structures caused by repeated freezing and thawing in various loamy sediments a comparison of active fossil and experimental data in this paper the authors present the results of both macroscopic and microscopic investigations on structure development created by repeated ice lensing in various loamy experiments experimental data are compared with observations performed on active forms in high arctic and alpine mountain environments those observations are also compared with phenomena observed in fossil periglacial formations of western europe platy and short prismatic structure formation is bonded to the hydraulic and thermal conditions during ice segregation when a long series of alternating freezing and thawing affects platy structures the fabric evolves also being influenced by slope and drainage conditions cryoturbations frostcreep and gelifluction can appear they are characterized by specific microfabrics which are better developed with an increasing number of cycles this is clear in experiments where hydraulic and thermal parameters are better controlled vesicles are also a prominent characteristic of the surface horizon in experiments and arctic soils the genesis of vesicles is discussed on the basis of new observations and is related to the mechanical collapse of frost created aggregates under the mechanical work of soil air escape during soil saturation by water at thaw

creep dike intrusion and magma chamber deflation model for the 2000 miyake eruption and the izu islands earthquakes 1 analysis of global positioning system data shows shrinkage of miyake island and the widening between nijima and kozu islands during the period of the miyake island volcanic activity and the ensuing izu islands earthquakes in 2000 the estimated time evolution of a model consisting of a dike creeping faults and a mogi source suggests that a crack opening on miyake island occurred immediately after the start of the seismic activities on 26 june and ended within several days at the west coast of miyake island after the seabed eruption on 27 june magma migrated from miyake island to kozu and nijima islands within several days the estimated volume of intruded magma totals around 1 2 109 m3 associated with the magma intrusion between miyake and kozu islands left lateral and right lateral creep motions occurred in regions off the west coast of miyake island and near kozu island the accumulated moment energy is equivalent to an earthquake of mw 6 6 and 6 6 for right lateral and left lateral creeping faults respectively the estimated magma chamber continued deflation beneath the southwestern part of miyake island from 26 june totaling around 0 12 109 m3 in volume change in addition to the collapse volume of 0 6 109 m3 at the summit of mount oyama on miyake island the volume change on miyake island can be compensated by the migrated magma toward kozu island from the deflation source beneath miyake island the deflation speed of the magma chamber beneath miyake island decreased and increased before and after the eruption of 14 15 july and 18 august suggesting a change in balance of mass influx and draining out rate of the magma chamber

magnetic anisotropy reveals the depositional and postdepositional history of a loess paleosol sequence at nussloch germany anisotropy of magnetic susceptibility ams is employed as a tool to unravel the depositional history of the 17 m thick nussloch p8 weichselian loess sequence located 10 km south of heidelberg germany through an ams study the primary aeolian depositional origin of the magnetic fabrics is evaluated and overprinting due to postdepositional reworking and or deformation is identified primary fabrics along the p8 sequence are defined by near vertical kmin axes and horizontal foliations eight intervals display secondary fabrics characterized by either prolate orientation distributions or oblate orientation distributions with dipping foliation planes these postdepositional fabrics are associated with laminated loess and tundra gley horizons it is proposed that increased moisture due to higher precipitation or enhanced snowmelt and repeated cryogenic processes were able to reorganize and rework the accumulated loess primary aeolian fabrics are archived within 6 45 m of cumulated depth or 38 of the profile and dominantly within the upper pleniglacial units even though maximum susceptibility axes of primary fabrics are statistically well resolved at the specimen e12 10 1 8 6 and population e12 6 level any inferred paleowind directions from the magnetic lineation remains speculative given the low concentration of ferrimagnetic minerals 0 03 wt tundra gley horizons upprofile display primary magnetic fabrics and no major changes in the degree of anisotropy or ams orientation distributions this suggests a weakening in gley induced diagenesis and therefore favorable environmental conditions needed moisture and presence of permafrost active layer to initiate their formation in loess deposits finally pedogenesis has not played an important role in modifying the magnetic fabric since paleosols display the same magnetic fabrics observed in primary loess

