elevation changes of ice caps in the canadian arctic archipelago 1 precise repeat airborne laser surveys were conducted over the major ice caps in the canadian arctic archipelago in the spring of 1995 and 2000 in order to measure elevation changes in the region our measurements reveal thinning at lower elevations below 1600 m on most of the ice caps and glaciers but either very little change or thickening at higher elevations in the ice cap accumulation zones recent increases in precipitation in the area can account for the slight thickening where it was observed but not for the thinning at lower elevations for the northern ice caps on the queen elizabeth islands thinning was generally 0 5 m yr 1 which is consistent with what would be expected from the warm temperature anomalies in the region for the 5 year period between surveys and appears to be a continuation of a trend that began in the mid 1980s farther south however on the barnes and penny ice caps on baffin island this thinning was much more pronounced at over 1 m yr 1 in the lower elevations here temperature anomalies were very small and the thinning at low elevations far exceeds any associated enhanced ablation the observations on barnes and perhaps penny are consistent with the idea that the observed thinning is part of a much longer term deglaciation as has been previously suggested for barnes ice cap on the basis of the regional relationships between elevation and elevation change in our data the 1995 2000 mass balance for the archipelago is estimated to be 25 km3 yr 1 of ice which corresponds to a sea level increase of 0 064 mm yr 1 this places it among the more significant sources of eustatic sea level rise though not as substantial as the greenland ice sheet alaskan glaciers or the patagonian ice fields

age and petrology of alkalic postshield and rejuvenated stage lava from kauai hawaii at the top of the waimea canyon basalt on the island of kauai rare flows of alkalic postshield stage hawaiite and mugearite overlie tholeiitic flows of the shield stage these postshield stage flows are 3 92 ma and provide a younger limit for the age of the tholeiitic shield stage the younger koloa volcanics consist of widespread alkalic rejuvenated stage flows and vents of alkalic basalt basanite nephelinite and nepheline melilitite that erupted between 3 65 and 0 52 ma all the flows older than 1 7 ma occur in the west northwestern half of the island and all the flows younger than 1 5 ma occur in the east southeastern half the lithologies have no spatial or chronological pattern the flows of the koloa volcanics are near primary magmas generated by variable small degrees of partial melting of a compositionally heterogeneous garnet bearing source that has about two thirds the concentration of p2o5 rare earth elements and sr of the source of the honolulu volcanics on the island of oahu the same lithology in the koloa and honolulu volcanics is generated by similar degrees of partial melting of distinct source compositions the lavas of the koloa volcanics can be generated by as little as 3 percent to as much as 17 percent partial melting for nepheline melilitite through alkalic basalt respectively phases that remain in the residue of the honolulu volcanics such as rutile and phlogopite are exhausted during formation of the koloa volcanics at all but the smallest degrees of partial melting the mantle source for kauai lava becomes systematically more depleted in 87sr 86sr as the volcano evolves from the tholeiitic shield stage to the alkalic postshield stage to the alkalic rejuvenated stage at the same time the lavas become systematically more enriched in incompatible trace elements on a shorter timescale the lavas of the koloa volcanics display the same compositional trends but at a lower rate of change the source characteristics of the koloa volcanics considered along with those of the honolulu volcanics support a mixing model in which the source of rejuvenated stage lava represents large percent melts of a plume source mixed with small amounts of small percent melts of a heterogeneous mid ocean ridge source

early growth of kohala volcano and formation of long hawaiian rift zones transitional composition pillow basalts from the toe of the hilo ridge collected from outcrop by submersible have yielded the oldest ages known from the island of hawaii 1138 34 to 1159 33 ka hilo ridge has long been interpreted as a submarine rift zone of mauna kea but the new ages validate proposals that it is the distal east rift zone of kohala the oldest subaerial volcano on the island these ages constrain the inception of tholeiitic volcanism at kohala provide the first measured duration of tholeiitic shield building 870 k y for any hawaiian volcano and show that this 125 km long rift zone developed to near total length during early growth of kohala long eastern trending rift zones of hawaiian volcanoes may follow fractures in oceanic crust activated by arching of the hawaiian swell in front of the propagating hotspot

surface elevation change and mass balance of icelandic ice caps derived from swath mode cryosat 2 altimetry we apply swath processing to cryosat 2 interferometric mode data acquired over the icelandic ice caps to generate maps of rates of surface elevation change at 0 5 km postings this high resolution mapping reveals complex surface elevation changes in the region related to climate ice dynamics and subglacial geothermal and magmatic processes we estimate rates of volume and mass change independently for the six major icelandic ice caps 90 of iceland s permanent ice cover for five glaciological years between october 2010 and september 2015 annual mass balance is highly variable during the 2014 2015 glaciological year the vatnajokull ice cap 70 of the glaciated area experienced positive mass balance for the first time since 1992 1993 our results indicate that between glaciological years 2010 2011and 2014 2015 icelandic ice caps have lost 5 8 0 7 gt a 1 on average 40 less than the preceding 15 years contributing 0 016 0 002 mm a 1 to sea level rise

seismic velocity model of the central united states version 1 description and simulation of the 18 april 2008 mt carmel illinois earthquake abstract we have developed a new three dimensional seismic velocity model of the central united states cusvm that includes the new madrid seismic zone nmsz and covers parts of arkansas mississippi alabama illinois missouri kentucky and tennessee the model represents a compilation of decades of crustal research consisting of seismic aeromagnetic and gravity profiles geologic mapping geophysical and geological borehole logs and inversions of the regional seismic properties the density p and s wave velocities are synthesized in a stand alone spatial database that can be queried to generate the required input for numerical seismic wave propagation simulations we test and calibrate the cusvm by simulating ground motions of the 18 april 2008 m w 5 4 mt carmel illinois earthquake and comparing the results with observed records within the model area the selected stations in the comparisons reflect different geological site conditions and cover distances ranging from 10 to 430 km from the epicenter the results based on a qualitative and quantitative goodness of fit gof characterization indicate that both within and outside the mississippi embayment the cusvm reasonably reproduces 1 the body and surface wave arrival times and 2 the observed regional variations in ground motion amplitude cumulative energy duration and frequency content up to a frequency of 1 0 hz in addition we discuss the probable structural causes for the ground motion patterns in the central united states that we observed in the recorded motions of the 18 april mt carmel earthquake online material simulated and observed waveforms and response spectral acceleration ground motion prediction equation comparison

giant blocks in the south kona landslide hawaii a large field of blocky sea floor hills up to 10 km long and 500 m high are gigantic slide blocks derived from the west flank of mauna loa volcano on the island of hawaii these megablocks are embedded in the toe of the south kona landslide which extends 80 km seaward from the present coastline to depths of nearly 5 km a 10 15 km wide belt of numerous smaller 1 3 km long slide blocks separates the area of giant blocks from two submarine benches at depths of 2600 and 3700 m depth that terminate seaward 20 to 30 km from the shoreline similar giant blocks are found on several other major submarine hawaiian landslides including those north of oahu and molokai but the south kona blocks are the first to be examined in detail using high resolution bathymetry dredging and submersible diving dredging of two of the giant blocks brought up pillowed tholeiitic lava observations from the u s navy submersible sea cliff on the asymmetrically steep eastern flank of one block 10 km long and 300 m high revealed a succession of fractured massive basalt laminar lava flows hyaloclastite and pillow lavas chemical analyses of dredged lava identified 19 units that overlap compositionally with lavas from the south rift zone ridge of mauna loa sulfur content indicates that most of the lavas were erupted in subaerial and shallow submarine

mass balance of devon ice cap canadian arctic interferometric synthetic aperture radar data show that devon ice cap dic northern canada is drained through a network of 11 glacier systems more than half of all ice discharge is through broad flows that converge to the southeast of the ice cap and these are grounded well below sea level at their termini a calculation of the ice cap mass budget reveals that the northwestern sector of dic is gaining mass and that all other sectors are losing mass we estimate that a 12 489 km 2 section of the main ice cap receives 3 46 0 65 gt of snowfall each year and loses 3 11 0 21 gt of water through runoff and 1 43 0 03 gt of ice through glacier discharge altogether the net mass balance of dic is 1 08 0 67 gt a 1 this loss corresponds to a 0 003 mm a 1 contribution to global sea levels and is about half the magnitude of earlier estimates

a geochemical comparison of manganese oxide deposits of the hawaiian archipelago and the deep sea data are presented on the composition of manganese crusts collected within the hawaiian exclusive economic zone heez these crusts were obtained in 80 of the dredge hauls between 800 and 3000 m although the chemistries of crusts on the cenozoic hawaiian ridge and an older cretaceous seamounts south and north of the ridge are quite similar there are marked differences both in composition and in mineralogical organization between shallow and deep crusts shallow crusts 1500 m are composed of five distinct phases i e silicate apatite iron oxide manganese oxide and non associated copper whereas the deep crusts display no obvious inter elemental organization based on dendrograms the mean composition of heez crusts differs from that of eastern tropical pacific nodules in that crusts are comparatively rich in as pb co ce fe and ti whereas nodules have comparatively more cu ni and sr compositional differences between shallow crusts and nodules are discussed in terms of 1 element source 2 mn oxide mineralogy and 3 redox conditions in the adjacent seawater it is concluded that the major differences between crust and nodules is due to metal sources water column for crusts sediments for nodules advective processes within the o2 minimum also affect the heez crusts

impact of earthquake induced liquefaction and related ground failure on a mississippian archeological site in the new madrid seismic zone central usa an investigation of earthquake induced liquefaction features and related ground failure at the east archeological site 3po610 located near the southern end of the new madrid seismic zone was crucial to the identification of cultural features and horizons and interpretation of archeological data through the examination of stratigraphic and structural relations in the archeological excavation as well as in three nearby trenches it was determined that cultural horizons and features including the floor of a sweat lodge are tilted displaced downward and buried by a vented sand deposit known as a sand blow this sand blow is up to 1 m thick and is composed of four major depositional units suggesting that it formed during a sequence of large earthquakes the compound sand blow directly overlies cultural horizons and features indicating that the earthquakes occurred near the end of or soon after occupation on the basis of radiocarbon dating of samples collected above and below the sand blow the earthquakes are estimated to have occurred between a d 1300 and 1670 a new madrid earthquake sequence ca a d 1450 150 was the probable cause of liquefaction and ground failure at the site and may have led to cultural abandonment of the site ironically the earthquakes that may have led to abandonment of the site also helped to preserve it for posterity

liquefaction related ground failure a case study in the new madrid seismic zone central united states large curvilinear sand blows resulting from earthquake induced liquefaction commonly occur along the margins of fine grained channel fill deposits in the st francis basin of the new madrid seismic zone one such example identified on aerial photographs and satellite images was studied in detail by examining relations of sedimentary deposits and liquefaction features in the field and by compiling borehole data previously collected by the army corps of engineers ground failure in this example included liquefaction of subsurface sandy deposits development of en echelon fissures in the overlying channel fill deposit forceful venting of sandbearing water to the ground surface resulting in the formation of sand dikes and sand blows and differential ground subsidence across the sand dikes a combination of mechanisms including the development of a water rich zone below the clayey surficial deposits may have contributed to the failure at the study site located in southeastern missouri the near surface sedimentary geology can be described as a two layered system with a sandy channel deposit below and a less permeable clayey overbank deposit above the contact between the two layers is roughly horizontal except where embedded by a channel fill deposit the basal contact of the channel fill deposit is inclined along its margin and extends below the base of the overbank deposits sand blows are abundant in the overbank deposits which are about 6 m thick in contrast sand blows rarely occur within the 18 m thick channel fill deposit except along its margin here feeder dikes of the sand blows are concentrated within 15 m of and arranged in an en echelon pattern subparallel to the margins of the channel fill deposit on the side of the feeder dikes toward the edge of the channel fill deposit the ground surface is displaced downward as much as 1 2 m large ground displacements often pose the greatest threat to the integrity of engineered structures as demonstrated in this case study the spatial relations of sedimentary deposits as well as their permeability and thickness appear to influence both the location and mode of ground failure a better understanding of factors contributing to liquefaction related ground failures can help to identify sites that may be prone to large ground displacements and thus to mitigate the hazard posed by earthquakes in this region

