the distribution of fe in the antarctic circumpolar current abstract the large scale distributions of dissolved and total fe in surface and deep waters of the antarctic circumpolar current exhibit strong relationships with hydrography and biological processes the mean dissolved fe concentrations are low in surface waters of the antarctic circumpolar current 0 31 0 49 nm with a minimum of 0 17 nm and higher averaging 1 11 9 nm in the polar frontal region enhanced dissolved surface water concentrations in the polar frontal region are attributed to input from the continental shelf and coincide with phytoplankton spring blooms of large diatoms the effects of sea ice melting and iceberg melting on the fe concentrations were relatively small dissolved deep water concentrations 400 m in the antarctic circumpolar current ranged from 0 4 to 2 8 nm circumpolar deep water has relatively high dissolved fe concentrations in the polar frontal region 0 4 2 8 nm compared with deep waters further to the south 0 6 1 1 nm similarly total dissolvable unfiltered fe concentrations in the upper circumpolar deep water tend to decrease southward from the polar frontal region in the lower circumpolar deep water total dissolvable fe concentrations are higher than in the upper circumpolar deep water due to the existing nepheloid layer and sources on the mid atlantic ridge dissolved and total dissolvable fe concentrations in the antarctic bottom water are higher than those of other water masses in the antarctic circumpolar current consistent with the nepheloid layer as well as diagenetic input from shelf sediments the high nutrient low chlorophyll areas of the antarctic ocean and northeast pacific ocean have different major fe input sources of similar magnitude in the antarctic circumpolar current upward transport of fe is the main input source whereas in the north pacific ocean aerosols are the dominant source

birth growth and morphologic evolution of the laghetto cinder cone during the 2001 etna eruption we have undertaken detailed observations of the formation of the laghetto cinder cone a new cone that formed during a 2 week period of intense activity in piano del lago on the upper slopes of mount etna in summer 2001 we describe the events leading to the formation of a small graben the formation of pit craters on the base of the graben the onset of phreatomagmatic activity a transition to intense strombolian activity and a return to phreatomagmatic activity as the eruption came to an end we discuss the reasons for these transitions and describe the morphological development of the cone during these events arcuate cracks on the southern part of the cone were related to withdrawal of magma at the end of the eruption other slope instabilities that developed during the eruption include the formation of small radial grain flows on the outer flanks of the cone and the collapse into the crater of part of the crater rim some of the failure planes we observed were first identified using a flir tm 695 thermal infrared camera this is the first time that infrared thermography has been used to detect instability of volcanic structures results obtained during this test case demonstrate that thermal cameras are a very useful tool for studies of volcanic instability

iron rich metalliferous sediments on the east pacific rise prototype of undifferentiated metalliferous sediments on divergent plate boundaries abstract sediments in a zone on the east pacific rise with an especially high spreading rate were studied chemically mineralogically and microscopically they consist of a mixture of metalliferous sediments and plankton tests the metalliferous sediments were formed by an acidic hydrothermal leaching of tholeiitic basalt with seawater and subsequent precipitation in contact with cold near bottom seawater we assume the precipitation from hydrothermal solutions in this part of the east pacific rise to be undifferentiated due to the high spreading rate and the resulting rapid flow on the water through the basalt thus these metalliferous sediments are an initial stage type that have not undergone differentiation mn mo la cu v ni fe zn co and y all of which are leachable in acidic hydrothermal solutions are enriched in the metalliferous sediments in comparison to the tholeiitic basalts zr al and ti on the other hand which under the same conditions are not easily leached are reduced in their concentrations all components of the metalliferous sediments precipitated as hydroxides or as adsorbed ions on the hydroxides of other elements this is due to the oxidizing conditions in the near bottom seawater the sedimentation rate is high the almost 3 m long cores reach only to the late pleistocene the only distinctly observable diagenetic process for this period of time is the formation of goethite from amorphous iron oxides only for na k and rb does it seem possible that a distinct enrichment in the sediments by adsorption from the seawater could have taken place ca sr pb and perhaps sc are primarily bound to the planktonic carbonate part of the sediments

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

characterization of volcanic thermal anomalies by means of sub pixel temperature distribution analysis the simultaneous solution of the planck equation involving the widely used dual band technique using two shortwave infrared swir bands allows for an estimate of the fractional area of the hottest part of an active lava flow f h and the background temperature of the cooler crust t c the use of a high spectral and spatial resolution imaging spectrometer with a wide dynamic range of 15 bits dais 7915 in the wavelength range from 0 501 to 12 67 m resulted in the identification of crustal temperature and fractional areas for an intra crater hot spot at mount etna italy this study indicates the existence of a relationship between these t c and f h extracted from dais and landsat tm data when the dual band equation system is performed on a lava flow a logarithmic distribution is obtained from a plot of the fractional area of the hottest temperature vs the temperature of the cooler crust an entirely different distribution is obtained over active degassing vents where increases in t c occur without any increase in f h this result indicates that we can use scatter plots of t c vs fh to discriminate between different types of volcanic activity in this case between degassing vents and lava flows using satellite thermal data

