thermal monitoring of north pacific volcanoes from space long term thermal modeling of volcanoes using satellite imagery provides an effective tool for monitoring remote yet dangerous volcanoes in the north pacific this region includes volcanoes in alaska the aleutian islands and the kamchatkan peninsula thermal infrared data collected multiple times per day from weather satellites show distinct signatures for three different types of volcanic activity at different volcanic centers near real time automated techniques are being developed to monitor relative changes in radiant temperature at volcanoes in this region radiant temperature values as a function of time are extracted and compared to background values for a series of active volcanoes by establishing a long term thermal record for these volcanoes significant deviations indicative of an impending eruption can be detected this tool is used to search for precursors to explosive eruptions in order to increase warning times and hazard mitigation for these potentially catastrophic events a six year archive of satellite imagery has been compiled for this active region and is available for study

infrared satellite monitoring at popocatepetl explosions exhalations and cycles of dome growth 1 since december 1994 activity at popocatepetl has evolved through two main phases the first was characterized by elevated seismic activity degassing and emissions of predominantly lithic ash however in march 1996 the volcano entered a magmatic phase which has involved the emplacement of at least eight lava domes within its summit crater we have used infrared radiance data acquired by the goes meteorological satellite alongside ground based geophysical data sets to analyze aspects of this activity we develop a technique to identify magmatic activity at the volcano in the absence of a volcanic heat source the radiance emitted from the hottest pixel pr contained within a 10 10 pixel goes subscene centered on popocatepetl s summit is well correlated with the average radiance emitted by the remaining pixels br because at any given time all pixels within the target box have similar temperatures varying as a function of season cloud cover and solar irradiance however during periods of heightened volcanic activity the radiance emitted by the hottest pixel varies as a function of a time independent volcanic heat source and changes in pr and br become decorrelated allowing volcanic activity to be identified exhalations intermittent ash emissions cannot be identified by routine analysis of goes data because of the low intensity of the associated thermal anomalies explosions however produce distinctive radiance signatures and can be reliably documented two dome growth episodes occurred during our study period one in november december 1998 and the other during february 2000 although the techniques we describe identified the 1998 dome event the 2000 dome went undetected this is explained in terms of their contrasting emplacement styles the 1998 dome was apparent to goes due to the explosions that disrupted its cool carapace scattered hot bombs around the summit cone and exposed its hotter interior to the satellite sensor in contrast the february 2000 dome was not apparent because elevated explosive activity did not accompany its emplacement

documenting surface magmatic activity at mount etna using atsr remote sensing analysis of thermally generated night time volcanic radiances recorded with a 1 km pixel size at 1 6 and 11 m during 1991 1993 and 1996 1999 for mount etna shows that lava flows extending beyond the summit craters can be distinguished from vent activity the two phenomena plot in different regions of feature space when the mean volcanic radiance per anomalous pixel at 11 m is plotted against the mean volcanic radiance at 1 6 m the distinct feature space characteristics of lava flow fields are apparent within 1 2 days of the onset of each effusive event such a plot also enables lava flow fields being fed by open channels to be distinguished from tube fed flow fields rank order analysis of the total 1 6 m volcanic radiance series shows that vent activity and lava flows belong to different populations and offers further scope for remotely identifying changes in eruptive state

spatial distribution of coarse woody debris dams in the lymington basin hampshire uk abstract debris dams of coarse woody debris have a significant influence on channel processes in forested areas but few detailed studies have been made of variations within a single basin results from previous research are standardised and show that average variations throughout basins include densities of debris dams up to 40 per 100 metres of channel and can involve a loading value of up to 225 kg per m2 of channel variations have been ascribed to distance downstream to channel width to land use effects to felling and to the management of coarse woody debris in streams this study of the lymington basin 110 4 km2 in drainage area shows that the input of storm debris resulting from blowdown accounts for 45 of the gross load the remaining 55 net load varies to distance downstream to land use with the greatest loads in deciduous woodland areas and according to management removal of debris from streams and multiple regression equations are provided it is deduced that as a consequence of long term management the present channel debris may be as little as 7 of the total net load that could have been present if no management had occurred

improved remote sensing estimates of lava flow cooling a case study of the 1991 1993 mount etna eruption infrared radiance data acquired by the landsat thematic mapper tm provide information regarding the thermal state of active lavas which can be used to estimate flow surface temperatures and thus lava cooling saturation of one or both of tm s short wave infrared swir wavebands has meant however that previous studies of lava flow cooling have approximated what is almost certainly an n thermal component flow surface temperature distribution where n 1 with a single pixel integrated temperature pit we show that the high sensitivity of tm s swir wavebands to the small amount of high temperature e g 1000 c material exposed in hot fractures within the flows cooler e g 200 c surface crust results in the calculation of pits that are higher than the temperature of this crust which is usually the dominant radiative component this causes heat loss from such pixels to be overestimated we present adaptations that allow more realistic heat loss estimates to be produced using tm data by assuming that a second high temperature component contributes to the radiance measured from saturated pixels and by defining an appropriate range for the temperature of the lava crust by analyzing a suite of five tm images acquired during the 1991 1993 eruption of mount etna we present more realistic estimates of how this flow cooled as well as results that show how the flow regime of the lava evolved over time the methods we present will continue to be of use as although the next generation of high spatial resolution sensors such as the landsat 7 enhanced thematic mapper plus etm and the terra advanced space borne thermal emission and reflection radiometer aster will be less susceptible to saturation than tm the problem will still persist

input storage and distribution of large woody debris along a mountain river continuum the drome river france abstract large woody debris lwd input storage and distribution were studied along the drome river a french alpine river with an active shifting channel and a well developed riparian forest lwd input from the floodplain is low 669 6 mg year 1 between 1948 and 1971 and 569 3 mg year 1 between 1971 and 1991 based on estimates of average lwd mass per study plot a range of 766 2122 mg year 1 of lwd were stored within the active channel e g unvegetated bars and low flow channel 60 km course covering 492 ha lwd accumulations are mainly observed on gravel bars at a limited number of preferential sites they are relatively rare and are randomly distributed in the low flow channel consequently lwd location is mainly associated with the decrease of flow level in shallow sectors in the low flow channel lwd stop en route is primarily caused by in channel structures such as boulders or vegetated islets general geomorphological factors e g pattern slope etc provide less explanation of lwd distribution moreover the residence time of lwd accumulations on the drome river is short lwd storage 1 3 3 7 times the annual lwd input from the floodplain and their morphogenic role is negligible few of the accumulations are buried or characterized by vegetation shoots and associated pools