sedimentary features influencing the occurrence and spatial variability of seismites late messinian gargano promontory southern italy abstract seventeen layers characterized by soft sediment deformation structures ssds were identified within the calcari di fiumicello an upper messinian miocene stratigraphic unit 30 m thick cropping out in the northern sector of the gargano promontory apulia southern italy facies analysis was performed on the whole outcrop and detailed sedimentological investigations were carried out on the deformed beds in order to interpret the deformation mechanism the driving mechanism and the possible trigger agent deformed layers occur in some thin bedded ooidal limestones skeletal calcarenite as well as in some pebble size conglomerate alternated with marls deposited in a protected embayment or barrier island lagoon system possibly characterized by high salinity and tidal influx ssds can be classified as load and slump slide structures the continuous exposures allow us to follow a single deformed layer along tens of meters hence several types of lateral variations were observed that can be summarised as follows 1 ssds disappear within a few meters with a decreasing pattern of their deformation or in an abrupt way 2 deformed layers laterally change in thickness and morphology and 3 a single deformed bed can laterally correspond to two deformed beds most of the soft sediment deformation features were identified as liquefaction and or fluidization features related to seismic shocks seismites seismites are often used as an indicator of seismic events especially along small outcrops trench excavation and core analysis this study highlights the value of the sedimentological analysis for paleoseismic investigations with the aim of improving criteria for identifying seismites in the sedimentary record and their suitability as marker of seismic events

perspectives on the production of a glacier inventory from multispectral satellite data in arctic canada cumberland peninsula baffin island the consequences of global warming on land ice masses are difficult to assess in detail as two dimensional glacier inventory data are still missing for many remote regions of the world as the largest future temperature increase is expected to occur at high latitudes the glaciers and ice caps in the arctic will be particularly susceptible to the expected warming this study demonstrates the possibilities of space borne glacier inventorying at a remote site on cumberland peninsula a part of baffin island in arctic canada thereby providing glacier inventory data for this region our approach combines landsat etm and terra aster satellite data an aster derived digital elevation model dem and geographic information system based processing we used thresholded ratio images from etm bands 3 and 5 and aster bands 3 and 4 for glacier mapping manual delineation of little ice age trimlines and moraines has been applied to calculate area changes for 225 glaciers yielding an average area loss of 11 a size distribution has been obtained for 770 glaciers that is very different from that for alpine glaciers numerous three dimensional glacier parameters were derived from the aster dem for a subset of 340 glaciers the amount of working time required for the processing has been tracked and resulted in 5 min per glacier or 7 years for all estimated 160 000 glaciers worldwide

elevation change of the antarctic ice sheet 1995 2000 from ers 2 satellite radar altimetry we analyzed antarctic ice sheet elevation change dh dt from 1995 to 2000 using 123 million elevation change measurements from european remote sensing 2 ice mode satellite radar altimeter data covering an area of about 7 2 million km sup 2 almost all drainage basins in east antarctica had average dh dt values within spl plusmn 3 0 cm year whereas drainage basins in west antarctica had substantial spatial variability with average dh dt values ranging between 11 to 12 cm year the east antarctic ice sheet had a five year trend of 1 spl plusmn 0 6 cm year where 13 out of the 14 basins had either a positive trend or a trend that was not significantly different than zero the west antarctic ice sheet had a five year trend of 3 6 spl plusmn 1 0 cm year due largely to strong negative trends of around 10 cm year for basins in marie byrd land along the pacific sector of the antarctic coast the continent as a whole had a five year dh dt trend of 0 4 spl plusmn 0 4 cm year finally time series constructed for the pine island thwaites de vicq and land glaciers in west antarctic showed five year dh dt trends from 26 to 135 cm year that were significantly more negative than the average dh dt trends in their respective basins the strongly negative dh dt values for these coastal glacier outlets are consistent with recently reported results indicating increased basal melting at these glaciers grounding lines caused by ocean thermal forcing

ice elevations and surface change on the malaspina glacier alaska 1 here we use ice cloud and land elevation satellite icesat derived elevations and surface characteristics to investigate the malaspina glacier of southern alaska although there is significant elevation variability between icesat tracks on this glacier we were able to discern general patterns in surface elevation change by using a regional digital elevation model dem as a reference surface specifically we report elevation differences between icesat laser 1 3 observations february 2003 november 2004 and a shuttle radar topography mission srtm derived dem from february 2000 elevation decreases of up to 20 25 m over a 3 4 year time period were observed across the folded loop moraine on the southern portion of the malaspina glacier

impact of the alluvial style on the geoarcheology of stream valleys abstract the extensive archeological record within river valleys provides an environment long favored for study by the archeologic community this record of human occupation varies with the alluvial style of the river resulting in each river valley having a unique archeological record controlled by three factors location of occupation sites preservation of those sites and recognition of the sites if problems of site preservation and recognition in a river valley can be recognized and addressed a better insight into settlement patterns and complex human environment interactions can result this study represents a synthesis of extensive published and secondary data sets pertaining to archaeology and alluvial geomorphology of the lower missouri red and mississippi rivers to examine the relationship of prehistoric site distribution with fluvial geomorphology the archeologic data are from published literature and government agencies the geomorphic data are from a variety of published and unpublished investigations including maps of alluvial geomorphology digital elevation models aerial photographs and topographic maps the data were input into spreadsheets and a gis for qualitative and quantitative analysis prehistoric human occupation of the narrow missouri valley floor is limited with only 0 061 recorded sites km2 additional sites are likely buried by thick vertical accretion sediment on the limited prehistoric portions of the floodplain and within alluvial colluvial fans along the valley margin non random preservation patterns such as the absence of sites from the youngest cultural period are attributed to shifts in settlement patterns in comparison to the lower missouri river valley prehistoric occupation of the lower red and mississippi rivers was much more extensive and the density of occupation was 0 274 sites km2 and 0 277 sites km2 respectively significant differences do exist in the age of sites and their relationship to different floodplain depositional environments many sites along the active meander belt of the red river were likely lost due to high rates of channel migration nevertheless intense occupation of paleo indian through caddoan groups assures that many significant sites have been preserved the wide valley and high rates of sedimentation suggest that many sites are likely buried particularly along natural levees flanking an older meander belt recorded sites are also present along streams that incise the terrace along the terrace margin and along small channels that cross the backswamp the spatial and temporal site distribution along the lower mississippi valley is distinct in comparison with the red river because the mississippi valley is wider the terraces are younger and less dissected and the floodplain has more relief and is not broadly inundated by floodwater with relatively low sediment concentrations most of the significant archaic through mississippian period floodplain sites are located along the surfaces of abandoned mississippi and distributary meander belts which aggraded above the adjacent backswamp and have rarely been influenced by flood sedimentation since abandonment abundant paleo indian through mississippian period sites are also widely distributed across undissected terraces only a few significant mississippian sites are present along the active meander belt and in the backswamp where flooding was common in comparison with the red river the archaeological record of the floodplain is less likely to be influenced by burial or erosion due to the mississippi river having lower rates of overbank sedimentation and channel migration respectively the variable alluvial styles of the lower missouri river lower red river and the lower mississippi river valleys presented varying opportunities and constraints to occupation and sustained settlement and resulted in widely varying archaeological patterns that are partly dependent upon the alluvial geomorphology

rapid intraplate strain accumulation in the new madrid seismic zone remeasurement of a triangulation network in the southern part of the new madrid seismic zone with the global positioning system has revealed rapid crustal strain accumulation since the 1950s this area experienced three large moment magnitudes 8 earthquakes in 1811 to 1812 the orientation and sense of shear is consistent with right lateral strike slip motion along a northeast trending fault zone as indicated by current seismicity detection of crustal strain accumulation may be a useful discriminant for identifying areas where potentially damaging intraplate earthquakes may occur despite the absence of large earthquakes during historic time

age determinations and growth rates of pacific ferromanganese deposits using strontium isotopes abstract 87 sr 86 sr ratios trace element and ree compositions and textural characteristics were determined for three hydrogenetic fe mn crusts one hydrothermal deposit and two mixed hydrothermalhydrogenetic crusts from the pacific the sr isotope data are compared to the sr seawater curve for the cenozoic to determine the ages and growth rates of the crusts the 87 sr 86 sr in the crusts does not increase monotonically with depth as expected if the sr were solely derived from seawater and perfectly preserved since deposition this indicates post depositional exchange of sr or heterogeneous sources for the sr originally contained in the crusts textures of hydrogenetic crusts generally correlate with sr isotopic variations the highest porosity intervals commonly exhibit the highest 87 sr 86 sr ratios indicating exchange with younger seawater intervals with the lowest porosity commonly have lower 87 sr 86 sr and may preserve the original sr isotopic ratios minimum ages of crust growth inception were calculated from dense low porosity intervals growth of the hydrogenetic crusts began at or after 23 ma although their substrates are cretaceous estimated average growth rates of the three hydrogenetic crusts vary between 0 9 and 2 7 mm ma consistent with published rates determined by other techniques within the marshall islands crust growth rates for individual layers varied greatly between 1 0 and 5 4 mm ma for one crust very low 87 sr 86 sr ratios occurred in detrital rich intervals hydrothermal fe mn oxide from the active lau basin back arc spreading axis valu fa ridge has an 87 sr 86 sr ratio with a predominantly seawater signature 87 sr 86 sr 0 709196 indicating a maximum age of 0 9 ma one crust from an off axis seamount west of gorda ridge may have begun precipitating hydrogenetically at 0 5 ma 0 709211 and had increasing hydrothermal or volcanic input in the top half of the crust indicated by a significantly lower 87 sr 86 sr ratio 0 709052

form and flow of the devon island ice cap canadian arctic 1 in this study 3370 km of 100 mhz ice penetrating radar data were acquired from devon ice cap arctic canada bed returns were obtained from 90 of flight tracks mean crossing point errors in ice surface elevation and ice thickness were 7 8 m digital elevation models of ice cap surface and bed elevation and ice thickness were produced and can be used as boundary conditions in numerical modeling devon ice cap including 1960 km2 of contiguous stagnant ice to its west is 14 010 km2 the ice cap proper is 12 050 km2 its largest drainage basin is 2630 km2 the ice cap crest has a maximum measured elevation of 1921 m maximum recorded ice thickness is 880 m ice cap volume is 3980 km3 about 10 mm sea level equivalent the bed 8 of which lies below sea level is an upland plateau dissected by steep sided valleys that control the locations of the major outlet glaciers which dominate ice cap drainage about 73 km 4 of the ice cap margin ends in tidewater the margin is not floating icebergs of 100 m were observed offshore only a single outlet glacier showed signs of past surge activity all major outlet glaciers along the eastern ice cap margin have retreated 1 3 km since 1960 synthetic aperture radar interferometic velocity structure shows slow undifferentiated flow predominating in the west and center with fast flowing outlet glaciers and intervening slow flowing ridges typical elsewhere outlet glacier velocities are 7 10 times higher than in areas of undifferentiated flow this velocity structure of fast flowing units within slower flowing ice appears typical of many large 103 km2 arctic ice caps

