holocene reef growth in torres strait the platform and fringing reefs of torres strait are morphologically similar to reefs of the northern great barrier reef to the south except that several are elongated in the direction of the strong tidal currents between the coral sea and the gulf of carpentaria surface and subsurface investigations and radiocarbon dating on yam warraber and hammond islands reveal that the initiation and mode of holocene reef growth reflect antecedent topography and sea level history on the granitic yam island fringing reefs have established in some places over a pleistocene limestone at about 6 m depth around 7000 years bp emergent holocene microatolls of porites sp indicate that the reefs have prograded seawards while sea level has fallen gradually from at least 0 8 m above present about 5800 years bp on the warraber island reef platform drilling near the centre indicated a pleistocene limestone foundation at a depth of about 6 m over which reefs established around 6700 years bp reef growth lagged behind that on yam island microatolls on the mature reef flat indicate that the reef reached sea level around 5300 years bp when the sea was around 0 8 1 0 m above present on the reef flat on the western side of hammond island bedrock was encountered at 7 8 m depth overlain by terrigenous mud a progradational reef sequence of only 1 2 m thickness has built seaward over these muds as sea level has fallen over the past 5800 years reef flat progradation on these reefs is interpreted to have occurred by a series of stepwise buildouts marked by lines of microatolls parallel to the reef crest marking individual coalescing coral heads detrital infill has occurred between these this pattern of reef progradation is consistent with the radiocarbon dating results from these reefs and with seismic investigations on the torres reefs

evaluation of various satellite sensors for waterline extraction in a coral reef environment majuro atoll marshall islands abstract the ability of five satellite sensor bands ikonos band 4 terra aster bands 3 and 4 and landsat etm bands 4 and 5 was examined to extract the waterline at coral reef coasts majuro atoll marshall islands using different wavelength regions near infrared nir and shortwave infrared swir and different spatial resolutions 4 15 and 30 m after performing georeferencing and normalization of the images density slicing was used to extract the waterline comparisons of extracted waterline positions with ground level data for eight transects and global positioning system gps tracks of the island shorelines showed that nir bands were superior to swir bands because of the characteristics of the coral reef coasts including a lack of foam and suspended sediments which can affect the nir wavelength region if present and the presence of remnant water on reef flats during low tide which can affect the swir wavelength region a linear relationship was found between the estimation errors of waterline positions and the spatial resolutions of the nir sensors analysis on estimation errors and image costs showed that terra aster band 3 was the most cost effective sensor for extracting waterlines with reasonable accuracy the results serve as general guidelines for using satellite derived data to estimate intertidal topography and detect and monitor shorelines in coral reef environments

ionospheric simulation compared with dynamics explorer observations for november 22 1981 dynamics explorer de 2 electric field and particle data have been used to constrain the inputs of a time dependent ionospheric model tdim for a simulation of the ionosphere on november 22 1981 the simulated densities have then been critically compared with the de 2 electron density observations this comparison uncovers a model data disagreement in the morning sector trough generally good agreement of the background density in the polar cap and evening sector trough and a difficulty in modeling the observed polar f layer patches from this comparison the consequences of structure in the electric field and precipitation inputs can be seen this is further highlighted during a substorm period for which de 1 auroral images were available using these images a revised dynamic particle precipitation pattern was used in the ionospheric model the resulting densities were different from the original simulation with this revised dynamic precipitation model improved density agreement is obtained in the auroral polar regions where the plasma convection is not stagnant however the dynamic study also reveals a difficulty of matching dynamic plasma convection is not stagnant however the dynamic study also reveals a difficulty of matching dynamic auroral patterns with static empirical convection patterns in this case more the matching of the models produced intense auroral precipitation in a stagnation region which in turn led to exceedingly large tdim densities less

rapid water exchange between the lagoon and the open ocean at majuro atoll due to wind waves and tide current measurements and conductivity temperature depth surveys of the lagoon and ocean at majuro atoll the republic of the marshall islands were made from january 10 to 24 1997 a vertically integrated tidal current model reproduced qualitatively well tidal ellipses calculated from the observed current measurements by fourier transform a three dimensional robust diagnostic residual current model explained the major features observed in the current measurements averaged over the dominant tidal cycles we used the diagnostic model to examine the effects of wind stress radiation stress density gradients and tidal stress on the exchange of water between the lagoon and the ocean wind effectively mixes the lagoon water in approximately 2 weeks tidal flushing appears to be restricted to a small area near the main channels connecting the lagoon to the ocean cross reef flat currents induced by radiation stress and flowing to the deep channels in the center of the northern boundary form the dominant mechanism for exchange between the lagoon and the open ocean causing water to exchange completely with the ocean in about 15 days computer generated particles tracked through the lagoon showed that radiation stress is also the main forcing mechanism for particle export from the lagoon however the coupling of tidal exchange through the calalin channel and wind stress induced mixing in the lagoon could also provide a significant export mechanism particularly for particles originating uniformly inside the lagoon

paleomagnetic evidence for the miocene counter clockwise rotation of northeast japan rifting process of the japan arc paleomagnetic results have been obtained from more than 700 oriented samples in igneous rocks of cretaceous to miocene age from northeast japan the remanent magnetizations of welded tuffs with age between 32 ma and 21 ma old from 17 widely distributed sampling sites in northeast japan are fairly well grouped with a mean ofd 41 2 i 56 5 95 7 2 the remanent magnetization of welded tuffs of 14 ma and 11 ma from 4 sites shows a northerly direction d 11 7 i 60 5 95 15 3 these data imply that northeast japan was apparently subjected to a counter clockwise rotation through 47 14 about a vertical axis on the representative point of northeast japan 141 e 39 n during the past 21 ma comparing with the period of the clockwise rotation of southwest japan the differential rotation between northeast japan and southwest japan is concluded to have occurred concurrently during the period between 21 ma and 12 ma a rifting model of the japan arc is proposed northeast japan rotated counter clockwise through 50 about a northern pivot at 146 e 44 n while southwest japan rotated clockwise through 54 about a southern pivot at 129 e 34 n the differential rotation about different rotation pivots gives rise to the opening of a diamond shaped back arc basin the japan sea

landsliding in partially saturated materials 1 rainfall induced landslides are pervasive in hillslope environments around the world and among the most costly and deadly natural hazards however capturing their occurrence with scientific instrumentation in a natural setting is extremely rare the prevailing thinking on landslide initiation particularly for those landslides that occur under intense precipitation is that the failure surface is saturated and has positive pore water pressures acting on it most analytic methods used for landslide hazard assessment are based on the above perception and assume that the failure surface is located beneath a water table by monitoring the pore water and soil suction response to rainfall we observed shallow landslide occurrence under partially saturated conditions for the first time in a natural setting we show that the partially saturated shallow landslide at this site is predictable using measured soil suction and water content and a novel unified effective stress concept for partially saturated earth materials

a total electron content space weather study of the nighttime weddell sea anomaly of 1996 1997 southern summer with topex poseidon radar altimetry this paper reports on a total electron content space weather study of the nighttime weddell sea anomaly overlooked by previously published topex poseidon climate studies and of the nighttime ionosphere during the 1996 1997 southern summer to ascertain the morphology of spatial tec distribution over the oceans in terms of hourly geomagnetic longitudinal and summer winter variations the topex tec magnetic and published neutral wind velocity data are utilized to understand the underlying physical processes the tec results are combined with inclination and declination data plus global magnetic field line maps to investigate spatial and temporal tec variations geographic magnetic latitudes and local times are computed as results show the nighttime weddell sea anomaly is a large 1 600 2 22 million km2 estimated for a steady ionosphere space weather feature extending between 200 e and 300 e geographic it is an ionization enhancement peaking at 50 s 60 s 250 e 270 e and continuing beyond 66 s it develops where the spacing between the magnetic field lines is wide medium easterly declination is large medium 20 50 and inclination is optimum 55 s its development and hourly variations are closely correlated with wind speed variations there is a noticeable 43 reduction in its average area during the high magnetic activity period investigated southern summer nighttime tecs follow closely the variations of declination and field line configuration and therefore introduce a longitudinal division of four indian western eastern pacific atlantic northern winter nighttime tecs measured over a limited area are rather uniform longitudinally because of the small declination variation topex maps depict the expected strong asymmetry in tec distribution about the magnetic dip equator