a new distinct mechanism of river bank erosion in a forested catchment abstract it has been thought that the two main processes responsible for river bank retreat are the removal of particles or layers of material by flow erosion or sloughing and collapse by slumping a third process involving the development of a subsurface cavity after washout of gravels which is succeeded by slow subsidence of a segment of the former channel bank has been identified at a site in the new forest southern england the process was monitored over a 9 month period and was observed to be assisted by the hydrological effects of a dam of coarse woody debris across the channel as these dams occur frequently the process is likely to have occurred elsewhere along channels in forested areas

river stabilisation due to changing climate and vegetation during the late quaternary in western tasmania australia abstract the stanley river in western tasmania australia contains sub fossil rainforest logs within the channel and floodplain of the more than 85 radiocarbon dates obtained all but 3 date from 17 ka to the present and permit an interpretation of fluvial and related environmental changes over this period particular attention is focused on the interactive relationship between the river and its riparian rainforest following the last glacial maximum the stanley river was a laterally active gravel load system reworking most of its valley floor in the upstream reaches with ameliorating conditions at the end of the pleistocene climate became less seasonal and flow regimes less energetic huon pines already present in the catchment re asserted themselves in the form of dense tree cover along the river banks and floodplains with basal floodplain deposition shifting from gravels to coarse sands and granules by about 3 5 ka a further change in climate reduced stream discharges substantially as a result the channel reduced in size transported finer sediment became laterally stable and the floodplain accreted with overbank deposits of sand and silt huon pines falling into the channel formed obstructions of woody debris some surviving for 2 ka these have reduced stream power and boundary shear stress further contributing to channel stability generational sequences of huon pines on the river banks some extending back 1 2 ka are additional evidence of this stability since the pleistocene changing climate and the re establishment of dense riparian rainforest appear to have stabilised the river channels and floodplains of western tasmania

long term infrared surveillance of lascar volcano contrasting activity cycles and cooling pyroclastics lascar volcano chile erupted on 20 july 2000 generating a 10 km high ash column satellite infrared data have previously indicated that lascar s large vulcanian explosions are preceded by significant cooling within the active crater suggesting that characteristic thermal radiance trends can act as remotely detectable eruption precursors new analyses and data extend the lascar s thermal history to cover all five large vulcanian eruptions occurring over the last 15 years the 2000 eruption follows a formerly undocumented style of infrared radiance variation and indicates that lascar may have modified its activity since 1993 the year of its greatest historical eruption therefore such patterns evident for over a decade at lascar can be unexpectedly modified and this has implications for the way apparent thermal precursors should be treated the largest 1993 eruption produced 8 5 km long pyroclastic flows which the infrared data indicate exhibited exponential cooling over an 8 12 months period

infrared image analysis of volcanic thermal features lascar volcano chile 1984 1992 fifteen landsat thematic mapper tm images of lascar volcano chile recorded between december 1984 and april 1992 document the evolution of a lava dome within the summit crater four of the scenes were acquired at night in every image the two short wavelength infrared bands 5 and 7 have detected thermal radiation from the volcano as a consequence of the planck distribution function the relative response of these two channels depends on the proportions of very hot 600 c surfaces occupying tiny pixel areas and broader regions at moderate temperatures 280 c intercomparison of bands 5 and 7 thereby provides a means for interpreting tm thermal anomalies even in the absence of ground observations pronounced changes in the configuration and intensity of the lascar anomaly suggest that the volcano has experienced at least two cycles of lava dome activity since 1984 the first of these progressed through a cooling period possibly reflecting a reduced flux of magmatic volatiles at the surface and culminated in an explosive eruption on september 16 1986 which appears to have completely destroyed the inferred lava dome the tm data indicate that a new dome had been emplaced by november 1987 more than 15 months before it was first discovered by local observers lascar s style of cyclical effusive and explosive activity is typical of many volcanoes and the remote sensing techniques presented herein could be applied elsewhere

log jam effects on bed load mobility from experiments conducted in a small gravel bed forest ditch abstract bed load transport experiments have been conducted in a steep gravel bed open ditch this initially straight ditch has been neglected for many years and looks at present like a second order natural stream channel the channel flows through a spruce forest and several log jams have produced chutes and pools creating supplementary roughness the total shear stress has been evaluated using the slope hydraulic radius product and the ratio between grain and bed form shear stresses has been calculated using different methods the shear stress has also been evaluated from the shear velocities and this gives a good evaluation of the grain shear stress additional experiments have been conducted with marked pebbles to estimate particle mobility and to improve the motion equations equations such as c a di d50 b b defined by andrews apply in these cases but the values of a and b are lower than those produced by this author in a second stage of experimentation we have destroyed the log jams resulting in a diminution of the roughness and critical shear stress when the total shear stress is used an increase of the grain shear stress and thus greater bed particle mobility for the same discharge it emerges from these experiments that the log jams contribute to the reduction of bed load evacuation and explain the very weak bed load discharge measured by a bed load trap 0 3 t km 2 yr 1

mediated equilibrium the influence of riparian vegetation and wood on the long term evolution and behaviour of a near pristine river analysis of the contemporary geomorphology vegetation and in channel wood within the relatively pristine thurra river in southeastern australia provides insight into river behaviour prior to european disturbance this sand bed river has an extremely low channel capacity with a pronounced pool riffle morphology lateral migration rates are low 11 24 mm a 1 as are floodplain aggradation rates average d 0 27 mm a 1 sedimentological evidence is used to place contemporary channel dynamics within a 16 ka evolutionary framework the floodplain has continuously aggraded over this interval despite a number of avulsions and numerous meander cutoffs avulsions occur on a timeframe of once in 5 ka or more while cutoffs occur around once in 1 ka the morphology and evolution of the thurra river are appraised in terms of a mediated equilibrium condition in which channel capacity hydraulics bedload transport rates bank erosion rates and in channel deposition are substantially influenced by vegetation and wood within the channel and on the floodplain copyright 2002 john wiley sons ltd