best fit results from application of a thermo rheological model for channelized lava flow to high spatial resolution morphological data 1 the flowgo thermo rheological model links heat loss core cooling crystallization rheology and flow dynamics for lava flowing in a channel we fit this model to laser altimeter lidar derived channel width data as well as effusion rate and flow velocity measurements to produce a best fit prediction of thermal and rheological conditions for lava flowing in a 1 6 km long channel active on mt etna italy on 16th september 2004 using as a starting condition for the model the mean channel width over the first 100 m 6 m and a depth of 1 m we obtain an initial velocity and instantaneous effusion rate of 0 3 0 6 m s and 3 m3 s respectively this compares with field and lidar derived values of 0 4 m s and 1 4 m3 s the best fit between model output and lidar measured channel widths comes from a hybrid run in which the proximal section of the channel is characterised by poorly insulated flow and the medial distal section by well insulated flow this best fit model implies that flow conditions evolve down channel where hot crusts on a free flowing channel maximise heat losses across the proximal section whereas thick stable mature crusts of a a clinker reduce heat losses across the medial distal section this results in core cooling per unit distance that decreases from 0 02 0 015 c m 1 across the proximal section to 0 005 c m 1 across the medial distal section this produces an increase in core viscosity from 3800 pa s at the vent to 8000 pa s across the distal section

the distal segment of etna s 2001 basaltic lava flow etna s 2001 basaltic lava flow provided a good example of the distal flow segment between the flow front and stable channel across which the flow evolves from channel contained to dispersed this zone was mapped with meter precision using lidar data collected during 2004 and 2005 these data supported by field mapping show that the flow front comprised eight lobes each 10 to 20 m high the flow front appears to have advanced not as a single unit but as a series of lobes moving forward one lobe at a time primary lobes were centered on the channel axis and marginal lobes were off axis the lobes advanced as breakouts of low yield strength lava from the flow core of the stalled flow front marginal lobes were abandoned and contributed to marginal levees flanking the transitional channel for etna s 2001 flow the transitional channel is 140 m wide 700 m long and fed a 240 m long zone of dispersed flow the change from stable to transitional channel occurred at a major reduction in slope above this the stable channel is 5 2 km long 55 to 105 m wide and bounded by 15 to 25 m high levees and the stable channel is located over a previous channel in a final stage of activity lava ponding at the break in slope that marks the terminus of the stable channel put pressure on the eastern levee causing it to fail liberated lava then fed a final break out to the east similar flow front features occur at other volcanoes indicating that similar processes are characteristic of dispersed flow zones

combined morphological and thermal analysis of lava flows a way to boost understanding of emplacement dynamics during emplacement lavas modify the pre existing topography and release a large amount of heat in spite of the relevance of both heat and mass release combined morphological and thermal analyses have been seldom carried out at a flow field scale here we consider a channelised lava flow unit formed at mt etna during the 2001 flank eruption and we show that by combining a morphological analysis of the pre and post emplacement topography with the analysis of the syn eruptive thermal signature critical insights about the processes driving mass and heat dissipation can be derived our results suggest that in the considered lava flow the pre emplacement slope controls heat dissipation and can influence the thickness of the final lava deposit with possible implications for hazard assessment the width of the lava channel instead appears less sensitive to the pre emplacement slope and tends to regularly increase with increasing distance from the vent

the july august 2001 eruption of mt etna sicily the july august 2001 eruption of mt etna stimulated widespread public and media interest caused significant damage to tourist facilities and for several days threatened the town of nicolosi on the s flank of the volcano seven eruptive fissures were active five on the s flank between 3 050 and 2 100 m altitude and two on the ne flank between 3 080 and 2 600 m elevation all produced lava flows over various periods during the eruption the most voluminous of which reached a length of 6 9 km mineralogically the 2001 lavas fall into two distinct groups indicating that magma was supplied through two different and largely independent pathways one extending laterally from the central conduit system through radial fissures the other being a vertically ascending eccentric dike furthermore one of the eccentric vents at 2 570 m elevation was the site of vigorous phreatomagmatic activity as the dike cut through a shallow aquifer during both the initial and closing stages of the eruption for 6 days the magma column feeding this vent was more or less effectively sealed from the aquifer permitting powerful explosive and effusive magmatic activity while the eruption was characterized by a highly dynamic evolution complex interactions between some of the eruptive fissures and changing eruptive styles its total volume 25 106 m3 of lava and 5 10 106 m3 of pyroclastics was relatively small in comparison with other recent eruptions of etna effusion rates were calculated on a daily basis and reached peaks of 14 16 m3 s 1 while the average effusion rate at all fissures was about 11 m3 s 1 which is not exceptionally high the eruption showed a number of peculiar features but none of these except the contemporaneous lateral and eccentric activity represented a significant deviation from etna s eruptive behavior in the long term however the 2001 eruption could be but the first in a series of flank eruptions some of which might be more voluminous and hazardous placed in a long term context the eruption confirms a distinct trend initiated during the past 50 years toward higher production rates and more frequent eruptions which might bring etna back to similar levels of activity as during the early to mid seventeenth century

calculation of lava effusion rates from landsat tm data we present a thermal model to calculate the total thermal flux for lava flowing in tubes on the surface or under shallow water once defined we use the total thermal flux to estimate effusion rates for active flows at kilauea hawaii on two dates input parameters were derived from landsat thematic mapper tm field and laboratory measurements using these parameters we obtain effusion rates of 1 76 0 57 and 0 78 0 27 m3 s 1 on 23 july and 11 october 1991 respectively these rates are corroborated by field measurements of 1 36 0 14 and 0 89 0 09 m3 s 1 for the same dates kauahikaua et al 1996 using weather satellite avhrr data of lower spatial resolution we obtain similar effusion rates for an additional 26 dates between the two tm derived measurements we assume that although total effusion rates at the source declined over the period the shut down of the ocean entry meant that effusion rates for the surface flows alone remained stable such synergetic use of remotely sensed data provides measurements that can a contribute to monitoring flow field evolution and b provide reliable numerical data for input into rheological and thermal models we look forward to being able to produce estimates for effusion rates using data from high spatial resolution sensors in the earth observing system eos era such as landsat 7 the hyperspectral imager the advanced spaceborne thermal emission spectrometer and the advanced land imager

