geomorphometric analysis of the 2014 2015 barðarbunga volcanic eruption iceland abstract topographical information is of fundamental interest for a wide range of disciplines including glaciology agriculture communication network planning or hazard management in volcanology elevation data are of particular importance when assessing material flows throughout a volcanic system to obtain accurate estimates of time varying topography in volcanic active regions high resolution digital elevation models dems are required to monitor and evaluate topographical changes and especially volumetric gains and losses during the 2014 2015 bar arbunga eruption iceland multi temporal tandem x dem sequences were evaluated the 2014 2015 volcanic eruption was associated with the rare event of a caldera collapse visible on the surface of the vatnajokull glacier as well as major lava effusion in the holuhraun plain before investigating topographical change at the two study areas the tandem x dems were analysed for absolute and relative height errors resulting from the radar system parameters the sar processing or the local environment the uncertainty investigation determined that acquisitions over the snow covered bar arbunga caldera were primarily affected by microwave penetration into snow and dems over the holuhraun lava field exhibited increased height errors due to active lava flows and dynamic outwash plain the topographical analysis of the 2014 2015 bar arbunga eruption revealed a maximum vertical displacement of approximately 65 m and 43 m at the study area of the bar arbunga caldera and holuhraun lava field respectively with a total subsidence volume of 1 40 0 13 km3 and a dense rock equivalent dre lava volume of 1 36 0 07 km3 known uncertainties in volume were decreased by approximately 35 and 77 accordingly taking into account the calculation of rates the temporal development of caldera collapse and lava effusion was found to exhibit a near exponential decrease the ratio between subsidence and dre lava volume moreover indicated the coupling between piston collapse and magma drainage

segmented lateral dyke growth in a rifting event at barðarbunga volcanic system iceland crust at many divergent plate boundaries forms primarily by the injection of vertical sheet like dykes some tens of kilometres long1 previous models of rifting events indicate either lateral dyke growth away from a feeding source with propagation rates decreasing as the dyke lengthens2 3 4 or magma flowing vertically into dykes from an underlying source5 6 with the role of topography on the evolution of lateral dykes not clear here we show how a recent segmented dyke intrusion in the bar arbunga volcanic system grew laterally for more than 45 kilometres at a variable rate with topography influencing the direction of propagation barriers at the ends of each segment were overcome by the build up of pressure in the dyke end then a new segment formed and dyke lengthening temporarily peaked the dyke evolution which occurred primarily over 14 days was revealed by propagating seismicity ground deformation mapped by global positioning system gps interferometric analysis of satellite radar images insar and graben formation the strike of the dyke segments varies from an initially radial direction away from the bar arbunga caldera towards alignment with that expected from regional stress at the distal end a model minimizing the combined strain and gravitational potential energy explains the propagation path dyke opening and seismicity focused at the most distal segment at any given time and were simultaneous with magma source deflation and slow collapse at the bar arbunga caldera accompanied by a series of magnitude m 5 earthquakes dyke growth was slowed down by an effusive fissure eruption near the end of the dyke lateral dyke growth with segment barrier breaking by pressure build up in the dyke distal end explains how focused upwelling of magma under central volcanoes is effectively redistributed over long distances to create new upper crust at divergent plate boundaries