is the high elevation region of devon ice cap thickening devon ice cap nunavut canada has been losing mass since at least 1960 laser altimetry surveys however suggest that the high elevation region 1200m of the ice cap thickened between 1995 and 2000 perhaps because of anomalously high accumulation rates during this period we derive an independent estimate of thickness change in this region by comparing 40 year mean annual net accumulation rates to mean specific outflow rates for 11 drainage basins the area averaged rate of thickness change across the whole region is within error of zero 0 01 0 12m w e a 1 but two drainage basins in the northwest are thickening significantly and two basins in the south are thinning significantly the laser altimetry observations are biased towards the drainage basins where we find thickening recent changes in the rate of accumulation or the rate of firnification cannot explain the observed thickening but decreased ice outflow due to the penetration of neoglacial cooling to and subsequent stiffening of the basal ice may provide an explanation thinning in the south may result from increased ice outflow from basins in which fast flow and basal sliding extend above 1200 m

fine resolution radar altimeter measurements on land and sea ice satellite radar altimeter ra measurements are important for continued monitoring of rapidly changing polar regions in 2010 the european space agency launched cryosat 2 carrying siral a ku band ra with objectives of determining the thickness and extent of sea ice and the topography of the ice sheets one difficulty with ku band radar surveys over snow and ice is unknown penetration of ra signal into snow cover improving our understanding of the interactions of ra signals with snow and ice is needed to produce accurate elevation products to this end we developed a low power ultrawideband 12 18 ghz ra for airborne surveys to provide fine resolution measurements capable of detecting both scattering from the surface and layers within sea ice and ice sheets these measurements provide a means of identifying the dominant scattering location of lower resolution ra measurements comparable to satellite based instruments we generated two products a full bandwidth waveform fbw to identify scattering targets at fine resolution and a reduced bandwidth waveform rbw to represent conventional ra measurements retrackers are used to generate height estimates over various surface conditions for comparisons over ice sheets the leading edge tracker provided consistent ice surface elevation measurements between the fbw and rbw results however there were significant differences between the results from the centroid tracker over sea ice the location of the dominant return between the results from snow covered sea ice is highly variable this paper provides an overview of ra surveys in polar regions a description of the cresis system and a discussion of the results

earthquake imprints on a lacustrine deltaic system the kurk delta along the east anatolian fault turkey deltas contain sedimentary records that are not only indicative of water level changes but also particularly sensitive to earthquake shaking typically resulting in soft sediment deformation structures the kurk lacustrine delta lies at the south western extremity of lake hazar in eastern turkey and is adjacent to the seismogenic east anatolian fault which has generated earthquakes of magnitude 7 this paper reevaluates water level changes and earthquake shaking that have affected the kurk delta combining geophysical data seismic reflection profiles and side scan sonar remote sensing images historical data onland outcrops and offshore coring the history of water level changes provides a temporal framework for the depositional record in addition to the common soft sediment deformation documented previously onland outcrops reveal a record of deformation fracturing tilt and clastic dykes linked to large earthquake induced liquefactions and lateral spreading the recurrent liquefaction structures can be used to obtain a palaeoseismological record five event horizons were identified that could be linked to historical earthquakes occurring in the last 1000 years along the east anatolian fault sedimentary cores sampling the most recent subaqueous sedimentation revealed the occurrence of another type of earthquake indicator based on radionuclide dating 137cs and 210pb two major sedimentary events were attributed to the ad 1874 1875 east anatolian fault earthquake sequence their sedimentological characteristics were determined by x ray imagery x ray diffraction loss on ignition grain size distribution and geophysical measurements the events are interpreted to be hyperpycnal deposits linked to post seismic sediment reworking of earthquake triggered landslides this article is protected by copyright all rights reserved

erratic continental rocks on volcanic seamounts off the us west coast sampling of volcanic seamounts with dredges and the remotely operated vehicle tiburon recovered erratic rocks in surprising abundance as far as 500km offshore of the us west coast the erratics usually have continental lithologies and appear to have been weathered in nearshore environments they are probably transported by kelp holdfasts drift logs and pinnipeds to the seamounts where they accumulate over time the erratics are concentrated as lag deposits and kept from becoming buried in sediment by currents that sweep the seamounts the erratics often have thinner manganese oxide crusts than rocks of the seamounts because they were delivered to the seafloor more recently and manganese oxide crusts precipitate over time the thinner crusts make erratics easier to collect while most of the erratics clearly did not originate by the volcanic processes that formed the seamounts careful evaluation of some is necessary to distinguish them as erratics failure to recognize the presence of erratics may result in unrealistically complex interpretations of regional geology

late holocene liquefaction at sites of contemporary liquefaction during the 2010 2011 canterbury earthquake sequence new zealand abstract the 2010 2011 canterbury earthquake sequence ces caused up to 10 episodes of liquefaction at highly susceptible sites in eastern canterbury resulting in severe damage to land and infrastructure subsurface investigations at five sites over two study areas revealed ces dikes and sills that align with and crosscut pre ces liquefaction features including dikes a lateral sill a sandblister and a buried compound sandblow crosscutting relationships combined with carbon 14 14 c dating constrain the timing of the pre ces liquefaction features to likely post a d 1321 and pre 1960 in one study area pre ces features in the second study area likely formed in three distinct episodes post a d 1458 and possibly during the 1901 cheviot earthquake between a d 1297 and 1901 and pre a d 1458 the liquefaction potential of known active faults within the wider canterbury region are evaluated from back calculated magnitude bound curves and peak ground acceleration pga approximated using a new zealand specific ground motion prediction equation and compared with global liquefaction triggering thresholds analysis indicates that many active faults within north canterbury and offshore that are within 50 km of the study sites and capable of triggering m w 6 5 earthquakes have the potential to cause widespread liquefaction ruptures of these faults may have formed the pre ces liquefaction features combining the backcalculation approach with the modeled pga proves effective in determining the active faults capable of triggering liquefaction at the study sites and are therefore capable of triggering liquefaction in the future online material overview and further discussion of the probabilistic magnitude bound methodology framework and derivative curves description of sediment units and table of peak ground acceleration pga

envisat radar altimeter measurements over continental surfaces and ice caps using the ice 2 retracking algorithm abstract this study presents the first results obtained with the envisat satellite radar altimeter ra 2 over lands and ice caps as radar altimetry was firstly devoted to ocean study this paper starts with a detailed description of the radar altimetry principle over continental surfaces a general formulation of the radar altimeter echoes according to different surface types is given and the retracking procedure ice 2 specially implemented on the envisat satellite ground segment to provide output parameters over continents is clearly presented the envisat ra 2 datasets processed with the ice 2 procedure are then mapped given an overall description of the output parameters over various surfaces the behaviour of these envisat altimetric parameters are analysed and related to main land surface characteristics such as surface volume echo specularity roughness apart from few unexpected signals which will need to be further investigated the new envisat dataset confirms the potential of inland altimetry and provides a new opportunity to monitor continental surfaces the ku band measurements confirm previous results recently obtained with the altimeters on board ers or topex poseidon and offer a temporal continuity the s band altimeter measurements are in accordance with theoretical expected ones and confirm previous topex poseidon observations in c band the s band and the use of the dual frequency thus bring new capabilities for altimetric applications with important deliveries for temporal evolution survey for instance s band will be used over continents to better detect wetlands located under vegetated areas or to better quantify wave penetration in terrestrial snowpack to accurately retrieve snow depth evolution over ice sheets the dual frequency s and ku band waveforms parameters will provide a more accurate height estimation as it will be possible to quantify the error on height measurements induced by snowpack structure change over time this will then provide a more confident survey of the ice sheets surface topography evolution the combination and complementarities with the other altimetry missions such as ers topex poseidon and jason look already promising and offer a 10 year span dataset for continental altimetry applications

archeological and pedological evidence for large prehistoric earthquakes in the new madrid seismic zone central united states prehistoric liquefaction features have been identified by careful observation of their structural and stratigraphic relations to native american occupation horizons and their subtle soil characteristics the ages of these liquefaction features have been estimated from radiocarbon dating of wood associated with the features and native american artifacts found within bounding occupation horizons at three sites near blytheville arkansas in the central part of the new madrid seismic zone one sand blow crater formed between a d 800 and 1400 two sand blow deposits formed between a d 800 and 1670 and three possibly four sand dikes formed since 4035 b c where not found in association with native american occupation horizons and artifacts prehistoric liquefaction features can be difficult to distinguish from features that formed during the great new madrid earthquakes of a d 1811 and 1812 this raises the possibility that prehistoric liquefaction features may have been misinterpreted during previous studies in the area nevertheless a paleoearthquake chronology is beginning to emerge for the new madrid seismic zone our findings are consistent with paleoseismological studies in the northern part of the seismic zone and suggest a recurrence interval of hundreds of years for earthquakes large enough to induce liquefaction in this region m 6 4 by mapping the age distribution of liquefaction features a more accurate assessment of the long term earthquake potential of the region will be possible

calcareous nannofossil biostratigraphic dating of a ferromanganese crust from schumann seamount abstract calcareous nannofossil biostratigraphy was employed to determine the age and growth rates of the different layers within ferromanganese crusts from schumann seamount 200 miles north of the island of kauai hawaii this work is part of a study to reconstruct the paleoceanographic history of crusts using various geochemical indicators the methods are based on the identification of coccolith imprints not actual coccolith remains age constraints on the time span of a particular horizon are defined either 1 by the presence of a species which was extant for only a limited geological time interval or 2 by the presence of two organisms whose time ranges overlapped age resolution is optimized by short time ranges or narrow overlaps in the crust studied there was considerable inter horizon variability in the preservation of coccolith imprints in imprint abundance and in species diversity some of the crust layers examined were narrowly constrained temporally 1 4 myr while others were less so 10 myr our results indicate that the minimum age for the interval at 27 mm depth is at least eocene this is the maximum age many believe any crust can be the position of this interval however is only about one half of the way through the crust while the data support previous estimates of average crust growth rates 0 5 mm myr the actual apparent growth rate appears to have varied by an order of magnitude 0 1 to 2 mm myr

mechanisms and controls on the formation of sand intrusions sandstone intrusions are found in all sedimentary environments but have been reported most commonly from deep water settings they also appear to be more frequently developed in tectonically active settings where applied tectonic stresses facilitate development of high fluid pressures within the sediments a variety of mechanisms have been cited as triggers for clastic intrusions these include seismicity induced liquefaction application of tectonic stresses excess pore fluid pressures generated by deposition related processes and the influx of an overpressured fluid from deeper within the basin into a shallow sand body the formation of sandstone dykes and sills is investigated here by considering them as natural hydraulic fractures when the seal on an unconsolidated overpressured sand body fails the resulting steep hydraulic gradient may cause the sand to fluidize the fluidized slurry can then inject along pre existing or new fractures to form clastic intrusions the scale and the geometry of an intrusive complex is governed by the stress state depth and pre existing joints or faults within the sedimentary succession as well as the nature of the host sediments for the simplest tectonic setting where the maximum stress in a basin is vertical gravitational loading small irregular intrusions commonly result in the formation of sills at shallow depths within a few metres of the surface whereas at greater depth dykes and sills forming clastic intrusion networks are more typical a simple relationship is derived to calculate the maximum burial depth at which a dyke sill complex forms as a function of the source bed to sill height the bulk density of the surrounding sediments and the ratio of the vertical to horizontal effective stresses k 0 when applied to three examples of large scale dyke sill complexes developed within paleocene and eocene deep water reservoir sand bodies of the north sea maximum burial depths in a range of 375 to c 500 m 450 700 m and 550 850 m are estimated for intrusion of each of the three complexes