distribution pattern of earthquake induced landslides triggered by the 12 may 2008 wenchuan earthquake abstract this paper presents the preliminary results of an extensive study of the mapping the distribution of landslides triggered by the wenchuan earthquake in sichuan province china on 12 may 2008 an extensive landslide interpretation was carried out using a large set of optical high resolution satellite images e g aster alos cartosat 1 spot 5 and ikonos as well as air photos for both the pre and post earthquake situation landslide scarps were mapped as points using multi temporal visual image interpretation taking into account shape tone texture pattern elevation and ridge and valley orientation nearly 60 000 individual landslide scarps were mapped the landslide distribution map was compared with the inventory map that was prepared directly after the earthquake which contains about 11 000 individual landslide points through the calculation of normalized landslide isopleths maps remarkable differences were observed as the earlier inventory mapping did not consider the pre earthquake situation and did not consider all individual landslides as part of the landslide inventory landslides were identified that had blocked the drainage and had formed landslide dams the landslide distribution was compared with a number of aspects such as the seismic parameters distance to epicenter distance to fault rupture co seismic fault geometry and co seismic slip distribution and geology the most remarkable correlation found was with the co seismic slip distribution and the fault geometry landslide distribution in the section of the fault that had mainly a thrust component with low angle fault plane was found to be much higher than the sections that had steeper fault angles and a major strike slip component

comparison of model high latitude electron densities with millstone hill observations model predictions of the diurnal variations of plasma convection velocities and electron densities in the high latitude ionosphere were compared with millstone hill incoherent scatter radar observations for an equinox day on which there was moderate magnetic activity on the observation day three major morphological features were evident at 500 km including a dayside high density region a nightside mid latitude trough and a region of slightly enhanced densities in the auroral zone although the dayside high density region was due to solar euv radiation it was not symmetrical about local noon 1000 1900 lt sector owing to the effect of horizontal transport the nightside mid latitude trough was the deepest the widest and reached its most equatorward latitude in the morning sector the model was able to reproduce these two features quite accurately in the dusk sector the trough was filled in and its latitudinal extent was restricted by a discrete auroral arc a feature not included in the ionospheric model except for this arc region the enhanced electron densities in the auroral zone were adequately described by the average precipitation fluxes used in the model the observed plasma drift velocities were consistent with a two cell asymmetric convection pattern with enhanced flow in the dusk sector outside the polar cap the fall off of the magnetospheric potential with latitude was proportional to the inverse of the sine of colatitude to the fourth power the convection pattern employed in the model included these features and had a 60 kv cross polar cap potential efforts to reproduce the observed behavior by using a larger cross polar cap potential 90 kv or a symmetric pattern are also presented these were generally less successful and demonstrate the sensitivity of the morphology of the f region at high latitudes to the convection process

investigating the relationships among the south atlantic magnetic anomaly southern nighttime midlatitude trough and nighttime weddell sea anomaly during southern summer 1 this study utilized the multi instrument data of the defense meteorological satellite program to investigate the evening nighttime topside ionosphere during the 1996 1997 southern summer a series of regional surface maps were constructed and permitted the tracking of the topside ionosphere s plasma density features plasma composition thermal structures and vertical and horizontal plasma flows these maps tracked a complete nighttime weddell sea anomaly wsa and strong horizontal plasma flows that registered the high conductivity regions of the south atlantic magnetic anomaly sama these regions developed over the southeastern pacific just equatorward of the wsa and over the south atlantic a heavy ion stagnation trough developed poleward of the sama affected regions thus the trough appeared on the wsa s equatorward side during periods of increasing magnetic activity the plasmapause was the wsa s poleward boundary a statistical study modeled the trough s magnetic activity dependence and revealed a strong east west hemispherical difference that was due to the sama effects when the ae6 was 0 nt the trough appeared at 57 49 2 82 s geomagnetic over the southwestern hemisphere owing to the sama s special electrodynamic effects the trough developed at lower latitudes 42 39 3 04 s over the southeastern hemisphere meanwhile the plasmapause occurred at 62 5 4 s and the wsa s peak appeared at 56 2 4 s hence there was a 20 lat separation between the trough and the plasmapause over the southeastern hemisphere between 210 e and 330 e geographic the wsa filled this gap with increasing magnetic activity the trough in the sama affected regions moved poleward at a rate of 0 0157 0 004 s nt elsewhere it had a 0 0196 0 002 s nt equatorward movement

comparison of simultaneous chatanika and millstone hill observations with ionospheric model predictions as part of the mithras program the chatanika and millstone hill incoherent scatter radars made coordinated observations of the polar ionosphere on june 27 and 28 1981 we compare these data with predictions made by a high latitude ionospheric model qualitatively the same features are evident in both the model and the radar data fairly constant densities on the dayside with a mid latitude trough forming poleward of 65 degrees around 1900 mlt magnetic local time this trough is seen to extend equatorward with increasing mlt such that the minimum densities occurring in the trough appear just after midnight around 60 degrees dipole latitude these features are primarily understood in terms of different regions of convection further influenced by photoionization and vertical transport the only areas of major disagreement between the measurements and model are noted in the auroral oval and at a portion of the times during which substorms occurred quantitatively equally good agreement is obtained between the model predictions and the radar data the densities predicted by the model are usually within 25 of those measured by the radars although appreciable differences occur in some regions of the ionosphere at certain times

response of reef island shorelines to seasonal climate oscillations south maalhosmadulu atoll maldives 1 the maldives experience seasonal shifts in monsoon winds from the west northwest to northeast the morphologic response of reef island beaches and shorelines to these predictable shifts in climate was examined on eight islands in south maalhosmadulu atoll based on global positioning system surveys of island shoreline planform in january and june 2002 and february 2003 surveys show that islands exhibit large gross changes 31 120 of beach area in shoreline position between seasons such changes reflect large reversals in sediment flux of 9 23 103 m3 on a biannual basis driven by seasonal reversals in wind and wave conditions annual net change is small 2 15 suggesting islands spatially exhibit a dynamic equilibrium an island oscillation index io is defined that describes the spatial extent of shoreline change around islands island shape ellipticity e is found to be positively correlated with io in the expression io 1 021e 0 275 suggesting island shape is a better indicator of the susceptibility of island shorelines to morphological change than wave energy exposure

evidence for smoothly falling sea level relative to north queensland australia during the past 6 000 yr post glacial sea level curves are expected to differ between different parts of the world as a result of global isostatic changes1 or perhaps other forms of geoidal changes2 i report here results from the inner part of the northern great barrier reef which seem to show a pattern of smoothly falling sea level during the past 6 000 yr the results are consistent with stratigraphical results from prograded mangrove coasts on the nearby north queensland mainland the region is remote from the tectonically active margin of the south west pacific ocean and the results contribute to the global data set relevant to isostatic changes being assembled by the international sea level project igcp project no 61 they also provide a baseline relevant to holocene coral reef growth in the inner great barrier reef

holocene sea level changes and barrier reef formation on an oceanic island palau islands western pacific abstract internal facies and development of an oceanic island s barrier reef were revealed by the stratigraphical study of six drill cores in palau islands western pacific the holocene reef development is primarily constrained at its foundation by the antecedent topography of pleistocene substratum holocene barrier reef is an increment on the pleistocene barrier reef which had been subaerially exposed during glacial stages about 8300 cal year bp calibrated calendar years b p branching acropora facies initially formed a bank on the seaward side of a pleistocene limestone surface with a vertical accumulation rate as high as 30 m ka ka 1000 years after 7200 cal year bp when the sea level rise rate decreased reef crest facies caught up with the sea surface with an accumulation rate of less than 2 2 m ka corals found in the reef crest facies are similar to the present day reef crest corals dominated by acropora digitifera and a humilis after the reef crest was formed bioclastic sand and gravel facies prograded lagoonward of the reef crest and consisted mostly of reef derived materials the construction of patch reefs post dated the barrier reef formation the mature barrier reef provided calm conditions inside the lagoon which then led to the construction of patch reefs and fringing reefs sea level changes deduced from the accumulation curves show rapid rise before 7200 cal year bp followed by a slight rise of 4 m at its maximum this change in sea level rise rate inspired the change in reef facies from branching acropora to reef crest

super plasma fountain and equatorial ionization anomaly during penetration electric field 1 relative importance of diffusion electric field and neutral wind on equatorial plasma fountain and equatorial ionization anomaly eia during a strong daytime eastward prompt penetration electric field ppef event are evaluated using the sheffield university plasmasphere ionosphere model and the recorded ppef during the super geomagnetic storm of 9 november 2004 the fountain rapidly develops into a super fountain during the ppef event the super fountain becomes strong with less poleward turning of the velocity vectors in the presence of an equatorward wind that reduces or stops the downward velocity component due to diffusion and raises the ionosphere to high altitudes of reduced chemical loss the eia crests in peak electron density and total electron content shift rapidly to higher than normal latitudes during the ppef event however the crests become stronger than normal only in the presence of an equatorward wind the results suggest that the presence of an equatorward neutral wind is required to produce a strong positive ionospheric storm during a daytime eastward ppef event the equatorward neutral wind need not be a storm time wind though stronger wind can lead to stronger ionospheric storms