pool spacing in forest channels field surveys of stream channels in forested mountain drainage basins in southeast alaska and washington reveal that pool spacing depends on large woody debris lwd loading and channel type slope and width mean pool spacing in pool riffle plane bed and forced pool riffle channels systematically decreases from greater than 13 channel widths per pool to less than 1 channel width with increasing lwd loading whereas pool spacing in generally steeper step pool channels is independent of lwd loading although plane bed and pool riffle channels occur at similar low lwd loading they exhibit typical pool spacings of greater than 9 and 2 4 channel widths respectively forced pool riffle channels have high lwd loading typical pool spacing of 2 channel widths and slopes that overlap the ranges of free formed pool riffle and plane bed channel types while a forced pool riffle morphology may mask either of these low lwd loading morphologies channel slope provides an indicator of probable morphologic response to wood loss in forced pool riffle reaches at all study sites less than 40 of the lwd pieces force the formation of a pool we also find that channel width strongly influences pool spacing in forest streams with similar debris loading and that reaches flowing through previously clear cut forests have lower lwd loading and hence fewer pools than reaches in pristine forests

discrimination of lava dome activity styles using satellite derived thermal structures abstract thermal imaging from satellites is one methodology used for the monitoring and scientific investigation of volcanoes including those characterised by active lava domes to be most effective the remote sensing techniques employed must allow the cause of any observed thermal anomaly to be identified ideally using information contained within the remote sensing data itself whilst using any ancillary field data to guide analysis and the necessary assumptions this study investigates a method by which such discrimination maybe accomplished for activity at lava domes for this purpose we use three landsat thematic mapper tm scenes of unzen volcano japan to determine the temperature structure of the active lava dome existing during 1991 1993 these data are of particularly high quality since the tm scenes were obtained during night time overpasses and a large amount of supplementary data are available to parameterise the model used to retrieve the subpixel temperature structure of the dome surface the results are matched to near contemporaneous geological sketch maps of the then current situation in order to identify the tm pixel groupings corresponding to the different styles of dome activity namely fumarolic degassing exogenous and endogenous dome growth and collapse deposits resulting from block and ash flows small scale pyroclastic flows and rockfalls the spatial and statistical characteristics of the resultant tm derived temperature distributions are then investigated to determine rule based criteria that may be used to differentiate the activity styles of lava domes based on their thermal structure within the remote sensing data results indicate that fumarolically active locations regions of active dome growth and areas of collapse deposition on the unzen dome can be differentiated using only the statistical distribution of the hotspot temperatures and fractional areas identified via analysis of tm imagery the statistics derived for hotspots at the fumarolically active areas show them to be in general significantly hotter and smaller than those found at the areas of active dome growth whereas hotspots retrieved on the areas of collapse deposition are cooler and larger we find that the frequency distributions of hotspot temperatures extracted for the areas of endogenous and exogenous dome growth exhibit statistically inseparable means but that discrimination between these two dome growth styles is possible using analysis of the spatial arrangement of the retrieved hotspots specifically the exogenous lobes are characterised by structures interpreted to be the effusing vent of new magma and the collapsing lobe front these features are absent at locations showing only endogenous growth it is hoped that the criteria developed here will prove useful during future quantitative analysis of the extended tm time series available for unzen and for identification of thermal anomalies of uncertain origin at other active domes observed via satellite remote sensing

structure and hydraulics of natural woody debris jams 1 numerous studies exist on the hydraulics of woody debris jams and the mechanisms driving their geomorphic influence while most hydraulic studies treat jams as single solid objects jams are clearly not individual cylindrical logs but rather an accumulation of pieces ranging in size from leaves and twigs to entire trunks here we treat debris jams as complex and porous accumulations of heterogeneous material to understand the relative importance of the different size fractions comprising a jam we systematically dismantled three deflector debris jams in four stages removing a total of 17 783 individual wood pieces to experimentally manipulate jam porosity we measured the surrounding velocity shear stress and drag force fd the assumption of nonporosity can result in a 10 20 overestimation of fd back calculated values of the combined drag coefficient and frontal area term cdaf calc represented the drag characteristics of natural debris jams whereas separating frontal area af emp and drag coefficient cd contributions in natural jams is misleading values of cdaf calc for each jam at each stage of removal captured the effects of size and composition of the jam wood piece size in debris jams dictates the surface area to volume relationship this association in turn determines the rate at which fd and cdaf calc change with the addition of material only low porosity jams produce the geomorphic and hydraulic characteristics commonly associated with deflector jams our results on natural debris jams also illustrate the importance of employing variable wood size fractions when using woody debris jams for river restoration

improved identification of volcanic features using landsat 7 etm volcanic eruptions can present unpredictable hazards to populations living within regions containing potentially active volcanoes and for people traveling in jet aircraft that intersect with ash laden eruption clouds methods of monitoring volcanic activity include searching for variations in the thermal signal from active fumaroles lava domes lava lakes flows and other features over many active volcanoes in the western hemisphere low spatial resolution 4 km pixel weather satellite data acquired every 15 min are used to identify changes in eruptive activity but are of insufficient spatial resolution to map active volcanic features the enhanced thematic mapper plus etm on landsat 7 can be used to monitor active volcanoes at a higher spatial resolution 15 to 60 m pixels etm also offers improvements over its predecessor the thematic mapper of landsats 4 and 5 by way of a 15 m panchromatic band and higher spatial resolution 60 m pixel thermal infrared ir band with higher spatial resolution panchromatic data we are able to map lava flow fields trace very high temperature lava channels and at lascar volcano identify an arcuate feature associated with a collapsed crater floor a phenomenon that may precede explosive activity with improved spatial resolution in the thermal ir we are able to map the bifurcation and braiding of underground lava tubes at kilauea identifying tube locations and tracking their extension are important because for a given volumetric lava production effusion rate tube fed flows can extend a much greater distance than surface flows at both kilauea and etna we are able to use the thermal data to estimate effusion rates an important parameter for assessing how far a flow is likely to extend and therefore the hazard it poses an improved etm data collection and distribution system includes a well formulated and executed long term acquisition plan and less expensive data that is available much faster than previously possible

