreat icy bay southern alaska abstract glacial retreat and opening of taan fjord an arm of icy bay alaska in the last two decades drove a base level fall of 400 m at the outlets of four tributary valleys in the region of the current tyndall glacier terminus response in the tributary valleys to this base level fall includes evacuation of stored sediment incision of slot gorges into bedrock and landsliding on valley walls fluvial transfer of eroded bedrock glacial deposits and stored nonglacial fluvial deposits after 1983 resulted in progradation of fan deltas toward the fjord centerline at the outlet of each of the four catchments in the largest nonglacial tributary valley 0 08 km 3 8 of the 0 59 km 3 of 500 m thick stored fluvial and colluvial deposits has been transferred to the adjacent fjord a percentage of the fjord sedimentation in the last two decades thus includes material eroded from bedrock and stored in the landscape during the previous glacial expansions distal deltaic deposits extend across the fjord floor and likely interfinger with distal proglacial deltaic deposits sourced from the tyndall glacier a paraglacial landscape response such as the one exhibited in upper taan fjord where sediment delivery to fjords from tributary sources in synchrony with sediment produced by primary bedrock erosion by glaciers helps to explain the order of magnitude discrepancy between sediment yields from alaskan tidewater glaciers on 10 0 to 10 2 year timescales and sediment yields and exhumation rates on 10 4 to 10 6 year timescales

determining the three dimensional structure of a volcanic plume using unoccupied aerial system uas imagery abstract this study presents a photogrammetric method for 3d reconstruction of a volcanic plume outline to retrieve its spatial properties a dataset of sequential multi view images was collected using a drone mounted camera for a small scale volcanic plume emitted from volcan pacaya guatemala a space carving algorithm has been applied to estimate the plume shape top height volume and drift direction the complete method workflow is presented herein including data capture camera projection image segmentation and model reconstruction the process applied is considered the simplest approach to reconstruct a 3d plume model from sequential imagery whilst accounting for scene evolution within a probabilistic framework the algorithm is sensitive to the method of image segmentation scene resolution and number of images used with unquantifiable uncertainty in the estimated plume volume due to the lack of ground truth data this proof of concept investigation confirms that 3d quantification of volcanic plume geometry can be achieved using uas based photogrammetry and shows promising results for a new method of measuring volcanic source parameters to validate and adjust dispersion models of volcanic plumes

ichnology of a glacially influenced continental shelf and slope the late cenozoic gulf of alaska yakataga formation abstract the study of trace fossils in glaciomarine strata is important because of the low preservation potential of fauna but glaciomarine settings have received little attention from ichnologists widespread biological activity is recorded by ichnofossil assemblages in glaciomarine strata of the late cenozoic 6 ma to present yakataga formation alaska glacial sedimentation began in the gulf of alaska in the miocene along a deep water active margin basin dominated by turbidity currents and debris flows later strata record progradation of the continental slope by mass flow processes and the establishment of a broad shelf influenced by repeated glaciation ice rafting of coarse debris changes in water depth and salinity storms earthquakes and high sedimentation rates yakataga formation strata show overall a limited ichnological diversity and low degree of bioturbation in relation to comparable non glacial settings although certain beds are highly bioturbated twenty four ichnotaxa are identified and grouped into nine assemblages characteristic of different depositional settings and substrate types ichnogenera and body fossil evidence shows that polychaetes arthropods molluscs and echinoderms were the dominant infaunal benthic organisms with deposit feeding being the predominant feeding strategy poorly consolidated muddy sediments excluded suspension feeders and limited the development of the skolithos ichnofacies typical of non glacial shelves characterized by clean shifting sand substrates evidence of rapid sedimentation is given by escape structures fugichnia the presence of diplocraterion and by the mass mortality of bivalves firm ground burrows typical of the glossifungites ichnofacies are associated with erosional surfaces boulder pavements and coquinas diminutive feeding traces may reflect salinities lowered by glacial meltwater inputs the downslope transport of food by turbidity currents and mass flows may explain the development of a diverse cruziana ichnofacies in water depths where in non glacial settings the nereites ichnofacies is found an ichnological summary is presented for the late cenozoic gulf of alaska continental margin similar ecological conditions obtain in the modern setting and provide valuable supportive data ichnofacies identified from the yakataga formation are probably widespread in late paleozoic and late cenozoic glacially influenced marine strata

experimental observations of water like behavior of initially fluidized dam break granular flows and their relevance for the propagation of ash rich pyroclastic flows the physics of ash rich pyroclastic flows were investigated through laboratory dam break experiments using both granular material and water flows of glass beads of 60 90 m in diameter generated from the release of initially fluidized slightly expanded 2 5 4 5 columns behave as their inertial water counterparts for most of their emplacement for a range of initial column height to length ratios of 0 5 3 both types of flows propagate in three stages controlled by the time scale of column free fall h0 g 1 2 where h0 denotes column height and g denotes gravitational acceleration flows first accelerate as the column collapses transition to a second constant velocity phase occurs at a time t h0 g 1 2 1 5 the flow velocity is then u equation image gh0 1 2 larger than that for dry initially nonfluidized granular flows transition to a last third phase occurs at t h0 g 1 2 4 granular flow behavior then departs from that of water flows as the former steadily decelerates and the front position varies as t1 3 as in dry flows motion ceases at t h0 g 1 2 6 5 with normalized runout x h0 5 5 6 the equivalent behavior of water and highly concentrated granular flows up to the end of the second phase indicates a similar overall bulk resistance although mechanisms of energy dissipation in both cases would be different interstitial air particle viscous interactions can be dominant and generate pore fluid pressure sufficient to confer a fluid inertial behavior to the dense granular flows before they enter a granular frictional regime at late stages efficient gas particle interactions in dense ash rich pyroclastic flows may promote a water like behavior during most of their propagation

the seismic stratigraphy of okanagan lake british columbia a record of rapid deglaciation in a deep fiord lake basin this paper presents the first detailed data regarding the newly discovered deep infill of okanagan lake okanagan lake 50 00 n 119 30 w is 120 km long 3 5 km wide and occupies a glacially overdeepened bedrock basin in the southern interior of british columbia this basin and other elongate lakes of the region e g shuswap kootenay kalamalka canim and mahood lakes mark the site of westward flowing ice streams within successive cordilleran ice sheets an air gun seismic survey of okanagan lake shows that the bedrock floor is nearly 650 m below sea level more than 2000 m below the rim of the surrounding plateau the maximum thickness of pleistocene sediment in okanagan lake basin approaches 800 m forty six seismic reflection traverses and an axial profile show a relatively simple stratigraphy composed of three seismic sequences argued to be no older than the last glacial cycle 30 ka a discontinuous basal unit sequence i characterized by large scale diffractions and up to 460 m thick infills the narrow v shaped bedrock floor of the basin and is interpreted as a boulder gravel deposited by subglacial meltwaters overlying seismic sequence ii is composed of two sub sequences sub sequence iia is a chaotic to massive facies up to 736 m thick lakeshore exposures close to where this unit reaches lake level show deformed and chaotically bedded glaciolacustrine silts containing gravel lens and large ice rafted boulders the surface topography of this sub sequence is irregular and in general mimics the form of the underlying bedrock as a result of compaction this sequence passes laterally into stratified facies sub sequence iib at the northern end of the basin seismic sequence ii appears to record rapid ice proximal dumping of glaciolacustrine silt as the okanagan glacier backwasted upvalley in a deep lake a thin 60 m max laminated seismic sequence iii drapes the hummocky surface of sequence ii and represents postglacial sedimentation from fan deltas the extreme thickness of sequences i and ii in okanagan lake reflects the focussing of large volumes of meltwater and sediment into the basin during deglaciation pre existing sediments that pre date the last glacial cycle appear to have been completely eroded glaciological conditions during sedimentation may have been similar to marine based outlet glaciers calving in deep water in fiord basins in contrast to marine settings where ice bergs are free to disperse large volumes of dead ice were trapped within the basin structural evidence for sedimentation around dead ice blocks has been previously used to argue that the cordilleran ice sheet downwasted in situ we emphasize in contrast the trapping of dead ice left behind by rapidly calving lake based outlet glaciers