chronology and products of the 2000 eruption of miyakejima volcano japan lateral migration of magma away from miyakejima volcanic island japan generated summit subsidence associated with summit explosions in the summer of 2000 an earthquake swarm beneath miyakejima began on the evening of 26 june 2000 followed by a submarine eruption the next morning strong seismic activity continued under the sea from beneath the coast of miyakejima to a few tens of kilometers northwest of the island summit eruptive event began with subsidence of the summit on 8 july and both explosions and subsidence continued intermittently through july and august the most intense eruptive event occurred on 18 august and was vulcanian to subplinian in type ash lofted into the stratosphere fell over the entire island and abundant volcanic bombs were erupted at this time another large explosion took place on 29 august this generated a low temperature pyroclastic surge which covered a residential area on the northern coast of the island the total volume of tephra erupted was 9 3 106 m3 dre much smaller than the volume of the resulting caldera 6 108 m3 migration of magma away from miyakejima was associated with crustal extension northwest of miyakejima and coincident shrinkage of miyakejima island itself during july august 2000 this magma migration probably caused stoping of roof rock into the magma reservoir generating subsurface cavities filled with hydrothermal fluid and or magmatic foam and formation of a caldera oyama caldera at the summit interaction of hydrothermal fluid with ascending magma drove a series of phreatic to phreatomagmatic eruptions it is likely that new magma was supplied to the reservoir from the bottom during waning stage of magma s migration resulting in explosive discharge on 18 august the 18 august event and phreatic explosions on 29 august produced a conduit system that allowed abundant so2 emission as high as 460 kg s 1 after the major eruptive events were over at the time of writing inhabitants of the island about 3 000 have been evacuated from miyakejima for more than 3 years

origins of oblique slip faulting during caldera subsidence 1 although conventionally described as purely dip slip faults at caldera volcanoes may have a strike slip displacement component examples occur in the calderas of olympus mons mars miyakejima japan and dolomieu la reunion to investigate this phenomenon we use numerical and analog simulations of caldera subsidence caused by magma reservoir deflation the numerical models constrain mechanical causes of oblique slip faulting from the three dimensional stress field in the initial elastic phase of subsidence the analog experiments directly characterize the development of oblique slip faulting especially in the later non elastic phases of subsidence the combined results of both approaches can account for the orientation mode and location of oblique slip faulting at natural calderas kinematically oblique slip faulting originates to resolve the following 1 horizontal components of displacement that are directed radially toward the caldera center and 2 horizontal translation arising from off centered or asymmetric subsidence we informally call these two origins the camera iris and sliding trapdoor effects respectively our findings emphasize the fundamentally three dimensional nature of deformation during caldera subsidence they hence provide an improved basis for analyzing structural geodetic and geophysical data from calderas as well as analogous systems such as mines and producing hydrocarbon reservoirs

time averaged discharge rate of subaerial lava at kīlauea volcano hawai i measured from tandem x interferometry implications for magma supply and storage during 2011 2013 differencing digital elevation models dems derived from terrasar add on for digital elevation measurements tandem x synthetic aperture radar imagery provides a measurement of elevation change over time on the east rift zone ezr of k lauea volcano hawai i the effusion of lava causes changes in topography when these elevation changes are summed over the area of an active lava flow it is possible to quantify the volume of lava emplaced at the surface during the time spanned by the tandem x data a parameter that can be difficult to measure across the entirety of an 100 km2 lava flow field using ground based techniques or optical remote sensing data based on the differences between multiple tandem x derived dems collected days to weeks apart the mean dense rock equivalent time averaged discharge rate of lava at k lauea between mid 2011 and mid 2013 was approximately 2 m3 s which is about half the long term average rate over the course of k lauea s 1983 present erz eruption this result implies that there was an increase in the proportion of lava stored versus erupted a decrease in the rate of magma supply to the volcano or some combination of both during this time period in addition to constraining the time averaged discharge rate of lava and the rates of magma supply and storage topographic change maps derived from space based tandem x data provide insights into the four dimensional evolution of k lauea s erz lava flow field tandem x data are a valuable complement to other space air and ground based observations of eruptive activity at k lauea and offer great promise at locations around the world for aiding with monitoring not just volcanic eruptions but any hazardous activity that results in surface change including landslides floods earthquakes and other natural and anthropogenic processes