rates of southeast greenland ice volume loss from combined icesat and aster observations 1 repeat satellite laser altimetry is critical for observing the rapidly changing mass balance of the greenland ice sheet however sparse sampling and high surface slopes over rapidly thinning coastal outlet glaciers may result in underestimation of mass loss here we supplement icesat derived surface elevation changes with differenced aster digital elevation models of outlet glaciers in southeastern greenland the region with the largest concentrated change in outlet glacier mass loss we estimate a 2002 2005 regional volume loss rate of 108 km3 yr our results are consistent with drainage scale grace and mass budget estimates when differences in observation periods are taken into account the two largest glaciers kangerdlugssuaq and helheim account for only 28 of the mass loss illustrating the combined importance of smaller glaciers and the need for complete observational coverage additionally we find that rapid concentrated thinning within the outlets represents a small contribution to the total volume change compared to dispersed inland thinning

overlapping volcanoes the origin of hilo ridge hawaii the submarine hilo ridge has been interpreted as a part of mauna kea volcano but is crossed at 1100 m depth by a submerged shoreline terrace composed of basalts that are isotopically distinct from those of mauna kea and similar to those of kohala volcano this terrace evidently is a product of kohala instead of mauna kea almost all of hilo ridge below the terrace therefore must predate the principal growth of mauna kea which has superficially isolated the ridge from its kohala source by overlapping its proximal segment the mauna kea section penetrated by the hawaii scientific drilling project is predicted to be thinner than expected previously owing to the overlap similar overlaps are suspected among other volcanoes and may cause significant changes in the understanding of hawaiian volcanism

thirty seven year mass balance of devon ice cap nunavut canada determined by shallow ice coring and melt modeling 1 in april may 2000 eight boreholes were drilled to 15 20 m depth on the devon ice cap 137cs activity profiles of each borehole showed a peak count rate at depth that is associated with fallout from atmospheric thermonuclear weapons testing in 1963 snow firn and ice densities were measured at each core site and were used to estimate the average pattern of mass balance across the accumulation zone of the ice cap over the period 1963 2000 the average mass balance across the entire ice cap for the period 1960 2000 was also estimated using a degree day model driven by data derived from on ice temperature sensors and long term measurements at resolute bay best fitting degree day factors were determined for different sectors of the ice cap by comparing model output with repeated annual mass balance measurements made along two transects koerner 1970 the results suggest that the ice cap has lost 1 6 km3 water per year equivalent to a mean net mass balance of approximately 0 13 m we a 1 estimates of the mean mass balance for individual drainage basins reveal regions of positive and negative mass balance that are consistent with remotely sensed observations of advancing and retreating ice cap margins respectively

the tholeiite to alkalic basalt transition at haleakala volcano maui hawaii previous studies of alkalic lavas erupted during the waning growth stages 0 9 ma to present of haleakala volcano identified systematic temporal changes in isotopic and incompatible element abundance ratios these geochemical trends reflect a mantle mixing process with a systematic change in the proportions of mixing components we studied lavas from a 250 m thick stratigraphic sequence in honomanu gulch that includes the oldest 1 1 ma subaerial basalts exposed at haleakaka the lower 200 m of section is intercalated tholeiitic and alkalic basalt with similar isotopic sr nd pb and incompatible element abundance ratios e g nb la la ce la sr hf sm ti eu these lava compositions are consistent with derivation of alkalic and tholeiitic basalt by partial melting of a compositionally homogeneous clinopyroxene rich garnet lherzolite source the intercalated tholeiitic and alkalic honomanu lavas may reflect a process which tapped melts generated in different portions of a rising plume and we infer that the tholeiitic lavas reflect a melting range of 10 to 15 while the intercalated alkalic lavas reflect a range of 6 5 to 8 melting however within the uppermost 50 m of section 87sr 86sr decreases from 0 70371 to 0 70328 as eruption age decreased from 0 97 ma to 0 78 ma we infer that as lava compositions changed from intercalated tholeiitic and alkalic lavas to only alkalic lavas at 0 93 ma the mixing proportions of source components changed with a morb related mantle component becoming increasingly important as eruption age decreased

north kona slump submarine flank failure during the early tholeiitic shield stage of hualalai volcano abstract the north kona slump is an elliptical region about 20 by 60 km 1000 km 2 area of multiple geometrically intricate benches and scarps mostly at water depths of 2000 4500 m on the west flank of hualalai volcano two dives up steep scarps in the slump area were made in september 2001 using the rov kaiko of the japan marine science and technology center jamstec as part of a collaborative japan usa project to improve understanding of the submarine flanks of hawaiian volcanoes both dives at water depths of 2700 4000 m encountered pillow lavas draping the scarp and bench slopes intact to only slightly broken pillow lobes and cylinders that are downward elongate dominate on the steepest mid sections of scarps while more equant and spherical pillow shapes are common near the tops and bases of scarps and locally protrude through cover of muddy sediment on bench flats notably absent are subaerially erupted hualalai lava flows interbedded hyaloclastite pillow breccia and or coastal sandy sediment that might have accumulated downslope from an active coastline the general structure of the north kona flank is interpreted as an intricate assemblage of downdropped lenticular blocks bounded by steeply dipping normal faults the undisturbed pillow lava drape indicates that slumping occurred during shield stage tholeiitic volcanism all analyzed samples of the pillow lava drape are tholeiite similar to published analyses from the submarine northwest rift zone of hual lai relatively low sulfur 330 600 ppm and water 0 18 0 47 wt contents of glass rinds suggest that the eruptive sources were in shallow water perhaps 500 1000 m depth in contrast saturation pressures calculated from carbon dioxide concentrations 100 190 ppm indicate deeper equilibration at or near sample sites at water depths of 3900 to 2800 m either vents close to the sample sites erupted mixtures of undegassed and degassed magmas or volatiles were resorbed from vesicles during flowage downslope after eruption in shallow water the glass volatile compositions suggest that the tholeiitic lavas that drape the slump blocks were erupted either 1 early during shield stage tholeiitic volcanism prior to emergence of a large subaerial edifice or alternatively 2 from submarine radial vents during subaerial shield building because no radial vents have been documented on land or underwater for the unbuttressed flanks of any hawaii volcano alternative 1 is favored in comparison to other well documented hawaiian slumps and landslides north kona structures suggest a more incipient slump event with smaller down slope motions and lateral displacements

60 myr records of major elements and pb nd isotopes from hydrogenous ferromanganese crusts reconstruction of seawater paleochemistry we compare the time series of major element geochemical and pb and nd isotopic composition obtained for seven hydrogenous ferromanganese crusts from the atlantic indian and pacific oceans which cover the last 60 myr average crust growth rates and age depth relationships were determined directly for the last about 10 myr using be 10 be 9 profiles in the absence of other information these were extrapolated to the base of the crusts assuming constant growth rates and constant initial be 10 be 9 ratios due to the lack of additional information co contents have also been used previously to estimate growth rates in co rich pacific and atlantic seamount crusts puteanus and halbach 1988 a comparison of be 10 be 9 and co based dating of three co rich crusts supports the validity of this approach and confirms the earlier chronologies derived from extrapolated be 10 be 9 based growth rates back to 60 ma our data show that the flux of co into co poor crusts has been considerably lower the relationship between growth rate and co content for the co poor crusts developed from these data is in good agreement with a previous study of a wider range of marine deposits manheim 1986 the results suggest that the co content provides detailed information on the growth history of ferromanganese crusts particularly prior to 10 12 ma where the be 10 based method is not applicable the distributions of pb and nd isotopes in the deep oceans over the last 60 myr are expected to be controlled by two main factors a variations of oceanic mixing patterns and flow paths of water masses with distinct isotopic signatures related to major paleogeographic changes and b variability of supply rates or provenance of detrital material delivered to the ocean linked to climate change glaciations or major tectonic uplift the major element profiles of crusts in this study show neither systematic features which are common to crusts with similar isotope records nor do they generally show coherent relationships to the isotope records within a single crust consequently any interpretation of time series of major element concentrations of a single crust in terms of paleoceanograghic variations must be considered with caution this is because local processes appear to have dominated over more basin wide paleoceanographic effects in this study co is the only element which shows a relationship to pb and nd isotopes in pacific crusts a possible link to changes of pacific deep water properties associated with an enhanced northward advection of antarctic bottom water from about 14 ma is consistent with the pb but not with the nd isotopic results the self consistent profiles of the pb and nd isotopes suggest that postdepositional diagenetic processes in hydrogenous crusts including phosphatization events have been insignificant for particle reactive elements such as pb be and nd isotope time series of pb and nd show no systematic relationships with major element contents of the crusts which supports their use as tracers of paleo seawater isotopic composition

characteristics of deformation and past seismicity associated with the 1819 kutch earthquake northwestern india the 1819 earthquake in kutch northwestern india is one of the most significant events to have occurred in a plate interior setting despite being the second largest among the stable continental region scr earthquakes this event has not been analyzed within the context of present day understanding of earthquake seismology coseismic changes related to this earthquake include massive ground deformation in a wide low lying tidal flat area although detailed historic accounts of this earthquake exist many questions regarding the mode of deformation and the seismic history of the region remain unresolved we explored the region nearly 180 years after the earthquake and the information gathered adds to our understanding of this event and provides a fresh perspective on this unique intraplate seismogenic zone a 90 km long tract of elevated land with a peak height of 4 3 m is the most visible surface expression of this earthquake we surveyed and analyzed the morphological features of this scarp and also carried out exploratory trenching in this region the scarp morphology is suggestive of a growing fold related to a buried north dipping thrust rather than a discrete fault that could have resulted from a surface rupture the extensive liquefaction field associated with the earthquake offered an ideal setting to explore the paleoearthquake history age data of liquefaction features suggest that a previous event of comparable size must have occurred 800 1000 years ago seismic activity appears to be related to the reactivation of an ancient rift in a stress regime that is dominated by nearly north south compression

diverse basalt types from loihi seamount hawaii loihi seamount is the southeasternmost active volcano in the hawaiian emperor volcanic chain the seamount is considered representative of the early phase of hawaiian volcanism because of its youth small size and location near the melting anomaly seventeen dredge stations recovered transitional basalt alkalic basalt and basanite in addition to the expected tholeiitic basalt four flows of alkalic basalt contain common small dunite xenoliths the recovered samples have thin palagonite rinds and almost no manganese on the glassy surfaces we estimate that the lavas are less than about 4 000 yr old and many are less than 1 000 yr old loihi seamount is apparently in a transitional growth phase between the early eruption of alkalic lavas and the commonly observed subaerial tholeiitic eruptive phase previously thought to dominate hawaiian volcanism from inception until the postcaldera collapse alkalic stage

antarctic elevation change from 1992 to 1996 satellite radar altimeter measurements show that the average elevation of the antarctic ice sheet interior fell by 0 9 0 5 centimeters per year from 1992 to 1996 if the variability of snowfall observed in antarctic ice cores is allowed for the mass imbalance of the interior this century is only 0 06 0 08 of the mean mass accumulation rate

recent ice sheet growth in the interior of greenland a continuous data set of greenland ice sheet altimeter height from european remote sensing satellites ers 1 and ers 2 1992 to 2003 has been analyzed an increase of 6 4 0 2 centimeters per year cm year is found in the vast interior areas above 1500 meters in contrast to previous reports of high elevation balance below 1500 meters the elevation change rate is 2 0 0 9 cm year in qualitative agreement with reported thinning in the ice sheet margins averaged over the study area the increase is 5 4 0 2 cm year or 60 cm over 11 years or 54 cm when corrected for isostatic uplift winter elevation changes are shown to be linked to the north atlantic oscillation