late quaternary glacial dynamics and sedimentation variability in the bering trough gulf of alaska ice dynamics tectonic setting and sediment supply are the key parameters controlling the architecture of high latitude margins and the formation of trough mouth fans tmfs current understanding of these archives of paleo ice streams is based on studies of ice sheets adjacent to stable passive margins while the behavior of active convergent glacier influenced margins remains relatively unconstrained we integrate high resolution seismic data and chronology from integrated ocean drilling program expedition 341 cores in southeast alaska across the actively converging yakutat terrane margin to examine the late quaternary evolution of the bering glacier the largest outlet glacier of the poorly understood cordilleran ice sheet cis we interpret at least eight glacial advances to the shelf break since the end of the mid pleistocene transition showing a more dynamic cis than hitherto realized during the past 130 k y the temperate meltwater charged bering glacier delivered 925 km 3 of sediment to the shelf and slope providing one of the highest rates of sustained sediment accumulation 5 10 m k y ever reported globally rapid formation of a tmf reaching 600 m thick in 130 k y emphasizes the extreme sediment flux that can be produced by wet based glacial systems and its critical role in the development of high latitude margin stratigraphy tmf formation despite initially steep tectonically controlled slopes in this active setting reflects an autogenic shift in the evolution of the bering trough suggesting that major transitions between sedimentary regimes need not reflect some externally driven change in climate variability

sediment evacuation and glacial erosion rates at a small alpine glacier 1 glacial erosion is known to be driven by sliding which occurs in brief episodes in the melt season what is not known is how well this sliding history is reflected in the sediment output from a glacier and to what degree temporary sediment storage in the glacier smoothes the history of sediment production we document sediment evacuation rates for three seasons at bench glacier a small temperate alpine glacier in the chugach range of alaska two lines of evidence suggest that subglacial sediment storage is small strong hysteresis in the relationship between sediment and water discharge argues for sediment exhaustion from the subglacial system on seasonal and flood event timescales uplift of the glacier surface during periods of enhanced basal motion reflects intimate contact of the glacier sole with up glacier inclined stoss slopes of bedrock bumps sediment evacuation rates at bench glacier should therefore closely track glacial erosion rates over annual timescales much of the sediment emerges in a major pulse that closely follows the termination of enhanced sliding each year suggesting that the conduits and well connected cavities that allowed removal of englacial water to terminate sliding also promoted efficient transport of sediment this small glacier efficiently modifies the landscape lowering its bed by 1 2 mm yr while sliding only 1 2 m yr our sparse measurements of instantaneous bed load discharge average 41 of concurrent suspended sediment discharge assuming that half of the suspended load derives from abrasion of subglacially quarried clasts roughly two thirds of the sediment evacuated can be attributed to quarrying

capturing volcanic plumes in 3d with uav based photogrammetry at yasur volcano vanuatu abstract as a precise volume of volcanic ash plume is essential to understand the dynamic of gas emission exchanges and the eruptive dynamics we have measured in 3d using photogrammetry a small size volcanic plume at the summit of yasur volcano vanuatu the objective was to collect the altitude and planform shape of the plume as well as the vertical variations of the shape and size to reach this objective the authors have used the structure from motion photogrammetric method applied to a series of photographs captured in a very short period of time around and above the plume a total of 146 photographs at 3000 4000 pixel were collected as well as the geolocation the pitch tilt and orientation of the cameras the results revealed a mushroom like shape of the plume with a narrow ascending column topped by a turbulent mixing zone the volume of the plume was calculated to be 13 430 m3 512 m3 with the error being the cube of the linear error from the ground control points for a maximum height above the terrain of 63 m the included error was also kept high because of the irregular distribution of the ground control points that could not be collected in dangerous areas due to the ongoing eruption based on this research it is therefore worth investigating the usage of multiple cameras to capture plumes in 3d over time and the method is also a good complement to the recent development of photogrammetry from space which can tackle larger scale eruption plumes

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

glacial and tectonic control on fjord morphology and sediment deposition in the magellan region 53 s chile in the patagonian andes erosion by temperate pleistocene glaciers has produced a deeply incised fjord system in which glacial and non glacial sedimentswere deposited since the late glacial glacier retreat so far fjord bathymetry and structures in the sediment infill were widely unexplored here we report the results of an investigation of morphology and sediment characteristics of a 250 km long fjord transect across the southernmost andes 53 s using multibeam and parametric echosounder data and sediment cores subaquatic morphology reveals continuity of on land tectonic lineaments mapped using field and remote sensing data our results indicate that glacial erosion and fjord orientation are strongly controlled by three major strike slip fault zones furthermore erosion is partly controlled by older and or reactivated fracture zones as well as by differential resistance of the basement units to denudation basement morphology is regionally superimposed by late glacial and holocene subaquatic moraines which are associated to known glacier advances the moraines preferentially occur on basement highs which constrained the glacier flows this suggests that the extent of glacier advances was also controlled by basement morphology subaquatic mass flows fluid vent sites as well as distinct late glacial and holocene sediment infills have furthermore modified fjord bathymetry in the western fjord system close to the strait of magellan subaquatic terraces occur in 20 to 30 m water depth providing an important tag for proglacial lake level during the late glacial

turbidity current channels in queen inlet glacier bay alaska queen inlet is unique among glacier bay fjords because it alone has a branching channel system incised in the holocene sediment fill of the fjord floor bathymetry and seismic reflection profiles s

sedimentary processes of canadian arctic fjords abstract conceptual models of circulation and sedimentation in arctic fjords are presented to illustrate the current understanding of these environments circulation is a vigorous process in these fjords and is enhanced by the loss of the freshwater cap during the long winter period of near zero inflow the process of brine rejection during the formation of sea ice and the role of glaciers and icebergs injecting freshwater at depth on the other hand the presence of sea ice blocks reduces the mixing action of wind which may otherwise represent the largest input of energy to fjord circulation it also provides a freshwater layer on melting and may in some circumstances damp the amplitude of tides during summer large loads of glacial sediment entering arctic fjords are separated into streams of overflowing suspended load and bed load in the presence of salt water as the concentrations of suspended load in the freshwater are normally much less than required to overcome the density of the salt water deposition occurs throughout the fjord by rapid settling of flocculated particles from the overflowing brackish water and from grain flows in the proximal environment created as the fluvial traction carpet moves over the delta foreset slope after sediment has been deposited it may be remobilized by slides which in turn may develop into fully turbulent flows as they move down the fjord floor a range of deposits from slump debris to minor turbidites are postulated to occur with the flocculated muds although not all have yet been examined in the arctic fjord stratigraphic record sea ice is an important sedimentological agent in arctic fjords it passively carries fluvial aeolian and colluvial material which is subsequently released from the ice during the stage of puddle draining at break up sea ice also actively incorporates fine and coarse sediments up to large boulders during freezing along the shores in winter and by wave and tidal current washing controlled by the presence of the ice during break up