interactions between semi natural vegetation and hydrogeomorphological processes abstract within britain lowland heaths and floodplain forests are rapidly disappearing from the landscape this paper considers the hydrogeomorphological significance of these two types of semi natural vegetation cover using research results gathered from a drainage basin in the new forest southern england whilst heathland vegetation communities are closely adjusted to the soil water hydrological regime floodplain forests have a distinctive and significant influence on the geomorphology of river channels both of these types of interaction are not only of hydrogeomorphological interest but provide an essential foundation for the effective management and restoration of catchments and rivers containing these types of vegetation cover

changes in woody debris and bed material texture in a gravel bed channel abstract this study investigated the response of bed material texture under two distinct periods of log jam conditions in a 900 m study reach of carnation creek vancouver island bc a field program extending over seven flood seasons coupled with existing streamflow records channel maps and low altitude aerial photography provides observations of jam stability and permeability surface and subsurface grain size as well as bed material fluxes sediment supply calibre streambed stability and sediment exchange near jams all jams functioned as partial dams throughout the field program but the overall perturbation of sediment transfers decreased when two jams were breached bed material texture exhibited the largest differences over the study reach during a period when log jams exerted a stronger influence over the passage of water and sediment at individual gravel bars most adjustments in surface and subsurface grain size constituted less than a 20 change in percentile values larger changes occurred primarily in subsurface sediment temporal patterns in bed material texture exhibited variation between bars but downstream of breached jams surface sediment conformed to the expected fining trend while the subsurface sediment increased in size surface and subsurface sediments evolved in the same direction only 64 of the time and the different magnitudes of adjustment caused local armor ratios to vary over time results highlight that the temporal dynamism of large woody debris lwd should be coupled with spatial considerations for effective stream restoration and management of streambed sediment

satellite thermal analyses of lava dome effusion rates at unzen volcano japan this paper presents analyses of infrared remote sensing data of the 1992 1994 lava dome growth episode of unzen volcano japan the primary aim is to determine whether such data can indicate trends in the rate of magma supply to the dome since this is one of the principal factors controlling the frequency of pyroclastic flow spaceborne low spatial resolution infrared radiance data correctly delimit the two discrete phases of magma supply to the dome and during phase 1 the short wavelength data are found to be strongly correlated with ground based estimates of lava effusion rate the correlation is however significantly weaker during phase 2 analysis of high spatial resolution data from airborne and satellite based systems allows us to determine the principal source of shortwave infrared flux as fumarolically heated dome surfaces these being significantly hotter than the actively growing lava lobes variations in the low spatial resolution shortwave infrared signal are therefore directly attributed to fluctuations in the size and temperature of the fumarolically heated area these fumarolic variations are largely dependent upon the flux rate of magmatic gas which in turn is partly dependent upon the rate of magma supply gas fluxes measured using correlation spectrometer cospec measurements of so2 concentration indicate that the relationship between fumarolic discharge and the effusion rate of lava was relatively stable during phase 1 but highly variable during phase 2 we suggest these variations as an explanation for the differing correlations observed between the emitted shortwave infrared flux and the effusion rate of lava during phases 1 and 2 we conclude that appropriate analysis of high and low spatial resolution shortwave infrared remote sensing data may assist in elucidating trends in lava supply at volcanoes exhibiting similar dome growth episodes to that experienced at unzen

temporal variations of large wood abundance and mobility in the blanco river affected by the chaiten volcanic eruption southern chile abstract the aim of this study is to analyze the temporal variation in abundance and transport of in channel wood along a river affected by a volcanic eruption considering the mobility and retention rates in detail the 2008 eruption of chaiten volcano southern chile severely affected the blanco river basin causing changes in channel morphology and large wood lw dynamics along the fluvial corridor of the river a fourth order stream on the southern slope of the volcano temporal dynamics of lw were investigated from january 2015 until march 2016 in three 80 m long study reaches of the active channel in the lower course of the river every wood element 1 m in length and 0 1 m in diameter within the active channel of each reach was georeferenced measured tagged and characterized wood mobility rate defined as the number of tagged wood pieces repositioned or not found within each study reach to total tagged lw in the same reach and retention rate defined as the number of tagged lw pieces found within each study reach to total tagged wood pieces in the same reach were calculated considering two periods one in summer and one in autumn winter a regional flood frequency analysis estimated flood magnitude defining a recurrence interval of 1 year for summer floods and 10 25 years for autumn winter floods results highlighted how eight years after the eruption the types of lw are still influenced by the impacts of pyroclastic density currents on riparian vegetation the characteristics and abundance of monitored lw are typical of a river system with frequent wood transport the mobility rate ranges between 42 and 94 during the summer and autumn winter period respectively while the wood volume decreases during the summer and increases in autumn winter large wood mobility was also found to vary according to the predominant morphological settings with lower values in narrower channels compared to wider wetted areas in this context the greatest abundance of lw was detected after the higher floods corresponding to an input of lw up to 285 35 m3 ha 1 along the blanco river ordinary floods deliver lw mainly through fluvial transport and bank erosion during higher floods appears as an additional and important wood recruitment process the bank erosion processes with up to 5200 m2 of eroded area confirmed the widening tendency occurring in river systems following volcanic disturbances as there are dead riparian trees along the easily erodible banks it is reasonable to suppose that the blanco river will continue to widen for a long period recruiting and transporting downstream huge volumes of lw in this context these analyses appear of fundamental importance to better manage the river system also for decreasing hazards to the downstream village of chaiten