a primitive equation ocean circulation model using a general vertical coordinate transformation 1 description and testing of the model the ocean general circulation model of the geophysical fluid dynamics laboratory has been modified to accommodate a generalized vertical coordinate transformation the model with a slightly modified transformation z h is applied to three simple test cases a clear improvement of barotropic and baroclinic topographic rossby waves has been achieved compared with the z coordinate model a somewhat more typical time independent problem for the overflow of dense water masses over a zonal ridge exhibits the potential benefits as well as the flaws of the new model vertically integrated mass transport is very sensitive to changes in bottom slope in regions where planetary and topographic are of comparable magnitudes this translates into large errors in the z model due to the crude approximation to the actual topography the deep flow in the z model does not follow the bottom exactly horizontal overshoots of dense water lead to convective mixing on the southern side of the ridge this can be a serious problem for modeling more realistic overflow situations with the z model increased diapycnal diffusion has been identified as the most serious problem with the terrain following coordinate system for this specific application

formation of afterflow silt loam deposits and structural modification due to drying under warm conditions an experimental and micromorphological approach in earlier papers the authors discussed several micromorphological and textural characteristics of loamy afterflow deposits derived from loess material and formed during overland flow without splash this discussion is completed by considering the critical load concentrations ccr for the start of sedimentation taking into account the hydraulic properties of laminar flow furthermore a remarkable combination of clayey and medium coarse sandy laminae was observed in the deposits produced under laboratory conditions mechanisms are proposed to explain the affinity of these fractions for simultaneous deposition when laminated silt loam deposits are found in the pleniglacial middle loess deposits in the southern part of the netherlands or in the belgian hesbayan loess showing structural modifications for example cracks formed after sedimentation it is not always clear whether these modifications were the results of cold or relatively warm conditions this paper describes micromorphological and laboratory investigations aimed at identifying criteria representative of warm conditions the experiments examined the effect of drying on the structure of laminated silt loam deposits produced by afterflow and enabled the characterization of the modifications formed drying could be done at room temperature with circulating warm air or at temperatures below 0 c elsewhere see coutard and mucher 1985 the influence of drying at temperatures below 0 c on the structures of an afterflow silt loam deposit will be discussed in comparison with the deformation in laminated silt loam deposits due to freeze drying these new formations are small and have only locally influenced the sedimentary structures these structure modifications are formations of cracks dominantly in clay layers and less about 25 per cent of the cracks in very fine silt layers consisting of grains smaller than 10 m in diameter with only very locally deformations of the laminated structure only incidentally the cracks are partly refilled by a subsequent overland flow deposit mostly only followed by sealing of cracks only incidentally the cracks are partly refilled by a subsequent overland flow deposit mostly only followed by sealing of cracks curling or argillaceous laminae maximum 5 mm in upward direction only very locally formations of the tiny waved laminae with a vertical amplitude between 100 and 400 m in combination with the occurrence of vesicles

how does the el nino generated coastal current propagate past the mendocino escarpment during an el nino an internal coastal kelvin wave bore propagates poleward along the west coast of north america leaving behind a steady anomalous coastal jet a nonlinear two layer plane shallow water model is used to determine the amplitude change of the steady coastal current over an escarpment as the el nino generated warm coastal current passes the mendocino escarpment off northern california its amplitude is marginally enhanced in contrast for a cold coastal current the amplitude will be reduced north of the mendocino escarpment when the kelvin wave bore travels over a depth increase the amplitude change is predicted to be much larger than over a depth decrease as in the case of the mendocino escarpment this model is also applicable to bottom water flowing equatorward along a western boundary in this case much larger amplitude changes are found

niveo aeolian deposits and denivation forms with special reference to the great kobuk sand dunes northwestern alaska the geomorphology lithology and chronostratigraphy of extensive late pleistocene inland and river dune sands aeolian sand sheets cover sands and loess deposits of periglacial origin in northwestern europe are well known however the idea that some of these aeolian sediments result from niveo aeolian processes is still an open question as no diagnostic sedimentary features have yet been reported moreover actual niveo aeolian sediments and related denivation forms reported from various cold climate regions are not suitable analogues recent observations in active dune fields in northwestern alaska indicate that interstratification of wind driven snow and sand preferentially occurs on slip faces of transverse barchanoid or parabolic dune ridges annual denivation forms develop e g snow ramparts sinkholes snow hummocks snow meltwater fans and tensional cracks the surface consists of a cracked wet sand layer with a dimpled surface and spongy structure although the preservation potential of these features is low in this specific case similar features may be observed in ancient sediments elsewhere and provide useful palaeoclimatic indicators the niveo aeolian concept should therefore not specifically be related to late pleistocene cover sand deposition in northwestern europe as previously assumed