high sedimentation rates and thrust fault modulation insights from ocean drilling offshore the st elias mountains southern alaska abstract the southern alaskan margin offshore the st elias mountains has experienced the highest recorded offshore sediment accumulation rates globally combined with high uplift rates active convergence and extensive temperate glaciation the margin provides a superb setting for evaluating competing influences of tectonic and surface processes on orogen development we correlate results from integrated ocean drilling program iodp expedition 341 sites u1420 and u1421 with regional seismic data to determine the spatial and temporal evolution of the pamplona zone fold thrust belt that forms the offshore st elias deformation front on the continental shelf our mapping shows that the pattern of active faulting changed from distributed across the shelf to localized away from the primary glacial depocenter over 300 780 kyrs following an order of magnitude increase in sediment accumulation rates simple coulomb stress calculations show that the suppression of faulting is partially controlled by the change in sediment accumulation rates which created a differential pore pressure regime between the underlying faulted strata and the overlying undeformed sediments

lithofacies and seismic reflection interpretation of temperate glacimarine sedimentation in tarr inlet glacier bay alaska abstract high resolution seismic reflection profiles of sediment fill within tarr inlet of glacier bay alaska show seismic facies changes with increasing distance from the glacial termini five types of seismic facies are recognized from analysis of huntec and minisparker records and seven lithofacies are determined from detailed sedimentologic study of gravity vibro and box cores and bottom grab samples lithofacies and seismic facies associations and fjordfloor morphology allow us to divide the fjord into three sedimentary environments ice proximal iceberg zone and ice distal the ice proximal environment characterized by a morainal bank depositional system can be subdivided into bank back bank core and bank front subenvironments each of which is characterized by a different depositional subsystem a bank back subsystem shows chaotic seismic facies with a mounded surface which we infer consists mainly of unsorted diamicton and poorly sorted coarse grained sediments a bank core depositional subsystem is a mixture of diamicton rubble gravel sand and mud seismic reflection records of this subsystem are characterized by chaotic seismic facies with abundant hyperbolic diffractions and a hummocky surface a bank front depositional subsystem consists of mainly stratified and massive sand and is characterized by internal hummocky facies on seismic reflection records with significant surface relief and sediment gravity flow channels the depositional system formed in the iceberg zone environment consists of rhythmically laminated mud interbedded with thin beds of weakly stratified diamicton and stratified or massive sand and silt on seismic reflection profiles this depositional system is characterized by discontinuously stratified facies with multiple channels on the surface in the proximal zone and a single channel on the largely flat sediment surface in the distal zone the depositional system formed in the ice distal environment consists of interbedded homogeneous or laminated mud and massive or stratified sand and coarse silt this depositional system shows continuously stratified seismic facies with smooth and flat surfaces on minisparker records and continuously stratified seismic facies which are interlayered with thin weakly stratified facies on huntec records

evaluation of dsms generated from multi temporal aerial photographs using emerging structure from motion multi view stereo technology abstract an accuracy assessment of digital surface models dsms generated from archived aerial photographs using the structure from motion multi view stereo sfm mvs technique was carried out a four step accuracy assessment procedure was adopted using aerial photography from eight periods as follows step 1 generate a dsm and orthophoto from digital aerial photographs taken in 2013 and ground control points gcps measured by gnss step 2 assess the accuracy of the dsm by comparison with altitude measured by leveling survey step 3 generate other historical dsms and orthophotos from historical aerial photographs using gcps extracted from the dsm of 2013 step 4 assess the accuracy of all historical dsms by comparing with the leveling survey then re calculate the accuracy of historical dsms by reducing the inherent error in the 2013 dsm the dsm based on the aerial photographs taken in 2013 was generated with a resolution of 48 2 cm the residual height error of the gcps was 15 4 cm validation against the altitudes of 171 points revealed that this dsm has a height root mean square error rmse of 24 1 cm and is 9 2 cm lower than the leveling data on average even using us military photos with unconfirmed detailed specifications the model can measure the altitude with an rmse value of 121 5 cm it appears therefore that analysis by sfm mvs can give comparable measurement accuracy to traditional aerial photogrammetry the low cost and high accuracy obtained with archived aerial photographs are worthy of special mention

proglacial sediment instability features on the scotian slope at 63 w abstract a small area of the scotian slope has been investigated in detail as a type example of a high latitude continental slope adjacent to a major ice outlet the geologic framework has been defined by airgun seismic profiles which show that late tertiary shales have irregular dips but overlie undisturbed strata these shales form a zone of diapirs at around 1200 m water depth which have ponded the prograding quaternary sediments upslope high resolution sparker profiles seamarc i mid range sidescan imagery and piston cores have been used to investigate the late quaternary sedimentary sequence a prominent gullied horizon about 40 m subbottom that is overlain by acoustically unstratified sediments sands is correlated with the occurrence of an early middle wisconsinan grounded icesheet at the top of the continental slope it is overlain by a thick sequence of proglacial muds and a thin veneer of holocene sediments much of the late wisconsinan sequence has been dissected by a series of closely spaced gullies both sidescan and subbottom profiler data show that slumping is common in the late wisconsinan sequence as a result of high sedimentation rates and local gully erosion piston cores provide evidence for debris flows and turbidity currents depositional sediment mounds in the diapir zone have accumulated sediment at three times the regional sedimentation rate suggesting that large amounts of fine sediment reached the slope in suspension and that much of the proglacial sediment by passed the continental slope

ground based and uav based photogrammetry a multi scale high resolution mapping tool for structural geology and paleoseismology this contribution reviews the use of modern 3d photo based surface reconstruction techniques for high fidelity surveys of trenches rock exposures and hand specimens to highlight their potential for paleoseismology and structural geology we outline the general approach to data acquisition and processing using ground based photographs acquired from standard dslr cameras and illustrate the use of similar processing approaches on imagery from unmanned aerial vehicles uavs it is shown that digital map and trench data can be acquired at ultra high resolution and in much shorter time intervals than would be normally achievable through conventional grid mapping the resulting point clouds and textured models are inherently multidimensional x y z point orientation colour texture archival and easily transformed into orthorectified photomosaics or digital elevation models dems we provide some examples for the use of such techniques in structural geology and paleoseismology while pointing the interested reader to free and commercial software packages for data processing visualization and 3d interpretation photogrammetric models serve to act as an ideal electronic repository for critical outcrops and observations similar to the electronic lab book approach employed in the biosciences this paper also highlights future possibilities for rapid semi automatic to automatic interpretation of the data and advances in technology

the holocene sedimentary history of the kangerlussuaq fjord valley fill west greenland abstract west greenland has been intensively studied to reconstruct and better understand past relative sea level changes and deglacial history this study extends these efforts by linking sea level and deglacial history to the sedimentary infill successions of kangerlussuaq fjord and associated landward valleys based on published and new land and sea based geophysical data radiocarbon dates and geological observations we have characterized the infill and reconstructed the sedimentation history during the holocene based on a revised sea level curve and data presented in this paper we defined three depositional phases phase i 7000 yr bp is represented by dominant glaciomarine deposition associated with a tide water glacier system as the greenland ice sheet gis continued to retreat it became land based during phase ii 7000 1500 yr bp two separate depocenters formed keglen delta depocenter arose from a temporary stabilization phase of the gis and prograded rapidly over the glaciomarine deposits of phase i further inland proglacial lake formation and subsequent sedimentary infill associated with the ongoing gis retreat is represents the second depocenter the watson river connected both depocenters by a flood plain which transferred sediment from the gis to the keglen delta ongoing sea level fall due to glacio isostastic uplift combined with a gradually cooler and dryer climate resulted in terrace formation along the watson river flood plain around 4000 yr bp the gis margin reached its most landward location and began to advance to its present location the final phase phase iii

