experiments on conduit flow and eruption behavior of basaltic volcanic eruptions multiphase flow in basaltic volcanic conduits is investigated using analog experiments and theoretical approaches depending on gas supply large gas bubbles gas slugs may rise through basaltic magma in regimes of distinct fluid dynamical behavior ascent of single slugs supplied slugs fed from the gas source during ascent and periodic slug flow an annular flow regime commences at the highest gas supply rates a first set of experiments demonstrates that the growth of gas slugs due to hydrostatic decompression does not affect their ascent velocity and that excess pressure in the slugs remain negligible the applicability of theoretical formulae describing slug ascent velocity as a function of liquid and conduit properties is evaluated in a second set of experiments a third set of experiments with continuous gas supply into a cylindrical conduit are scaled to basaltic conditions over morton eotvos reynolds and froude numbers gas flow rate and liquid viscosity are varied over the whole range of flow regimes to observe flow dynamics and to measure gas and liquid eruption rates foam generation by slug bursting at the surface and partial slug disruption by wake turbulence can modify the bubble content and size distribution of the magma at the transition from slug to annular flow when the liquid bridges between the gas slugs disappear pressure at the conduit entrance drops by 60 from the hydrostatic value to the dynamic flow resistance of the annular flow which may trigger further degassing in a stored magma to maintain the annular flow regime until the gas supply is exhausted and the eruption ends abruptly magma discharge may also terminate when magma ascent is hindered by wall friction in long volcanic conduits and the annular gas flow erodes all magma from the conduit supplied slugs are found to reach much higher rise velocities than unsupplied slugs and to collapse to turbulent annular flow upon bursting at the surface a fourth set of experiments uses a conduit partially blocked by built in obstacles providing traps for gas pockets once gas pockets are filled rising gas slugs deform but remain intact as they move around obstacles without coalescence or significant velocity changes bursting of bubbles coalescing with trapped gas pockets causes pressure signals at least 3 orders of magnitude more powerful than gas pocket oscillation induced by passing liquid our experiments suggest a refined classification of strombolian and hawaiian eruptions according to time dependant behavior into sporadically pulsating lava fountains driven by stochastic rise of single slugs periodically pulsating lava fountains resulting from slug flow and quasi steady lava fountains oscillating at the frequency of annular flow turbulence

lava fountain heights at pu u o o kilauea hawaii indicators of amount and variations of exsolved magma volatiles we review the factors determining lava fountain heights in hawaiian style basaltic eruptions such as those occurring during the recent series of eruptive episodes at the pu u o o vent east rift zone of kilauea volcano hawaii numerical solutions to the equations describing the fluid dynamics of such eruptions predict that lava fountain heights which are indicators of the velocity of magmas in vents should be controlled much more strongly by amounts of exsolved volatiles than by any other factors the next most important factor is the width of the conduit system which determines frictional losses and can be characterized by the volume flux of magma the diameter of the surface vent required to accommodate a given discharge i e instantaneous volume rate of eruption is also a function of exsolved magma volatile content but is less dependent on this factor than is the fountain height we simulate fountain heights for typical discharges at pu u o o and find implied exsolved gas contents very close to those determined by other methods the corresponding predicted vent diameters are comparable with and somewhat smaller than the observed diameter of the pu u o o vent the discrepancy is probably a consequence of processes occurring in the lava pond which is present over the vent during eruptions the variation of fountain height with time during eruptive episodes can be used as a measure of changing exsolved magma volatile content which can be related to processes occurring in the subsurface dike system

a model of the geochemical and physical fluctuations of the lava lake at erebus volcano antarctica abstract erebus volcano antarctica exhibits periodical surface fluctuations of both geochemical and physical nature modeling the physics driving the lake oscillation is a challenge even with a relatively simple theoretical framework we present a quantitative analysis that aims to reconcile both lake level and gas geochemical cycles our model is based on the assumption that the periodicity is caused by the regular release of magma batches and or core annular flow that have a fixed volume of melt and ascend and degas in equilibrium results suggest that cycles are not caused by the mixing between magma residing in the lake and a deep magma but by two distinct deep sources that rise separately these sources of bubbly magma come from at most 2 3 km depth and rise buoyantly individual batches detach from the rising magmas at depths of 20 250 m the two batch types can coexist in a single conduit up to a depth of 30 m above which they rise alternately to release respectively 19 and 23 kg s of gas at the lake surface every 10 min the temperature of the descending flow is between 890 and 950 c which is roughly 100 c colder than the ascending currents batch pairs have shapes likely constrained by the conduit width regardless of their shapes the pairs reach very high porosities near the surface and have diameters of 4 14 m that are consistent with video observations showing spreading waves at the lake surface the alternating arrival of these large batches suggests a lava lake mostly filled with gas rich magma