holocene tectonic activity along kachchh mainland fault impact on late mature harappan civilization kachchh western india abstract paleoseismic and archaeological records of the kachchh rift basin krb of western india indicates that the region become tectonically active during the period of middle to late holocene to understand the relationship between strain accumulation earthquake genesis and landform development we analyzed uplifted late quaternary terraces and archaeological evidence along the kachchh mainland fault kmf zone dividing the elevation of the bedrock strath at each site by their ages yields vertical uplift rates of 0 29 1 17 mm y for the kmf zones archaeological data from the excavation of the kotada bhadli site suggest that the site was occupied during the late mature harappan 2300 2500 bce period and abandoned around 1900 bce the ruins of harappan civilization at kotada bhadli location are resting over the middle holocene fluvial sediments the oldest fluvial sediment is dated to 4 ka whereas the youngest sediment yielded an age of 3 ka the chronological constraints in geomorphic and archaeological records suggest that the area was hit by an earthquake around 2200 bc 3 5ka the geomorphic and chronologically constrained uplift rates reveal that the kmf zone of the intraplate region of the kachchh is geodynamically controlled by several fault segments which are consistent with the ambient tectonic stress field owing to the northward movement of the indian plate concerning the eurasian plate

icesat antarctic elevation data preliminary precision and accuracy assessment 1 since first light on february 20th 2003 nasa s ice cloud and land elevation satellite icesat has derived surface elevations from 86 n to 86 s latitude these unique altimetry data have been acquired in a series of observation periods in repeated track patterns using all three geoscience laser altimeter system glas lasers here we focus on antarctic ice sheet elevation data that were obtained in 2003 2004 we present preliminary precision and accuracy assessments of selected elevation data and discuss factors impacting elevation change detection we show that for low slope and clear sky conditions the precision of gla12 laser 2a release 21 data is 2 1 cm and the relative accuracy of icesat elevations is 14 cm based on crossover differences

elevation changes of bering glacier system alaska from 1992 to 2010 observed by satellite radar altimetry abstract satellite radar altimetry has been extensively used to estimate ice sheet elevation change rates over antarctica and greenland from repeated measurements of surface elevation changes through either crossover or collinear repeat track analysis however there has been no attempt to use satellite radar altimetry over mountain glaciers because the instrument often loses lock or does not provide usable measurements over the rough terrains and steep slopes due to its large footprint size in this study we demonstrate the feasibility of satellite radar altimetry to estimate elevation change rates over the bering glacier system in alaska for the period of 1992 2010 from topex poseidon and envisat radar altimeter measurements we are able to observe the 1993 1995 and 2008 2011 surge events from the t p and envisat time series respectively we also observe the accelerated elevation decreases in 2002 2007 after slightly negative or near nil elevation changes in 1996 2001 which are related to the temperature and snow depth variations our method can be applied to other wide 7 km glaciers worldwide and provide new insights into the behavior of glaciers responding to climate change

the proximal part of the giant submarine wailau landslide molokai hawaii abstract the main break in slope on the northern submarine flank of molokai at 1500 to 1250 m is a shoreline feature that has been only modestly modified by the wailau landslide submarine canyons above the break in slope including one meandering stream were subaerially carved where such canyons cross the break in slope plunge pools may form by erosion from bedload sediment carried down the canyons west molokai volcano continued infrequent volcanic activity that formed a series of small coastal sea cliffs now submerged as the island subsided lavas exposed at the break in slope are subaerially erupted and emplaced tholeiitic shield lavas submarine rejuvenated stage volcanic cones formed after the landslide took place and following at least 400 500 m of subsidence after the main break in slope had formed the sea cliff on east molokai is not the headwall of the landslide nor did it form entirely by erosion it may mark the location of a listric fault similar to the hilina faults on present day kilauea volcano the wailau landslide occurred about 1 5 ma and the kalaupapa peninsula most likely formed 330 5 ka molokai is presently stable relative to sea level and has subsided no more than 30 m in the last 330 ka at their peak west and east molokai stood 1 6 and 3 km above sea level high rainfall causes high surface runoff and formation of canyons and increases groundwater pressure that during dike intrusions may lead to flank failure active shield or postshield volcanism with dikes injected along rift zones and high rainfall appear to be two components needed to trigger the deep seated giant hawaiian landslides

ages rare earth element enrichment and petrogenesis of tholeiitic and alkalic basalts from kahoolawe island hawaii kahoolawe island hawaii 18 11 km is a basaltic shield volcano with caldera filling lavas seven identified postshield vents and at least two occurrences of apparent rejuvenated stage eruptive we examined 42 samples that represent all stages of kahoolawe volcano stratigraphy for their petrography whole rock major and trace element contents mineral compositions and k ar ages the two oldest shield samples have an average age of 1 34 0 08 ma and four postshield samples 3 are alkalic average 1 15 0 03 ma ages of 1 08 and 0 99 ma for two additional tholeiitic samples probably are minimum ages whole rock major and trace element and mineral compositions of kahoolawe shield and caldera fill laves are generally similar to the lavas forming kilauea and mauna loa tholeiitic shields but in detail kahoolawe shield lavas have distinctive compositions an unusual aspect of many postshield ka hoolawe lavas is anomalously high ree and y abundances up to 200 ppm la and 175 ppm y and negative ce anomalies these enrichments reflect surficial processes where weathering and soil development promoted ree y transport at the weathering front major element abundances mgo 10 6 wt for shield and caldera fill basalts are consistent with fractionation of ol px pl in frequently replenished magma reservoirs in general tholeiitic basalts erupted from late vents are higher in sio2 than the shield lavas and temporal differences in parental magma compositions are the likely explanation alkalic basalts that erupted from vents are comparable in composition to those at other hawaiian volcanoes trace element abundance ratios indicate that alkalic basalts represent either relatively lower degrees of melting of the shield source or a distinct source apparent rejuvenated stage basalts i e emplaced after substantial kahoolawe erosion are tholeiitic unlike the rejuvenated stages at other hawaiian volcanoes alkalic kahoolawe like several other hawaiian volcanoes has intercalated tholeiitic and alkalic basalts in the postshield stage but it is the only volcano that appears to have produced tholeiitic rejuvenated stage lavas

hawaiian submarine manganese iron oxide crusts a dating tool black manganese iron oxide crusts form on most exposed rock on the ocean floor such crusts are well developed on the steep lava slopes of the hawaiian ridge and have been sampled during dredging and submersible dives the crusts also occur on fragments detached from bedrock by mass wasting on submerged coral reefs and on poorly lithified sedimentary rocks the thickness of the crusts was measured on samples collected since 1965 on the hawaiian ridge from 140 dive or dredge localities fifty nine 42 of the sites were collected in 2001 by remotely operated vehicles rovs the thinner crusts on many samples apparently result from post depositional breakage landsliding and intermittent burial of outcrops by sediment the maximum crust thickness was selected from each dredge or dive site to best represent crusts on the original rock surface at that site the measurements show an irregular progressive thickening of the crusts toward the northwest i e progressive thickening toward the older volcanic features with increasing distance from the hawaiian hotspot comparison of the maximum crust thickness with radiometric ages of related subaerial features supports previous studies that indicate a crust growth rate of about 2 5 mm m y the thickness information not only allows a comparison of the relative exposure ages of two or more features offshore from different volcanoes but also provides specific age estimates of volcanic and landslide deposits the data indicate that some of the landslide blocks within the south kona landslide are the oldest exposed rock on mauna loa kilauea or loihi volcanoes crusts on the floors of submarine canyons off kohala and east molokai volcanoes indicate that these canyons are no longer serving as channelways for down slope sediment laden currents mahukona volcano was approximately synchronous with hilo ridge both being younger than hana ridge the nuuanu landslide is considerably older than the wailau landslide the waianae landslide southwest of oahu has yielded samples with the greatest manganese iron oxide crusts 9 5 mm thick and therefore apparently represents the oldest submarine material yet found in the study area the submarine volcanic field 100 km southwest of oahu is apparently younger than the waianae landslide

ground deformation in an area later damaged by an earthquake monitoring the avcilar district of istanbul turkey by satellite radar interferometry 1992 1999 summary the avcilar district of istanbul was severely damaged by the m 7 4 izmit kocaeli earthquake of 1999 the same area underwent ground subsidence before the earthquake as revealed by geodetic monitoring analysis of 14 synthetic aperture radar images acquired by the ers 1 and ers 2 satellites between 1992 and 1999 by interferometry insar measures the rate of subsidence using the general inversion for phase technique gipht we analyse a set of 12 interferometric pairs the interferometric fringe patterns show a rounded triangular shape that we interpret as secular subsidence at a constant rate the maximum subsidence rate of 6 mm per year occurs at a point located at latitude 40 98 n and longitude 28 71 e a simple four parameter elastic mogi model consisting of three infinitesimal spherical sinks at a depth of 2 4 0 4 km deflating at 78 000 16 000 cubic metres per year describes subsidence signal to first order the model also accounts for tropospheric effects by estimating a vertical phase gradient and an additive offset for each image acquisition epoch the model fits the data with a cost of 0 18 cycles per datum for the 4644 phase measurements included in the inversion this fit is significantly better than either the null hypothesis or the initial model with 95 per cent confidence for 32 free parameters the association of ground deformation with earthquake damage may be interpreted in terms of weak compressible material in shallow subsurface layers

geology and petrology of mahukona volcano hawaii the submarine mahukona volcano west of the island of hawaii is located on the loa loci line between kahoolawe and hualalai volcanoes the west rift zone ridge of the volcano extends across a drowned coral reef at about 1150 m and a major slope break at about 1340 m both of which represent former shoreines the summit of the volcano apparently reached to about 250 m above sea level now at 1100 m depth did was surmounted by a roughly circular caldera a econd rift zone probably extended toward the east or sutheast but is completely covered by younger lavas from the adjacent subaerial volcanoes samples were vecovered from nine dredges and four submersible lives using subsidence rates and the compositions of flows which drape the dated shoreline terraces we infer that the voluminous phase of tholeiitic shield growth ended about 470 ka but tholeiitic eruptions continued until at least 435 ka basalt transitional between tholeiitic and alkalic basalt erupted at the end of tholeiitic volcanism but no postshield alkalic stage volcanism occurred the summit of the volcano apparently subcided below sea level between 435 and 365 ka the tholeiitic lavas recovered are compositionally diverse

microfossil assemblages on tuscaloosa seamount and their constraints on the age of the nuʻuanu landslide north of oahu hi abstract the nu uanu submarine landslide north of the island of oahu is the largest of many debris avalanches along the flanks of the hawaiian islands several attempts have been made to date the nu uanu landslide and to assess its relationship to the shield building stage of ko olau volcano as an indication of hazards that might be anticipated during the evolution of oceanic volcanoes previous age determinations based on magnetostratigraphy and the temporal distribution of turbidites have yielded a range of possible ages we describe a distinctive fine grained silty mudstone representing mantling sediment on the largest landslide block within the debris field tuscaloosa seamount this mudstone contains foraminifera and nannofossil assemblages that yield a micropaleontological age and paleoenvironmental determination for the interval immediately following landslide emplacement the microfossils constrain the mantling sediment to have been deposited between 2 5 and 3 3 ma in offshore mid to lower bathyal 1500 3000 m water depth consistent with a position on the upper flanks of tuscaloosa seamount these findings indicate that landsliding occurred prior to or near the end of shield building at ko olau volcano 2 9 ma and may have precipitated dramatic changes in volcano growth and deformation behavior as well as changes in basalt geochemistry