digital photogrammetry and gis based analysis of the bio geomorphological evolution of sakurajima volcano diachronic analysis from 1947 to 2006 abstract the sakurajima volcano is one of the most active volcanoes in the world with regular activity dominated by vulcanian eruptions since 1955 located in kagoshima prefecture kyushu island japan the sakurajima volcano is a stratovolcano with two main vents at the summit the kitadake and the minamidake and a third smaller central vent the nakadake the two firsts peak at 1117 and 1060 m dominate the slopes mainly composed of lava flow deposits secondary volcaniclastic material and recent ejectas from the vulcanian eruptions although the volcano has been very closely monitored by japanese universities mostly kyoto university and kagoshima university and governmental agencies there has been very little geomorphological investigation of the structure of the volcano using the digital photogammetric method sfm mvs structure from motion and multiple view stereophotogrammetry applied to historical aerial photographs the present contribution aims to provide an analysis of the volcanic structure and the recent bio geomorphological evolution for the period 1947 2006 first the results have proved that sfm mvs is a method that can be successfully applied to aerial photographs for diachronic reconstruction of geomorphological landscape evolution this method is especially important in active volcanic areas as the geomorphology can change very rapidly within the historical period secondly the results have shown that during the last 60 years the summit area of the sakurajima has greatly evolved the morpholology of the minamidake crater has changed due to its regular explosive activity the upper slopes have been covered in ejecta modifying their elevation and their smoothness the lower slopes have seen the apparition of lahar deposition areas while valleys upslope have widened due to the lahar activity and the upward progression of the deposits the 3d derived from sfm mvs has also shown how the lahar deposits are using the topographic low created on top of the lava deposits and in between lava deposit to accumulate mid slopes rather than accumulating on the lower volcanic apron this is accentuated by the construction of sabo dams that keep a large amount of the material on the slopes finally as this publication has been carried out using the freely available imagery from the gsi geospatial information authority of japan at 200 dpi higher resolution imagery can even open further possibilities for the monitoring of volcano evolution in japan and in countries providing long series of historical imagery

volcanic ash concentration during the 12 august 2011 etna eruption mount etna in italy is one of the most active volcanoes in the world and an ideal laboratory to improve volcano ash monitoring and forecasting during the volcanic episode on 12 august 2011 an eruption column rose up to several kilometers above sea level asl and the volcanic plume dispersed to the southeast from the video surveillance system we were able to estimate variations in the column height peak value of 9 5 0 5 km above sea level with time we derived the time varying discharge rate peak value of 60 m3 s 1 and determined the ash concentration using a volcanic ash dispersal model the modeled ash concentration was compared with lidar measurements using different particle effective radius and differences are within the error bars volcanic ash concentrations range from 0 5 to 35 5 10 3 g m 3 the comparison highlights that to improve volcanic ash forecasting during volcanic crises it is necessary to take into account the time varying discharge rate of explosive eruptions

evaluation of conditions along the grounding line of temperate marine glaciers an example from muir inlet glacier bay alaska abstract in the marine environment stability of the glacier terminus and the location of subglacial streams are the dominant controls on the distribution of grounding line deposits within morainal banks a morainal bank complex in muir inlet glacier bay se alaska is used to develop a model of terminus stability and location of subglacial streams along the grounding line of temperate marine glaciers this model can be used to interpret former grounding line conditions in other glacimarine settings from the facies architecture within morainal bank deposits the muir inlet morainal bank complex was deposited between 1860 a d and 1899 a d and historical observations provide a record of terminus positions glacial retreat rates and sedimentary sources these data are used to reconstruct the depositional environment and to develop a correlation between sedimentary facies and conditions along the grounding line four seismic facies identified on the high resolution seismic reflection profiles are used to interpret sedimentary facies within the morainal bank complex terminus stability is interpreted from the distribution of sedimentary facies within three distinct submarine geomorphic features a grounding line fan stratified ridges and a field of push ridges the grounding line fan was deposited along a stable terminus and is represented on seismic reflection profiles by two distinct seismic facies a proximal and a distal fan facies the proximal fan facies was deposited at the efflux of subglacial streams and indicates the location of former glacifluvial discharges into the sea stratified ridges formed as a result of the influence of a quasi stable terminus on the distribution of sedimentary facies along the grounding line a field of push ridges formed along the grounding line of an unstable terminus that completely reworked the grounding line deposits through glacitectonic deformation between 1860 a d and 1899 a d 39 years 8 96 10 8 m 3 of sediment were deposited within the muir inlet morainal bank complex at an average annual sediment accumulation rate of 2 3 10 7 m 3 a this rate represents the annual sediment production capacity of the glacier when the muir inlet drainage basin is filled with glacial ice

timescale dependence of glacial erosion rates a case study of marinelli glacier cordillera darwin southern patagonia 1 erosion rates have been estimated for a number of glaciated basins around the world mostly based on modern observations last few decades of sediment fluxes to fjords we use time constrained sediment volumes delivered by marinelli glacier 55 s an outlet glacier of the cordillera darwin ice cap southern patagonian andes tierra del fuego to determine erosion rates across different timescales sediment volumes are derived using a dense grid of high and low frequency single channel seismic data and swath bathymetry data along with piston and kasten cores our results show dramatic differences in erosion rates over different timescales erosion rates at marinelli glacier diminish about 80 or by factor of 5 with each ten fold increase in the time span over which erosion rates are averaged 29 3 mm yr for the last 45 years 5 3 mm yr for the last 364 years and 0 5 mm yr for the last 12 500 years these results indicate that modern sediment yields and erosion rates from temperate tidewater glaciers can exceed long term values over the time of deglaciation after the last glacial maximum centennial and millennial timescales by up to 2 orders of magnitude in view of the low exhumation rates of cordillera darwin 0 07 mm yr average for the last 30 myr modern erosion rates could be up to 3 orders of magnitude higher than rates over geological time we conclude that the pattern of erosion rate variation with time reflects the sensitivity of glaciers to climate variability

glaciation in alaska the geologic record edited by thomas d hamilton katherine m reed and robert m thorson alaska geological society anchorage 1986 265 pp us 18 95

morphometry and evolution of arc volcanoes volcanoes change shape as they grow through eruption intrusion erosion and deforma tion to study volcano shape evolution we apply a comprehensive morphometric analysis to two contrasting arcs central america and the southern central andes using shuttle radar topography mission srtm digital elevation models we compute and defi ne parameters for plan ellipticity irregularity and profi le height width summit basal width slope shape as well as size height width volume we classify volcanoes as cones sub cones and massifs and recognize several evolutionary trends many cones grow to a critical height 1200 m and volume 10 km 3 after which most widen into sub cones or massifs but some grow into large cones large cones undergo sector collapse and or gravitational spreading without sig nifi cant morphometry change other smaller cones evolve by vent migration to elliptical sub cones and massifs before reaching the critical height the evolutionary trends can be related to magma fl ux edifi ce strength structure and tectonics in particular trends may be controlled by two balancing factors magma pressure versus lithostatic pressure and conduit resistance versus edifi ce resistance morphometric analysis allows for the long term state of individual or volcano groups to be assessed morphological trends can be integrated with geological geophysical and geochemical data to better defi ne volcano evolution models