the 2007 stromboli eruption event chronology and effusion rates using thermal infrared data accepted for publication in journal of geophysical research copyright 2009 american geophysical union further reproduction or electronic distribution is not permitted

hydrothermal iron rich deposits from the teahitia mehitia and macdonald hot spot areas southwest pacific abstract during cruise so 47 of r v sonne iron oxyhydroxide crusts of restricted extent were recovered from teahitia and moua pihaa seamounts in the teahitia mehetia hot spot area and from macdonald seamount in the macdonald hot spot area the crusts show complex layering and incorporate volcanic ash layers they consist of goethite feldspar and pyroxene and display low contents of transition elements apart from fe it is believed that the crusts were deposited from relatively low temperature hydrothermal fluids these low temperatures preclude the formation of sulphide deposits the type of hydrothermal mineral recovered may be a function of the thermal regime of the system and the elevation which controls the pressure of the venting fluids the shallower depths of these seamounts compared to the axes of mid ocean ridges may therefore be responsible for the style of mineralization initially magmatic vapours migrating upwards through the hot spot volcano are thought to be absorbed into seawater at comparatively shallow levels to deposit sulphide minerals within the volcanic pile the fe oxyhydroxide deposits are the residual low temperature deposits formed when the spent hydrothermal fluid reached the crest of the seamount these deposits therefore differ fundamentally from those found at the crest of mid ocean ridges where sulphide mounds are deposited directly upon interaction of the boiling hydrothermal fluid with seawater the discovery of hydrothermal iron oxyhydroxide crusts in these two hot spot areas is only the second such finding after loihi seamount southeast of hawaii

morphometric analysis of lava flow units case study over lidar derived topography at mount etna italy abstract high resolution lidar derived digital elevation models of volcanic areas can significantly improve knowledge of lava flow morphology and emplacement mechanisms here we focus on single flow units presenting a new semi automatic procedure which provides a quantitative analysis of their shape the method relies on the automatic processing of the elevation profiles obtained on transects orthogonal to the flow unit axis the initial phase of the mount etna flank eruption from september 2004 is taken as test case and the procedure is applied on an active lava flow which was emplaced on the eastern flank of the volcano the main topographic dataset used is a 2 m resolution digital elevation model obtained from a lidar survey starting from the axis of a lava flow unit our method yields morphometric data on the flow unit at a 2 m spacing calculating parameters including flow width channel width the heights of the levees inward and outward slope of levees and estimating pre emplacement slope along the axis the procedure is embedded in a customized gis which allows easy processing handling and displaying of data the procedure has also been applied to another flow unit emplaced during the october november 1999 overflow from the bocca nuova crater results show that the channel width seems to accommodate first order trends of the pre emplacement slope along the flow unit axis while it is little affected by high frequency changes in slope in contrast flow unit width and flow unit thickness are apparently influenced by small scale changes in slope the different emplacement conditions of the two flow units are reflected by the overall contrasting morphologies as shown by the different average thickness and by the different ratios between i flow width vs channel width and ii flow unit section area vs channel width the new method provides an enhanced systematic and thorough morphometric description of flow units which may improve the understanding of the emplacement mechanisms of lava flows on earth and other planets

manganese and iron in indian ocean waters abstract the first vertical profiles of dissolved mn and fe for the nw indian ocean are reported the area is characterized by seasonal upwelling and a broad oxygen minimum zone in intermediate waters the dissolved fe profile exhibits a maximum 5 1 nm in the oxygen minimum zone with low values both in surface waters 0 3 nm and deep waters around 1 nm mn concentrations in the surface waters are elevated 2 0 4 3 nm and decrease rapidly in an offshore direction below the first 25 m concentrations decrease dramatically 0 5 1 3 nm indicating removal by oxidation and particle scavenging further down various mn maxima are observed which can be related to hydrographic features sigma 1 1 intermediate water originating from the red sea lost its dissolved o2 while flowing northward along the omani coast and exhibits a strong mn maximum 4 6 6 5 nm coincident with the deep o2 minimum 2 2 at the two inshore stations in the gulf of oman this is overlain by relatively modest mn maxima 2 7 nm related to arabian gulf overflow water 3 3 finally the strong mn maxima 4 4 5 6 nm in the oxygen minimum zone at the two offshore stations are related to yet another watermass below these various maxima concentrations decrease gradually to values as low as 90 pm at 2000 meters depth towards the seafloor concentrations increase again leading to a modest bottom water maximum 0 7 1 5 nm the overall vertical distributions of mn and fe are strikingly similar also in actual concentrations to those previously reported for the eastern equatorial pacific an area also characterized by an extensive o2 minimum zone

cooling rate of some active lavas determined using an orbital imaging spectrometer 1 the surface temperature of an active lava flow is an important physical property to measure through its influence on lava crystallinity cooling exerts a fundamental control on lava rheology remotely sensed thermal radiance data acquired by multispectral sensors such as landsat thematic mapper and the terra advanced spaceborne thermal emission and reflection radiometer are of insufficient spectral and radiometric fidelity to allow for realistic determination of lava surface temperatures from earth orbit this paper presents results obtained from the analysis of active lava flows using hyperspectral data acquired by nasa s earth observing 1 hyperion imaging spectrometer the contiguous nature of the measured radiance spectrum in the 0 4 2 5 m region means that although sensor saturation most certainly occurs unsaturated radiance data are always available from even the hottest and most radiant active lava flow surfaces the increased number of wave bands available allows for the assumption of more complex flow surface temperature distributions in the radiance to temperature inversion processes the technique is illustrated by using a hyperspectral image of the active lava lake at erta ale volcano ethiopia a well characterized calibration target a time series of three hyperion images of an active lava flow acquired during a 4 day period at mount etna sicily as well as a lava flow erupted at nyamuragira democratic republic of congo the results provide insights into the temperature radiance mixture modeling problem that will aid in the analysis of data acquired by future hyperspectral remote sensing missions such as nasa s proposed hyspiri mission