focal depths and fault plane solutions of earthquakes and active tectonics of the himalaya synthetic seismograms were compared with long period body waves for nine earthquakes with epicenters in the himalayan arc to determine depths of foci and to improve fault plane solutions focal depths are shallow 10 20 km inferred slip vectors are locally perpendicular to the mountain range they plunge very gently about 10 deg in the eastern sections of the range and more steeply about 25 deg in western sections assuming india to be a rigid plate the radially oriented slip vectors imply that southern tibet extends at about half the rate of underthrusting in the himalaya and therefore probably at about 5 10 mm yr the shallow depths and gentle dips of the fault planes at least for the events in the eastern half of the range are consistent with coherent underthrusting of the indian plate beneath at least the lesser himalaya the steeper dips of fault planes in the western part of the arc might reflect deformation of the overriding thrust plate or simply a steepening of the main underthrusting zone beneath the greater himalaya

lava flow volume and morphology from digitised contour maps a case study at mount etna sicily abstract the volume and morphology of a lava flow field can be measured by mapping and comparing the topography before and after lava emplacement contour maps are a widely available source of topographic data containing a record of the geomorphological changes at volcanoes due to lava emplacement this paper explores the use of 1 25 000 scale digitised contour maps for mapping two lava flows of diverse eruption history and morphology at mount etna sicily we find that subtracting dems created from these maps gives a good representation of volume and shape for thicker lava flows 10 m mean thickness in the case of the 1983 lava flow however thinner

size and volume evaluation of the caldera collapse on piton de la fournaise volcano during the april 2007 eruption using aster stereo imagery 1 the scale of summit collapse during the april 2007 eruption of piton de la fournaise volcano reunion island western indian ocean was evaluated using before and after differential digital elevation models dems derived from nadir and backward looking images from the advanced spaceborne emission and reflection radiometer aster instrument the dimensions of horizontal length and width volume and depth of the depression were estimated as 1 100 800 m 9 6 10 7 m 3 and 320 m respectively these estimates show excellent agreement with field survey data a ring shaped thermal anomaly diameter of about 500 m was found at dolomieu crater during or just after the collapse on nighttime aster swir image it may correspond to the high temperature areas associated with the cross section of a hydrothermal zone at a constant altitude inside the crater our analysis of aster orbital data documents topographic and related thermal changes as a result of the 2007 eruption and demonstrates the power of aster as a volcanological tool citation urai m n geshi and t staudacher 2007 size and volume evaluation of the caldera collapse on piton de la fournaise volcano during the april 2007 eruption using aster stereo imagery geophys

volumetric change quantification of the 2010 merapi eruption using tandem x insar abstract accurate and up to date information on the time varying topography of active volcanoes is crucial for assessing material flows through these volcanic systems and along their surfaces as dome building volcanoes can change on meter scale within short time intervals in active phases conventionally used repeat pass sar interferometry insar often fails due to decorrelation effects while other methods to measure topography like aerial photogrammetry or lidar depend on the availability of the local infrastructure and on good weather conditions here we show the potential of the spaceborne earth observation mission tandem x to monitor topographic changes at active dome building volcanoes in this innovative satellite mission two nearly identical satellites fly in a close formation taking radar images of the earth s surface at the same time in bistatic mode this opens the possibility to generate digital elevation models dems of volcanoes analyzing a series of repeated dems enables assessment of volume changes caused by lava dome activity we apply this method to merapi in indonesia by analyzing the volume changes during the hazardous 2010 eruption during this eruption the old lava dome collapsed and a new lava dome was extruded which collapsed again within twelve days we show three dems derived from bistatic tandem x insar in descending orbit taken before and after the eruption we found a mean volume change of 19 10 6 m 3 in the summit area the two estimates differ by 0 4 10 6 m 3 which is 2 of the average dome volume change the tandem x based results are about 25 lower than reference data which can be explained by the shadow masks that were introduced to exclude geometrically decorrelated areas resulting in conservative volume change estimates