glacial debris flow deposits on the baffin island shelf seismic facies architecture of till tongue like deposits abstract 3 d seismic facies modeling of late foxe wisconsin glacial deposits in the savage basin provides important new data concerning the morphology and origin of acoustically unstratified seismic units on high latitude continental shelves savage basin contains a thick sequence up to 110 m of morainal bank deposits unit ii similar to till tongue root deposits described from the scotian and norwegian shelves in 2 d longitudinal cross section unit ii thins and differentiates northward into two acoustically unstratified wedges or till tongue like deposits units iiaw and iibw which are observed to interbed with stratified glacimarine sediments unit i sediment transport was northeastward away from a late glacial ice margin in outer frobisher bay both unstratified wedges are lobate in plan view with the thickest portion 5 m to 50 m lying along the lobe axis upper surface contours are convex to the north and concentric to the lobate margin southward at the transition to the morainal bank the contours become concave to the north this morphology is consistent with that of lobate debris flow deposits with the concave contours defining a zone of sediment failure the data indicate sediment failure within morainal bank deposits which accumulated near the terminus of a temperate tide water ice sheet truncations of unit i reflectors against the lower surface of the debris flows indicate that the flows were deposited episodically and that they remobilized or eroded some of the unit i sediments this unconformable relationship gives the same stratigraphic sequence that king et al 1991 proposed to explain till tongue formation from subglacial meltout beneath buoyant glacier ice in contact with the seabed coalescing debris flow lobes are observed along the entire distal slope of the morainal bank these give the appearance of a continuous till tongue wedge in seismic cross sections taken parallel and distal to the paleoice margin without 3 d geometry reconstructed at contour intervals 10 m the complex lobate morphology could not be resolved

comparison of the shapes and sizes of seafloor volcanoes on earth and pancake domes on venus the fact that flat topped pancake domes observed on venus resemble flat topped volcanoes on earth s seafloor suggests that volcanic processes on the seafloor and on venus may operate to construct volcanic forms with similar characteristics to test this the shapes and size distributions of terrestrial submarine volcanoes seamounts from several magmatic and tectonic provinces are quantitatively compared with those of venusian pancake domes seamount heights and diameters are highly correlated suggesting that there may be a universal mechanism for their growth the 2014 point sample mean of the height to diameter ratio is d 0 10 0 04 in contrast heights and diameters of 52 pancake domes exhibit no obvious trend and values of d are as much as three orders of magnitude smaller with a 52 point sample mean of d 0 02 0 03 seamounts with basal diameters db 10 km have flatness values ratio of top to bottom diameter that span the entire range between 0 pointed cone and 1 truncated cone larger sized seamounts tend to have small values of flatness and more pointed tops this is not true for pancake domes which show large flatnesses at all sizes additionally seamounts have distinctive profiles with their flank slopes increasing in gradient toward the summit flank slopes of pancake domes however commonly increase in gradient toward the base with respect to sizes the diameter distributions of the different seamount populations are consistent with a model in which the number of seamounts decreases exponentially with increasing diameter the diameter distribution of 126 pancake domes by contrast is more uniform its mean is db 22 13 km this size is at least an order of magnitude larger than the estimated characteristic diameters of the seamount populations based on the above results i conclude that seamounts have significantly different shapes and size distributions than venusian pancake domes that have been identified and measured to date this suggests that one or more of the variables e g magma composition crystallinity magma volume effusion rate cooling rate pre existing topography governing their formation differs in terms of shapes and size distributions the small db 20 km volcanic edifices first identified from venera data are good morphologic matches to seamounts and should be the focus of future work investigating the formation of comparable volcanic features in these two different planetary environments

strain partitioning in southeastern alaska is the chatham strait fault active abstract a 1200 km long transform plate boundary passes through southeastern alaska and northwestern british columbia and represents one of the most seismically active but poorly understood continental margins of north america although most of the plate motion is accommodated by the right lateral queen charlotte fairweather fault qcff system which has produced at least six m 7 earthquakes since 1920 seismic hazard assessments also include the chatham strait fault csf as a potentially active 400 km long strike slip fault that cuts northward through southeastern alaska connecting with the eastern denali fault nearly the entire length of the csf is submerged beneath chatham strait and lynn canal and has never been systematically imaged using high resolution marine geophysical approaches in this study we present an integrated analysis of new marine seismic reflection data acquired across lynn canal and tectonic block modeling constrained by data from continuous and campaign gps sites seismic profiles cross the csf at twelve locations spanning 50 km of fault length they reveal thick up to 300 m packages of glaciomarine sedimentary facies emplaced on an unconformity surface that formed during the last glacial maximum lgm localized warping of post lgm stratigraphy 13 9 kyr b p to present appears to correlate with sediment drape on basement topography and current controlled deposition there is no evidence for an active fault along the axis of lynn canal in the seismic reflection data crustal block models constrained by gps data allow but do not require a maximum slip rate of 2 3 mm yr along the csf higher slip rates on the csf result in significant misfit to gps data in the surrounding region based on the combined marine geophysical and gps observations it is plausible that the csf has not generated resolvable coseismic deformation in the last 13 ka and that the modern slip rate is

collecting field data in volcanic landscapes using small uas suas drones abstract the last several years have seen a very rapid increase in the development and availability of unmanned aerial vehicles systems uav or uas more commonly called drones uas are remotely operated aerial vehicles that can be fixed wing planes helicopters or aerial systems with multiple propellers small versions of uas here called suas in particular have become so prevalent that they can be easily purchased at general retail stores this paper seeks to review and summarize the use of suas in volcanic research given their size low cost and relative durability suas provide a light weight tool platform that is easy to transport to field locations quick to set up and easy to launch and control they require very little launch and recovery space because of these characteristics suas are useful in collecting immediate and real time aerial data especially in remote inaccessible dynamic and or hazardous volcanic environments in volcanic areas suas have been used for mapping sample collection thermal imaging magnetic surveys slope stability studies and as platforms for sensors to measure outgassing of co 2 and so 2 they are also becoming invaluable for real time hazard assessment during and after an eruption they are however limited by their flight time which is greatly affected by wind speeds since they are predominately made of plastic they are also impacted by the high thermal temperatures found in active volcanic areas which can degrade their structure and performance with continued technological improvement however suas have the potential to dramatically improve our ability to collect field data because of additional natural technological and legal challenges related to their use it is critical that users be aware of and adhere to all national and local laws associated with suas

shallow magma mingling driven strombolian eruptions at mt yasur volcano vanuatu 1 mt yasur volcano vanuatu has been increasingly recognized for its high frequency strombolian eruptions strombolian activity is often regarded as a product of the rapid ascent of gas slugs originating from a deep magma which mingle with a batch of shallow magma upon eruption heterogeneous crystal distribution as well as bimodal bubble size distributions in the eruptive products generally supports this view here the strombolian activity at mt yasur is analyzed a rheological investigation indicates that the basaltic andesitic eruptive products contain an apparently homogeneous glass phase and yet exhibit evidence of a distinct range of glass transition temperatures with multiple peaks occurring in individual samples such anomalous behavior is proposed to result from the mingling of magmas with contrasting oxidation states the unstable nature of the measured glass transition behavior leads us to the inference that mingling is located in the shallow parts of the eruptive conduits partly driven by rejuvenation of material slumped from the crater walls into an open conduit system the dynamics of this process may expose the periodicity of the eruptions themselves