decadal persistence of cycles in lava lake motion at erebus volcano antarctica article history studies of erebus volcano s active lava lake have shown that many of its observable properties gas composition surface motion and radiant heat output exhibit cyclic behaviour with a period of 10 min we investigate the multi year progression of the cycles in surface motion of the lake using an extended but intermittent dataset of thermal infrared images collected by the mount erebus volcano observatory between 2004 and 2011 cycles with a period of 5 18 min are found to be a persistent feature of the lake s behaviour and no obvious long term change is observed despite variations in lake level and surface area the times at which gas bubbles arrive at the lake s surface are found to be random with respect to the phase of the motion cycles suggesting that the remarkable behaviour of the lake is governed by magma exchange rather than an intermittent flux of gases from the underlying magma reservoir

cyclic degassing of erebus volcano antarctica field observations have previously identified rapid cyclic changes in the behaviour of the lava lake of erebus volcano in order to understand more fully the nature and origins of these cycles we present here a wavelet based frequency analysis of time series measurements of gas emissions from the lava lake obtained by open path fourier transform infrared spectroscopy this reveals i a cyclic change in total gas column amount a likely proxy for gas flux with a period of about 10 min and ii a similarly phased cyclic change in proportions of volcanic gases which can be explained in terms of chemical equilibria and pressure dependent solubilities notably the wavelet analysis shows a persistent periodicity in the co2 co ratio and strong periodicity in h2o and so2 degassing the peaks of the cycles defined by maxima in h2o and so2 column amounts coincide with high co2 co ratios and proportionally smaller increases in column amounts of co2 co and ocs we interpret the cycles to arise from recharge of the lake by intermittent pulses of magma from shallow depths which degas h2o at low pressure combined with a background gas flux that is decoupled from this very shallow magma degassing

seasonal and interannual variabilities in terminus position glacier velocity and surface elevation at helheim and kangerlussuaq glaciers from 2008 to 2016 the dynamic response of greenland tidewater glaciers to oceanic and atmospheric change has varied both spatially and temporally while some of this variability is likely related to regional climate signals glacier geometry also appears to be important in this study we investigated the environmental and geometric controls on the seasonal and interannual evolution of helheim and kangerlussuaq glaciers southeast greenland from 2008 to 2016 by combining year round satellite measurements of terminus position glacier velocity and surface elevation while helheim remained relatively stable with a lightly grounded terminus over this time period kangerlussuaq continued to lose mass as its grounding line retreated into deeper water by summer 2011 kangerlussuaq s grounding line had retreated into shallower water and the glacier had a 5 km long floating ice tongue we also observed seasonal variations in surface velocity and elevation at both glaciers at helheim seasonal speedups and dynamic thinning occurred in the late summer when the terminus was most retreated at kangerlussuaq we observed summer speedups due to surface melt induced basal lubrication and winter speedups due to ice shelf retreat we suggest that helheim and kangerlussuaq behaved differently on a seasonal timescale due to differences in the spatial extent of floating ice near their termini which affected iceberg calving behavior given that seasonal speedups and dynamic thinning can alter this spatial extent these variations may be important for understanding the long term evolution of these and other greenland tidewater glaciers

slug stability in flaring geometries and ramifications for lava lake degassing long lived persistently active lava lakes are rare but have been studied extensively because they may provide a natural laboratory for studying magmatic convection in basaltic and other low viscosity volcanoes however lava lakes differ from other volcanic systems in various ways particularly geometry the presence of the lava lake requires a sudden and significant flaring of the conduit the goal of this paper is to advance our understanding of the effect that a sudden increase in the conduit width has on the stability of large gas slugs and bubbles ascending from the plumbing system we investigate this question by linking analog laboratory experiments to direct numerical simulations in two dimensions we find that the rapid change in the geometry associated with the transition from the conduit to the lava lake causes large gas slugs to break up the nondimensional regime over which we observe the breakup depends sensitively on the flare angle of the lava lake and the importance of inertial effects in the flow implying that degassing related eruptive activity at open system volcanoes is sensitive to the upper conduit and lake geometries applying this idea to the likely geometries and viscosities of actual lava lakes our study suggests that all lava lakes except erebus fall well within the regime where large gas slugs are prone to breakup