japan sea opening history and mechanism a synthesis the respective tectonic effects of back arc spreading and continental collision in asia are considered either as two independent processes or as closely interrelated extrusion tectonics assumes that the opening of the south china sea and the left lateral motion along the red river fault are geometrically linked in a pull apart manner this model is not accepted by several workers because the structural link between the two processes is not clearly demonstrated in the case of the japan sea we can show without ambiguity that back arc opening was controlled by large intracontinental strike slip faults which can be easily understood as effects of the india asia collision far from the indenter the japan sea opened in the early miocene in a broad pull apart zone between two major dextral strike slip shear zones the first one extends from north sakhalin to central japan along 2000 km it has accommodated about 400 km of finite displacement deformation along it varies from dextral transpression in the north to dextral transtension in the south the second is between korea and sw japan and has accommodated a smaller displacement of about 200 km the extensional domain in between lies in the back arc region of japan distributed stretching of the arc crust resulted in the formation of most of the japan sea while localized oceanic spreading at the southern termination of the eastern transpressional shear zone shaped the japan basin the first oceanic crust was formed in a small triangle based on the eastern shear zone and spreading propagated westward inside the pull apart region timing of oceanic crust formation of formation of the dextral shear zones and of block rotation in between as well as the internal structure of the basins and the geometry of deformation along the master shear zones are used to reconstruct the opening history this evolution is discussed by comparison to other manifestations of the arc and back arc activity such as the history of sedimentation and volcanism the paper then suggests that the collision of india can have tectonic consequences as far north as japan and sakhalin and describes the geometrical relation of back arc opening there and diffuse extrusion

geology tectonics and the 2002 2003 eruption of the semeru volcano indonesia interpreted from high spatial resolution satellite imagery abstract the paper illustrates the application of high spatial resolution satellite images in interpreting volcanic structures and eruption impacts in the tengger semeru massif in east java indonesia we use high spatial resolution images ikonos and spot 5 and aerial photos in order to analyze the structures of semeru volcano and map the deposits geological and tectonic mapping is based on two dems and on the interpretation of aerial photos and four spot and ikonos optical satellite images acquired between 1996 and 2002 we also compared two thermal surface kinetic temperature aster images before and after the 2002 2003 eruption in order to delineate and evaluate the impacts of the pyroclastic density currents semeru s principal structural features are probably due to the tectonic setting of the volcano a structural map of the tengger semeru massif shows four groups of faults orientated n40 n160 n75 and n105 to n140 conspicuous structures such as the se trending horseshoe shaped scar on semeru s summit cone coincide with the n160 trending faults the direction of minor scars on the east flank parallels the first and second groups of faults the semeru composite cone hosts the currently active jonggring seloko vent this is located on and buttressed against the mahameru edifice at the head of a large scar that may reflect a failure plane at shallow depth dipping 35 towards the se this failure plane may correspond to a weak basal layer of weathered volcaniclastic rocks of tertiary age we suggest that the deformation pattern of semeru and its large scar may be induced by flank spreading over the weak basal layer of the volcano it is therefore necessary to consider the potential for flank and summit collapse in the future the last major eruption took place in december 2002 january 2003 and involved emplacement of block and ash flows we have used the 2003 aster surface kinetic temperature image to map the 2002 2003 pyroclastic density current deposits we have also compared two 10 m pixel images acquired before and after the event to describe the extent and impact of an estimated volume of 5 45 106 m3 of block and ash flow deposits an ash rich pyroclastic surge escaped from one of the valley confined block and ash flows at 5 to 8 km distance from the crater and swept across the forest and tilled land on the sw side of the bang river valley downvalley the temperature of the pyroclastic surge decreased and a mud rich deposit coated the banks of the bang river valley thus hazard mitigation at semeru should combine 1 continuous monitoring of the eruptive activity through an early warning system and 2 continuous remote sensing of the morphological changes in the drainage system due to the impact of frequent pyroclastic density currents and lahars

remote sensing techniques for landslide studies and hazard zonation in europe abstract an inventory is presented of researches concerning the use of remote sensing for landslide studies and hazard zonation as mainly carried out in the countries belonging to the european community an overview is given of the applicability of remote sensing in the following phases of landslide studies 1 1 detection and classification of landslides special emphasis is given to the types of imagery required at different scales of analysis 2 2 monitoring the activity of existing landslides using g p s photogrammetrical techniques and radar interferometry 3 3 analysis and prediction in space and time of slope failures the different factors required in a landslide hazard study are evaluated and the optimum remote sensing imagery for obtaining each of these factors is indicated examples are given of research work carried out in these three phases from ec countries finally an evaluation is given of the aspects of uncertainty associated with the use of remote sensing data and conclusions are given as to the incorporation of remote sensing techniques within the overall framework of techniques

landslide hazard evaluation a review of current techniques and their application in a multi scale study central italy in recent years growing population and expansion of settlements and life lines over hazardous areas have largely increased the impact of natural disasters both in industrialized and developing countries third world countries have difficulty meeting the high costs of controlling natural hazards through major engineering works and rational land use planning industrialized societies are increasingly reluctant to invest money in structural measures that can reduce natural risks hence the new issue is to implement warning systems and land utilization regulations aimed at minimizing the loss of lives and property without investing in long term costly projects of ground stabilization government and research institutions worldwide have long attempted to assess landslide hazard and risks and to portray its spatial distribution in maps several different methods for assessing landslide hazard were proposed or implemented the reliability of these maps and the criteria behind these hazard evaluations are ill formalized or poorly documented geomorphological information remains largely descriptive and subjective it is hence somewhat unsuitable to engineers policy makers or developers when planning land resources and mitigating the effects of geological hazards in the umbria and marche regions of central italy attempts at testing the proficiency and limitations of multivariate statistical techniques and of different methodologies for dividing the territory into suitable areas for landslide hazard assessment have been completed or are in progress at various scales these experiments showed that despite the operational and conceptual limitations landslide hazard assessment may indeed constitute a suitable cost effective aid to land use planning within this framework engineering geomorphology may play a renewed role in assessing areas at high landslide hazard and helping mitigate the associated risk

assessment of gps global ionosphere maps gim by comparison between code gim and topex jason tec data ionospheric perspective 1 we performed a comprehensive comparison between gps global ionosphere map gim and topex jason t j total electron content tec data for the periods of 1998 2009 in order to assess the performance of gim over the global ocean where the gps ground stations are very sparse using the gim model constructed by the center for orbit determination in europe at the university of bern the gim tec values were obtained along the t j satellite orbit at specific locations and times of measurements and then binned into various geophysical conditions for direct comparison with the t j tec on the whole the gim model was able to reproduce the spatial and temporal variations of the global ionosphere as well as the seasonal variations however the gim model was not accurate enough to represent the well known ionospheric structures such as the equatorial anomaly the weddell sea anomaly and the longitudinal wave structure furthermore a fundamental limitation of the model seems to be evident in the unexpected negative differences i e gps t j at night represent the plasmaspheric contribution to gps tec which is maximized reaching up to 100 of the corresponding t j tec values in the early morning sector in particular the relative differences decreased with increasing solar activity and this may indicate that the plasmaspheric contribution to the maintenance of the nighttime ionosphere does not increase with solar activity which is different from what we normally anticipate

development of microcracks in granites during cooling and uplift examples from the variscan basement in ne bavaria germany abstract microcracks in two late variscan granites in ne bavaria provide information about regional paleostress directions and p t conditions during cooling and uplift in both granites three prominent generations of healed microcracks called ci cii ciii constitute an orthorhombic fabric the orientation of which is closely related to the mesoscopic joint pattern we present a model relating this orthorhombic crack fabric not only to external deviatoric stresses but also to internal stresses on the grain scale resulting from the strong thermal contraction of quartz relative to the feldspar framework at the deepest level 1 subvertical steep ci cracks developed normal to 3 and selectively in the quartz their formation caused a stress uncoupling of quartz aggregates from the external 3 direction so that further contraction of quartz produced steep cii cracks normal to 2 forming bridges between ci cracks at higher levels 2 subvertical the same process reactivated the ci cracks and now formed horizontal crack bridges ciii p t estimates based on fluid inclusion data and inferred geothermal gradients are 250 400 c at 1 5 3 kbar for ci cii cracks and 150 200 c at 1 2 kbar for ciii cracks the orientation of the younger open cracks which formed at higher crustal levels partly corresponds to the present regional stress field