seismic facies changes along a nearly continuous 24 latitudinal transect the fjords of chile and the northern antarctic peninsula abstract high resolution seismic reflection profiles and piston cores from bays fjords and straits of the inland passage of chile and the northern antarctic peninsula region were used to examine changes in seismic facies along a nearly continuous 24 latitudinal transect that encompasses temperate subpolar and polar climatic regimes these climatic regimes are characterized by differences in seismic facies eight seismic facies are recognized on the basis of reflection character intensity of acoustic contrast at bounding surfaces and external shape of the unit the northern and central chilean fjord region is a temperate maritime setting characterized by thick ice proximal and ice distal glacial marine strata and a variety of morainal features the southern inland passage and the south shetland islands of antarctica represent transitional sub polar glacial marine settings these areas are characterized by relict ice proximal glacialmarine facies and relatively thin ice distal glacial marine facies morainal ridges occur in bays and fjords of chile the northern antarctic peninsula is a polar climatic setting the straits bays and fjords of the region have been virtually scraped clean of sediments a thin draping glacial marine unit occurs locally in these areas

seismic reflection characteristics of glacial and glacimarine sediment in the gulf of alaska and adjacent fjords abstract glaciation together with tectonism have been dominant factors affecting sedimentation in the gulf of alaska area from at least the late miocene throughout the quaternary the effects of tectonism are apparent in high mountains that border the gulf raised terraces of middleton island and the eastern gulf coastal zone and numerous active faults and related earthquakes glacial evidence includes magnificent glaciers and their onshore deposits spectacular fjords large sea valleys incised in the continental shelf submarine morainal ridges at mouths of bays and sea valleys and thick glacimarine sedimentary sequences diamicts that are exposed onshore and at the sea floor along the outer shelf seismic reflection profiling and sampling of the uppermost marine sedimentary sequences in the gulf of alaska and adjacent fjords and bays have allowed identification of three discrete glacially related stratigraphic units these units were delineated on the basis of seismic signature geometry physiographic location stratigraphic position and sedimentologic characteristics the oldest unit a quaternary diamict is portrayed on seismic profiles by irregular discontinuous reflections this unit probably includes till outwash and glacimarine sediment a geographically restricted unit one incorporating holocene end moraines at bay mouths and associated with some sea valleys consists of jumbled masses of discontinuous reflections and very irregular surface morphology the youngest unit a blanket of holocene sand to clayey silt prograding as a sediment wedge across the shelf contains nearly horizontal parallel reflections except where disrupted by mass movement although seismic reflection data alone cannot provide definitive proof of the presence of glacial sediment when combined with sea floor sampling seismic profiling is a powerful tool for determining the continuity of marine sedimentary units and relationships to past and modern glaciers

morphology of a submarine slide kitimat arm british columbia a digitally acquired scale corrected side scan sonar survey yielded high resolution imagery of a submarine landslide in british columbia the landslide in a fjord head setting at kitimat was last active in 1975 and created a wide area of deformed sea floor the sediment failure involved shallow rotational movements on the slopes of a fjord head delta marginal tearing translational sliding compressional folding and block gliding of fjord bottom marine clays the slide is shallow and elongate and appears to have been produced by failure in mobile low strength sediments

models of glaciomarine sedimentation and their application to the interpretation of ancient glacial sequences abstract this paper argues that glaciomarine environments can be regarded as special glacially influenced types of continental margin environments e g continental shelf slope rise and basin plain knowledge of the stratigraphic architecture and typical sedimentary sequences of non glacial margins is becoming well known but remains limited for those that have been glacially modified the principal influences on sedimentation in these environments relate to the glacial sediment input controlled by relief of basin margin glacier thermal regime and ice flow dynamics and depositional environments influence of traction currents substrate relief and proximity to nearby ice margins typical ranges of sedimentation rates can be established for glacially influenced continental margin environments and these may provide a framework for ancient sequences starvation of sediment supply to glacially influenced continental margins is common the nature of sub ice shelf sedimentation a model that has been applied to many ancient glacial sequences is critically reviewed the significance of such sedimentation in the rock record has probably been exaggerated because of oversimplistic interpretations of diamictite sequences existing process models of glaciomarine sedimentation derived from study of modern environments are sometimes difficult to employ in investigation of ancient sedimentary sequences because simple lithofacies criteria and typical vertical profiles are not available to aid in interpretation in addition compositional data emphasized by many workers for distinguishing glaciomarine from continental glacial diamict ite s frequently fingerprint sediment source and not mode of deposition the importance of facies analysis methods for isolating depositional environments is illustrated by three examples of ancient glaciomarine sequences these are the early proterozoic gowganda formation 2 3 ga of northern ontario canada the late proterozoic port askaig formation 670 ma of scotland and ireland and the late cenozoic yakataga formation 20 ma to recent of the gulf of alaska these examples illustrate the significance of detailed genetic studies of ancient glacial rocks in the interpretation of palaeogeographic and tectonic settings diamictite units in ancient glaciomarine sequences cannot be easily interpreted in terms of climatic or ice advance retreat cycles because of the varied controls on diamict accumulation and diamictite preservation in marine basins

imaging evidence for hubbard glacier advances and retreats since the last glacial maximum in yakutat and disenchantment bays alaska high resolution 2 d multichannel seismic data collected during the 2012 utig usgs national earthquake hazards reduction program survey of disenchantment and yakutat bays in southeast alaska provide insight into their glacial history these data show evidence of two unconformities appearing in the form of channels and are interpreted to be advance pathways for hubbard glacier the youngest observable channel thought to have culminated near the main phase of the little ice age lia is imaged in disenchantment bay and ends at a terminal moraine near blizhni point an older channel thought to be from an advance that culminated in the early phase of the lia extends from disenchantment bay into the northeastern edge of yakutat bay turning southward at knight island and terminating on the southeastern edge of yakutat bay our interpretation is that hubbard glacier has repeatedly advanced around the east side of yakutat bay in knight island channel possibly due to the presence of malaspina glacier cutting off access to central yakutat bay during times of mutual advance we observe two distinct erosional surfaces and retreat sequences of hubbard glacier in yakutat bay supporting the hypothesis that minor glacial advances in fjords do not erode all prior sediment accumulations interpretation of chaotic seismic facies between these two unconformities suggests that hubbard glacier exhibits rapid retreats and that disenchantment bay is subject to numerous episodes of outburst flooding and morainal bank collapse these findings also suggest that tidewater glaciers preferentially reoccupy the same channels in bay and marine settings during advances

a study of japanese landscapes using structure from motion derived dsms and dems based on historical aerial photographs new opportunities for vegetation monitoring and diachronic geomorphology abstract sfm mvs structure from motion and multiple view stereophotogrammetry is part of a series of technological progresses brought to the field of earth sciences during the last decade or so which has allowed geoscientists to collect unprecedented precise and extensive dsms digital surface model for virtually no cost rivaling lidar light detection and ranging technology previous work on sfm mvs in geosciences has been solely exploring data acquired for the purpose of sfm mvs but no research has been done in the exploration of photographic archives for geomorphological purposes therefore the present publications aims to present the usage of sfm mvs applied to historical aerial photographs in japan in order to 1 demonstrate the potentials to extract topographical and vegetation data and 2 to present the potential for chronological analysis of landscape evolution sfm mvs was implemented on black and white and colour aerial photographs of 1966 1976 1996 2006 and 2013 using the commercial software photoscanpro firstly the photographs were masked tied to gps points secondly the positions of the cameras and the 3d pointcloud were calculated and thirdly the 3d surface was created data were then exported in the gis software arcgis for analysis results also proved satisfactory for the reconstruction of 3d past geomorphological landscapes in coastal areas riverine areas and in hilly and volcanic areas they also prove that the height of trees and large vegetation features can also be calculated from aerial photographs alone diachronic analysis of the evolution in 3d landforms presented more difficulties because the resolution of the early photographs was lower than the recent ones volume and surface calculations should therefore be conducted carefully although the method holds merit and great promise in the exploration of active landscapes that have widely changed during the 20th century the authors have also reflected on the issues linked to large datasets mostly because the processing of these large datasets is still in need of improvement moreover there is no proof that an ever increasing resolution brings any major advance to the geomorphological paradigms