terrestrial laser scanning observations of geomorphic changes and varying lava lake levels at erebus volcano antarctica abstract a terrestrial laser scanning tls instrument was used to image the topography of the main crater at erebus volcano each december in 2008 2009 and 2010 our high spatial resolution tls scans provide unique insights into annual and decadal scale geomorphic evolution of the summit area when integrated with comparable data collected by an airborne instrument in 2001 we observe both a pattern of subsidence within the inner crater of the volcano and an 3 m per year drop in the lava lake level over the same time period that are suggestive of decreasing overpressure in an underlying magma reservoir we also scanned the active phonolite lava lake hosted within the inner crater and recorded rapid cyclic fluctuations in the level of the lake these were sporadically interrupted by minor explosions by bursting gas bubbles at the lake surface the tls data permit calculation of lake level rise and fall speeds and associated rates of volumetric change within the lake these new observations when considered with prior determinations of rates of lake surface motion and gas output are indicative of unsteady magma flow in the conduit and its associated variability in gas volume fraction

gas driven lava lake fluctuations at erta ale volcano ethiopia revealed by modis measurements the long lived lava lake of erta ale volcano ethiopia is remotely monitored by moderate resolution imaging spectroradiometers modis installed on satellites the normalised thermal index nti wright et al remote sens environ 82 135 155 2002 is shown to be proportional to the volume of the lava lake based on visual observations the lava lake s variable level can be plausibly related to a stable foam i e a mixture composed of densely packed non coalescing bubbles in suspension within a liquid this foam is trapped at the top of the magma reservoir and its thickness changes in response to the gas flux feeding the foam being successively turned on and off the temporal evolution of the foam thickness and the resulting variation of the volume of the lava lake is calculated numerically by assuming that the gas flux feeding the foam initially constant and homogeneous since december 9 2002 is suddenly stopped on december 13 2002 and not restarted before may 2003 the best fit between the theoretical foam thickness and the level of the lava lake deduced from the nti provides an estimate of both the reservoir radius 155 170 m and the gas flux feeding the foam 5 5 10 3 7 2 10 3 m 3 s 1 when existing this is in agreement with previous estimates from acoustic measurements bouche et al earth planet sci lett 295 37 48 2010 the very good agreement between the theoretical foam thickness and that deduced from modis data shows for the first time the existence of a regime based on the behaviour of a stable foam whose spreading towards the conduit wide conduit condition can explain the long lived activity our predictive model which links the gas flux at the vent to the foam spreading could potentially be used on any volcano with a long lived activity the underlying gas flux and the horizontal surface area of the magma reservoir can then be deduced by combining modelling to continuous measurements of gas flux the lava lake when high often shows regular rise and fall of its level we have recognised a minimum of 26 very well marked cycles between january 2001 and december 13 2002 corresponding to a typical return time of 10 8 2 3 days and a gas volume of 8 3 105 2 0 105 m 3 this corresponds to a gas volume fraction in the reservoir equal to 0 023 0 063 the yearly gas flux estimated between december 13 2002 and september 27 2004 varies between 2 3 10 6 and 5 9 10 6 m 3 s 1 at the depth of the reservoir the long time series provided by infra red sensors mounted on satellites could be used on any persistent volcano to detect potential periodic variations in the level of lava lakes or lava columns providing that the vent has a funnel shape as often and is sufficiently large

satellite observations reveal little inter annual variability in the radiant flux from the mount erebus lava lake abstract satellite remote sensing represents a mature technology for long term monitoring of volcanic activity at mount erebus either independently or as a complement to field instrumentation observations made on 4290 discrete occasions over a six year period by nasa s moderate resolution imaging spectroradiometer modis indicate that the radiant flux from the volcano s summit crater and by inference the lava lake contained therein while variable on the time scale of days to weeks has varied little on an inter annual basis over this period the average radiant flux from the lake during this time was 15 mw with a maximum flux of 100 mw such heat flux time series have been shown to act as a reliable proxy for general levels of activity at erupting volcanoes around the world particularly when these time series are of a long duration the apparent stability of erebus power output is in marked contrast to fluxes observed at three other terrestrial volcanoes erta ale ethiopia nyiragongo democratic republic of congo and ambrym vanuatu which while also hosting active lava lakes all exhibit much greater variability in radiant flux over the same period of time the results presented in this paper are confluent with those obtained from geochemical considerations of the erebus degassing regime and confirm that remarkably stable open system volcanism appears to be characteristic of this long active volcano