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

modeling of the steady state temperature field in lava flow levees the rationale of lava flow deviation is to prevent major damage and among the possible techniques the opening of the flow levees has often been demonstrated to be suitable and reliable the best way to open the levees in the right point in order to obtain the required effect is to produce an explosion in situ and it is then necessary to map with the highest precision the temperature field inside the levees in order to design a safe and successful intervention the levees are formed by lava flows due to their non newtonian rheology where the shear stress is lower than the yield stress the levees then cool and solidify due to heat loss into the atmosphere in this work we present analytical solutions of the steady state heat conduction problem in a levee using the method of conformal mapping for simple geometrical shapes of the levee cross section triangular or square numerical solutions are obtained with a finite element code for more complex realistic geometries

classification of paleosols despite increased interest in paleosols during the past decade no satisfactory classification is in current use presented here is a largely descriptive classification system that utilizes those pedogenic features that have the highest preservation potential in the rock record emphasized in the classification are morphological and mineralogical features that are easily recognizable in the field and through the petrographic microscope the classification is based on evaluation of the relative prominence in a paleosol of six pedogenic features or processes organic matter content horizonation redox conditions in situ mineral alteration illuviation of insoluble minerals compounds and accumulation of soluble minerals the most prominent of these six features processes provides the key to classifying a paleosol into one of nine orders four of the order names are borrowed from soil taxonomy histosol spodosol oxisol vertisol whereas the other five order names are presented here for the first time calcisol gypsisol gleysol argillisol protosol the orders may be preceded by one or more subordinate modifiers that describe other important features of the paleosol the classification is relatively easy to apply to the rock record and should enhance communication and aid in the standardization of terminology

analysis of the 2001 lava flow eruption of mt etna from three dimensional mapping 1 the 2001 etna eruption was characterized by a complex temporal evolution with the opening of seven eruptive fissures each feeding different lava flows this work describes a method adopted to obtain the three dimensional geometry of the whole lava flow field and for the reconstruction based on topographic data of the temporal evolution of the largest lava flow emitted from a vent located at 2100 m a s l preeruption and posteruption digital elevation models dem were extracted from vector contour maps comparison of the two dems and analysis of posteruption orthophotos allowed us to estimate flow area thickness and bulk volume additionally the two dimensional temporal evolution of the 2100 flow was precisely reconstructed by means of maps compiled during the eruption these data together with estimates of flow thickness allowed us to evaluate emitted lava volumes and in turn the average volumetric flow rates the analysis performed in this paper provided a total lava bulk volume of 40 1 106 m3 for the whole lava flow field most of which emitted from the 2100 vent 21 4 106 m3 the derived effusion rate trend shows an initial period of waxing flow followed by a longer period of waning flow this is in agreement not only with the few available effusion rate measurements performed during the eruption but also with the theoretical model of wadge 1981 for the temporal variation in discharge during the tapping of a pressurized source

spatial variations in lava flow field thermal structure and effusion rate derived from very high spatial resolution hyperspectral mivis data 1 high spatial resolution hyperspectral measurements of volcanic thermal anomalies allow for an unconstrained solution of a two component thermal model this can be used for identification of lava flow emplacement style and the calculation of lava flow heat and volume flux the multispectral infrared and visible imaging spectrometer mivis is an airborne sensor equipped with 72 bands in the short infrared range and 10 bands in the thermal infrared region of the spectrum we used mivis acquired for mount etna italy during the july august 2001 eruption to solve the dual band equations in an unconstrained fashion using three bands of unsaturated data our results suggest a complex thermal structure for etnean lava flows this is characterized by a downflow transition from a lightly crusted active channel to a more heavily crusted distal section both surrounded by zones of stagnant cooling flow where exposed molten material is absent and maximum temperatures are thus lower the total flow field effusion rate obtained for 29 july 2001 0700 local time of 8 16 m3 s is in excellent agreement with that obtained from ground based measurements and advanced very high resolution radiometer data flow by flow effusion rates obtained from the mivis data vary depending on whether the vent is linked to the central conduit or the dyke that was injected from greater depth as well as vent elevation with lower elevation vents experiencing higher effusion rates

a wrb based buried paleosol classification abstract present classification systems for buried paleosols are inadequately developed several classification systems for paleosols based on the us soil taxonomy have been developed recently but their use is still very limited we propose appilcation of the world reference base for soil resources which uses only substantial profile characteristics as a background for the development of a new buried paleosol classification the system was adapted for the use for buried paleosols dynamic criteria which could be altered by diagenesis were disregarded and the definitions of most horizons were modified a new prefix infra was applied for modified diagnostic horizons and properties and for refernce groups of buried paleosols as a result 11 diagnostic horizons 2 properties and 2 materials were left with their definitions and names 9 diagnostic horizons and 2 properties were modified and named with the prefix infra 14 diagnostic horizons 6 properties and 4 materials were excluded or joined with others and two new diagnostic horizons were proposed this relationship reflects the balance between stable and dynamic properties in the diagnostic criteria used by the wrb the number of soil units proposed for buried paleosols is fewer than for surface soils in the wrb 25 instead of 30 the use of wrb modifiers reflecting dynamic soil properties was tentatively recommended for the second level buried paleosols classification with prefixes pedo for pedogenically derived properties and dia for the properties caused by post burial processes the application of the proposed system to a set of paleosols previously described in the literature showed its utility for buried paleosol classification