the deglacial transition on the southeastern alaska margin meltwater input sea level rise marine productivity and sedimentary anoxia 1 oxygen isotope data from planktonic and benthic foraminifera on a high resolution age model 44 14c dates spanning 17 400 years document deglacial environmental change on the southeast alaska margin 59 33 32 n 144 9 21 w 682 m water depth surface freshening i e 18o reduction of 0 8 began at 16 650 170 cal years b p during an interval of ice proximal sedimentation likely due to freshwater input from melting glaciers a sharp transition to laminated hemipelagic sediments constrains retreat of regional outlet glaciers onto land circa 14 790 380 cal years b p abrupt warming and or freshening of the surface ocean i e additional 18o reduction of 0 9 coincides with the bolling interstade of northern europe and greenland cooling and or higher salinities returned during the allerod interval coincident with the antarctic cold reversal and continue until 11 740 200 cal years b p when onset of warming coincides with the end of the younger dryas an abrupt 1 reduction in benthic 18o at 14 250 290 cal years b p likely reflects a decrease in bottom water salinity driven by deep mixing of glacial meltwater a regional megaflood event or brine formation associated with sea ice two laminated opal rich intervals record discrete episodes of high productivity during the last deglaciation these events precisely dated here at 14 790 380 to 12 990 190 cal years b p and 11 160 130 to 10 750 220 cal years b p likely correlate to similar features observed elsewhere on the margins of the north pacific and are coeval with episodes of rapid sea level rise remobilization of iron from newly inundated continental shelves may have helped to fuel these episodes of elevated primary productivity and sedimentary anoxia

volcano monitoring applications of the ozone monitoring instrument the ozone monitoring instrument omi is a satellite based ultraviolet uv spectrometer with unprecedented sensitivity to atmospheric sulphur dioxide so2 concentrations since late 2004 omi has provided a high quality so2 dataset with near continuous daily global coverage in this review we discuss the principal applications of this dataset to volcano monitoring 1 the detection and tracking of large eruption clouds primarily for aviation hazard mitigation and 2 the use of omi data for long term monitoring of volcanic degassing this latter application is relatively novel and despite showing some promise requires further study into a number of key uncertainties we discuss these uncertainties and illustrate their potential impact on volcano monitoring with omi through four new case studies we also discuss potential future avenues of research using omi data with a particular emphasis on the need for greater integration between various monitoring strategies instruments and datasets

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

inviscid behaviour of fines rich pyroclastic flows inferred from experiments on gas particle mixtures abstract experiments were carried out on granular flows generated by instantaneous release of gas fluidised bidisperse mixtures and propagating into a horizontal channel the mixture consists of fine 100 m particles of same density with corresponding grain size ratios of 2 to 9 initial fluidisation of the mixture destroys the interparticle frictional contacts and the flow behaviour then depends on the initial bed packing and on the timescale required to re establish strong frictional contacts at a fines mass fraction below that of optimal packing 40 the initial mixtures consist of a continuous network of coarse particles with fines in interstitial voids strong frictional contacts between the coarse particles are probably rapidly re established and the flows steadily decelerate some internal friction reduction appears to occur as and the grain size ratio increases possibly due to particle rolling and the lower roughness of internal shear surfaces segregation only occurs at large grain size ratio due to dynamical sieving with fines concentrated at the flow base in contrast at above that for optimal packing the initial mixtures consist of coarse particles embedded in a matrix of fines flow velocities and run outs are similar to that of the monodisperse fine end member thus showing that the coarse particles are transported passively within the matrix whatever their amount and grain size are these flows propagate at constant height and velocity as inviscid fluid gravity currents thus suggesting negligible interparticle friction we have determined a froude number of 2 61 0 08 consistent with the dam break model for fluid flows and with no significant variation as a function of the grain size ratio and the initial bed expansion very little segregation occurs which suggests low intensity particle interactions during flow propagation and that active fluidisation is not taking place strong frictional contacts are only re established in the final stages of emplacement and stop the flow motion we infer that fines rich i e matrix supported pyroclastic flows propagate as inviscid fluid gravity currents for most of their emplacement and this is consistent with some field data

multiple pleistocene ice advances into the skagerrak a detailed seismic stratigraphy from high resolution seismic profiles abstract a detailed pleistocene seismic stratigraphy is proposed for the skagerrak an over 700 m deep elongated depression in the northeastern north sea by comparing our high resolution seismic results with those from glacial environments of canada alaska and antarctica we conclude that at least during the weichselian if not also during the saalian a glacier grounded in the eastern skagerrak and advanced well into its western part as indicated by a thick layer of basal till the surging glacier truncated the basinal flank of a ridge like delta moraine that was presumably deposited under uniform glacial conditions in an ice distal environment the deposition of the hirtshals moraine in shallow waters of hirtshals might originate from a glacier that advanced from sweden into north jutland soon after the ice withdrawal from the skagerrak a layer of well stratified glaciomarine sediments was deposited over the basal till suggesting floating ice conditions in a fjord like environment due to the rising sea level in the late pleistocene fluvioglacial and shallow marine deposits soon dominated over the glaciomarine sediments indicating an end of glacial conditions in this region these post glacial sediments were first deposited in the western skagerrak but as the transgression came to an end in the mid holocene the depocenter shifted to the east today the highest sedimentation rates are found in this eastern part

coupled stratigraphic and structural evolution of a glaciated orogenic wedge offshore st elias orogen alaska 1 the st elias orogen is the result of 10 myr of oblique convergence and flat slab subduction in the gulf of alaska between north america and the yakutat microplate extensive glaciation and a complex tectonic environment make this region a unique case study in which to examine the details of terrane accretion and the possible coupled influence of climate and tectonic drivers on the structural and topographic evolution of an orogenic wedge reflection seismic profiles across the offshore pamplona zone fold thrust belt the frontal st elias orogenic wedge provide constraints for quantifying pleistocene deformation recorded in the glaciomarine yakataga formation the total amount of pleistocene shortening observed varies from 3 to 5 mm yr compared to the current gps derived yakutat north america convergence rate across the st elias orogen of 45 mm yr growth strata and kinematic fold analysis allow comparison of relative timing of fault activity which reveals temporal and spatial shifting of active deformation during the glacial period faulting localized adjacent to the coastline and at the current submarine deformation front the abandoned currently inactive region is colocated with the major glacial depocenter in the region the bering trough these observations imply that glacial processes such as sediment loading and focused erosion during advance retreat cycles has a direct effect on the evolution of individual faults within the pamplona zone and the overall deformation pattern in the offshore st elias margin this information provides key constraints for understanding how climatic shifts may have affected the evolution of margin architecture during pleistocene glacial interglacial periods

the broughton trough on the continental shelf of eastern baffin island northwest territories bathymetric and seismic surveys of the trough across the continental shelf of baffin island at broughton island indicate that there were four stages in its development the first involved deposition of cretaceous and early tertiary marine sediments before and during formation of a graben associated with the opening of baffin bay with the uplift of baffin island extensive deltaic deposits at the distal end of the trough were laid down in the second stage these deposits are thought to represent the products of a river system raised much above grade flowing in the trough and the fiords to the southwest and depositing in a sea with a relative level 300 400 m below present in the third stage during pliocene pleistocene glaciation the proximal regions of the trough were eroded to more than 700 m below present sea level lateral moraines indicate the extension of ice to the edge of the continental shelf although the relatively small amount of erosion in the distal region suggests that the ice may have be