using so 2 camera imagery and seismicity to examine degassing and gas accumulation at kīlauea volcano may 2010 abstract so 2 camera measurements at k lauea volcano hawaii in may of 2010 captured two occurrences of lava lake rise and fall within the halema um au crater summit vent during high lava stands we observed diminished so 2 emission rates and decreased seismic tremor similar events at k lauea have been described as the result of sporadic degassing following gas accumulation beneath a mostly impermeable lava lake surface incorporation of so 2 camera data into a multi parameter dataset gives credence to the likelihood of shallow gas accumulation as the cause of these high stand events with accumulated gas release upon lake level drop compensating for the gas deficit reached during accumulation

shallowly driven fluctuations in lava lake outgassing gas pistoning kīlauea volcano abstract lava lakes provide ideal venues for directly observing and understanding the nature of outgassing in basaltic magmatic systems k lauea volcano s summit lava lake has persisted for several years during which seismic and infrasonic tremor amplitudes have exhibited episodic behavior associated with a rise and fall of the lava surface gas pistoning since 2010 the outgassing regime of the lake has been tied to the presence or absence of gas pistoning during normal behavior no gas pistoning the lake is in a spattering regime consisting of higher tremor amplitudes and gas emissions in comparison gas piston events are associated with an abrupt rise in lava level up to 20 m during which the lake enters a non spattering regime with greatly decreased tremor and gas emissions we study this episodic behavior using long term multidisciplinary monitoring of the lake including seismicity infrasound gas emission and geochemistry and time lapse camera observations the non spattering regime i e rise phase of a gas piston cycle reflects gas bubbles accumulating near the top of the lake perhaps as a shallow foam while spattering regimes represent more efficient decoupling of gas from the lake we speculate that the gas pistoning might be controlled by time varying porosity and or permeability in the upper portions of the lava lake which may modulate foam formation and collapse competing models for gas pistoning such as deeply sourced gas slugs or dynamic pressure balances are not consistent with our observations unlike other lava lakes which have cyclic behavior that is thought to be controlled by deeply sourced processes external to the lake itself we show an example of lava lake fluctuations driven by cycles of activity at shallow depth and close to the lake s surface these observations highlight the complex and unsteady nature of outgassing from basaltic magmatic systems

the role of large bubbles detected from acoustic measurements on the dynamics of erta ale lava lake ethiopia the activity at the surface of the lava lake on erta ale volcano ethiopia shows that large bubbles are regularly breaking at a fixed position on the lava lake this is also where the small lava fountains are sometimes produced since this location is likely to be directly above the volcanic conduit feeding the lava lake we have done continuous measurements between march 22 and 26 2003 to understand the degassing of a volcano in permanent activity the bubble size has been first estimated from videos which once combined with the acoustic pressure can constrain the source of the sound the gas volume and overpressure stayed roughly constant between 36 700 m3 and 4 103 1 8 104 pa respectively simultaneous thermal measurements showed regular peaks which occurred when the crust was broken by a large bubble hence gave a direct indication on the typical return time between the bubbles 1 h these spherical cap bubbles had a high reynolds number 4600 20000 therefore a wake periodically unstable formed and detached from the bubble bottom the bubbly wake if the detachment occurs close to the surface can explain the duration of lava fountains measured on the videos the periodic arrival of bubbly wakes which mostly detach from the driving spherical cap within the lava lake could explain the absence of cooling at erta ale erebus antartica villarica chile and nyiragongo democratic republic of congo without invoking a convective downflow of magma in the conduit as previously done

explosive volcanic eruptions viii the role of magma recycling in controlling the behaviour of hawaiian style lava fountains explosive eruptions of mafic magmas produce lava fountains whose heights are a function of the exsolved volatile content of the magma its erupted mass flux and the geometry of the vent which may be an elongate fissure or a localized near circular conduit the geometry of the initial vent and the eruptive behaviour can be distinctly modified by lava drainback and accumulating ejecta hot pyroclasts landing near the vent may coalesce to form rootless flows some of which may drain back into the vent to be recycled into the eruption products rootless flows may be at least partially confined by pre existing topographic features or by spatter or cinder ramparts being built up by the eruption itself so that they accumulate into a lava pond over and around the vent the erupting jet of magmatic gas and pyroclasts must force its way through such a pond and will entrain some of the pond lava as it does so the energy expended in entraining and accelerating previously erupted materials will reduce the eruption velocity and the lava fountain height by an amount which can be calculated as a function of the eruption conditions and the lava pond depth or lava drainback rate the results of such calculations are presented and are used to assess the influence of this process on attempts to infer magma volatile contents from field observations of lava fountain heights