volcanic sands of iceland diverse origins of aeolian sand deposits revealed at dyngjusandur and lambahraun the origin formation and evolution of volcanic sands are less well known than the formation of the much more common quartz rich sand sheets combining active volcanism and a cold climate iceland is covered for about 21 of its surface by sandy areas the sands were analyzed in detail at two sites and results reveal their diverse origins the first site is dyngjusandur located north of vatnajokull and the second site is the lambahraun area located south of langjokull at both sites the sand origin is determined from field observations wind directions from ventifacts chemical and mineralogical analyses of rocks and sands at dyngjusandur the sand is dominated by glass grains a situation typical of sand plains in iceland hyaloclastite ridges presently buried beneath vatnajokull are the dominant source of the sand and only large size plagioclase crystals 0 5 cm in sands seem to be derived from the lava flows hyaloclastite ridges were crushed by glaciers and mechanically eroded sediments were washed out by melt water onto flood plains the sand chemical composition is spatially homogeneous and similar to the average composition of neighboring sub aerial lava flows reflecting efficient mixing of distinct sources below the glacier the presence of sand north of dyngjujokull can be taken as a way to explore the average chemical composition of non exposed volcanic material beneath the glacier in the case of lambahraun prevailing winds indicate several potential sources of sand at the north of the sand sheet comparison of chemical and mineralogical analyses of sands and rock samples helped to refine the exact origin in contrast with the first site the sand is dominated by crystals and is chemically consistent with a mixture of material derived from the lava flows of eldborgir and skersli shield volcanoes analysis of the contact between the lava flows and the glacier reveals that basaltic sand grains formed as the result of recent advances of the glacier abrading the rocks the direct interaction of glacial and fluvio glacial activity with basaltic plains appears to be necessary to produce a large amount of sands in a relatively short period of time 4000years this site appears to be an excellent natural laboratory for further studies concerning the sand evolution and physical sorting processes in basaltic material which have important implications for understanding aeolian processes on mars copyright c 2011 john wiley sons ltd

crustal deformation caused by magma migration in the northern izu islands japan intense crustal activity including earthquake swarms eruptions and a caldera formation in the northern izu islands started on june 26 2000 accompanied with large crustal deformation permanent gps data reveals the spatial pattern and time evolution of ground deformation the observations reveal shrinking and subsidence of miyakejima and extension between kouzushima and niijima we constructed a source model to explain the observed displacements during the period between june 26 and the end of august the model consists of a deflation source 0 12km beneath miyakejima tensile faults 1 04km located between miyakejima and kouzushima and several shear faults mass balance considerations suggest that a large amount of magma migrated 30km from miyakejima toward kouzushima

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

interferometric synthetic aperture radar study of okmok volcano alaska 1992 2003 magma supply dynamics and postemplacement lava flow deformation 1 okmok volcano located in the central aleutian arc alaska is a dominantly basaltic complex topped with a 10 km wide caldera that formed circa 2 05 ka okmok erupted several times during the 20th century most recently in 1997 eruptions in 1945 1958 and 1997 produced lava flows within the caldera we used 80 interferometric synthetic aperture radar insar images interferograms to study transient deformation of the volcano before during and after the 1997 eruption point source models suggest that a magma reservoir at a depth of 3 2 km below sea level located beneath the center of the caldera and about 5 km northeast of the 1997 vent is responsible for observed volcano wide deformation the preeruption uplift rate decreased from about 10 cm yr 1 during 1992 1993 to 2 3 cm yr 1 during 1993 1995 and then to about 1 2 cm yr 1 during 1995 1996 the posteruption inflation rate generally decreased with time during 1997 2001 but increased significantly during 2001 2003 by the summer of 2003 30 60 of the magma volume lost from the reservoir in the 1997 eruption had been replenished interferograms for periods before the 1997 eruption indicate consistent subsidence of the surface of the 1958 lava flows most likely due to thermal contraction interferograms for periods after the eruption suggest at least four distinct deformation processes 1 volcano wide inflation due to replenishment of the shallow magma reservoir 2 subsidence of the 1997 lava flows most likely due to thermal contraction 3 deformation of the 1958 lava flows due to loading by the 1997 flows and 4 continuing subsidence of 1958 lava flows buried beneath 1997 flows our results provide insights into the postemplacement behavior of lava flows and have cautionary implications for the interpretation of inflation patterns at active volcanoes