effusion rate trends at etna and krafla and their implications for eruptive mechanisms abstract using effusion rates obtained from ground and satellite based data we build a data set of 381 effusion rate measurements during effusive activity at etna and krafla between 1980 and 1999 this allows us to construct detailed effusion rate curves for six fissure fed eruptions at etna and krafla and four summit fed eruptions at etna these define two trends type i and ii type i trends have effusion rates that rise rapidly to an initial peak before declining more slowly resulting in an exponential decrease in eruption rate and declining growth in cumulative volume type ii trends are characterised by steady effusion and eruption rates and hence a linear increase in cumulative volume the former is typical of fissure eruptions and can be explained by tapping of an enclosed pressurised system the latter are typical of persistent etnean summit eruptions plus one persistent effusive eruption at stromboli 1985 1986 examined here and can be explained by overflow of the time averaged magma supply we use our effusion rate data to assess the magma balance at etna 1980 1995 and krafla 1975 1984 between 1980 and 1995 etna was supplied at a time averaged rate of 6 8 2 3 m 3 s 1 of which 13 was erupted at krafla 817 30 10 6 m 3 was erupted and intruded during 1975 1984 and the ratio of erupted to intruded volume was 0 3 at etna there is evidence for intrusion of the unerupted magma within and beneath the edifice as well as storage in the central magma column at krafla unerupted magma was intruded into a rift zone but an increasing proportion of the supply was erupted from 1980 onwards a result of the rift zone capacity being reached magma intruded prior to an eruptive event may also be entrained and or pushed out during eruption to contribute to the initial high effusion rate phases of type i events the detail in our effusion rate curves was only possible using a thermal approach which estimates effusion rates using satellite data we look forward to analysing satellite derived effusion rate trends in real time using data from current and soon to be launched sensors

goes satellite and field observations of the 1998 eruption of volcan cerro azul galapagos islands the 1998 eruption of volcan cerro azul isla isabela galapagos islands was observed in near real time by the geostationary operational environmental satellite 8 goes 8 weather satellite due to the remote location of the eruption site 3 9 m radiance values derived from goes band 2 provide the best timing of the start and termination of the eruption which occurred on 15 sept and 21 oct respectively throughout the 36 day long eruption a total of 1335 thermal infrared images were collected of which 851 were cloud free and permitted the thermal anomaly to be detected a detailed chronology including 77 separate events was assembled from the goes data and field observations numerous attributes of the eruption were observed from the goes data including the sizes and dispersal of seven eruption plumes and the occurrence and timing of intra caldera effusive activity the growth of a lava flow on the se flank the formation of smoke and volcanic haze from the flank vent and burning of vegetation caused by lava flows entering vegetated areas were monitored both on the ground and with the satellite data in most cases goes images were processed as they were received every 30 min and were then distributed over the internet within minutes of reception these data provided timely high temporal information to field parties as well as enabled the documentation of the eruption the goes observations of cerro azul serve as a further example of the way in which the remote sensing community and field volcanologists can collaborate during future eruptions and permit the temporal and spatial resolution requirements for future satellites systems to be better defined

the distribution of large woody debris accumulations and pools in relation to woodland stream management in a small low gradient stream this paper focuses upon the natural dynamics of large woody debris lwd the impact of management on lwd dynamics and the impact of lwd removal and channelization on the distribution and size of pools in a british second to third order headwater catchment the study stream is rather different from those subject to lwd accumulations which have been studied in north america the most important contrast is that it is surrounded by predominantly deciduous rather than coniferous woodland in terms of its width 1 8 4 5 m and gradient 0 013 m m 1 it falls within the lower range of channels studied in north america nevertheless there are similarities in lwd dam and pool spacing with some north american studies the information on lwd dynamics during a period without management and on recovery of lwd dams after clearance covers a 16 year period 1982 1997 the paper illustrates that seven to eight years after clearance the total number of lwd dams has recovered but the most hydraulically active dam type has not recovered to pre clearance levels an analysis of geomorphological maps of the channel surveyed in 1982 and 1996 97 shows an overall decrease in the number and size of pools along the section that was cleared of lwd dams the magnitude of the decrease and the associated adjustments in pools through changes in their size and location differ according to location with respect to a section of the study stream which was channelized in c 1966 and which has subsequently incised its bed copyright 1998 john wiley sons ltd

radiative temperature measurements at kupaianaha lava lake kilauea volcano hawaii field spectroradiometer data in the wavelength range of 0 4 2 5 m and spectral resolution of 1 5 nm have been used to compute the radiative temperature of the surface of kupaianaha lava lake kilauea volcano hawaii two sets of observations a total of 120 spectra were made on october 12 1987 and january 23 1988 when the lava lake was in a period of active overturning the area of the surface for which temperatures were measured was 0 23 0 55 m2 two numerical models of two and three components have been used to match the measured radiant flux ratios and to describe the surface of the lava pond in terms of radiant area and temperature three stages of activity on the lake surface are identified stage 1 characterized by magma fountaining and overturning events exhibited the hottest crustal temperatures 180 572 c and the largest fractional hot areas 10 3 stage 1 average flux densities were 2 2 104 w m2 the highest recorded for the three stages of activity on either day the largest radiative area of fresh magma was 29 at 1100 c while cooling from magmatic temperatures to newly formed crust at 790 c took place in a matter of seconds stage 2 marked by rifting events between plates of crust exhibited crustal temperatures between 100 and 340 c with fractional hot areas at least an order of magnitude lower than those found for stage 1 average flux densities calculated for three examples of stage 2 activity were 5 3 103 w m2 stage 3 which was quiescent periods when the lake was covered by a thick crust dominated the activity of the lake both temporally and spatially over 90 of the time the characteristic crustal temperature of stage 3 was 80 345 c with most solutions near 200 300 c and fractional hot areas of 10 5 of the viewing area average flux densities for stage 3 were 4 9 103 w m2 for many stage 3 examples a two component model was sufficient to describe the spectral data however for almost all of the stage 1 and 2 examples and the remainder of the stage 3 examples a three component model was required these determinations of lava temperature and radiant area have relevance for satellite and airborne measurements of the thermal characteristics of active volcanoes and indicate that temporal variability of the thermal output of lava lakes occurs on the time scale of seconds to minutes

the variability of volcanic activity at zamama culann and tupan patera on io as seen by the galileo near infrared mapping spectrometer abstract zamama culann and tupan patera are three large persistent volcanic centers on the jovian moon io as part of an ongoing project to quantify contributions from individual volcanic centers to io s thermal budget we have quantified the radiant flux from all suitable observations made by the galileo near infrared mapping spectrometer nims of these volcanoes in some cases filling omissions in previous analyses at zamama after a long period of cooling we see a peak in thermal emission that corresponds with new plume activity subsequently toward the end of the galileo epoch thermal emission from zamama drops off in a manner consistent with a greatly reduced eruption rate and the cooling of emplaced flows culann exhibits possible episodic activity we present the full tupan patera nims dataset and derive new estimates of thermal output and temporal behavior eruption rates at these three volcanoes are on the order of 30 m 3 s 1 consistent with a previous analysis of nims observations of prometheus and nearly an order of magnitude greater than kilauea volcano hawai i earth s most active volcano we propose that future missions to the jovian system could better constrain activity at these volcanoes and others where similar styles of activity are taking place by obtaining data on a time scale of ideally at least one observation per day observations at similar or even shorter timescales are desirable during initial waxing phases of eruption episodes these eruptions are identifiable from their characteristic spectral signatures and temporal behavior