niveo aeolian sedimentation of loess and sand an experimental and micromorphological approach the concept of a niveo aeolian influence on the genesis of northwest european pleistocene aeolian sand and loess deposits has been advocated in the past both to explain the presence and the absence of lamination field experiments were carried out on artificially deposited alternating layers of sand and snow and of loess and snow to investigate the role of a niveo aeolian mode of deposition on resulting sedimentary structures field observations of sand plots revealed minor changes in surface morphology typical of denivation surfaces the thin sections showed a characteristic porous structure deformations of the depositional structure and indications for erosion and redeposition were limited however the originally smooth aeolian sedimentary surface of the loess changed considerably the thin sections showed also a porous spongy structure indications were found for disturbances by frost action liquefaction during melting of the snow and ice and redeposition of loess by meltwater the experimental results strongly suggest that sand and loess deposited as niveo aeolian material are characterized both by a porous structure and that the original sedimentary structure of the sand is not affected by snowmelt whereas loess becomes non laminated thus the intercalation of snow during sedimentation of sand and loess does not in itself induce a laminated structure

a slow slip event triggered by teleseismic surface waves 1 in recent years slow slip events sse have been observed to occur at regular intervals on the deep portions of subduction zone interfaces these are accompanied by seismic tremor that occurs over their duration it has been observed that tremor activity shows transient modulations in response to earth tides and the passage of seismic waves from distant earthquakes here we show for the first time geodetic evidence for the triggering of an interplate sse itself by teleseismic surface waves this sse in southwest japan which had an equivalent magnitude mw 5 3 and duration of 1 5 days was triggered by the surface waves of a mw 7 6 earthquake in tonga this evidence was captured by a newly deployed sensitive strainmeter network the triggered sse occurred on a place on the plate interface where the recurrence time for such events had almost expired whereas other regions at up to 90 of the recurrence time were not triggered this provides information for the conditions for triggering and generation of sses and perhaps for regular earthquakes

a primitive equation ocean circulation model using a general vertical coordinate transformation 2 application to an overflow problem the version of the ocean general circulation model of the geophysical fluid dynamics laboratory with a generalized vertical coordinate transformation introduced in part 1 is used to study the overflow of a zonal ridge in a coarse resolution grid typical for climate applications the configuration roughly resembles the greenland scotland ridge with respect to scale latitude and height of the ridge reasonable qualitative agreement with observed conditions over the iceland faroe section has been achieved especially when a deeper passage was included at the eastern end of the idealized model ridge upwelling of deep water occurs at the eastern boundary where friction and more importantly diapycnal diffusion accomplish the necessary changes in potential vorticity the overflow consists of intermediate water when the renewal time for the deep water is made much larger than that for intermediate water the meridional mass transport is most sensitive to geometric factors like the height of the ridge frictional and diapycnal processes are crucial for the potential vorticity conversion at the ridge and have a strong effect on the water mass distribution bottom friction increases the near bottom flow across f h lines resulting in a large amount of northern basin deep water south of the ridge this effect can be represented only when the frictional bottom boundary layer is adequately resolved by the numerical grid

m w dependence of the preseismic ionospheric electron enhancements ionospheric electron enhancement was reported to have occurred 40 min before the 2011 tohoku oki mw9 0 earthquake japan by observing total electron content tec with global navigation satellite systems receivers their reality has been repeatedly questioned due mainly to the ambiguity in the derivation of the reference tec curves from which anomalies are defined here we propose a numerical approach based on akaike s information criterion to detect positive breaks sudden increase of tec rate in the vertical tec time series without using reference curves we demonstrate that such breaks are detected 25 80 min before the eight recent large earthquakes with moment magnitudes mw of 8 2 9 2 the amounts of precursory rate changes were found to depend upon background tec as well as mw the precursor times also showed mw dependence and the precursors of intraplate earthquakes tend to start earlier than interplate earthquakes we also performed the same analyses during periods without earthquakes to evaluate the usefulness of tec observations for short term earthquake prediction