controls on patterns of liquefaction in a coastal dune environment christchurch new zealand abstract liquefaction features in the geological record are important off fault markers of moderate to large 5 mw paleoearthquakes the study of contemporary liquefaction features provides a better understanding of where to find past paleo liquefaction features which if correctly identified and dated can provide information on the occurrence magnitude and timing of past earthquakes this is particularly important in areas with blind active faults this paper describes liquefaction features in the coastal setting of christchurch south island of new zealand and explores the role of liquefaction and fluidization in the surface soil profile and their role in controlling surface ejection the paper also compares the styles of liquefaction surface manifestation in the alluvial and coastal settings and the role played by the sedimentary architecture in both environments this analysis contributes to our understanding of which of the two environments provides a better target for paleoliquefaction studies and which geomorphic setting within those environments is most likely to host paleoliquefaction features the coastal setting in particular young coastal areas 1000 years old a better target for paleoliquefaction studies

ferromanganese deposits in the hawaiian archipelago abstract dredge sampling and bottom photography of submarine terraces in the hawaiian archipelago find that ferromanganese deposits encrust rock outcrops and form widespread pavements these deposits are economically interesting because of their cobalt content and location within the 200 mile zone ferromanganese crusts and pavements are most prevalent on two deep terrace levels the laualualei 370 560 m and waho 900 1200 m recognized throughout the archipelago although crust thickness and element content vary considerably on both regional and local scales the characteristic variability in crust thickness and element content suggests that environmental conditions vary on small spacial and temporal scales we find no relationship between substrate composition and crust thickness or element content indicating that ferromanganese oxides are deposited from seawater and accumulate on any exposed hard substrate surface we speculate that structural and sedimentary processes regulate the exposure of resistant substrate as a prerequisite for crust layers deposited during intermittent accretion episodes an enrichment in cobalt is correlated to mn fe ratio and the relative proportions of mno2 and feooh which are the principal crust components cobalt content cannot be correlated to water depth crust thickness or basement age of the deep terrace localities since crust thickness and cobalt content generally increase along the archipelago to the northwest deposits found on the wide terraces of the leeward archipelago have the most economic potential this study concludes that hydrogenous deposition of ferromanganese oxides from seawater is affected considerably by local environmental conditions during the evolution of deep terraces on the submarine of slopes of the hawaiian archipelago

estimation of volume change rates of greenland s ice sheet from icesat data using overlapping footprints abstract data from the icesat glas laser altimetry mission is used to obtain an estimate of the volume change of greenland s ice sheet over the time span of february 2003 to april 2007 a novel processing strategy is developed and applied it uses approximately 1 million icesat elevation differences at geometrically overlapping footprints of both crossing and repeated tracks the data are edited using quality flags defined by the icesat glas science team as well as other additional criteria in order to reduce the influence of surface slope we propose a correction based on the icesat glas laser altimetry digital elevation model three slightly different processing strategies to convert the observed temporal elevation differences to elevation volume changes are compared for 6 different drainage systems further divided into regions above and below 2000 m in elevation the final chosen strategy includes the correction for surface slopes but does not include the removal of outlying elevation changes for the region above 2000 m a positive elevation change rate of 2 cm year is obtained which corresponds to a volume change rate of 21 km3 year for the region below 2000 m the estimated elevation change rate is 24 cm year which corresponds to a volume loss of 168 km3 year in general the obtained results are in agreement with trends discovered by other authors that were also derived from laser altimetry nevertheless the estimation obtained in this study suggests a more negative trend than those obtained previously the differences can be explained by differences in the sampling of the region below 2000 m and to a certain extent by different time spans of the datasets used a representative sampling of coastal areas is identified as the most critical issue for an accurate estimation of volume change rates in greenland

formation of submarine flat topped volcanic cones in hawai i high resolution bathymetric mapping has shown that submarine flat topped volcanic cones morphologically similar to ones on the deep sea floor and near mid ocean ridges are common on or near submarine rift zones of kilauea kohala or mauna kea mahukona and haleakala volcanoes four flat topped cones on kohala were explored and sampled with the pisces v submersible in october 1998 samples show that flat topped cones on rift zones are constructed of tholeiitic basalt erupted during the shield stage similarly shaped flat topped cones on the northwest submarine flank of ni ihau are apparently formed of alkalic basalt erupted during the rejuvenated stage submarine postshield stage eruptions on hilo ridge mahukona hana ridge and offshore ni ihau form pointed cones of alkalic basalt and hawaiite the shield stage flat topped cones have steep 25 sides remarkably flat horizontal tops basal diameters of 1 3 km and heights 300 m the flat tops commonly have either a low mound or a deep crater in the center the rejuvenated stage flat topped cones have the same shape with steep sides and flat horizontal tops but are much larger with basal diameters up to 5 5 km and heights commonly greater than 200 m the flat tops have a central low mound shallow crater or levees that surrounded lava ponds as large as 1 km across most of the rejuvenated stage flat topped cones formed on slopes 10 and formed adjacent semicircular steps down the flank of ni ihau rather than circular structures all the flat topped cones appear to be monogenetic and formed during steady effusive eruptions lasting years to decades these and other submarine volcanic cones of similar size and shape apparently form as continuously overflowing submarine lava ponds a lava pond surrounded by a levee forms above a sea floor vent as lava continues to flow into the pond the lava flow surface rises and overflows the lowest point on the levee forming elongate pillow lava flows that simultaneously build the rim outward and upward but also dam and fill in the low point on the rim the process repeats at the new lowest point forming a circular structure with a flat horizontal top and steep pillowed margins there is a delicate balance between lava heat supply to the pond and cooling and thickening of the floating crust factors that facilitate construction of such landforms include effusive eruption of lava with low volatile contents moderate to high confining pressure at moderate to great ocean depth long lived steady eruption years to decades moderate effusion rates probably ca 0 1 km3 year and low but not necessarily flat slopes with higher effusion rates sheet flows flood the slope with lower effusion rates pillow mounds form hawaiian shield stage eruptions begin as fissure eruptions if the eruption is too brief it will not consolidate activity at a point and fissure fed flows will form a pond with irregular levees the pond will solidify between eruptive pulses if the eruption is not steady lava that is too volatile rich or that is erupted in too shallow water will produce fragmental and highly vesicular lava that will accumulate to form steep pointed cones as occurs during the post shield stage the steady effusion of lava on land constructs lava shields which are probably the subaerial analogs to submarine flat topped cones but formed under different cooling conditions

a low relief shield volcano origin for the south kaua i swell 1 the south kaua i swell sks is a 110 km x 80 km ovoid bathymetric feature that stands 2 km high and abuts the southern flank of the island of kaua i the origin of the sks was investigated using multibeam bathymetry and acoustic backscatter gravity data radiometric ages and geochemistry of rock samples most of the sks rock samples are tholeiitic in composition with ages of 3 9 5 4 ma indicating they were derived from shield volcanism the ages and compositions of the sks rocks partially overlap with those of the nearby ni ihau kaua i and west ka ena volcano complexes the sks was originally described as a landslide however this interpretation is problematic given the ovoid shape of sks its relatively smooth flat to convex surface and the lack of an obvious source region that could accommodate what would be one of earth s most voluminous 6 x 103 km3 landslides the morphology size and the surrounding gravity anomaly are more consistent with the sks being a low relief shield volcano which was partially covered with a small volume of landside debris from south kaua i and later with some secondary volcanic seamounts a shield origin would imply that hawaiian and possibly other hotspot shield volcanoes can take on a wider variety of forms than is commonly thought ranging from tall island building shields to smaller edifices such as ka ena ridge and mahukona to even lower relief volcanoes represented by the sks and possibly the south west o ahu volcanic field

liquefaction features produced by the 2010 2011 canterbury earthquake sequence in southwest christchurch new zealand and preliminary assessment of paleoliquefaction features liquefaction features and the geologic environment in which they formed were carefully studied at two sites near lincoln in southwest christchurch we undertook geomorphic mapping excavated trenches and obtained hand cores in areas with surficial evidence for liquefaction and areas where no surficial evidence for liquefaction was present at two sites hardwick and marchand the liquefaction features identified include 1 sand blows singular and aligned along linear fissures 2 blisters or injections of subhorizontal dikes into the topsoil 3 dikes related to the blows and blisters and 4 a collapse structure the spatial distribution of these surface liquefaction features correlates strongly with the ridges of scroll bars in meander settings in addition we discovered paleoliquefaction features including several dikes and a sand blow in excavations at the sites of modern liquefaction the paleoliquefaction event at the hardwick site is dated at a d 908 1336 and the one at the marchand site is dated at a d 1017 1840 95 confidence intervals of probability density functions obtained by bayesian analysis if both events are the same given proximity of the sites the time of the event is a d 1019 1337 if they are not the one at the marchand site could have been much younger taking into account a preliminary liquefaction triggering threshold of equivalent peak ground acceleration for an m w 7 5 event pga7 5 of 0 07 g existing magnitude bounded relations for paleoliquefaction and the timing of the paleoearthquakes and the potential pga7 5 estimated for regional faults we propose that the porters pass fault alpine fault or the subduction zone faults are the most likely sources that could have triggered liquefaction at the study sites there are other nearby regional faults that may have been the source but there is no paleoseismic data with which to make the temporal link online material figures showing areas of liquefaction trench logs information on dike and sand blow parameters dike azimuths core logs radiocarbon samples and oxcal analysis and tables detailing units exposed in the trenches and stereonets

heterogeneous and rapid ice loss over the patagonian ice fields revealed by cryosat 2 swath radar altimetry abstract the northern and southern patagonian ice fields npi and spi in south america are the largest bodies of ice in the southern hemisphere outside of antarctica and the largest contributors to eustatic sea level rise slr in the world per unit area here we exploit swath processed cryosat 2 interferometric data to produce maps of surface elevation change at sub kilometer spatial resolution over the ice fields for six glaciological years between april 2011 and march 2017 mass balance is calculated independently for nine sub regions including six individual glaciers larger than 300 km2 overall between 2011 and 2017 the patagonian ice fields have lost mass at a combined rate of 21 29 1 98 gt a 1 contributing 0 059 0 005 mm a 1 to slr we observe widespread thinning on the ice fields particularly north of 49 s however the pattern of surface elevation change is highly heterogeneous partly reflecting the importance of dynamic processes on the ice fields the jorge montt glacier spi whose tidewater terminus is approaching floatation retreated 2 5 km during our study period and lost mass at the rate of 2 20 0 38 gt a 1 4 64 0 80 mwe a 1 in contrast with the general pattern of retreat and mass loss pio xi the largest glacier in south america is advancing and gaining mass at 0 67 0 29 gt a 1 rate

a comparison of recent elevation change estimates of the devon ice cap as measured by the icesat and envisat satellite altimeters we have used surface elevation measurements acquired by the ice cloud and land elevation satellite geoscience laser altimeter system glas and envisat radar altimeter 2 ra 2 satellite altimeters to assess the elevation change of the 13 700 km2 devon ice cap dic in arctic canada between 2002 and 2008 we present algorithms for the retrieval of elevation change rates over ice caps using data acquired from these satellites a comparison of glas elevation data to those acquired by the ra 2 shows reasonable agreement between the two instruments the root mean square elevation change difference was 56 cm and the correlation coefficient between the two data sets was 0 68 using only ra 2 elevation measurements which are spatially and temporally more continuous we determined the elevation change rate of the areas of the dic where the surface geometry allows the ra 2 retracker to maintain lock this includes most of the dic excluding large parts of the eastern half of the ice cap the elevation change rate was found to be insignificant given a statistical estimate of the measurement error 0 09 0 29 m a we also present an assessment of the regional variations of the dic elevation change including a significant 0 71 0 49 m a elevation change rate of the 1980 km2 western arm furthermore we present evidence of a localized 2 m drop in the surface elevation of the south croker bay glacier during summer 2007 this drop is apparent within both satellite data sets and we interpret this signal to reflect a sudden speedup of the glacier