fluvial processes and vegetation glimpses of the past the present and perhaps the future abstract most research before 1960 into interactions among fluvial processes resulting landforms and vegetation was descriptive since then however research has become more detailed and quantitative permitting numerical modeling and applications including agricultural erosion abatement and rehabilitation of altered bottomlands although progress was largely observational the empiricism increasingly yielded to objective recognition of how vegetation interacts with and influences geomorphic process a review of advances relating fluvial processes and vegetation during the last 50 years centers on hydrologic reconstructions from tree rings plant indicators of flow and flood frequency parameters hydrologic controls on plant species regulation of sediment movement by vegetation vegetative controls on mass movement and relations between plant cover and sediment movement extension of present studies of vegetation as a regulator of bottomland hydrologic and geomorphic processes may become markedly more sophisticated and widespread than at present research emphases that are likely to continue include vegetative considerations for erosion modeling response of riparian zone forests to disturbance such as dams and water diversion the effect of vegetation on channel and bottomland dynamics and rehabilitation of stream corridors research topics that presently are receiving attention are the effect of woody vegetation on the roughness of stream corridors and hence processes of flood conveyance and flood plain sedimentation the development of a theoretical basis for rehabilitation projects as opposed to fully empirical approaches the effect of invasive plant species on the dynamics of bottomland vegetation the quantification of below surface biomass and related soil stability factors for use in erosion prediction models and the effect of impoundments on downstream narrowing of channels and accompanying encroachment of vegetation bottomland vegetation partially controls and is controlled by fluvial geomorphic processes the purposes of this paper are to identify and review investigations that have related vegetation to bottomland features and processes to distinguish the present status of these investigations and to anticipate future research into how hydrologic and fluvial geomorphic processes of bottomlands interact with vegetation

complex effusive events at kīlauea as documented by the goes satellite and remote video cameras goes provides thermal data for all of the hawaiian volcanoes once every 15 min we show how volcanic radiance time series produced from this data stream can be used as a simple measure of effusive activity two types of radiance trends in these time series can be used to monitor effusive activity a gradual variations in radiance reveal steady flow field extension and tube development b discrete spikes correlate with short bursts of activity such as lava fountaining or lava lake overflows we are confident that any effusive event covering more than 10 000 m2 of ground in less than 60 min will be unambiguously detectable using this approach we demonstrate this capability using goes video camera and ground based observational data for the current eruption of k lauea volcano hawai i a goes radiance time series was constructed from 3987 images between 19 june and 12 august 1997 this time series displayed 24 radiance spikes elevated more than two standard deviations above the mean 19 of these are correlated with video recorded short burst effusive events less ambiguous events are interpreted assessed and related to specific volcanic events by simultaneous use of permanently recording video camera data and ground observer reports the goes radiance time series are automatically processed on data reception and made available in near real time so such time series can contribute to three main monitoring functions a automatically alerting major effusive events b event confirmation and assessment and c establishing effusive event chronology

logjam controls on channel floodplain interactions in wooded catchments and their role in the formation of multi channel patterns the role of wood in the formation and maintenance of complex dynamic floodplain surfaces is important and to date has received relatively limited attention compared to in channel habitat processes this paper explores the role of logjams as important agents of channel floodplain interaction we draw on a specific case study as well as examples from the literature to show that although the processes of interaction differ the resulting dynamic floodplain patchwork is a common feature of rivers with logjams in addition we contend that the presence of logjams is an important factor in the evolution and maintenance of multiple channel patterns in both montane and lowland river environments these observations have important implications for the definition of reference targets for river restoration the specific results of this research show 1 the presence of a range of types of multiple channel network dissecting the floodplains of low order channels that are strongly associated with the presence of logjams 2 the relatively rapid formation of floodplain channels following logjam formation 3 the dynamic nature of logjams within headwater channels on both seasonal and annual timescales that lead to a highly dynamic habitat mosaic on the floodplain surface 4 an increased frequency of overbank flooding and high rates of floodplain sediment accumulation upstream of logjams and along floodplain channel networks that create the complex topography observed in the case study forested floodplains

fluvial geomorphological analysis of the recruitment of large woody debris in the yalobusha river network central mississippi usa abstract the management of large woody debris lwd should be based on a rational assessment of its recruitment rate relative to its natural decay and removal lwd recruitment may be controlled by natural episodic terrestrial factors or by in channel geomorphological controls related to the rate of bank erosion the geomorphological controls are hard to quantify in laterally migrating channels but in incising channels a conceptual model may be developed based on the density of riparian trees relative to the knickpoint migration rate and bank stability analyses that predict the post knickpoint width of the channel the yalobusha river network in central mississippi usa has twice been destabilised by channel straightening for flood defence and land drainage most recently in 1967 system wide rejuvenation has followed through a series of upstream migrating knickpoints several metres high that have caused mass failure of streambanks and the recruitment of large volumes of trees to the channel lwd recruitment is maximised at the transition between stage iii and stage iv channels focusing attention on 11 sites in the network the sites are upstream of knickzones ranging between 2 2 and 5 4 m high and migrating at rates of 0 13 8 m year 1 based on 23 30 months of monitoring riparian conditions in 500 m2 plots on each bank upstream of the knickpoints range from treeless to forested containing 0 98 trees with an average diameter at breast height of 0 18 m and average maximum height of 14 0 m the average volume of wood on each bank is 0 02 m3 m 2 under rapid drawdown conditions bank stability analyses suggest that the channels will widen in amounts ranging from 1 8 to 31 5 m combined with the knickpoint migration rates riparian land losses are estimated to range from 8 0 to 433 8 m year 1 resulting in the recruitment of almost 28 m3 of wood or 100 trees annually from the 11 sites assuming this lwd recruitment rate a model is developed for the in situ potential for debris dam initiation and growth based on the ratio of tree height to channel width under current and post knickpoint conditions the annual delivery of large trees and the annual total of lwd recruitment by volume a longer term model is also developed based on knickpoint severity and vegetation density in upstream and headwater riparian zones of each tributary the 11 study sites are classified into groups with similar lwd management concerns based on these analyses the models developed in this research provide the first precise quantification of lwd recruitment according to geomorphological controls and standing vegetation and a rational assessment of its meaning but further research is required to improve the accuracy of such estimates