deformation of laminated silt loam due to repeated freezing and thawing cycles the effect of repeated freezing and thawing cycles on an experimentally produced laminated silt loam was studied with the purpose of obtaining more insight into the genesis of macro and microstructures observed in the loessic formations of northwestern europe the laminated silt loam was subsequently subjected to 18 cycles of alternate freezing and thawing the minimum temperature recorded after 11 days of frost was 7 c at a depth of 5 cm and 4 c at 29 cm the underlying sediments compact loam except its upper part and sand always remained unfrozen the experiment reproduced a seasonal superficially frozen ground new structures and microfabrics in the form of vesicles platy structures shear planes and micro undulations were created by ice segregation and thawing mechanical stress and subsequent frost creep the impact of the freezing and thawing cycles is very strong all the laminae being deformed or broken judging by the abundance and the diversity of the structures created freezing is a more important process than simple drying without frost as is evidenced by the range in temperature chosen for the experiment and the low number of cycles these structures do not necessarily require severe climatic conditions to develop unlike frost cracks or ice wedge casts they could develop in winter conditions similar to those present today in the french southern alps

the timing of coversand deposition in northwest norfolk uk a cautionary tale abstract coversand deposits consisting largely of reworked fluvial and glaciofluvial sediments blanket the landscape in discrete areas of northern and eastern england a newly discovered zone of coversand deposits has been found in northwest norfolk which shows stratigraphic evidence of episodic sand accretion the presence of involutions within the coversand at leziate signifies the occurrence of post depositional periglacial activity infra red stimulated luminescence irsl dating of feldspars has been undertaken on five samples from four sites within the new coversand zone three of the samples were insufficiently zeroed at deposition to provide accurate dates for deposition of the sand sheets challenging the assumption that coversands are all well bleached with consequent implications for existing thermoluminescence tl dates on uk coversands an irsl age of 12 825 1910 yr for well bleached sands at leziate shows that sand accretion occurred during the period of rapid climate transition at the end of the last glacial late holocene aeolian activity resulted in sand emplacement at ling common

response of loess materials to simulated translocation by water micromorphological observations structural differences between loess material deposits produced by splash flow without splash and by rainwash i e combined splash and flow respectively were reported earlier mucher and de ploey 1977 deposits from splash alone proved to be non layered and had incurred almost no additional particle sorting deposits from flow without splash were well layered while individual laminae displayed excellent sorting rainwash produced poorly layered deposits with poorly sorted individual laminae only horizontal and subhorizontal bedding and no cross bedding were observed similar features appeared in samples from naturally layered loess deposits collected from excavations the present paper focuses on the granulometric character of the artificially created layers experiments normally involved the combined use of an erosion and a sedimentation flume slope angles of the flumes varied mainly form 0 25 to 4 degrees precipitation intensities varied from 7 to 120 mm per hour unit discharges ranged from 0 2 to 9 2 cm3 cm s flow was laminar or smooth turbulent either subcritical or supercritical froude numbers between 0 5 and 3 8 raindrop impact had little influence on the flow velocity and thickness of the surficial water film but it significantly increased transportation capacity and flow competence savat 1976 1977 undisturbed samples were collected during the experiments and impregnated with unsaturated polyester resin thin sections of 20 m thickness were studied under a polarizing microscope comparative observations were made on naturally layered loess materials during rainwash clay size particles are removed and exported whereas laminae with particles from 10 to 50 microns are more frequently produced than those with particles from 10 to 30 microns flow without splash produced relatively more laminae with grains smaller than 30 microns diameter striking in all samples is the absence of laminae composed of 30 50 m grains aggregates were only deposited by smooth turbulent flow either disturbed or undisturbed by raindrop impact in view of the experimental results the naturally formed loess deposits may be interpreted as follows the bulk of the loess from the excavation near tongrinne belgium was reworked under influence of turbulent rainwash only one sample contained laminae consisting of clay particles smaller than 10 m and of particles from 10 30 m respectively suggesting deposition from flow without splash this was taken from a gully infilling a gully fill from the excavation heverlee near leuven belgium is characterized by poorly sorted laminae dominated by the coarser silt fractions this suggests infilling under influence of turbulent rainwash