seasonal variations of the high latitude f region for strong convection we combined a plasma convection model with an inosphere atmospheric composition model in order to study the seasonal variations of the high latitude f region for strong convection our numerical study produced time dependent three dimensional ion density distributions for the ions no sup o sub 2 sup n sub 2 sup o sup n sup and he sup we covered the high latitude ionosphere above 42 sup 0 n magnetic latitude and at altitudes between 160 and 800 km for a time period of one complete day from our study we found the following 1 for strong convection the high altitude ionosphere exhibits a significant ut variation both during winter and summer 2 in general the electron density is lower in winter than in summer however at certain universal times the electron density in the dayside polar cap is larger in winter than in summer owing to the effect of the mid latitude winter anomaly in combination with strong antisunward convection 3 in both summer and winter the major region of low electron density is associated with the main or mid latitudde trough the trough is deeper and its local time extend is much greater in winter than in summer 4 typically the electron density exhibits a muchmore larger variation with altitude in winter than in summer 5 the ion composition and molecular atomic ion transition altitude are highly ut dependent in both summer and winter 6 the ion composition also displays a significant seasonal variation however at a given location the seasonal variation can be opposite at different universal times 7 high speed convection cells should display a marked seasonal variation with a much larger concentration of molecular ions near the f region peak in summer than in winter less

seasonal dependence of northern high latitude upper thermospheric winds a quiet time climatological study based on ground based and space based measurements this paper investigates the large scale seasonal dependence of geomagnetically quiet time northern high latitude f region thermospheric winds by combining extensive observations from eight ground based optical remote sensing and three space based optical remote sensing and in situ instruments to provide a comprehensive picture of the wind morphology data are assimilated into a seasonal empirical vector wind model as a function of season latitude and local time in magnetic coordinates the model accurately represents the behavior of the constituent data sets there is good general agreement among the various data sets but there are some major offsets between goce and the other data sets especially on the duskside the assimilated wind patterns exhibit a strong and large duskside anticyclonic circulation cell sharp latitudinal gradients in the duskside auroral zone strong antisunward winds in the polar cap and a weaker tendency toward a dawnside cyclonic circulation cell the high latitude wind system shows a progressive intensification of wind patterns from winter to equinox to summer the latitudinal extent of the duskside circulation cell does not depend strongly on season zonal winds show a mainly diurnal variation two extrema around polar and middle latitudes and semidiurnal variation four extrema at auroral latitudes meridional winds are primarily diurnal at all high latitudes the strength of zonal winds channeling through the auroral zone on the duskside is strongest in the summer season the vorticity of the wind pattern increases from winter to summer whereas divergence is maximum in equinox in all three seasons divergence is weaker than vorticity

behavior of the f2 peak ionosphere over the south pacific at dusk during quiet summer conditions from cosmic data 1 the six satellite constellation observing system for meteorology ionosphere and climate cosmic mission makes routine ionospheric measurements over the entire globe using occultation techniques these observations have been used in this study to develop global scale climate maps of nmf2 and hmf2 during the southern northern summer winter enhanced electron densities that appear to be associated with the southern equatorial appleton anomaly are displaced far southward at dusk and within about an hour form the weddell sea anomaly coincidentally the height of the f2 peak increases on the northern boundary of this anomaly this height increase is also displaced southward as the enhanced electron densities are displaced southward suggesting that the electron density increases are associated with the f2 peak rising as well as being an interesting phenomenon in its own right this behavior may shed new light on the formation of the weddell sea anomaly no unambiguous explanation for this behavior can be determined from the data presently available but an examination of some possibilities suggests that an evening downward flux of plasma from the plasmasphere may be at least partly responsible for the phenomenon

remote sensing evidence of lava ground ice interactions associated with the lost jim lava flow seward peninsula alaska thermokarst terrains develop when ice bearing permafrost melts and causes the overlying surface to subside or collapse this process occurs widely throughout arctic regions due to environmental and climatological factors but can also be induced by localized melting of ground ice by active lava flows the lost jim lava flow ljlf on the seward peninsula of alaska provides evidence of former lava ground ice interactions associated geomorphic features on the scale of meters to tens of meters were identified using satellite orthoimages and stereo derived digital terrain models the flow exhibits positive and mixed relief features including tumuli n 26 and shatter rings n 4 as well as negative relief features such as lava tube skylights n 100 and irregularly shaped topographic depressions n 1188 that are interpreted to include lava rise pits and lava induced thermokarst terrain along the margins of the flow there are also clusters of small peripheral pits that may be the products of meltwater or steam escape on mars we observed morphologically similar pits near lava flow margins in northeastern elysium planitia which suggests a common formation mechanism investigating the ljlf may therefore help to elucidate processes of lava ground ice interaction on both earth and mars

wave set up on coral reefs 2 set up on reefs with various profiles abstract all available laboratory data for wave set up on two dimensional reef profiles of various shapes have been compared with data from an idealised horizontal reef with a steep reef face gourlay 1996 the data is generally well represented by a relationship between the relative set up parameter gh r t o and the submergence parameter g h r h r h o and the relative set up on reef profiles of natural form is found to be less than that observed on the idealised horizontal reef the important influences of reef rim slope and variable water depths on the reef top have been investigated and some methods for allowing for them are suggested comparison of data for irregular waves with that for regular waves has led to the development of a simple method for estimating the effects of wave groups upon the magnitude of the steady state mean wave set up gh r the results of the analyses are applied to the determination of wave set up and its effects at three specific coral reef sites

detection of shallow subtidal corals from ikonos satellite and qtc view 50 200 khz single beam sonar data arabian gulf dubai uae we compared the results of seafloor classifications with special emphasis on detecting coral versus non coral areas that were obtained from a 4 4 m pixel resolution multispectral ikonos satellite image and two acoustic surveys using a qtc view series 5 system on 50 and 200 khz signal frequency a detailed radiative transfer model was obtained by in situ measurement of optical parameters that then allowed calibration of the ikonos image against in situ optical measurements and a series of ground truthing points eight benthic classes were distinguished optically with an overall accuracy of 69 and a tau index t of 65 the classification of the ikonos image allowed discrimination of three different coral assemblages dense live dense dead sparse which were confirmed by ground truthing data evaluation of the acoustic surveys involved culling of datapoints with 90 accuracy and 30 probability were used and 60 accurate t 53 when less processed data selcted classes only all data were used accuracy against ground truthing points of the most highly processed dataset was 56 t 46 these results indicate that results from optical and acoustic surveys have some degree of commonality therefore there is a potential to produce maps outlining coral areas from optical remote sensing in shallow areas and acoustic methods in adjacent deeper areas beyond optical resolution with the limitation that acoustic maps will resolve fewer habitat classes and have lower accuracy

paleomagnetism rock magnetism and fission track dating of the kurihashi granodiorite in northeast japan evidence for a cretaceous hydrothermal event and differential rotation along the eastern eurasian margin samples from the late cretaceous kurihashi granodiorite on the pacific coast of northeast japan are divided into two groups based on paleomagnetic data one group a preserves stable single thermoremanent magnetizations trm with large westerly deflected declinations the other group b has two or three distinct components of natural remanent magnetization nrm components with high middle and low unblocking temperatures show westerly declinations nearly identical with the stable trm directions of group a as well as northerly and easterly declinations rock magnetic experiments indicate that the dominant magnetic mineral of both groups is ti poor titanomagnetite group a samples contain superparamagnetic sp titanomagnetite because they show a frequency dependence with the initial susceptibility measurements hysteresis parameters of group b samples are consistent with a mixture of single domain sd and multidomain md grains electron microscopy confirms the presence of md size magnetite in the group b samples fission track thermochronology indicates that the kurihashi granodiorite underwent a post cooling hydrothermal event during the late cretaceous thus the northerly and easterly nrm components seem to have a thermoviscous origin many samples have anomalously high unblocking temperatures up to 560 c compared to predictions of sd theory and probably result from long thermal demagnetization tails of thermoviscous remanent magnetizations tvrm carried by md magnetite a strong tvrm was acquired during the hydrothermal event and is correlated with the long normal polarity superchron of the geomagnetic field because highly oblique left lateral subduction was active along the eastern eurasian margin during the same period the primary trm and tvrm components record counterclockwise rotation 120 of the kurihashi granodiorite and remarkable wrench deformation along the continental margin