subsidence and volcanism of the haleakala ridge hawaii abstract side looking sonar gloria mapping has revealed a series of four arcuate bands of high sonic backscatter on the crest of the haleakala ridge a major rift zone ridge extending 135 km east of the island of maui dredge recovery indicates that the shallowest of these bands is a drowned coral reef and the deeper bands are also inferred to be coral reefs the reefs occur above a prominent submarine bench 1500 2500 m deep on the ridge h terrace that marks the shoreline at the end of vigorous shield building of haleakala volcano when lava flows ceased crossing and reworking the shoreline since their growth these reefs have subsided as much as 2200 m and have tilted systematically about 20 m km southward as a result of post reef volcanic loading on the island of hawaii whose center of mass is about directly south of the haleakala ridge the 234u 238u age of the dredged coral is 750 13 ka in reasonable agreement with an age of 850 ka for the underlying h terrace previously estimated from its relationship to other dated reefs to the southwest basalt glass fragments dredged from the haleakala ridge below the h terrace are tholeiitic and contain high sulfur indicative of eruption in water deeper than 200 m basalt glass fragments associated with the reefs above the h terrace are dominantly tholeiitic and contain intermediate sulfur contents indicative of subaqueous eruption in shallow near shore conditions one alkalic glass fragment was recovered above the h terrace these relations indicate that the morphologic end of shield building as recorded by construction of the h terrace was not accompanyed by a change from tholeiitic to alkalic basalt instead tholeiite eruptions continued for some time before the erupted lava became alkalic

multiple late holocene earthquakes along the reelfoot fault central new madrid seismic zone the reelfoot fault is an east vergent reverse fault underlying the lake county uplift a low amplitude late holocene anticline bordered on the east by the 32 km long reelfoot scarp fluvial deposits across the scarp define an 8 m high east facing monocline most near surface deformation along the scarp is accommodated via folding rather than faulting we interpret the scarp as a fault propagation fold developed over a wcst dipping reverse fault interpreted from shallow seismic reflection data trench exposurcs provide evidence for three episodes of deformation along the reelfoot fault within thc past approximately 2400 years between a d 780 and 1000 between a d 1260 and 1650 and during a d 1812 our best estimate of the average recurrence interval for deformation along the scarp is 400 500 years each episode of deformation had a slightly different style the third most recent event produced a small graben a few tens of centimeters deep in the hanging wall of the reverse fault the second most recent earthquake produced about 1 3 m of throw in the graben as well as folding along the updip projection of the reverse fault and development of the scarp thesc relations suggest that graben development increased through time concomitant with growth of the monocline or that the events are of different magnitude the 1811 1812 episode of deformation produced abundant liquefaction prominent folding of fluvial strata along the scarp and minor faulting in the graben

recent changes in thickness of the devon island ice cap canada 1 long term rates of thickness change were derived at several spatial scales using a variety of methods for most of the devon island ice cap nunavut canada basin wide thickness change calculations were derived for the accumulation zones of all major drainage basins as the area averaged volume difference between balance and insar fluxes at the altitude of the long term equilibrium line ela thickness changes for ablation zones were derived as a function of the surface mass balance flux across the el and calving flux averaged across the ablation areas average rates of thickness change are near zero in the accumulation zones of the northern and southwestern basins but reach 0 23 0 11 m a 1 w e in the southeast basin due to dynamic thinning thickness changes were also estimated along five major outlet glaciers as a function of flux divergence and net surface mass balance and along the belcher glacier by comparing elevation values derived from 1960s aerial photography with those derived from 2005 nasa airborne topographic mapper atm surveys ice dynamics have had a significant influence on the pattern of thickness change of all outlet glaciers examined in this study volume changes derived from the basin wide values indicate a net loss of 76 8 7 km3 water equivalent from the main portion of the ice cap from 1960 to 1999 contributing 0 21 0 02 mm to global sea level over this time this value is 44 greater than previous estimates of volume change based on volume area scaling methods and surface mass balance alone

reef growth and volcanism on the submarine southwest rift zone of mauna loa hawaii a marine sampling program utilizing the pisces 5 submersible operated by the hawaii undersea research laboratory noaa has confirmed the presence of a major submerged coral reef offshore from ka lae south point hawaii the top of the reef is now 150 160 m below sea level radiocarbon and useries dating indicates that it drowned about 13 9 ka by the combined effects of island subsidence 2 5 mm year and the rapid rise of sea level at the end of the last glaciation so that the relative submergence rate of more than 10 mm year exceeded the upward growth rate of the reef the submerged reef caps the offshore part of the southwest rift zone ridge of mauna loa which has apparently undergone little volcanic activity offshore since 170 ka and possibly since 270 ka this fact suggests that rift zone activity is becoming increasingly restricted toward the upper part of the volcano a condition possibly heralding the end of the shield building stage

coastal lava flows from mauna loa and hualalai volcanoes kona hawaii a major carbonate reef which drowned 13 ka is now submerged 150 m below sea level on the west coast of the island of hawaii a 25 km span of this reef was investigated using the submersiblemakali i the reef occurs on the flanks of two active volcanoes mauna loa and hualalai and the lavas from both volcanoes both underlie and overlie the submerged reef most of the basaltic lava flows that crossed the reef did so when the water was much shallower and when they had to flow a shorter distance from shoreline to reef face lava flows on top of the reef have protected it from erosion and solution and now occur at seaward projecting salients on the reef face these relations suggest that the reef has retreated shoreward as much as 50 m since it formed a 7 km wide shadow zone occurs where no hualalai lava flows cross the reef south of kailua these lava flows were probably diverted around a large summit cone complex a similar shadow zone on the flank of mauna loa volcano in the kealakekua bay region is downslope from the present mauna loa caldera which ponds mauna loa lava and prevents it from reaching the coastline south of the mauna loa shadow zone the 150 m reef has been totally covered and obscured by mauna loa lava the boundary between hualalai and mauna loa lava on land occurs over a 6 km wide zone whereas flows crossing the 150 m reef show a sharper boundary offshore from the north side of the subaerial transition zone this indicates that since the formation of the reef hualalai lava has migrated south mantling mauna loa lava more recently mauna loa lava is again encroaching north on hualalai lava

prodigious submarine landslides on the hawaiian ridge the extensive area covered by major submarine mass wasting deposits on or near the hawaiian ridge has been delimited by systematic mapping of the hawaiian exclusive economic zone using the side looking sonar system gloria these surveys show that slumps and debris avalanche deposits are exposed over about 100 000 km2 of the ridge and adjacent seafloor from kauai to hawaii covering an area more than 5 times the land area of the islands some of the individual debris avalanches are more than 200 km long and about 5000 km3 in volume ranking them among the largest on earth the slope failures that produce these deposits begin early in the history of individual volcanoes when they are small submarine seamounts culminate near the end of subaerial shield building and apparently continue long after dormancy consequently landslide debris is an important element in the internal structure of the volcanoes the dynamic behavior of the volcanoes can be modulated by slope failure and the structural features of the landslides are related to elements of the volcanoes including rift zones and fault systems the landslides are of two general types slumps and debris avalanches the slumps are slow moving wide up to 110 km and thick about 10 km with transverse blocky ridges and steep toes the debris avalanches are fast moving long up to 230 km compared to width and thinner 0 05 2 km they commonly have a well defined amphitheater at their head and hummocky terrain in the lower part oceanic disturbance caused by rapid emplacement of debris avalanches may have produced high level wave deposits such as the 365 m elevation hulopoe gravel on lanai that are found on several islands most present day submarine canyons were originally carved subaerially in the upper parts of debris avalanches subaerial canyon cutting was apparently promoted by the recently steepened and stripped slopes of the landslide amphitheaters

south arch volcanic field newly identified young lava flows on the sea floor south of the hawaiian ridge several young lava fields were imaged by gloria sidescan sonar along the hawaiian arch south of hawaii the largest 35 by 50 km across includes a central area characterized by high sonar backscatter and composed of several flow lobes radiating from a vent area reflection profiling and sea floor photography indicate that the central lobes are flat sheet flowsbounded by pillowed margins thin surface sediment and thin palagonite rinds on lava surfaces suggest ages of 1 10 ka vents are localized along the arch crest near bases of cretaceous seamounts two dredged flows are basanite and alkalic basalt broadly similar to rejuvenated stage and some pre shield alkalic lavas on the hawaiian ridge arch volcanism representsperipheral leakage of melt from the hawaiian hot spot over much larger areas than previously recognized

cobalt manganese and iron near the hawaiian islands a potential concentrating mechanism for cobalt within a cyclonic eddy and implications for the hybrid type trace metals abstract the vertical distributions of cobalt iron and manganese in the water column were studied during the e flux program e flux ii and iii which focused on the biogeochemistry of cold core cyclonic eddies that form in the lee of the hawaiian islands during e flux ii january 2005 and e flux iii march 2005 17 stations were sampled for cobalt n 147 all of which demonstrated nutrient like depletion in surface waters during e flux iii two depth profiles collected from within a mesoscale cold core eddy cyclone opal revealed small distinct maxima in cobalt at 100 m depth and a larger inventory of cobalt within the eddy we hypothesize that this was due to a cobalt concentrating effect within the eddy where upwelled cobalt was subsequently associated with sinking particulate organic carbon poc via biological activity and was released at a depth coincident with nearly complete poc remineralization benitez nelson c bidigare r r dickey t d landry m r leonard c l brown s l nencioli f rii y m maiti k becker j w bibby t s black w cai w j carlson c a chen f kuwahara v s mahaffey c mcandrew p m quay p d rappe m s selph k e simmons m p yang e j 2007 mesoscale eddies drive increased silica export in the subtropical pacific ocean science 316 1017 1020 there is also evidence for the formation of a correlation between cobalt and soluble reactive phosphorus during e flux iii relative to the e flux ii cruise that we suggest is due to increased productivity implying a minimum threshold of primary production below which cobalt phosphate coupling does not occur dissolved iron was measured in e flux ii and found in somewhat elevated concentrations 0 5 nm in surface waters relative to the iron depleted waters of the surrounding pacific fitzwater s e coale k h gordon m r johnson k s ondrusek m e 1996 iron deficiency and phytoplankton growth in the equatorial pacific deep sea research ii 43 4 6 995 1015 possibly due to island effects associated with the iron rich volcanic soil from the hawaiian islands and or anthropogenic inputs distinct depth maxima in total dissolved cobalt were observed at 400 600 m depth suggestive of the release of metals from the shelf area of comparable depth that surrounds these islands

paleoliquefaction in christchurch new zealand liquefaction during the 2010 moment magnitude mw 7 1 darfield earthquake and large aftershocks known as the canterbury earthquake sequence caused severe damage to land and infrastructure in christchurch new zealand liquefaction occurred at mw weighted peak ground accelerations pga7 5 as low as 0 06 g at highly susceptible sites trenching investigations conducted at two sites in eastern christchurch enabled documentation of the geologic expressions of recurrent liquefaction and determination of whether evidence of pre canterbury earthquake sequence liquefaction is present excavation to water table depths 1 2 m below surface across sand blow vents and fissures revealed multiple generations of canterbury earthquake sequence liquefaction feeder dikes that crosscut holocene to recent fluvial and anthropogenic stratigraphy canterbury earthquake sequence dikes crosscut and intrude oxidized and weathered dikes and sills at both sites that are interpreted as evidence of pre canterbury earthquake sequence liquefaction crosscutting relationships combined with 14c dating constrain the timing of the pre canterbury earthquake sequence liquefaction to post a d 1660 to pre ca a d 1905 at one site and post a d 1415 to pre ca a d 1910 at another site the pga7 5 of five well documented historical earthquakes that caused regional damage between 1869 and 1922 are approximated for the study sites using a new zealand specific ground motion prediction equation only the june 1869 mw 4 8 christchurch earthquake produces a median modeled pga7 5 that exceeds the pga7 5 0 06 g threshold for liquefaction prehistoric earthquakes sourced from regional faults including the 1717 alpine fault mw 7 9 0 3 and ca 500 600 yr b p mw 7 1 porters pass fault earthquakes provide additional potential paleoseismic sources for pre canterbury earthquake sequence liquefaction the recognition of pre canterbury earthquake sequence liquefaction in late holocene sediments is consistent with hazard model based predicted return times of pgas exceeding the liquefaction triggering threshold in christchurch residential development in eastern christchurch from ca 1860 to 2005 occurred in areas where geologic evidence for pre canterbury earthquake sequence liquefaction was present highlighting the potential of paleoliquefaction studies to predict locations of future liquefaction and to contribute to seismic hazard assessments and land use planning