wood storage within the active zone of a large european gravel bed river wood storage within the active zone of the dynamic gravel bed fiume tagliamento italy was investigated at eight sites along the river s main stem the quantity nature and mode of wood storage revealed a number of trends related to active zone morphology cover type and distance from the river s source relatively small quantities of wood were stored on open gravel surfaces estimates ranged from 1 to 21 t ha 1 intermediate quantities were associated with established islands 24 186 t ha 1 and large quantities were associated with pioneer islands 293 1664 t ha 1 thus variations in the geomorphological style of the river which are associated with changes in these three cover types are reflected in variations in the amount of wood that is stored in different reaches in addition although wood was found in many locations within the active zone it was preferentially stored in three specific locations i bar crests the main open gravel location for wood accumulations and pioneer islands ii the margins and iii surfaces of established islands the proportion of the stored wood that was living sprouting increased downstream and was higher on the open gravel than in association with established islands there was a downstream gradient in the dominant type of wood accumulation individual logs predominated at the most upstream site thereafter on the open gravel whole shrubs and trees dominated the more confined sites in the headwaters and middle reaches whereas jams were the most frequent form of accumulation in the downstream reaches jams were the most frequent type of accumulation associated with established islands throughout the river in contrast to small streams where debris dams constitute the major type of wood accumulation complex patterns and trends of wood storage were revealed along the tagliamento although further studies are needed it is clear that erosion of woody vegetation its subsequent transport and deposition play a major role in structuring the geomorphological and ecological character of this relatively natural large european river system insight into the mechanisms underlying the observed spatial patterns will contribute to a better understanding of the dynamic processes involved and is essential for more effective management of river ecosystems

influence of logjam formed hard points on the formation of valley bottom landforms in an old growth forest valley queets river washington usa abstract field surveys and radiocarbon dating of buried logjams in the floodplain of an old growth forest river demonstrate the formation of erosion resistant hard points on the floodplain of the queets river washington these hard points provide refugia for development of old growth forest patches in frequently disturbed riparian environments dominated by immature forest our surveys show that local bed aggradation associated with logjams not only influences channel patterns and profiles but leads to development of a patchwork of elevated landforms that can coalesce to form portions of the valley bottom with substantial i e 1 to 4 m relief above the bankfull elevation in addition logjam formed hard points promote channel avulsion anastomosing morphology and growth of mature patches of floodplain forest that in turn provide large logs needed to form more logjam formed hard points hence our findings substantiate the potential for a feedback mechanism through which hard points sustain complex channel morphology and a patchwork floodplain composed of variable elevation surfaces conversely such a feedback further implies that major changes in riparian forest characteristics associated with land use can lead to dramatic simplification in channel and floodplain morphology

evolution of lava flow fields at mount etna 27 28 october 1999 observed by landsat 7 etm landsat 7 enhanced thematic mapper etm data are presented which document the thermal characteristics of a series of lava flows emplaced at mount etna volcano sicily during 27 28 october 1999 by examining the composition of the short wave infrared swir signal emitted from the flow surface we identified distinctive flow units the first unit appears to comprise recently active lava flows with relatively cool crusts which by virtue of the integrity of this crust as determined from the etm data we infer are stationary or barely moving the second unit is characterized by much higher levels of swir radiance consistent with a channel fed active flow unit analysis of the swir data confirm that this is fed by a lava channel the properties of which are consistent with vigorously active channels observed on kilauea hawaii model predictions of the maximum length that such flows could attain compare favorably with the actual flow lengths observed in the etm data indicating that the cooler flows had indeed stopped advancing and may have attained a cooling limited rather than volume limited maximum length our observations and modeling provide a physical corroboration for the supposition made by wadge 1978 in his analysis of the shape of lava flow fields on mount etna which in the cooling limited case principal flows are active one after the other and not at the same time

overview of the eruption of soufriere hills volcano montserrat 18 july 1995 to december 1997 the onset of phreatic volcanic activity at the soufriere hills volcano montserrat on 18 july 1995 followed a three year period of heightened volcano seismic activity beneath the island phreatic explosions gave way to continuous eruption of juvenile andesitic magma in the form of a lava dome on or around 15 november 1995 magma production rate has varied leading to changes in eruptive style an explosive eruption on 17 september 1996 followed a period of enhanced dome growth and large scale gravitational collapses from its eastern flank increasing dome volume led to stressing and overtopping of the confining crater walls to the southwest north and west during early 1997 sustained high magma production rate since june 1997 has led to three periods of major gravitational dome collapses followed by vulcanian explosive eruptions dome growth re started immediately after the cessation of the latest of these explosive phases in october 1997 and continues as of december 1997

chronology of the episode 54 eruption at kilauea volcano hawaii from goes 9 satellite data the free availability of goes satellite data every 15 minutes makes these data an attractive tool for studying short term changes on cloud free volcanoes in the pacific basin we use cloud free goes 9 data to investigate the chronology of the january 1997 episode 54 eruption of kilauea volcano hawaii seventy six images for this effusive eruption were collected over a 60 hour period and show the opening and shutdown of active fissures the draining and refilling of the pu u o o lava lake and the cessation of activity at the ocean entry