seasonal landslide mapping and estimation of landslide mobilization rates using aerial and satellite images abstract we tested the possibility of using digital color aerial ortho photographs and monoscopic panchromatic satellite images of comparable spatial and radiometric resolution to map recent landslides in italy and to update existing measures of landslide mobilization in a 90 km 2 area in umbria central apennines rainfall resulted in abundant landslides in the period from september 2004 to june 2005 analysis of the rainfall record determined the approximate dates of landslide occurrence and revealed that the slope failures occurred in response to moderately wet rainfall periods the slope failures occurred primarily in cultivated terrain and left subtle morphological and land cover signatures making the recognition and mapping of the individual landslides problematic despite the difficulty with the identification of the landslides without the use of stereoscopic visualization visual analysis of the aerial and satellite images allowed mapping 457 new landslides ranging in area 3 0 10 1 a l 4 m 2 for a total landslide area a lt 6 92 10 5 m 2 to identify the landslides the investigators adopted the interpretation criteria commonly used to identify and map landslides on aerial photography the result confirms that monoscopic very high resolution images taken by airborne and satellite sensors can be used to prepare landslide maps even where slope failures are difficult to detect provided the imagery has sufficient geometric and radiometric resolutions the different dates of the aerial march 2005 and the satellite june july 2005 images allowed the temporal segmentation of the landslide information and studying the statistics of landslide area and volume for different periods compared to pre existing information on the abundance and size of the landslides in the area the inventory obtained by studying the aerial and satellite images proved more complete the new mapping showed 145 more landslides and 85 more landslide area than a pre existing reconnaissance inventory as a result of the improved mapping the rate of landslide mobilization for the 2004 2005 landslide season was determined to be l 27 1 mm year 1 30 higher than a previous estimate for the same period this seasonal rate of landslide mobilization is significantly larger than the long term regional erosion rate in the central apennines the accelerated rate is attributed to agricultural practices that favor slope instability

large scale patterns of auroral ionospheric convection observed with the chatanika radar ionospheric convection at auroral latitudes has been examined during a series of long duration experiments with the chatanika alaska incoherent scatter radar these experiments have been carefully designed to obtain maximum latitudinal coverage 56 75 while maintaining a temporal resolution of 30 min in order to resolve the effects of individual substorms on the convection pattern design criteria for the experiments are described together with presentation of observational data acquired during 400 hr of radar operations during various levels of geophysical disturbance the data accentuate the repeatability of the gross features of the auroral convection and its basic conformity to the two cell pattern predicted from the large scale magnetospheric circulation for moderate to active geomagnetic conditions uniform sunward convection with velocities of 800 1200 m s spans the 62 to 72 latitude band at both dawn and dusk in quieter circumstances the sunward convection continues in this region but has smaller speeds and is centered at higher latitudes little evidence of a throat in the dayside convection pattern is seen at latitudes below 75 except in very disturbed circumstances during several experiments coordinated operation of the chatanika and millstone hill massachusetts radars permitted the simultaneous observation of the auroral convection pattern at two different local times substorms affect the convection at all local times and appear to generally enhance the rate of convection without seriously changing its direction near midnight latitudinal displacements and expansions of the convection pattern during substorms may result in a local rotation or reversal of the direction of convection while near dawn and dusk convection velocities are enhanced and the region of sunward flow expands to lower latitudes

universal time dependence of nighttime f region densities at high latitudes coordinated eiscat chatanika and millstone hill incoherent scatter radar observations have revealed that in the auroral zone the nighttime f region densities vary substantially with the longitude of the observing site eiscat s densities are the largest and millstone hill s are the lowest the nighttime f region densities measured by the individual radars are not uniform the regions where the densities are maximum are the so called blobs or patches that have been reported previously the observations are consistent with the hypothesis that the nighttime densities are produced in significant amounts not by particle precipitation but by solar euv radiation and that they have been transported across the polar cap the observed differences can be explained by the offset of the geographic and geomagnetic poles a larger portion of the magnetospheric convection pattern is sunlit when eiscat is in the midnight sector than when chatanika is in winter when millstone hill is in the midnight sector almost all the auroral oval is in darkness this universal time effect which was observed on all coordinated three radar experiments september 1981 to february 1982 is illustrated using two periods of coincident radar and satellite observations november 18 19 and december 15 16 1981 these two periods were selected because they corresponded to relatively steady conditions dynamics explorer de measurements are used to aid in interpreting the radar observations de 1 auroral images show what portion of the oval was sunlit de 2 data are used to measure the ion drift across the polar cap because the altitude of the ionization peak was high the decay time of the f region density was substantially longer than the transit time across the polar cap the southward meridional wind that was observed coincidentally with the ionization patches at chatanika and eiscat contributed to the maintenance of the f region by raising the altitude of the peak de 2 langmuir probe measurements of electron density clearly showed a ut dependence the same as that in the radar measurements

equatorial plasma fountain and its effects over three locations evidence for an additional layer the f 3 layer the equatorial plasma fountain and equatorial anomaly in the ionospheres over jicamarca 77 w trivandrum 77 e and fortaleza 38 w are presented using the sheffield university plasmasphere ionosphere model under magnetically quiet equinoctial conditions at high solar activity the daytime plasma fountain and its effects in the regions outside the fountain lead to the formation of an additional layer the f3 layer at latitudes within about plus or minus 10 of the magnetic equator in each ionosphere the maximum plasma concentration of the f3 layer which occurs at about 550 km altitude becomes greater than that of the f2 layer for a short period of time before noon when the vertical e b drift is large within the f3 layer the plasma temperature decreases by as much as 100 k the ionograms recorded at fortaleza on january 15 1995 provide observational evidence for the development and decay of an f3 layer before noon the neutral wind which causes large north south asymmetries in the plasma fountain in each ionosphere during both daytime and nighttime becomes least effective during the prereversal strengthening of the upward drift during this time the plasma fountain is symmetrical with respect to the magnetic equator and rises to over 1200 km altitude at the equator with accompanying plasma density depletions in the bottomside of the underlying f region the north south asymmetries of the equatorial plasma fountain and equatorial anomaly are more strongly dependent upon the displacement of the geomagnetic and geographic equators jicamarca and trivandrum than on the magnetic declination angle fortaleza

wave driven flow over shallow reefs long term 1 month observations of waves and currents over a natural reef are presented which show a strong correlation between offshore rms incident wave height and cross reef currents at subtidal frequencies the energy spectrum of the cross reef currents shows a significant peak at twice the semidiurnal tidal frequency while the spectrum of sea surface elevation over the reef flat shows no corresponding peak furthermore experimental results reported by gourlay 1993 show setup over the reef occurs in the absence of a beach and the cross reef transport decreases with an increase in the sea surface slope across the reef flat due to an increase in setup at the top of the reef face analytic solutions for flow forced by wave breaking over an idealized reef explain the above features of cross reef flows in the absence of a beach through the surf zone on the reef face the cross reef gradient in the radiation stress due to wave breaking is partitioned between balancing an offshore pressure gradient associated with setup over the reef and forcing a mean flow across the reef over the reef flat where the depth is constant there is no forcing due to wave breaking and the flow is driven by a pressure gradient which results from the setup through the surf zone the magnitude of the setup through the surf zone is such that the transport across the reef flat matches the transport through the surf zone which is forced by the gradient in the radiation stress solutions are presented for general reef geometry defined by the reef width and slope of the seaward reef face and incident wave forcing defined by the depth at the breakpoint and the depth of water over the reef as the depth over the reef goes to zero the solutions converge to the plane beach solutions described by longuet higgins and stewart 1964 wave setup is maximized and the cross reef transport is zero in other cases the relative magnitudes of the setup and the cross reef transport depend on the geometry of the reef and the incident wave forcing

an investigation of the northern hemisphere midlatitude nighttime plasma density enhancements and their relations to the midlatitude nighttime trough during summer this study has utilized regional surface maps and field aligned latitudinal profiles derived from multiinstrument dmsp f15 data it investigates northern midlatitude plasma enhancements in the nighttime topside ionosphere during summer and their relation to the midlatitude heavy ion stagnation trough the tracked midlatitude summer enhancements showed significant longitudinal variations their best development occurred in the 50 n 60 n 110 e 170 e geographic region proven by coupled thermosphere ionosphere plasmasphere wind velocity simulations equatorward winds were strongest there this region is the northern hemisphere equivalent of the weddell sea anomalys wsa locality there northern summer plasma enhancements resembled the nighttime wsa a southern summer equinoctial phenomenon and thus were named as wsa like feature their plasma density increased mainly owing to the mechanical or direct effects of the equatorward winds however as results show the wsa like feature was an ordinary northern midlatitude nighttime enhancement occurring in summer this was further confirmed by the wsa like features relation to the trough and by the troughs movement over the northern hemisphere the summer trough appeared at 62 461 2 93 n geomagnetic poleward of the wsa like feature and other midlatitude plasma enhancements and moved equatorward with a rate of 0 097 0 04 n nt when magnetic activity increased as our previous wsa investigation indicates the southern summer trough develops at lower latitudes at 47 1564 2 16 s equatorward of the nighttime wsa and moves poleward with a rate of 0 0497 0 003 s nt with increasing magnetic activity under the combined influence of the nighttime wsa and south atlantic magnetic anomaly copyright 2009 by the american geophysical union