a submarine landslide source for the devastating 1964 chenega tsunami southern alaska abstract during the 1964 great alaska earthquake m w 9 2 several fjords straits and bays throughout southern alaska experienced significant tsunami runup of localized but unexplained origin dangerous passage is a glacimarine fjord in western prince william sound which experienced a tsunami that devastated the village of chenega where 23 of 75 inhabitants were lost the highest relative loss of any community during the earthquake previous studies suggested the source of the devastating tsunami was either from a local submarine landslide of unknown origin or from coseismic tectonic displacement here we present new observations from high resolution multibeam bathymetry and seismic reflection surveys conducted in the waters adjacent to the village of chenega the seabed morphology and substrate architecture reveal a large submarine landslide complex in water depths of 120 360 m analysis of bathymetric change between 1957 and 2014 indicates the upper 20 50 m 0 7 km3 of glacimarine sediment was destabilized and evacuated from the steep face of a submerged moraine and an adjacent 21 km2 perched sedimentary basin once mobilized landslide debris poured over the steep 130 m high face of a deeper moraine and then blanketed the terminal basin 465 m water depth in 11 5 m of sediment these results combined with inverse tsunami travel time modeling suggest that earthquake triggered submarine landslides generated the tsunami that struck the village of chenega roughly 4 min after shaking began unlike other tsunamigenic landslides observed in and around prince william sound in 1964 the failures in dangerous passage are not linked to an active submarine delta the requisite environmental conditions needed to generate large submarine landslides in glacimarine fjords around the world may be more common than previously thought

experiments on deaerating granular flows and implications for pyroclastic flow mobility 1 granular flows were generated by the release of beds of particles in various fluidized states which then deaerated in a horizontal channel we describe characteristics of the flows and their deposits morphological similarities between deposits in experiments and in the field suggest that pyroclastic flow deposits form from a fluidized mixture the experiments show that slightly expanded fluidized flows are more mobile than non fluidized flows of equivalent volume and material composition they travel to a fixed distance from their source which depends only weakly on their initial degree of fluidization flows of fine particles 100 m deaerate slowly and are highly mobile pyroclastic flows commonly have large amounts of fine ash which may have a controlling influence on their high mobility

dam break wave front celerity this work is concerned with the role that friction and inertia effects can play on the magnitude of dam break wave front celerity classic analytical solutions are presented a large collection of experimental data is used covering a wide range of different initial conditions fixed bed or mobile bed five types of bed material dry or wet bed downstream and with or without bed step to overcome the limitations of analytical solutions a numerical model is used the model is based on the shallow water approach with contact load dominated sediment transport and it makes use of developments recently made in the study of sheet flows the analytical and numerical results are compared with experimental data it was found that the celerity is mainly dictated by the friction coefficient by the sediment inertia by the initial downstream water depth and by the initial bed step height for good data fitting the friction coefficient must be influenced by the type of bed fixed or mobile in the latter the coefficient must vary with the bed material characteristics the dissimilarities between the experimental analytical and numerical results are interpreted

straightforward reconstruction of 3d surfaces and topography with a camera accuracy and geoscience application topographic measurements for detailed studies of processes such as erosion or mass movement are usually acquired by expensive laser scanners or rigorous photogrammetry here we test and use an alternative technique based on freely available computer vision software which allows general geoscientists to easily create accurate 3d models from field photographs taken with a consumer grade camera the approach integrates structure from motion sfm and multi view stereo mvs algorithms and in contrast to traditional photogrammetry techniques it requires little expertise and few control measurements and processing is automated to assess the precision of the results we compare sfm mvs models spanning spatial scales of centimeters a hand sample to kilometers the summit craters of piton de la fournaise volcano with data acquired from laser scanning and formal close range photogrammetry the relative precision ratio achieved by sfm mvs measurement precision observation distance is limited by the straightforward camera calibration model used in the software but generally exceeds 1 1000 i e centimeter level precision over measurement distances of 10s of meters we apply sfm mvs at an intermediate scale to determine erosion rates along a 50 m long coastal cliff seven surveys carried out over a year indicate an average retreat rate of 0 70 0 05 m a 1 sequential erosion maps at 0 05 m grid resolution highlight the spatio temporal variability in the retreat with semivariogram analysis indicating a correlation between volume loss and length scale compared with a laser scanner survey of the same site sfm mvs produced comparable data and reduced data collection time by 80

quaternary sedimentation in shelikof strait alaska abstract shelikof strait a nearly parallel sided marine channel between the kodiak island group and the alaska penninsula has experienced a succession of distinct sedimentary environments during quaternary time pleistocene glaciers carved a deep basin into bedrock in the southwest part of the strait and a shallower platform surface with incised channels in the northeast the basin and channels were filled with glacial and glacialmarine sediment before and during the time that ice retreated and oceanic conditions returned restricted marine conditions prevailed in early holocene time and sediment prograded transversely into the strait from the adjacent landmasses with some localized dispersal to the deep central strait onset of modern open marine conditions commenced when regional currents breached the sill across kennedy and stevenson entrances to combine with sediment laden outflow from cook inlet and deposit a blanket of well stratified sediment throughout the strait

extent and timing of the last glacial maximum in southwestern alaska a glacier complex composed of confluent alpine glaciers island ice caps and piedmont lobes covered much of the alaska peninsula and kodiak island during the last glacial maximum lgm because this glacier complex formed the southeastern border of beringia its dynamics may have been important in the timing and feasibility of the northwest coast route for human migration into lower latitude north america radiocarbon dates from stratigraphic sections on kodiak island and in the bristol bay lowlands bracket the lgm in southwestern alaska between 23 000 and 14 700 yr b p reconstruction of ice thickness based on glacier trimlines moraines and calculations of basal shear stress depict the alaska peninsula glacier complex flowing to the outer edge of the continental shelf in the gulf of alaska equilibrium line altitudes elas were 300 to 700 m lower than today and approached sea level on the southwestern alaska peninsula in northeastern areas where elas were higher bedrock topography largely controlled ice flow except where ice saddles bridged straits and inlets

holocene history of hubbard glacier in yakutat bay and russell fiord southern alaska stratigraphic and geomorphic data defined by radiocarbon ages tree ring dates and historical observations provide evidence of three major holocene expansions of hubbard glacier early in each advance the hubbard glacier margin blocked russell fiord to create russell lake raising base level and causing stream beds and fan deltas throughout the russell drainage basin to aggrade each hubbard glacier expansion continued with an ice lobe advancing through disenchantment and yakutat bays in the west and an eastern lobe advancing into russell fiord the earlier two holocene expansions were respectively under way at 7690 and 5600 calibrated yr b p and each advance culminated more than 1 k y later the late holocene advance was under way by 3100 yr ago and reached 13 km farther south in russell fiord than the preceding two expansions late holocene deglaciation of yakutat and disenchantment bays was complete before a d 1791 nunatak glacier flowing from neves east of russell fiord became the primary ice source to the russell fiord lobe at or before this date ice retreat from the southern end of russell fiord began in the late eighteenth century and the penultimate russell lake drained ca a d 1860 the relatively slow advances and more rapid retreats of hubbard glacier are consistent with the model of the iceberg calving glacier cycle hubbard glacier is currently advancing and will likely reestablish russell lake in the near future affecting local fisheries however glacier lobes are unlikely to reach the area of the town of yakutat built on late holocene glacial deposits in the next 1 k y