porosity and volume assessments of large wood lw accumulations abstract the formation of large wood lw accumulations during floods represents a major hazard for constricted river cross sections e g bridges and weirs as it affects flow hydraulics and sediment transport to better assess lw accumulations reliable strategies and techniques are required there are currently practical limits on monitoring accumulation configurations both laser scans and photogrammetric techniques can be used to scan the outer contours of lw accumulations but cannot practically assess the wood content and porosity details of the outer deposit are captured in high resolution but the core of the deposit remains occluded and estimation is necessary this becomes more challenging for deposits of increasing size relative to wood elements to develop a more efficient workflow for lw accumulation assessment in the field we performed a laboratory study to develop a relationship between the envelope volume of water worked lw jams during a single flood hydrograph and the volume of woody elements within explicitly accounting for porosity we used photogrammetric techniques now in common use for reconnaissance surveys of debris accumulations on wood accumulations scaled for the laboratory the study s aim is to develop a semi automated assessment method enabling efficient image acquisition processing and computation of lw accumulation volume using a multi camera array above the laboratory channel and applying structure from motion photogrammetry we developed 3d models for 16 experimental flow formed wood accumulations each with 50 individual wooden dowels no correlations were found between porosity and flow magnitude porosity was found to be similar for most deposits 66 as a result of this accumulation structure the envelope volume used in 3d and 2 5d photogrammetric methods tended to overestimate wood content by 3 and 2 6 respectively the results obtained here will contribute to a more reliable volumetric assessment for inventories of wood mass in river systems

automated volcanic eruption detection using modis abstract the moderate resolution imaging spectroradiometer modis flown on board nasa s first earth observing system eos platform terra offers complete global data coverage every 1 2 days at spatial resolutions of 250 500 and 1000 m its ability to detect emitted radiation in the short 4 m and long 12 m wave infrared regions of the electromagnetic spectrum combined with the excellent geolocation of the image pixels 200 m makes it an ideal source of data for automatically detecting and monitoring high temperature volcanic thermal anomalies this paper describes the underlying principles of and results obtained from just such a system our algorithm interrogates the modis level 1b data stream for evidence of high temperature volcanic features once a hotspot has been identified its details location emitted spectral radiance satellite observational parameters are written to an ascii text file and transferred via file transfer protocol ftp to the hawaii institute of geophysics and planetology higp where the results are posted on the internet http modis higp hawaii edu the global distribution of volcanic hotspots can be examined visually at a variety of scales using this website which also allows easy access to the quantitative data contained in the ascii files themselves we outline how the algorithm has proven robust as a hotspot detection tool for a wide range of eruptive styles at both permanently and sporadically active volcanoes including soufriere hills montserrat popocatepetl mexico bezymianny russia and merapi java amongst others we also present case studies of how the system has allowed the onset development and cessation of discrete eruptive events to be monitored at nyamuragira congo piton de la fournaise reunion island and shiveluch russia

strong intracontinental lithospheric deformation in south china implications from seismic observations and geodynamic modeling abstract classical plate tectonics theory predicts concentrated deformation at plate boundaries and weak deformation within plates yet the existence of intracontinental orogens shows that highly deformed regions can occur within continental plates which is geodynamically incompletely understood shear wave splitting measurements in south china show belt parallel i e ne sw fast directions beneath the wulingshan xuefengshan belts while no dominant fast direction is found in the cratonic sichuan basin tomographic studies in the mantle in the same area show that the thickness of lithosphere beneath the intracontinental orogen is larger than that beneath the cratonic sichuan basin in order to better understand these seismic observations we performed numerical experiments of intracontinental lithospheric deformation with the presence of cratonic basin by comparing systematic model results with topography data and constraints on the accumulated amount of shortening in the study region we find that the best fitting result is obtained for models with a strong upper and a wet lower crust and with a weak mantle lithosphere beneath the orogen belt which has an effective viscosity that is 2 orders of magnitude smaller than that of the craton our numerical model successfully explains the belt parallel anisotropy and high velocity anomaly beneath intracontinental orogen and suggests that significant intracontinental lithospheric deformation occurred in south china

influence of large woody debris on morphological evolution of incised sand bed channels this paper documents the influence of large woody debris lwd on the morphological evolution of unstable degrading sand bed rivers in the yazoo basin north mississippi usa the study was performed as part of the demonstration erosion control dec project twenty three river reaches were studied with the aim of determining whether the presence of lwd was beneficial or detrimental to the recovery of stability in degrading sand bed river systems and to provide the geomorphic understanding necessary to underpin enhanced lwd management strategies the results demonstrate that locations of lwd inputs volumes of lwd stored in different reaches and number of jams per unit channel length are causally related to the morphological processes occurring during different stages of adjustment in these unstable incised fluvial systems and may be explained using a channel evolution model cem the net impact of lwd jams on reach scale sediment budgets was found in general to be positive that is jams trap more sediment than they mobilise this suggests that lwd probably accelerates rather than retards recovery of a stable longitudinal profile and channel configuration following incision field typing of lwd jams based on their impacts on the flow pattern reveals that jam type is a function of the size of large key elements in the jam in relation to the channel width a debris jam classification scheme is proposed on this basis with the spatial relationship between jam type and drainage basin area expressed using a dimensionless function of the ratio between channel width and average riparian tree height the scheme features four jam types underflow dam deflector and flow parallel bar head each of which has a different morphological impact on local channel geometry these jam types may be used to classify lwd jams as an aid in determining appropriate management strategies according to their location within the drainage basin

a chronology of the 1991 to 1993 mount etna eruption using advanced very high resolution radiometer data implications for real time thermal volcano monitoring between december 1991 and march 1993 a continuous effusive eruption at mount etna built a 7 6 km2 lava flow field flows extended to within 1 km of the town of zafferana before a successful artificial diversion was carried out higher up the volcano during this eruption the spaceborne advanced very high resolution radiometer avhrr acquired 308 images on which the activity could be detected since these data can be freely and directly available such coverage potentially allows regular real time monitoring ground observations and a flow map that we produced using a spot image and electronic distance measurement allowed us to develop and test data extraction techniques avhrr radiance maps were consistent with known locations of surface activity these documented the transition from channel to tube fed phases the changing threat to zafferana and flow diversion quantitative analysis of the avhrr data enabled estimation of active lava area thermal flux effusion rates and total flow field volume our estimates for eruption rate and total flow field volume 5 6 to 7 6 m3 s and 220 106 to 300 106 m3 respectively are in agreement with published ground based estimates of 5 8 m3 s and 235 106 m3 these correlations demonstrate the high degree of confidence that can now be placed in interpretations of avhrr time series for eruptions where ground based data are scanty