the 2006 pyroclastic deposits of merapi volcano java indonesia high spatial resolution ikonos images and complementary ground based observations abstract on 16 june 2006 an overpass of ikonos coincided with the emplacement of an active block and ash flow fed by a lava dome collapse at merapi volcano java indonesia it was the first moving pyroclastic flow recorded on a satellite image the very high spatial resolution of the image indicated the extent and impact of pyroclastic material that was deposited during and prior to the day of image acquisition a number of features associated with the hazardous block and ash flows emplaced in narrow deep gorges were mapped interpreted and analysed the high spatial resolution ikonos imagery worked extremely well for identifying pyroclastic deposits the block and ash flow and surge deposits recognized in the ikonos images include 1 several channel confined flow lobes and tongues in the box shaped gorge 2 thin ash cloud surge deposit and knocked down trees in constricted areas on both slopes of the gorge 3 fan like overbank deposits on the gendol tlogo interfluves from which flows were re routed in the tlogo minor valley 4 massive overbank flow lobes on the right bank of the gendol river which destroyed the village of kaliadem 0 5 km from the main channel a small part of this flow was re channelled into the opak tributary valley the high resolution ikonos images also helped us to identify geomorphic obstacles that enabled flows to ramp up and spill out from the sinuous channel as flow avulsion flow avulsions are dangerous as the redirect flows to unexpected areas away from the main channel valley fills from previous deposits channel bends and anthropogenic barriers in the channel locally known as sabo dams influence the down valley passage of the flows sabo dams originally built to ameliorate the effect of high sediment load streams caused block and ash flows to avulse of the containing channel and devastate populated areas

a sensitivity analysis of the waterline method of constructing a digital elevation model for intertidal areas in ers sar scene of eastern england abstract a sensitivity analysis of the waterline method of constructing a digital elevation model dem of an intertidal zone using remote sensing and hydrodynamic modelling is described variation in vertical height accuracy as a function of beach slope is investigated using a set of nine ers synthetic aperture radar sar images of the humber wash area on the english east coast acquired between 1992 and 1994 waterlines from these images are heighted using a hydrodynamic tide surge model and interpolated using block kriging on 1 500 slope beaches an average block height estimation standard deviation of 18 22 cm is achieved this rises to 27 cm on 1 100 slope beaches and 32 cm on 1 30 slope beaches the average heighting error at different slopes is decomposed into components due to waterline heighting error inadequate sensor resolution and interpolation inaccuracy it is shown that at 1 500 slope waterline heighting error and interpolation inaccuracy are the main error sources whilst at 1 30 slope errors due to inadequate sensor resolution become dominant the ability of the technique to generate intertidal dems for almost the entire coastal zone in a complete ers sar scene covering 100 100 km is demonstrated

construction of an inter tidal digital elevation model by the water line method progress in the development of a method for constructing a digital elevation model dem of an inter tidal zone using remote sensing and hydrodynamic modelling is described the method allows the construction of an inter tidal dem over large areas relatively quickly as well as frequent subsequent monitoring of the dem to detect changes and is particularly suited to sar satellite data because of the all weather day night capability of sar the resulting dem may be used for the development of improved hydrodynamic models and for studying sediment mass transport in the inter tidal zone

progressive segmentation and systematic block rotation within a plutonic body palaeomagnetism of the cretaceous kurihashi granodiorite in northeast japan summary intensive palaeomagnetic and rock magnetic studies clarify the history of multiple block rotational events within an active plate margin the cretaceous kurihashi granodiorite in northeast japan preserves multi component remanent magnetization high unblocking temperature tub thermoremanent magnetization trm acquired during the initial cooling of the granodiorite and middle low tub thermoviscous remanent magnetization tvrm acquired during succeeding hydrothermal activities the observed directional difference between the three magnetic components requires the first counter clockwise rotation event within a part 1 km of northeast japan as a result of left lateral plate motion in the late cretaceous later clockwise rotation probably related with right lateral faulting during the course of the miocene backarc spreading of the japan sea is indicated by significant easterly deflections in the low tub component on the other hand scatter in the high tub trm declinations implies that the second deformation phase was achieved as non rigid rotation of fault bounded blocks as wide as 100 m the latest and most confined rotation events are confirmed by complicated deflections of the trm and tvrm in a fault zone a shear zone as wide as 30 m with dense fractures near the main fault is sharply divided into three compartments which have been rotated around three orthogonal poles systematic block rotations may accommodate differential slips on fault planes within a plutonic body genetically containing orthogonal fractures as reactivated intrinsic cooling joints we interpret our results to show that the kurihashi granodiorite has been progressively segmented since the cretaceous under varied stresses

a study of the weddell sea anomaly observed by formosat 3 cosmic 1 more than two years of cosmic electron density profiles at low solar activities are collected to study the evolution of the weddell sea anomaly wsa which appears as an evening enhancement in electron density during local summer observations show that the change in nmf2 the f2 peak electron density is associated with the change in hmf2 the f2 peak height while the latter is correlated closely with the components of the geomagnetic field we find that 1 in the afternoon hmf2 is more liable to rise drastically in regions with a larger jsin 2i j value which would occur early at certain declinations eastward in the southern hemisphere and westward in the northern hemisphere 2 subsequently a larger increment of hmf2 is coincidentally followed by a stronger enhancement of nmf2 and the enhancement ends just around the local sunset and 3 in midlatitudes the evolution pattern of hmf2 in the evening of equinoxes and winter is similar to that in summer albeit without a lasting nmf2 enhancement as that in summer these features suggest that the nmf2 enhancement and the hmf2 increase could arise from the thermospheric wind effect and solar photoionization plays a crucial role in the enhancement as well the general midlatitude f2 layer enhancement in local summer evening is consistent with the wsa on the above features indicating that the wsa is a manifestation with a particular geometry of the magnetic field of the evening enhancement induced by the winds

geomagnetic and gravity modeling of the fore arc shelf of north east japan abstract northeast japan is one of the continental slivers of the eurasian continent rifted by the miocene fan shaped genesis of the japan sea a pair of longitudinal geomagnetic anomalies are traced along the pacific coast of northeast japan basement core samples obtained from miti kesennuma oki well drilled on the southernmost part of anomaly belt are examined the basement which is identified as biotite granite and characterized by sheared fabric shows early cretaceous radiometric ages through rock magnetic experiments it was confirmed that the granitic basement holds thermoremanent magnetization trm strong enough to cause the observed anomaly with a minor contribution from induced magnetization the carrier of trm is multi domain titanomagnetite on the basis of experimental results two dimensional geomagnetic and gravity modeling for semi infinite magnetized polygons have been constructed along two e w seismic lines on the fore arc shelf of northeast japan vector components of magnetization are tuned through fitting anomaly peaks caused by basement topography delineated by seismic survey as for the northern part of study area the inclination of westerly deflected magnetization vector should be 30 or smaller the amount required to restore the cretaceous northeast japan to the south of southwest japan the gravity model for the same lines as the geomagnetic modeling suggests that fore arc basement off the northern kitakami terrane consists of granitic rocks except for a conspicuous basalt whereas the non magnetic basement off the southern abukuma terrane consists of a variety of blocks of different density the anomalous direction of remanent magnetization and variety in gravity data are linked to nnw sse sinistral transcurrent faults activated throughout the paleogene

monitoring landslides from optical remotely sensed imagery the case history of tessina landslide italy collecting information on landslide occurrence and activity over wide areas is a crucial task for landslide hazard assessment field techniques despite being very precise are usually not sufficient to achieve this goal since they mostly provide pointbased measurements mainly because of its synoptic view and its capability for repetitive observations optical visible infrared remotely sensed imagery acquired at different dates and at high spatial resolution can be considered as an effective complementary tool for field techniques to derive such information an image processing method to map and monitor landslide activity using multitemporal optical imagery is proposed the method entails automatic change detection of suitably pre processed geometrically registered and radiometrically normalised sequential images followed by thresholding into landslide related change pixels subsequent filtering based on the degree of rectangularity of regions can also be considered to eliminate pixel clusters corresponding to man made land use changes the application of this method is illustrated in the complex tessina landslide in the eastern italian alps it has focused on discriminating the effects of a major reactivation that occurred in 1992 hence inferring the dynamics of the landslide at that time although the method has been devised for optical remote sensing imagery in general in the absence of high resolution satellite imagery covering that period digital images derived by scanning existing aerial photograph diapositives at 1 m pixel size have been used the method is able to classify image pixels according to landslide activity conditions d 2003 elsevier science b v all rights reserved