detection of short term slow slip events along the nankai trough southwest japan using gnss data 1 we detected short term slow slip events sses previously observable only with tilt and strain data along the nankai trough southwest japan using gnss global navigation satellite system data offsets detected in gnss time series using akaike s information criterion helped automatically identify 207 episodes with a motion direction opposite to that of the relative plate motion from june 1996 to january 2012 by nonlinear inversion of the detected displacement we estimated rectangular fault models for 133 probable and 25 possible short term sses over 15 years the sse moment magnitudes range from 5 5 to 6 3 most sse fault models are located in a narrow band of non volcanic tremors on the interfaces of the subducting philippine sea plate large sses moment magnitude mw 6 often occur in western and central shikoku the cumulative slip is distributed heterogeneously along the strike generally decreasing eastward with the maximum slip 50 cm in western shikoku no definite short term sses were found in the kii channel but several short term sses occurred in ise bay both regions are known as tremor gaps the local maximum of the cumulative slip fills in the tremor gap located in ise bay the long term rate of short term sse cumulative moment increased by threefold around 2003 in eastern shikoku whereas it was almost constant in other regions comparison with short term sse catalogues using tilt data suggests that both this study and previous studies missed some sses along the nankai trough a combination of geodetic data is important in the monitoring of the spatiotemporal distribution of short term sses

structural development of sumisu rift izu bonin arc geophysical swath mapping multichannel seismic profiling and ocean drilling data are used to document the structural evolution of sumisu rift and to analyze the pattern of strain resulting from extension of an intraoceanic island arc the 120 km long 30 50 km wide sumisu rift is bounded to the north and south by structural and volcanic highs west of the sumisu and torishima calderas and longitudinally by curvilinear border fault zones with both convex and concave dip slopes the zig zag pattern of normal faults average strikes 337 and 355 indicates extension oriented 076 10 orthogonal to the volcanic arc three oblique transfer zones divide the rift along strike into four segments with different fault trends and uplift subsidence patterns differential strain across the transfer zones is accommodated by interdigitating rift parallel faults and sometimes by cross rift volcanism rather than by strike or oblique slip faults from estimates of extension 2 5 km the age of the rift 2 ma and the accelerating subsidence we infer that sumisu rift is in the early synrift stage of back arc basin formation following an early sag phase half graben formed with synthetically faulted structural rollovers facing large offset 2 2 5 km throw border fault zones in the three northern rift segments the largest faults are on the arc side and dip 60 75 w whereas in the southern segment they are on the west side and dip 25 50 e the present full graben stage is dominated by hanging wall antithetic faulting basin widening by footwall collapse and a concentration of subsidence in an inner rift the hanging wall collapses but not necessarily as a result of border fault propagation from adjacent rift segments whereas the border faults may penetrate the theologically weak lithosphere te 3 km many of the hanging wall and footwall collapse structures are detached only a few kilometers below the seafloor back arc volcanism usually erupted along faults occurs in the rift and along the protoremnant arc during both stages where drilled the arc margin has been uplifted 1 1 0 5 km concurrently with 1 1 km of rift basin subsidence extremely high sedimentation rates up to 6 m kyr in the inner rift have kept pace with synrift faulting created a smooth basin floor and resulted in sediment thicknesses that mimic the differential basin subsidence a linear zone of weakness caused by the greater temperatures and crustal thickness along the arc volcanic line controls the initial locus of rifting rifts are better developed between the arc edifices intrusions may be accommodating extensional strain adjacent to the arc volcanoes no obvious correlations are observed between the rift structures and preexisting cross arc trends

on stratified flow over a ridge intersecting coastlines abstract the adjustment between two interconnecting basins of stratified fluid resulting from the formation of a pool of dense water in one is investigated with an 18 level numerical general circulation model cycm it is found that basic features of the adjustment i e i the generation of low frequency coastally trapped kelvin waves which carry information about the alongshore pressure gradient created by the denser water toward the dividing ridge ii the subsequent generation of barotropic double kelvin waves by the jebar joint effect of baroclinicity and relief effect which propagate infinitely rapidly along the ridge setting up an anticyclonic gyre iii the generation of further coastally trapped kelvin waves at the opposite coast due to an alongshore pressure gradient created by upwelling at the ridge edge associated with the closure of the barotropic gym iv the generation of a coastally confined cyclonic gyre at the opposite ridge by the jebar effect and viscous and diffusive