surface temperature measurements of active lava flows on kilauea volcano hawai i systematic hand held radiometer measurements of lava surface temperatures in active flows and tubes on kilauea volcano hawai i reveal complexities that cannot be resolved in remotely sensed data from aircraft or satellites using portable infrared minolta land cyclops radiometers we measured surface temperatures of flows at various distances from their sources and investigated cooling rates and the development of crust our measurements suggest that the upper surface of these lava flows can be split into a minimum of four thermal components core 1050 c visco elastic skin 750 900 c rigid solid crust 750 c and flow margins 175 c for the a a flows investigated a cool rigid crust characteristically developed in the central part of channels within 30 m of the source vent and incandescent lava was exposed in the marginal shear zones of channels this affects the heat loss and morphology of lava in active channels our investigations of temperature distributions on pahoehoe flow fields reveal temperature anomalies of up to 150 c above active tubes and tumuli

the changing morphology of an open lava channel on mt etna an open channel lava flow on mt etna sicily was observed during may 30 31 2001 data collected using a forward looking infrared flir thermal camera and a minolta land cyclops 300 thermal infrared thermometer showed that the bulk volume flux of lava flowing in the channel varied greatly over time cyclic changes in the channel s volumetric flow rate occurred over several hours with cycle durations of 113 190 min and discharges peaking at 0 7 m3 s 1 and waning to 0 1 m3 s 1 each cycle was characterized by a relatively short high volume flux phase during which a pulse of lava with a well defined flow front would propagate down channel followed by a period of waning flow during which volume flux lowered pulses involved lava moving at relatively high velocities up to 0 29 m s 1 and were related to some change in the flow conditions occurring up channel possibly at the vent they implied either a change in the dense rock effusion rate at the source vent and or cyclic variation in the vesicle content of the lava changing its bulk volume flux pulses would generally overspill the channel to emplace p hoehoe overflows during periods of waning flow velocities fell to 0 05 m s 1 blockages forming during such phases caused lava to back up occasionally backup resulted in overflows of slow moving a that would advance a few tens of meters down the levee flank compound levees were thus a symptom of unsteady flow where overflow levees were emplaced as relatively fast moving p hoehoe sheets during pulses and as slow moving a units during backup small localized fluctuations in channel volume flux also occurred on timescales of minutes volumes of lava backed up behind blockages that formed at constrictions in the channel blockage collapse and or enhanced flow under around the blockage would then feed short lived wave like down channel surges real fluctuations in channel volume flux due to pulses and surges can lead to significant errors in effusion rate calculations

oceanic ridge crest processes oceanic ridge crest processes constitute a vigorous frontier of multidisciplinary research with global ramifications in the earth atmospheric and biologic sciences this deep ocean frontier is gradually opening in response to investigations which are elucidating the role of these processes in the lithosphere hydrosphere atmosphere and biosphere and the application of advanced instrumental and interpretive techniques which are increasing the quality and quantity of data these techniques include crustal drilling with borehole logging deep sea drilling project reports high resolution bathymetry sea beam etc side scan sonar seamarc i and ii gloria etc imagery with video and photography multichannel seismics determination of water column properties ctd with rosette sampler etc and submersible applications

investigating lava flow rheology using video analysis and numerical flow models abstract lava rheology is a major control on lava flow behavior and a critical parameter in flow simulations but is very difficult to measure at field conditions or correctly extrapolate from the lab scale we present a new methodology for investigating lava rheology through a combination of controlled experiments image analysis and numerical forward modeling our experimental setup part of the syracuse university lava project http lavaproject syr edu includes a large furnace capable of melting up to 450 kg of basalt at temperatures well above the basalt liquidus the lava is poured onto either a tilted bed of sand or a steel channel to produce meter long flows this experimental setup is probably the only facility that allows such large scale controlled lava flows made of natural basaltic material we document the motion of the lava using a high resolution video camera placed directly above the flows and the temperature using infrared probes and cameras after collecting the footage we analyze the images for lava deformation and compare with numerical forward models to constrain the rheological parameters and laws which best describe the flowing lava for the video analysis we employ the technique of differential optical flow which uses the time variations of the spatial gradients of the image intensity to estimate velocity between consecutive frames an important benefit for using optical flow compared with other velocimetry methods is that it outputs a spatially coherent flow field rather than point measurements we demonstrate that the optical flow results agree with other measures of the flow velocity and estimate the error due to noise and time variability to be under 30 of the measured velocity our forward models are calculated by solving the stokes flow equations on an unstructured finite element mesh defined using the geometry of the observed flow itself we explore a range of rheological parameters including the lava s apparent viscosity the power law exponent m and the thermal activation energy our measurements of apparent viscosity agree well with predictions of the composition based shaw 1972 and grd model giordano russell and dingwell 2008 we find that for the high temperature portion of the flow a weakly shear thinning or newtonian rheology m 0 7 with an effective activation energy of b 5500 j gives the best fit to the data our methodology is the first time that high resolution optical flow analysis of flowing lava is combined with numerical flow models to constrain rheology the methodology we present here can be used in field conditions to obtain in situ information on lava rheology without physical interaction with the flow and without being limited to point wise low strain rate local measurements currently available through the use of rotational viscometers in the field