a comparative analysis of terrain stability models for predicting shallow landslides in colluvial soils abstract most of the slopes of the hilly areas of the apennines are composed of colluvial soils originating from the weathering of the bedrock and down slope transportation shallow slides affect this superficial cover depend largely on the surface topography and are a recurrent problem sinmap and shalstab are terrain stability models that combine steady state hydrology assumptions with the infinite slope stability model to quantify shallow slope stability they have a similar physical basis but they use different indices to quantify instability the purposes of this study are to test and compare the approaches of sinmap and shalstab models for slope stability analysis and to compare the results of these analyses with the locations of the shallow landslides that occurred on november 2002 in an area of the oltrepo pavese northern apennines the territory of s giuletta characterized by clayey silty colluvial soils represents the test site the digital elevation model was constructed from a 1 5000 scale contour map and was used to estimate the slope of the terrain as well as the potential soil moisture conditions in situ and laboratory tests provided the basis for measuring values for soil hydraulic and geotechnical parameters moisture content soil suction atterberg limits methylene blue dye adsorption hydraulic conductivity soil thickness was extracted from a soil database an inventory of landslide from interpretation of aerial photographs and field surveys was used to document sites of instability mostly soil slips and to provide a test of model performance by comparing observed landslide locations with model predictions the study discusses the practical advantages and limitations of the two models in connection with the geological characteristics of the studied area which could be representative of similar geological contexts in the apennines

lagoonal facies ages and sedimentation in three atolls in the pacific abstract in order to investigate pacific atoll lagoonal facies and temporal evolution we collected and analyzed surface and core sediments from three pacific atoll lagoons of various sizes and depths kayangel of palau islands enewetak and majuro of the marshall islands the lagoons were divided into three facies calcarina facies calcarina heterostegina mixed facies and heterostegina facies these were based on the presence or absence of the tests of two larger benthic foraminifera calcarina and heterostegina as indicators of reef flat and deep lagoon environments respectively the calcarina facies is composed of allochthonous reef derived materials the calcarina heterostegina mixed facies is a mixture of reef derived and in situ lagoonal materials and the heterostegina facies is composed mainly of in situ lagoonal materials as both foraminifera are widely distributed in the western to central pacific region the facies classification presented in this study can be applicable to other pacific atolls based on the results of radiocarbon dating on samples obtained from cores at majuro lagoon the accumulation rates of the lagoonal sediments were estimated as 0 65 m kyr 1 calcium carbonate production was calculated on the basis of the accumulation rates and density of sediments to be 710 g caco 3 m 2 yr 1

semi automatic recognition and mapping of rainfall induced shallow landslides using optical satellite images abstract we present a method for the semi automatic recognition and mapping of recent rainfall induced shallow landslides the method exploits vhr panchromatic and hr multispectral satellite images and was tested in a 9 4 km2 area in sicily italy where on 1 october 2009 a high intensity rainfall event caused shallow landslides soil erosion and inundation pre event and post event images of the study area taken by the quickbird satellite and information on the location and type of landslides obtained in the field and through the interpretation of post event aerial photographs were used to construct and validate a set of terrain classification models the models classify each image element pixel based on the probability that the pixel contains or does not contain a new rainfall induced landslide to construct and validate the models a procedure in five steps was adopted first the pre event and the post event images were pan sharpened ortho rectified co registered and corrected for atmospheric disturbance next variables describing changes between the pre event and the post event images attributed to landslide occurrence were selected next three classification models were calibrated in a training area using different multivariate statistical techniques the calibrated models were then applied in a validation area using the same set of independent variables and the same statistical techniques lastly combined terrain classification models were prepared for the training and the validation areas the performances of the models were evaluated using four fold plots and receiver operating characteristic curves the method proved capable of detecting and mapping the new rainfall induced landslides in the study area we expect the method to be capable of detecting analogous shallow landslides caused by similar rainfall or different e g earthquake triggers provided that the event slope failures leave discernable features captured by the post event satellite images and that the terrain information and satellite images are of adequate quality the proposed method can facilitate the rapid production of accurate landslide event inventory maps and we expect that it will improve our ability to map landslides consistently over large areas application of the method will advance our ability to evaluate landslide hazards and will foster our understanding of the evolution of landscapes shaped by mass wasting processes

late cretaceous palaeomagnetic results from sikhote alin far eastern russia tectonic implications for the eastern margin of the mongolia block summary wepresent palaeomagnetic results from late cretaceous welded tuffs in the kisin group monastirskaya suite primorskaya series collected at 27 sites from the sikhote alin mountain range a high unblocking temperature magnetization component 590 c was isolated after stepwise thermal demagnetization from 25 sites combined with previously reported data reliable characteristic remanence directions from 39 sites are distributed at eight areas ranging from 46 7 n 138 1 e to 43 4 n 134 8 e in the sikhote alin block the bedding tilt test is positive for two area mean directions and inconclusive for the remaining six areas the data set for all 39 sites reveals a positive bedding tilt test at the 99 per cent confidence level and their tilt corrected mean direction is d 335 6 i 54 4 95 8 5 corresponding to a palaeopole at 71 5 n 38 9 e with a95 9 9 this westerly direction is ascertained through the tilt corrected mean direction d 331 1 i 53 5 95 8 5 based on the 25 data selected from four areas kema river terney plastun and moryak rybolov where each data set passes the positive bedding tilt test or reveals an increase in the precision parameter after tilt correction palaeomagnetic declination indicates that the sikhote alin block has rotated counterclockwise by 41 16 with respect to the eurasian continent between late cretaceous times and 53 50 ma compared with palaeomagnetic data from the surrounding regions we find that the rotation recorded in sikhote alin extends westward into the interior of the mongolia block the eastern margin of the asian continent experienced both counterclockwise rotation of the eastern part of the mongolia block and clockwise rotation of the eastern part of the north china block over the cretaceous we interpret these data in terms of a strong net horizontal force towards the ocean side acting on the lithosphere at the eastern margin of the asian continent between the late cretaceous and 53 50 ma intermittently occurring upwellings of mantle and associated horizontal flows may have played an important role in producing the net horizontal force acting on the continental block during late cretaceous times

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

high resolution satellite imagery analysis for inferring surface subsurface water relationships in unstable slopes abstract we investigate the instability of slopes in a 15 6 km 2 catchment area in the southern apennine mountains italy traversed by a mid slope road and characterized by predominance of clay rich flysch units high resolution multispectral satellite imagery is used to identify active landslides to investigate their close association with seasonally wet zones areas covered by free surface water including ponds migrating surface water seeps as well as to guide subsurface hydrogeological investigations by combining the remotely sensed surface information and the extensive subsurface dataset from over 40 monitoring piezometer boreholes we demonstrate that many wet zones initially mapped from the ikonos imagery are indicative of sites with seasonally persistent very high groundwater levels within landslide prone slopes and on intermittently active landslides where such surface subsurface water linkage can be established the appearance of the wet zones fully saturated ground soil resulting from groundwater discharge or seepage can be used as a forewarning signal of the increased susceptibility to landsliding since the hillslopes with shallow groundwater tables are generally more prone to failure the information about changing surface water conditions retrieved from high resolution satellite data timely acquired during rainy seasons can thus provide crucial input for temporal and spatial landslide hazard assessments we anticipate that in the near future high resolution optical space borne remote sensing will become a commonly used tool for monitoring landslide activity and for providing temporal series of spatial data necessary to improve our understanding of causative and triggering processes leading to slope failures

waterline extraction from landsat tm data in a tidal flat a case study in gomso bay korea waterline extraction is potentially one of the most effective satellite remote sensing tools for studying changes in tidal flat environment and coastlines however its application to the study of tidal flats has not been investigated in detail the waterline in a tidal flat in gomso bay korea is characterized and evaluated using 27 sets of landsat thematic mapper tm and earth observing system terra eos terra advanced spaceborne thermal emission and radiometer aster data ground truth data including grain size soil moisture content ground levelling and waterline tracking have been obtained the choice of spectral bands in terms of tidal conditions turned out to play a key role in locating the waterline while the waterlines extracted from near infrared nir short wavelength infrared swir and thermal infrared tir data are commonly reliable on the flood tide the discrepancies between different bands become large on the ebb tide the bands tir nir and swir are in that order decreasingly effective in extracting the waterline while ebb tides are in progress the effect of turbid water on nir can be reduced by a ratioing of nir and the visible band the location of the waterline is also an important factor to consider the discrepancy is largest on the middle tidal flat selection of the proper band for waterline extraction under various conditions is suggested however no single band can accommodate all aspects of the tidal flat environment a schematic model associated with the spectral reflectance of the tidal flat is proposed in which the remnant water scattered on the surface after exposure is emphasized as an additional factor