tracking lava flow emplacement on the east rift zone of kīlauea hawai i with synthetic aperture radar coherence 1 lava flow mapping is both an essential component of volcano monitoring and a valuable tool for investigating lava flow behavior although maps are traditionally created through field surveys remote sensing allows an extraordinary view of active lava flows while avoiding the difficulties of mapping on location synthetic aperture radar sar imagery in particular can detect changes in a flow field by comparing two images collected at different times with sar coherence new lava flows radically alter the scattering properties of the surface making the radar signal decorrelated in sar coherence images we describe a new technique sar coherence mapping scm to map lava flows automatically from coherence images independent of look angle or satellite path we use this approach to map lava flow emplacement during the pu u kupaianaha eruption at k lauea hawai i the resulting flow maps correspond well with field mapping and better resolve the internal structure of surface flows as well as the locations of active flow paths however the scm technique is only moderately successful at mapping flows that enter vegetation which is also often decorrelated between successive sar images along with measurements of planform morphology we are able to show that the length of time a flow stays decorrelated after initial emplacement is linearly related to the flow thickness finally we use interferograms obtained after flow surfaces become correlated to show that persistent decorrelation is caused by post emplacement flow subsidence

sources of crustal deformation associated with the krafla iceland eruption of september 1984 a decade long plate boundary rifting episode in northern iceland ended with the september 1984 fissure eruption of krafla volcano we apply a nonlinear inversion method to geodetic data collected before and after the eruption to infer the location geometry and strengths of deformation sources associated with the eruption the net outflow of magma from a 3 km deep magma chamber beneath the krafla caldera was 30 120 106 m a similar volume of magma 50 70 106 m was emplaced in a 1 meter wide 9 km long dike extending from the surface to 7 km depth furthermore at least 110 106 m of magma erupted accordingly a surplus of magma must have been expelled from a second reservoir the location of which although uncertain is likely to lie at depths greater than 5 km beneath krafla volcano it would be difficult to detect this deeper source because of the narrow aperture of the geodetic networks

insights into the 3d architecture of an active caldera ring fault at tendurek volcano through modeling of geodetic data abstract the three dimensional assessment of ring fault geometries and kinematics at active caldera volcanoes is typically limited by sparse field geodetic or seismological data or by only partial ring fault rupture or slip here we use a novel combination of spatially dense insar time series data numerical models and sand box experiments to determine the three dimensional geometry and kinematics of a sub surface ring fault at tendurek volcano in turkey the insar data reveal that the area within the ring fault not only subsides but also shows substantial westward directed lateral movement the models and experiments explain this as a consequence of a sliding trapdoor ring fault architecture that is mostly composed of outward inclined reverse segments most markedly so on the volcano s western flanks but includes inward inclined normal segments on its eastern flanks furthermore the model ring fault exhibits dextral and sinistral strike slip components that are roughly bilaterally distributed onto its northern and southern segments respectively our more complex numerical model describes the deformation at tendurek better than an analytical solution for a single rectangular dislocation in a half space comparison to ring faults defined at glen coe fernandina and bar arbunga calderas suggests that sliding trapdoor ring fault geometries may be common in nature and should therefore be considered in geological and geophysical interpretations of ring faults at different scales worldwide

experimental study of caldera formation scaled experiments have been carried out on caldera collapse mechanisms using silicone as analogue magma and dry sand as analogue rock experiments were carried out in two and three dimensions using a range of roof aspect ratios thickness width 0 2 to 4 5 appropriate for caldera collapse they reveal a general mechanism of collapse only weakly dependent on the shape of the reservoir for low roof aspect ratios 1 subsidence starts by flexure of the roof and the formation of outward dipping reverse ring faults which in turn trigger formation of peripheral inward dipping normal ring faults the subsidence always occurs asymmetrically in cross section the reverse faults delimit a coherent piston bounded on each side by an annular zone of inwardly tilted strata located between the reverse and normal ring fault sets the surface depression consists of a nondeformed area piston surrounded by an annular extensional zone tilted strata for high aspect ratios 1 multiple reverse faults break up the roof into large pieces and subsidence occurred as a series of nested wedges 2 d or cones 3 d the extensional zone dominates the surface depression in the case where preexisting regional faults do not play a major role the collapse mechanics of calderas probably depends strongly on the roof aspect ratio calderas with low roof aspect ratios are predicted to collapse as coherent pistons along reverse faults the annular extensional zone might be the source of the large landslides that generate intracaldera megabreccias collapse into magma reservoirs with high roof aspect ratios may be the origin of some funnel calderas where explosive reaming is not dominant