an experimental study of the surface thermal signature of hot subaerial isoviscous gravity currents implications for thermal monitoring of lava flows and domes received 22 july 2011 revised 23 november 2011 accepted 23 november 2011 published 7 february 2012 1 management of eruptions requires a knowledge of lava effusion rates for which a safe thermal proxy is often used however this thermal proxy does not take into account the flow dynamics and is basically time independent in order to establish a more robust framework that can link eruption rates and surface thermal signals of lavas measured remotely we investigate the spreading of a hot isoviscous axisymmetric subaerial gravity current injected at constant rate from a point source onto a horizontal substrate we performed laboratory experiments and found that the surface thermal structure became steady after an initial transient we develop a theoretical model for a spreading fluid cooled by radiation and convection at its surface that also predicts a steady thermal regime we show that despite the model s simplicity relative to lava flows it yields the correct order of magnitude for the effusion rate required to produce the radiant flux measured on natural lava flows for typical thermal lava properties and an effusion rate between 0 1 and 10 m 3 s 1 the model predicts a steady radiated heat flux ranging from 10 8 to 10 10 w the assessed effusion rate varies quasi linearly with the steady heat flux with much weaker dependence on the flow viscosity this relationship is valid only after a transient time which scales as the diffusive time ranging from a few days for small basaltic flows to several years for lava domes the thermal proxy appears thus less reliable to follow sharp variations of the effusion rate during an eruption

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

dispersal patterns for hydrothermal plumes in the south pacific using manganese as a tracer abstract manganese profiles over the spreading axis of the east pacific rise epr between 22 15 s and 19 25 s disclose a series of plumes which are formed by buoyant emanations of hot hydrothermal vent fluids the plume ceilings or anomaly maxima can occur several hundred meters above the sea floor these plumes are dispersed laterally and are detectable as mid depth manganese anomalies 2000 km from the spreading axis along this section the plumes are dispersed mainly westward but at 30 s the plumes are advected eastward the asymmetrical dispersal pattern inferred from these data is coincident with the asymmetrical distribution of metalliferous sediments about the epr which suggests that plumes generated by high temperature venting play a dominant role in the formation of these sediments

the initial cooling of pahoehoe flow lobes in this paper we describe a new thermal model for the initial cooling of pahoehoe lava flows the accurate modeling of this initial cooling is important for understanding the formation of the distinctive surface textures on pahoehoe lava flows as well as being the first step in modeling such key pahoehoe emplacement processes as lava flow inflation and lava tube formation this model is constructed from the physical phenomena observed to control the initial cooling of pahoehoe flows and is not an empirical fit to field data we find that the only significant processes are a heat loss by thermal radiation b heat loss by atmospheric convection c heat transport within the flow by conduction with temperature and porosity dependent thermal properties and d the release of latent heat during crystallization the numerical model is better able to reproduce field measurements made in hawai i between 1989 and 1993 than other published thermal models by adjusting one parameter at a time the effect of each of the input parameters on the cooling rate was determined we show that a the surfaces of porous flows cool more quickly than the surfaces of dense flows b the surface cooling is very sensitive to the efficiency of atmospheric convective cooling and c changes in the glass forming tendency of the lava may have observable petrographic and thermal signatures these model results provide a quantitative explanation for the recently observed relationship between the surface cooling rate of pahoehoe lobes and the porosity of those lobes jones 1992 1993 the predicted sensitivity of cooling to atmospheric convection suggests a simple field experiment for verification and the model provides a tool to begin studies of the dynamic crystallization of real lavas future versions of the model can also be made applicable to extraterrestrial submarine silicic and pyroclastic flows

lava effusion rate definition and measurement a review measurement of effusion rate is a primary objective for studies that model lava flow and magma system dynamics as well as for monitoring efforts during on going eruptions however its exact definition remains a source of confusion and problems occur when comparing volume flux values that are averaged over different time periods or spatial scales or measured using different approaches thus our aims are to 1 define effusion rate terminology and 2 assess the various measurement methods and their results we first distinguish between instantaneous effusion rate and time averaged discharge rate eruption rate is next defined as the total volume of lava emplaced since the beginning of the eruption divided by the time since the eruption began the ultimate extension of this is mean output rate this being the final volume of erupted lava divided by total eruption duration whether these values are total values i e the flux feeding all flow units across the entire flow field or local i e the flux feeding a single active unit within a flow field across which many units are active also needs to be specified no approach is without its problems and all can have large error up to 50 however good agreement between diverse approaches shows that reliable estimates can be made if each approach is applied carefully and takes into account the caveats we detail here there are three important factors to consider and state when measuring giving or using an effusion rate first the time period over which the value was averaged second whether the measurement applies to the entire active flow field or a single lava flow within that field and third the measurement technique and its accompanying assumptions