a theoretical study of the global f region for june solstice solar maximum and low magnetic activity we constructed a time dependent three dimensional multi ion numerical model of the global ionosphere at f region altitudes the model takes account of all the processes included in the existing regional models of the ionosphere the inputs needed for our global model are the neutral temperature composition and wind the magnetospheric and equatorial electric field distributions the auroral precipitation pattern the solar euv spectrum and a magnetic field model the model produces ion no o2 n2 n o he density distributions as a function of time for our first global study we selected solar maximum low geomagnetic activity and june solstice conditions from this study we found the following 1 the global ionosphere exhibits an appreciable ut variation with the largest variation occurring in the southern winter hemisphere 2 at a given time nmf2 varies by almost three orders of magnitude over the globe with the largest densities 5 106 cm 3 occurring in the equatorial region and the lowest 7 10 cm 3 in the southern hemisphere mid latitude trough 3 our appleton peak characteristics differ slightly from those obtained in previous model studies owing to our adopted equatorial electric field distribution but the existing data are not sufficient to resolve the differences between the models 4 interhemispheric flow has an appreciable effect on the f region below about 25 magnetic latitude 5 in the southern winter hemisphere the mid latitude trough nearly circles the globe the dayside trough forms because there is a latitudinal gap of several degrees between the terminator and the dayside oval in this gap there is no strong ion production source and the ionosphere decays 6 for low geomagnetic activity the effect of the auroral oval on the densities is not very apparent in the summer hemisphere but is clearly evident in the winter hemisphere 7 the densities in both the northern and southern polar caps exhibit a complex temporal variation owing to the competition between the various photochemical and transport processes

cenozoic northward translation of the kitakami massif in northeast japan paleomagnetic evidence abstract paleogene and early cretaceous welded tuffs have been sampled from eleven sites at the omoe peninsula 39 6 n 142 0 e in the kitakami massif of northeast japan for paleomagnetic study characteristic paleomagnetic directions with a high unblocking temperature component above 560 c are isolated westerly declinations with shallow inclination are identified after tilt correction in the 62 71 ma heizaki volcanics d 283 5 i 9 4 95 8 0 and in the 114 119 ma harachiyama formation d 274 2 i 20 4 the shallow inclination which was previously reported from early cretaceous plutonic rocks without tilt correction in the kitakami massif has been discovered in the tilt corrected paleomagnetic directions the presence of both normal and reversed polarities suggests reliability of this shallow and westerly paleomagnetic direction the shallow inclination indicates that the kitakami massif was located at low latitude 5 4 n at 71 62 ma taking into account a reference paleomagnetic pole of the paleocene expected from sikhote alin the kitakami massif was translated northward over 25 in latitude since 65 ma the kitakami massif can be subjected to latitudinal northward motion more than 24 during the last 70 ma when it was transported by push of the moving pacific plate and reached the asian continental margin near sikhote alin later than 30 ma we conclude that the kitakami massif was incorporated into northeast japan at some time between 30 and 22 ma after the cenozoic northward translation

three dimensional ionospheric electron density structure of the weddell sea anomaly 1 this paper provides the first three dimensional description of the ionospheric density structure of the weddell sea anomaly wsa the wsa is characterized by a nighttime ionospheric density greater than that in daytime in the weddell sea region around the antarctic peninsula during the southern hemisphere summer it was first observed by ground based ionosondes located in the antarctica back in the 1950s and was further investigated by two dimensional maps over the oceans using tec measurements collected by the topex poseidon recently although these tec maps have provided two dimensional views for tracking the time evolution and spatial coverage of the wsa the vertical distribution of this peculiar feature is still unavailable with the vertical ionospheric density profiles observed by the formosat 3 cosmic three dimensional density structure of the wsa is presented here for the first time meanwhile a similar wsa signature is observed in the northern and eastern hemisphere during june solstice by both the gps tec and the formosat 3 cosmic electron density observations from the observed altitudinal structure of the wsa during 1800 2400 lt and the similar feature occurred in the opposite hemisphere suggest that the southward offset of the magnetic equator with respect to the geographic equator plays a major role for the wsa formation

fore arc transcurrent faults in northeast japan hybrid geophysical models of an island arc upper crust origin of a conspicuous longitudinal geomagnetic anomaly on the fore arc of northeast japan kitakami magnetic belt kmb is investigated on the basis of fission track dating rock magnetic experiments reflection seismic interpretation and potential field modeling radiometric ages suggest that the basement core samples obtained from the numanohata sk 2d southern hokkaido and ministry of international trade and industry kesennuma oki offshore honshu boreholes are part of the voluminous cretaceous plutons in northeast japan two dimensional gravity models on fore arc seismic profiles show that acoustic basement with geomagnetic anomaly has densities comparable with those of cored granites magnetic carrier of the granite is identified as multi domain sized titanomagnetite strong thermoremanent magnetization trm and high qn ratios of the samples indicate significant contribution of trm of the granitic basement as a source of observed anomaly conspicuous paired anomaly is caused by consistent normal remanence of the granitic basement acquired during the cretaceous long normal chron c34n as a result of geomagnetic modeling optimized direction of the remanence is characterized by westerly deflection and abnormally shallow inclination 30 which requires to restore the kitakami massif northern part of northeast japan to the south of southwest japan significant northward translation since the cretaceous may have been compensated by left lateral motions on transcurrent faults along the eurasian margin such as the offshore trend a identified in this study gravity modeling indicates that the basement off the abukuma massif southern part of northeast japan which does not show geomagnetic anomaly consists of varied density blocks that are bounded by transcurrent faults

empirical high latitude electric field models electric field measurements from the dynamics explorer 2 satellite have been analyzed to extend the empirical models previously developed from dawn dusk ogo 6 measurements j p heppner 1977 the analysis embraces large quantities of data from polar crossings entering and exiting the high latitudes in all magnetic local time zones paralleling the previous analysis the modeling is based on the distinctly different polar cap and dayside convective patterns that occur as a function of the sign of the y component of the interplanetary magnetic field the objective which is to represent the typical distributions of convective electric fields with a minimum number of characteristic patterns is met by deriving one pattern model bc for the northern hemisphere with a y interplanetary magnetic field imf and southern hemisphere with a y imf and two patterns models a and de for the northern hemisphere with a y imf and southern hemisphere with a y imf the most significant large scale revisions of the ogo 6 models are 1 on the dayside where the latitudinal overlap of morning and evening convection cells reverses with the sign of the imf y component 2 on the nightside where a westward flow region poleward from the harang discontinuity appears under model bc conditions and 3 magnetic local time shifts in the positions of the convection cell foci the modeling above was followed by a detailed examination of cases where the imf z component was clearly positive northward neglecting the seasonally dependent cases where irregularities obscure pattern recognition the observations range from reasonable agreement with the new bc and de models to cases where different characteristics appeared primarily at dayside high latitudes the analysis of these differences for strong bz conditions using passes through different mlt zones led to finding that the deviations from both the bc and de models could be modeled by extending the evening cell foci toward and beyond noon with a deformation that roughly resembles a rotational twist of the extended evening cell the morning cell accommodation to the model bc deformation produces a narrow tongue of eastward convection near 75 invariant latitude on the dayside the model de deformation compresses the morning cell toward the night hours such that the sunward convection in the morning cell is diverted to polar latitudes in the 0400 to 0700 mlt sector in both cases the deformations of the two cell patterns lead to sunward convection in dayside polar regions while maintaining the integrity of the nightside convection pattern thus the nightside dilemmas that plague three and four cell models designed to explain sunward convection in polar regions under bz conditions do not appear

ikonos satellite imagery and products the ikonos satellite simultaneously collects 1 m panchromatic and 4 m multispectral images providing the commercial and scientific community with a dramatic improvement in spatial resolution over previously available satellite imagery the sun synchronous ikonos orbit provides global coverage consistent access times and near nadir viewing angles the system is capable of 1 10 000 scale mapping without ground control and 1 2400 scale mapping with ground control the ikonos ground station produces radiometrically corrected images georectified images orthorectified images stereo pairs and digital elevation models dems for image analysis photogrammetric and cartographic applications this article provides an overview of the ikonos satellite ground systems products and applications