april 2007 collapse of piton de la fournaise a new example of caldera formation collapse calderas are frequent in the evolution of volcanic systems but very few have formed during historical times piton de la fournaise is one of the world s most active basaltic shield volcanoes the caldera collapse which occurred during the april 2007 lateral eruption is one of the few large documented collapse events on this volcano it helps to understand the mode and origin of caldera collapses in basaltic volcanoes field observations gps and seismic data show that the collapse occurred at an early stage of the eruption the cyclic seismic signal suggests a step by step collapse that directly influenced the lateral eruption rate likely the caldera results from the combined effect of i the progressive collapse of the plumbing system above the magma chamber since 2000 and ii the large amount of magma withdrawal during the early stage of the eruption by both a significant intrusion within the edifice and an important emission rate

the 2007 8 volcanic eruption on jebel at tair island red sea observed by satellite radar and optical images we use high resolution optical images and interferometric synthetic aperture radar insar data to study the september 2007 january 2008 jebel at tair eruption comparison of pre and post eruption optical images reveals several fresh ground fissures a new scoria cone near the summit and that 5 9 0 1 km2 of new lava covered about half of the island decorrelation in the insar images indicates that lava flowed both to the western and to the northeastern part of the island after the start of the eruption while later lavas were mainly deposited near the summit and onto the north flank of the volcano from the insar data we also estimate that the average thickness of the lava flows is 3 8 m resulting in a bulk volume of around 2 2 107 m3 we observe no volcano wide pre or post eruption uplift which suggests that the magma source may be deep the co eruption interferograms on the other hand reveal local and rather complex deformation we use these observations to constrain a tensile dislocation model that represents the dike intrusion that fed the eruption the model results show that the orientation of the dike is perpendicular to the red sea rift implying that the local stresses within the volcanic edifice are decoupled from the regional stress field

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

methodology for quantifying uncertainty in coal assessments with an application to a texas lignite deposit a common practice for characterizing uncertainty in coal resource assessments has been the itemization of tonnage at the mining unit level and the classification of such units according to distance to drilling holes distance criteria such as those used in u s geological survey circular 891 are still widely used for public disclosure a major deficiency of distance methods is that they do not provide a quantitative measure of uncertainty additionally relying on distance between data points alone does not take into consideration other factors known to have an influence on uncertainty such as spatial correlation type of probability distribution followed by the data geological discontinuities and boundary of the deposit several geostatistical methods have been combined to formulate a quantitative characterization for appraising uncertainty drill hole datasets ranging from widespread exploration drilling to detailed development drilling from a lignite deposit in texas were used to illustrate the modeling the results show that distance to the nearest drill hole is almost completely unrelated to uncertainty which confirms the inadequacy of characterizing uncertainty based solely on a simple classification of resources by distance classes the more complex statistical methods used in this study quantify uncertainty and show good agreement between confidence intervals in the uncertainty predictions and data from additional drilling