lava flow thermal analysis using three infrared bands of remote sensing imagery a study case from mount etna 2001 eruption abstract infrared remotely sensed data can be used to estimate heat flux and thermal features of active volcanoes the model proposed by crisp and baloga crisp j baloga s 1990 a model for lava flows with two thermal components journal of geophysical research 95 1255 1270 for active lava flows considers the thermal flux a function of the fractional area of two thermally distinct radiant surfaces the larger surface area corresponds to the cooler crust of the flow the smaller one to fractures in the crust in this model the crust temperature t c the temperature of the cracks t h and the fractional area of the hottest component f h represent the three unknowns to work out the simultaneous solution of the planck equation dual band technique for two distinct shortwave infrared swir bands allows to estimate any two of the parameters t c t h f h if the third is assumed dozier j 1981 a method for satellite identification of surface temperature fields of subpixel resolution remote sensing environment 11 221 229 the airborne sensor mivis was flown on mount etna during the july august 2001 eruption this hyperspectral imaging spectrometer offers 72 bands in the swir range and 10 bands in thermal infrared tir region of the spectrum which can be used to solve the dual band system without any assumptions therefore we can combine three spectral mivis bands to obtain simultaneous solutions for the three unknowns here the procedure for solving such a system is presented it is then demonstrated that a tir channel is required to better pinpoint solutions to the 2 components model finally the spatial and statistical characteristic of the resultant mivis derived temperature and flux distributions are introduced and statistics for each hot spot investigated

effects of the curvature of a lava channel on flow dynamics and crust formation summary bends in lava channels are often observed in volcanic fields the curvature of a channel affects flow dynamics and surface morphology and may be a trigger for the formation of lava tube we propose a model to describe the effects of curvature on velocity shear stress and the formation of crust at the flow surface lava is described as a newtonian homogeneous isotropic and incompressible fluid the steady state solution of the navier stokes equation is found for a unidirectional flow in cylindrical coordinates the flow levees are described as arcs of concentric circumferences with their centres in the origin of the coordinate system under the assumption that the gravity force has no radial component in the bend the fluid moves parallel to the levees the velocity is assumed to depend on the radial coordinate only as an effect of curvature velocity and shear stress are asymmetric with respect to the centre of the channel the maximum of surface velocity is shifted toward the internal levee and the shear stress has larger values close to the internal levee this effect is greater for wider channels heatradiationandconvectionintotheatmosphereareconsideredasthemaincooling mechanisms and the temperature distribution along the channel is calculated crust formation at the flow surface is considered under the assumption that solid lava is a plastic body the amount of crust coverage is mainly controlled by the channel width narrow channels have a greater coverage than wide channels for a given radius of curvature the effect of a bend is to favour the crust growth toward the internal levee while the crust coverage toward the external levee decreases the presence of a bend in a lava channel may favour the formation of a lava tube the analytical solution will serve as a benchmark for numerical models understanding the mechanism of formation of lava tubes is crucial to the simulation of actual lava flows and to evaluation of the associated hazard

thermal distributions at fumarole fields implications for infrared remote sensing of active volcanoes abstract multispectral satellite data recorded in the short wavelength infrared swir region have been used to estimate temperatures of hot volcanic features such as fumaroles and lava bodies this has required the assumption that thermal distributions across the surfaces in question can be adequately represented by a very few usually two temperature components we investigate here the applicability of such simple descriptions to fumarole fields an important class of thermal phenomena our surface temperature surveys conducted at momotombo nicaragua and vulcano italy suggest that swir emission from the interiors of high temperature fumarole vents far exceeds that from their surroundings in contrast cooling crust on active lava bodies can contribute more swir radiation than the small areas of exposed incandescent material that are often present such a distinction should be discernible in the relative response of the two landsat thematic mapper tm swir bands providing a basis for identification of the volcanic nature of thermal anomalies in landsat tm or similar data even in the absence of field observations however estimates of subpixel temperatures and heat flux made from such satellite data must be considered unreliable

hydrothermal methane and manganese variation in the plume over the superfast spreading southern east pacific rise abstract onboard analyses of dissolved ch4 and mn were conducted on the water column along the southern east pacific rise between 13 50 and 18 40 s during the 1993 ridge flux cruise many hydrothermal plumes were identified by chemical anomalies which overlie more than half of the surveyed ridge crest the ch 4 mn ratio in the plumes shows wide variability ranges from about 0 05 to 3 9 due to wide range of ch 4 concentration the ch 4 rich plumes were detected in the region of 16 00 18 40 s where vigorous magmatic budget was confirmed by previous studies moreover the ch 4 mn ratio of the plumes is highly correlated with other volatile metal parameters such as the s fe ratio in plume particulate these results strongly suggest that volatile input caused by magmatic perturbation to hydrothermal systems is responsible for the ch 4 mn variability in the southern epr plumes based on analogy of the case at the epr 9 50 n site the detection of several volatile rich plumes and the extensive hydrothermal flux of volatile species are attributed to frequent magmatic events in the superfast spreading southern epr

differences in landsat tm derived lava flow thermal structures during summit and flank eruption at mount etna abstract the simultaneous solution of the planck equation the so called dual band technique for two shortwave infrared landsat thematic mapper tm bands allows an estimate of the fractional area of the hottest part of an active flow and the temperature of the cooler crust here the dual band method has been applied to a time series of mount etna eruptions the frequency distribution of the fractional area of the hottest component reveals specific differences between summit and flank lava flows the shape of the density function shows a trend consistent with a gaussian distribution and suggests a relationship between the moments of the distribution and the emplacement environment because flow composition of etnean lavas generally remains constant during the duration of their emplacement it appears that the shape of any particular frequency distribution is probably related to fluid mechanical aspects of flow emplacement that affect flow velocity and flow heat loss and thus the rate of formation of the surface crust these factors include the influence of topographical features such as changes in slope gradient changes in volume effusion rate and progressive downflow increases in bulk or effective viscosity a form of the general theoretical solution for the dual band system which illustrates the relationship between radiance in tm bands 5 and 7 corresponding to hot fractional area and crust temperature is presented generally speaking it appears that for a given flow at any point in time larger fractional areas of exposed hot material are correlated with higher temperatures and that while the overall shape of that distribution is common for the flows studied its amplitude and slope reflect individual flow rheological regimes