holocene palaeosols and aeolian activities in the umimmalissuaq valley west greenland aeolian sand sheets and active dunefields preserve an ancient holocene land surface represented by palaeosols that occur around the present ice margin in the kangerlussuaq area west greenland to determine the relation between holocene aeolian activities and periods of soil formation both substantially dependent on the deglaciation history palaeosols aeolian sand sheets and dunefields were analysed using field data grain size analyses optically stimulated luminescence dating and ams 14c data in an area of about 15 km2 of the umimmalissuaq valley palaeosols are developed close to the ice margin 60 wt are comparable with aeolian sand sheets currently formed at greater distances 4 5 km from the present ice margin we propose a transport distance for fine aeolian sediments in which the palaeosols are formed of at least 4 km from inboard of the present ice margin soil for

quasi periodic slow slip events in the afterslip area of the 1996 hyuga nada earthquakes japan 1 the time evolution of afterslip on a plate boundary experiencing interplate earthquakes is expected to show logarithmic decay the global positioning system network in japan has been monitoring transient deformation since the occurrence of two large interplate earthquakes with moment magnitudes of 6 8 and 6 7 in the hyuga nada area southwest japan in 1996 the spatial and temporal evolution of aseismic interplate slip based on crustal deformation data indicates that afterslip followed the two earthquakes and gradually declined to background rates by around 2004 with total moment magnitude of 7 3 however quasi periodic slow slip events suddenly began within the afterslip area in 2005 with approximately one year duration and two year recurrence interval the moment magnitudes of the three slow slip events since january 2005 range from 6 7 to 6 8 this differs greatly from the expected behavior of logarithmic decay over time both velocity strengthening and velocity weakening rate and state modes have been implicated as the cause of afterslip whose location is complementary to the main shock area of velocity weakening while a slow slip event occurs in the velocity weakening area with different frictional properties from those of an afterslip area in light of the seemingly different frictional properties the coexistence of afterslip and slow slip events in the same area would provide additional information about precisely how the plate interface is behaving the monitoring of these slow slip events should give the clues to understanding the coexistence of long term afterslip and slow slip events and the increasing risk of earthquakes in neighboring areas

sublimation and aeolian sand movement from a frozen surface experimental results from presqu ile beach ontario abstract recent aeolian literature has indicated that sand movement can and does take place on frozen surfaces the winter aeolian process is influenced by the pore ice which binds the sand grains together and increases the surface resistance to wind action sublimation of the frozen moisture provides loose grains of sand which subsequently can be entrained by the wind field experiments carried out on the presqu ile beach ontario in the 1992 1993 winter provide some data on variables which affect sand loss from frozen surfaces because of sublimation sand moisture content determines the resistivity of the surface to sublimation induced sand loss frozen surfaces with higher moisture contents experience less sand loss the existing literature has indicated that temperature plays an important role in the occurrence of sublimation higher temperatures i e temperatures which are closer to 0 c result in higher rates of sublimation however the presqu ile experiments show that wind speed is more strongly correlated with sublimation induced particle loss than temperature or relative humidity higher wind speeds allow sand from the surface and sublimation produced water vapour to be removed from the area thus providing an incentive for further sublimation and sand loss to take place information on the variables which affect sublimation induced sand loss from frozen surfaces can be used to increase understanding of the processes involved in sand movement on frozen surfaces under subzero temperatures