caldera collapse during the 2000 eruption of miyakejima volcano japan a collapsed caldera 1 6 km in diameter and 450 m in depth was formed at the summit of miyakejima volcano during the 2000 eruption the collapsed caldera appeared on 8 july with a minor phreatic eruption 12 days after seismic activity and magma intrusion occurred northwest of the volcano growth of the caldera took from 8 july to the middle of august with seismic swarms associated with the continuous intrusion of magma northwest of the volcano the growth rate of the caldera was about 1 4 107 m3 day and the final volume of the collapsed caldera was about 6 108 m3 major phreatomagmatic eruptions produced a total of about 1 6 1010 kg 1 1 107 m3 of volcanic ash after caldera growth the caldera structure and the nature of the eruptive materials of the first collapse on 8 july suggest that the surface subsidence was caused by the upward migration of a steam filled cavity with stoping of the roof rock above the magma reservoir the diameter of the stoping column was estimated to be 600 700 m from circumferential faults that developed in the caldera floor and the collapse of the caldera wall enlarged the diameter of the caldera to 1 6 km the total volume of the caldera and the horizontal diameter of the stoping column gave a subsidence of the caldera floor of 1 6 2 1 km

magma compressibility and the missing source for some dike intrusions 1 dike intrusions are often accompanied by localized deflation interpreted as depressurizing magma chambers feeding the dike in some cases the inferred volume decrease is a factor of 4 or 5 less than the volume increase of the dike here we explore whether this discrepancy can be explained by compressibility of the magma combined with the fact that cracks are much more compliant than equidimensional magma chambers if pressure changes are small the magma compressibility m is constant and the dike ends up in hydrostatic equilibrium with an ellipsoidal magma chamber at the same depth the ratio rv of the volume of the crack to the volume lost by the chamber is rv 1 4 m 3 1 where is the host rock rigidity for gas poor magmas m 0 6 2 10 10 pa 1 and 3 25 gpa we find 1 2 rv 7 7 large changes in magma compressibility due to gas exsolution increase rv

mass changes of outlet glaciers along the nordensjkold coast northern antarctic peninsula based on tandem x satellite measurements we analyzed volume change and mass balance of outlet glaciers of the northern antarctic peninsula over the period 2011 to 2013 using topographic data of high vertical accuracy and great spatial detail acquired by bistatic radar interferometry of the tandem x terrasar x satellite formation the study area includes glaciers draining into the larsen a larsen inlet and prince gustav channel embayments after collapse of buttressing ice shelves in 1995 the glaciers became tidewater calving glaciers and accelerated resulting in increased ice export downwasting of most glaciers is going on but at reduced rates compared to previous years in accordance with deceleration of ice flow the rate of mass depletion is 4 2 0 4 gt a 1 with the largest contribution by drygalski glacier amounting to 2 2 0 2 gt a 1 on the technological side the investigations demonstrate the capability of satellite borne single pass radar interferometry as a new tool for accurate and detailed monitoring of glacier volume change

surface movements of emplaced lava flows measured by synthetic aperture radar interferometry lava flows continue to move after they have been emplaced by flow mechanisms this movement is largely vertical and can be detected using differential synthetic aperture radar sar interferometry there are three main components to this motion 1 movement of surface scatterers resulting in radar phase decorrelation 2 measurable subsidence of the flow surface due to thermal contraction and clast repacking and 3 time dependent depression of the flow substrate these effects act in proportion to the thickness of the lava flow and decay with time although there is a time lag before the third component becomes significant we explore these effects using sar data from the ers satellites over the etna volcano sicily phase decorrelation on young thick a a lava flows persists for a few years and probably results from surface block rotations during flow contraction maximum measured subsidence rates of the 1991 1993 lava flow over a period of 70 days are about 0 7 mm day 1 but are potentially greater in areas of data decorrelation these rates fall to 2 7 10 2 mm day 1 after about 20 years in flows about 50 m thick sooner for thinner flows comparison with measured subsidence rates on kilauean lava lakes suggests that thermal contraction only accounts for about one third of the observed subsidence the remaining motion is thought to come from surface clast repacking during cooling and from creep mechanisms in the flow substrate measurements of postemplacement surface movement provide new constraints on the thermomechanical properties of lava flows and have cautionary implications for the interpretation of interferometric sar data of volcanoes 2001 american geophysical union