iron enrichments in hydrothermal plumes over the east pacific rise abstract manganese iron and helium isotopes have been measured in samples taken near the crest of the east pacific rise at 19 s samples were enriched in mn and in he isotopes as is typical for waters of this area samples were also enriched in fe fe enrichments covary with mn and 3 he enrichments the fe mn ratio at four sites ranged from about 2 to 9 spanning the average value found for metalliferous sediments 3 5

assumptions in the evaluation of lava effusion rates from heat radiation 1 the availability of high resolution thermal imagery of active lava flows has stimulated the use of radiance maps for the evaluation of lava effusion rates this is made possible by simple formulae relating the lava flow rate to the energy radiated per unit time from the planimetric surface of the flow such formulae are based on a specific flow model and consequently their validity is subject to the model assumptions an analysis of these assumptions reveals that the current use of the formulae is not consistent with the model the reason why they provide reasonable although very rough values for effusion rates appears to be that the actual radiated energy is controlled by a feature the nonuniform temperature of flow surface which is not accounted for by the model and which counterbalances the effect of inconsistent use of the formulae

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

low cost volcano surveillance from space case studies from etna krafla cerro negro fogo lascar and erebus satellite data offer a means of supplementing ground based monitoring during volcanic eruptions especially at times or locations where ground based monitoring is difficult being directly and freely available several times a day data from the advanced very high resolution radiometer avhrr offers great potential for near real time monitoring of all volcanoes across large 3000 3000 km areas herein we describe techniques to detect and locate activity estimate lava area thermal flux effusion rates and cumulative volume and distinguish types of activity application is demonstrated using data for active lavas at krafla etna fogo cerro negro and erebus a pyroclastic flow at lascar and open vent systems at etna and stromboli automated near real time analysis of avhrr data could be achieved at existing or cheap to install receiving stations offering a supplement to conventional monitoring methods

a major helium 3 source at 15 s on the east pacific rise an extensive plume of water enriched with helium 3 has been discovered in the deep pacific ocean at latitude 15 s on the east pacific rise in the core of the plume at a depth of 2500 meters over the ridge crest the helium 3 helium 4 ratio is 50 percent higher than the ratio in atmospheric helium indicating a strong injection of mantle or primordial helium at the spreading center axis through local hydrothermal systems the helium 3 plume is completely absent east of the rise but it can be traced over 2000 kilometers to the west above a newly observed physical feature a density discontinuity here caled the ridge crest front the injected plume provides a unique deep sea tracer with an asymmetric distribution which shows that the deep circulation across the rise is from east to west the striking intensity and lateral extent of this helium 3 anomaly compared to observations at known oceanic hydrohrmal sites suggest that the largest hydrothermal fields in the ocean are yet to be discovered and that they will be found near 15 s on the east pacific rise

image based measurement of flux variation in distal regions of active lava flows 1 understanding the processes involved with the advance of lava flows is critical for improving hazard assessments at many volcanoes here we describe the application of computer vision and oblique photogrammetric techniques to visible and thermal images of active a flows in order to investigate distal flow processes at mount etna sicily photogrammetric surveys were carried out to produce repeated topographic data sets for calculation of volumetric lava flux at the flow fronts velocity profiles from a distal channel were obtained by rectification of a thermal image sequence and are used to investigate the rheological properties of the lava significant variations of the magma flux were observed and pulses of increased flux arrived within the flow front region on timescales of several hours the pulses are believed to be the distal result of more frequent flux changes observed in the vent region hence they reflect the importance of flow processes which are believed to cause the coalescence of flux pulses along the channel system as well as short period variations in effusion rate in considering advance processes for the individual flow fronts it must be assumed that they were fed by a highly unsteady flux which was volumetrically at least an order of magnitude lower than that observed near the vent

a hydrothermal deposit from explorer ridge in the northeast pacific ocean abstract crusts composed of nontronite and ferromanganese oxides were recovered from explorer ridge a spreading ridge segment in the northeastern pacific ocean located off the west coast of canada the chemical and mineralogical composition of the crusts closely resembles that of the mound like hydrothermal deposits recently discovered at the famous site on the mid atlantic ridge and on the galapagos spreading centre compositional anomalies suggest that the crusts are precipitates of hydrothermal vent solutions which were ejected discontinuously and subsequently mixed with seawater

topographic control on lava flow paths at mount etna italy implications for hazard assessment 1 assessment of the hazard from lava flow inundation at the active volcano of mount etna italy was performed by calculating the probability of lava flow inundation at each position on the volcano a probability distribution for the formation of new vents was calculated using geological and volcanological data from past eruptions the simulated lava flows from these vents were emplaced using a maximum expected flow length derived from geological data on previous lava flows simulations were run using downflow a digital elevation model based model designed to predict lava flow paths different eruptive scenarios were simulated by varying the elevation and probability distribution of eruptive points inundation maps show that the city of catania and the coastal zone may only be impacted by flows erupted from low altitude vents 2000 m preferentially inundate the northeast and southern sectors of the volcano as well as the valle del bove eruptions occurring in the summit area 3000 m elevation pose no threat to the local population discrepancies between the results of simple hydrological models and those of the downflow model show that hydrological approaches are inappropriate when dealing with etnean lava flows because hydrological approaches are not designed to reproduce the full complexity of lava flow spreading they underestimate the catchment basins when the fluid has a complex rheology