depth extent of the long term slow slip event in the tokai district central japan a new insight 1 temporal changes to interplate coupling and long term aseismic slip in the tokai region of central japan from july 1996 to june 2009 are statically inverted using continuous global positioning system gps data and leveling observations and examined using a new interpretation of aseismic slip in this interpretation the interplate coupling and the aseismic slip should be inferred and compared with reference to a state of no coupling on the plate interface rather than assuming steady state interplate coupling before the occurrence of the aseismic event as previous works have done for this purpose we used original time series data without subtracting any linear trends the inferred distribution shows that the entire period can be divided into three subperiods based on the existence of the aseismic slip area from 2000 to 2005 the strength of the interplate coupling does not change throughout the observed period even though the distribution narrows along the dip direction after the aseismic slip terminates the aseismic slip area inferred in this study based on the no coupling reference was determined to be deeper than the area where the long term slow slip event sse defined as the slip corresponding to the residual displacement from the steady state was hypothesized to have occurred in numerous previous studies the total seismic moment released by the aseismic slip is equivalent to a mw 6 6 earthquake while the sse in previous works was considered to be equivalent to a mw 7 0 to 7 1 earthquake this difference can be attributed primarily to the effects on the interplate coupling which previous studies did not take into account when defining the sse the aseismic slip area coincides well with the distribution of other types of plate interactions such as short term slow slip events and low frequency earthquakes

transient crustal movement in the northern izu bonin arc starting in 2004 a large slow slip event or a slow back arc rifting event abstract the izu bonin arc lies along the convergent boundary where the pacific plate subducts beneath the philippine sea plate horizontal velocities of continuous global navigation satellite system stations on the izu islands move eastward by up to 1 cm year relative to the stable part of the philippine sea plate suggesting active back arc rifting behind the northern part of the arc here we report that such eastward movements transiently accelerated in the middle of 2004 resulting in 3 cm extra movements in 3 years we compare three different mechanisms possibly responsible for this transient movement i e 1 postseismic movement of the 2004 september earthquake sequence off the kii peninsula far to the west 2 a temporary activation of the back arc rifting to the west dynamically triggered by seismic waves from a nearby earthquake and 3 a large slow slip event in the izu bonin trench to the east by comparing crustal movements in different regions the first possibility can be shown unlikely it is difficult to rule out the second possibility but current evidence support the third possibility i e a large slow slip event with moment magnitude of 7 5 may have occurred there

ancient and modern cold climate aeolian sand deposition a review although partly active aeolian sand sheets and dunes cover large areas in the zones of dis continuous permafrost little precise information is available about the influence of cold climate conditions on modern aeolian processes this means that palaeoenvironmental reconstructions in the stabilised mainly late pleistocene dune fields and cover sand regions in the sand belts of the european lowlands and the northern great plains of the usa and canada are necessarily still based on ancient evidence cold climate wind deposits are typically derived from areas of abundant sediment supply like unvegetated flood plains glacial outwash plains till plains and lake shores the common parabolic and transverse dune forms resemble those observed in temperate regions although a variety of periglacial features has been identified in late pleistocene dune and cover sands none of them indicate that permafrost is crucial to aeolian activity specific structures in aeolian strata permit tentative interpretation of the moisture content of depositional sand surfaces the nature of annual sedimentation cycles and the processes by which strata were deposited and or contorted but surprisingly little is known about the role of vegetation in the process of sand accumulation dunes are most informative with respect to reconstructions of past wind regimes which offer important data for verification of palaeoclimatic simulations

the micromorphology of unconsolidated sediments this paper aims to describe the use of thin sections micromorphology in the sedimentology of unconsolidated sediments it provides examples of the use of thin sections in a variety of sedimentary environments from fault gouge through caves and volcanics to aeolian fluviatile marine periglacial and glacial it demonstrates that in the latter three fields the use of micromorphology is relatively widespread and that in glacial sedimentology it has revolutionised our way of thinking about subglacial sediments although micromorphology has been mainly descriptive so far methods of quantification observations are demonstrated some of the important aspects of micromorphology are its use for microstratigraphy and the possibility of relating observations to documented processes thereby allowing a more robust sedimentological interpretation of modern and ancient sediments

geodetic evidence of back arc spreading in the mariana trough 1 repeated gps surveys in the mariana islands show that the mariana block is moving apart from the philippine sea plate the velocities of the islands relative to the philippine sea plate range from about 15 mm yr in the northern islands to about 45 mm yr near guam the data also suggest convergence rates for the mariana forearc with respect to the pacific plate of 35 45 mm yr at 19 n increasing to 55 70 mm yr at 13 5 n in addition the velocity vectors show a slight north south expansion of the arc the estimated location of the euler pole of the mariana forearc with respect to the philippine sea plate is well south of the geographical point where the back arc basin narrows to zero width