on the recent elevation changes at the flade isblink ice cap northern greenland 1 we have used radar altimeter 2 ra 2 onboard esa s envisat and geosciences laser altimeter system glas onboard nasa s icesat to map the elevation change of the flade isblink ice cap fiic in northern greenland based on ra 2 data we show that the mean surface elevation change of the fiic has been near zero 0 03 0 03 m a between fall 2002 and fall 2009 we present the elevation change rate maps and assess the elevation change rates of areas above the late summer snow line 0 09 0 04 m a and below it 0 16 0 05 m a the glas elevation change rate maps show that some outlet glaciers previously reported to have been in a surge state are thickening rapidly using the ra 2 measured average elevation change rates for different parts of the ice cap we present a mass change rate estimate of 0 0 0 5 gt a for the fiic we compare the annual elevation changes with surface mass balance smb estimates from a regional atmospheric climate model racmo2 we find a strong correlation between the two r 0 94 and p 0 002 suggesting that the surface elevation changes of the fiic are mainly driven by net smb the correlation of modeled net smb and measured elevation change is strong in the southern areas of the fiic r 0 97 and p 0 0005 but insignificant in the northern areas r 0 38 and p 0 40 this is likely due to higher variability of glacier flow in the north relative to the south

evidence for liquefaction identified in peeled slices of holocene deposits along the lower columbia river washington peels made from 10 geoslices beneath a riverbank at washington9s hunting island 45 km inland from the pacific coast aid in identifying sand that liquefied during prehistoric earthquakes of estimated magnitude 8 9 at the cascadia subduction zone each slice was obtained by driving sheetpile and a shutter plate to depths of 6 8 m the resulting sample as long as 8 m had a trapezoidal cross section 42 55 cm by 8 cm the slicing created few artifacts other than bending and smearing at slice edges each slice is dominated by well stratified sand and mud deposited by the tidal columbia river nearly 90 of the sand is distinctly laminated the sand contains mud beds as thick as 0 5 m and at least 20 m long and it is capped by a mud bed that contains a buried soil that marks the 1700 cascadia earthquake of estimated magnitude 9 every slice intersected sills and dikes of fluidized sand and many slices show folds and faults as well sills which outnumber dikes mostly follow and locally invade the undersides of mud beds the mud beds probably impeded diffuse upward flow of water expelled from liquefied sand trapped beneath mud beds this water flowed laterally destroyed bedding by entraining fluidizing sand and locally scoured the overlying mud horizontal zones of folded sand extend at least 10 or 20 m and some contain low angle faults many of the folds probably formed while sand was weakened by liquefaction the low angle faults may mark the soles of river bottom slumps or lateral spreads as many as four great cascadia earthquakes in the past 2000 yr contributed to the intrusions folds and faults this subsurface evidence for fluid escape and deformation casts doubt on maximum accelerations that were previously inferred from local absence of liquefaction features at the ground surface along the columbia river the geosliced evidence for liquefaction abounds not only beneath banks riddled with dikes but also beneath banks in which dikes are absent such dike free banks of the columbia river if interpreted without study of postdepositional structures in deposits beneath them provide insufficient basis for setting upper bounds on the strength of shaking from great cascadia earthquakes online material data from outcrop surveys vibracores and penetrometer tests tabular summary of depositional and postdepositional features in geoslices

ka ena volcano a precursor volcano of the island of o ahu hawai i ka ena and wai alu ridges form prominent submarine ridges nw of the island of o ahu hawai i we evaluate whether or not either one of these ridges represents a submarine extension of wai anae volcano on o ahu using new bottom observations geophysical surveys and geochemical data acquired on new samples from the region wai alu ridge has the morphology of a submarine rift zone but is too shallow for its distance from the o ahu shoreline ka ena ridge also is unusually shallow and is surmounted by two topographic shields ka ena and wai alu ridges have similar magmatic and volcanic evolutionary histories beginning ca 5 ma with a submarine shield phase of volcanism that produced high sio 2 low feo tholeiites with higher 208 pb 204 pb than in the adjacent wai anae volcano late shield volcanism included transitional and alkalic rock types with lower sio 2 and enrichment in incompatible elements especially p 2 o 5 nb zr ti and light rare earth elements the transition from shield to late shield stage occurred as the edifice was beginning to emerge from the sea geological observations and k ar ages indicate that ka ena emerged above sea level ca 3 5 ma reaching a maximum height of 4000 m above the abyssal ocean floor and 1000 m above sea level relatively weak gravity anomalies topographic lineaments and the orientation of dike complexes indicate a volcanic structure that is independent of wai anae volcano thus volcanic structure geochemistry and age all indicate a precursor volcano to the island of o ahu which we call ka ena volcano after emergence ka ena volcano tilted 2 to the south we estimate a total volume of 20 27 10 3 km 3 for ka ena volcano taking into account overlapping geometry of concurrently active volcanoes sample compositions from the ka ena landslide deposit are entirely consistent with derivation from ka ena whereas most samples from the wai anae slump are likely derived from wai anae volcano uniformly oriented dikes in the wai anae nw rift zone likely reflect buttressing by a preexisting ka ena volcano unusual isotopic compositions of some wai anae samples including unique hydrous silicic lavas probably reflect interaction with underlying ka ena crust a newly recognized lava flow field on the southern flank of ka ena ridge extends the previously known distribution of secondary volcanism in the kaua i channel putative submarine volcanic activity in the region in 1956 cannot have built a large edifice and is unlikely to have produced pumice that was found on o ahu shores this eruptive activity therefore remains unconfirmed

geoarchaeological evidence of strong prehistoric earthquakes in the new madrid missouri seismic zone sand blows and fissures that cover 10 500 km sup 2 in northeastern arkansas and southeastern missouri attest to the severity of the 1811 1812 earthquake series in the new madrid seismic zone however except for one occurence near new madrid missouri the region has been devoid of any evidence of other major shocks for at least 1 3 ka prior to 1811 and possibly for 9 ka stratigraphic relations and radiocarbon dating at a recently excavated archaeological site near east prairie missouri have revealed liquifaction phenomena attributable to a shock dated to within about 100 yr prior to a d 539 and a probable second one dated between about a d 539 and 991

polygenetic sand volcanoes on the features of liquefaction processes generated by a single event 2012 emilia romagna 5 9 mw earthquake italy one of the most important geological effects generated by the seismic events of emilia romagna italy 2012 was the liquefaction the first earthquake took place on 20th may 5 9 mw and generated liquefaction in the locality of san carlo mainly recorded as large fissure sand volcanoes detailed stratigraphic and sedimentology analyses of these sand bodies indicated the assemblage of rhythmic normal graded beds of sand for many individual sand volcanoes this is interpreted as repeated individual sand extrusions generating polygenetic sand blows for a single earthquake this original analysis made for first time in a case of extensive seismic liquefaction indicates that the different pulses sand extrusion occurred after seismic shaking and therefore no related to the cyclic seismic shearing stimulated by surface seismic waves underground liquefaction of shallow sandy layers and ground cracking assisted by relevant lateral spreading promoted water and sand ejections e w direction localised and repeated ground subsidence and bulging supported by the ejection of the underlying fluidized sediments feedback transient ground undulations and repeated sand ejections the unstable undulating behaviour of the ground reinforced and sustained the liquefaction process through time after the seismic shaking leading the occurrence of polygenetic sand volcanoes in summary the seismic liquefaction is the starting point of the process although only if these sand ejections could promote the instability of the ground since underground sand depletions feedback the liquefaction process through time the process stops when the hydrostatic balance is recovered in the affected zone

associations between sediment architecture and liquefaction susceptibility in fluvial settings the 2010 2011 canterbury earthquake sequence new zealand abstract this study focuses on the sedimentary architecture of sites in the halswell floodplain christchurch new zealand that experienced liquefaction during the 2010 2011 canterbury earthquake sequence we investigated landforms where ejecta were and were not observed and define their 3d geometry and sediment characteristics the first site straddles an abandoned channel of the halswell river that is overlain by a crevasse splay deposit the second site is located on the inside bend of an active meander of the river both sites were severely affected by liquefaction during the darfield and christchurch earthquakes a suite of techniques was used in the characterization of both sites detailed geomorphic and liquefaction mapping with dems derived from lidar ground penetrating radar gpr paleoseismic trenches hand piston cores radiocarbon dating grain size analysis and cone penetration tests potentially liquefiable sands based on their grain characteristics and water saturation were found in many environments within the alluvial setting studied river channel point bar deposits and flood plain the surficial geology of the two study sites is mapped as crevasse splay and point bar deposits however the layers that liquefied were at depth within buried abandoned channel and point bar deposits at the hardwick site and within buried point bar deposits at the marchand site the location of the surface manifestation of liquefaction was characterized by specific geometry of the sedimentary architecture of the alluvial floodplain that facilitated or hindered flow of the slurry of water and entrained sediment towards the surface on the one hand the inclined contacts of paleochannel and point bar deposits created pathways for the liquefied material to travel to the surface on the other hand in the floodplain with no ejecta sand and silty sand layers interfingered with clay lenses lack the specific geometry that facilitates the ejecta at the surface the cpt analysis showed that liquefaction ejecta occurred above a thick homogeneous layer of sand whereas liquefaction ejecta did not occur or sand blows did not form where clay lenses were interfingered with sand at both sites the surface manifestation of liquefaction was mainly located on slightly higher topographic areas suggesting the topography is an additional controlling factor on the surface distribution of liquefaction ejecta in summary the surface manifestation of liquefaction is a result of a specific sediment type that was saturated sedimentary setting that facilitated flow of fluidized sediment to the surface and topographic relief prone to cracking

glaciers dominate eustatic sea level rise in the 21st century ice loss to the sea currently accounts for virtually all of the sea level rise that is not attributable to ocean warming and about 60 of the ice loss is from glaciers and ice caps rather than from the two ice sheets the contribution of these smaller glaciers has accelerated over the past decade in part due to marked thinning and retreat of marine terminating glaciers associated with a dynamic instability that is generally not considered in mass balance and climate modeling this acceleration of glacier melt may cause 0 1 to 0 25 meter of additional sea level rise by 2100

recent elevation changes on the ice streams and ridges of the ross embayment from icesat crossovers 1 we analyze differences in icesat elevation estimates at orbital crossover locations to determine short term rates of elevation change for small regions within the ross embayment of the west antarctic ice sheet a linear regression of crossover elevation difference against time difference gives an estimate of the mean elevation change rate during the icesat mission to date we observe prevalent elevation change in the south with uplift in the upstream end of kamb ice stream at 0 24 0 30 m a 1 and thinning in the parts of whillans ice stream mercer ice stream and the adjacent conway and engelhardt ice ridges at 0 05 0 18 m a 1 these rates of elevation change are too large to be explained by the 0 02 0 03 m a 1 formal regression error by seasonal height variations or by accumulation or densification rate variability suggesting that they reflect real variations stemming from ice dynamics of the region