radiative heat power at stromboli volcano during 2000 2011 twelve years of modis observations abstract twelve years of night time modis moderate resolution imaging spectroradiometer observations has been analysed to detect and quantify the radiative heat power emitted by stromboli volcano from march 2000 to september 2011 using an accurate background subtraction of the modis signal at 4 m we were able to discriminate two main regimes of thermal radiation related to different levels of volcanic activity effusive eruptions occurred on december 28 2002 and february 27 2007 radiated at an average of 186 mw with a frequency of alert detection of 50 95 conversely during the typical strombolian activity an average of 9 mw is radiated with a frequency of alert detection of 0 45 although during the effusive eruptions the radiative power is basically controlled by the lava discharge rate our results suggest that during non effusive periods strombolian regime both the intensity and the frequency of modis alerts are controlled by the height of the magmatic column feeding the activity at the surface in particular we found that a radiative power of 50 mw corresponds to a high magma column which is exposed in the vent area at the same rate in which the deeper gas rich magma is typically supplied within the feeding system of stromboli 0 3 m3 s 1 in this condition the magmatic system approaches steady state regimes above this threshold a transition from strombolian to effusive regimes may occur as shown by the detection of 50 mw 8 10 days before the onset of both the last two major flank eruptions these values were reached after 1 2 months of gradual increase of the radiative power which was likely associated the rising of the magma column within the shallowest portion of the conduit in addition our data suggest that over the years 2000 2011 several cycles of rise and fall of the magma column have occurred which however did not culminate into an effusive eruption but only into recurrent episodes of sustained spattering or fountaining and summit overflows these fluctuations has substantially increased in frequency and intensity after the 2007 eruption thus suggesting that this event has perturbed in some way the shallow plumbing system of stromboli we stress that the detection of a radiative power higher than 50 mw is a clear evidence of a very high magma column which may prelude the onset of an effusive eruption and or periods of sustained vent activity in conclusion we suggest that systematic analysis of modis data can be used to detect variations in the intensity of strombolian activity and may considerably improve volcano surveillance at stromboli as well as at other open system volcanoes

extraterrestrial lava lakes abstract active lava lakes are rare on earth with only ten documented examples all formed by lavas of basaltic composition and housed inside summit craters or calderas the existence of lava lakes on other planetary bodies may imply similarities in either composition or volcano tectonic settings and so has important implications for understanding the link between melt production and volcanism we review lava lakes on earth and other planets particularly active caldera like features interpreted to be currently containing active lava lakes on jupiter s moon io and features interpreted as remnants of lava lakes on venus and mars mercury and the moon do not boast the major calderas or shield volcanoes of their larger rocky neighbors partly due to a horizontally compressive tectonic regime arising from global contraction that makes it difficult to move melts through the upper crust we discuss the evidence for active lava lakes on io and show how modeling based on terrestrial lava lakes can reveal how these phenomena differ on both bodies the superficial similarities do not necessarily imply that the plumbing is similar observations of the largest lava lake on io loki patera provide insight into the nature of ionian lava lakes in general which may be more similar to eruptive episodes on the east pacific rise on earth which lead to temporary lava lakes although temporal data for io s lava lake activity are scarce studies of temporal variability of lava lakes on earth are useful for providing ground truth for comparisons future studies of earth by remote sensing and field observations and of io by both ground based observations and future missions are needed to answer many questions including why lava lakes rare on earth appear to be common on io

an analogue experimental model of depth fluctuations in lava lakes lava lakes consisting of molten degassing lava in summit craters of active basaltic volcanoes sometimes exhibit complex cycles of filling and emptying on time scales of hours to weeks such as recorded at pu u o o in hawaii and oldoinyo lengai in tanzania here we report on a new series of analogue laboratory experiments of two phase flow in a reservoir conduit lava lake system which spontaneously generates oscillations in the depth of liquid within the lake during the recharge phase gas supplied from a subsurface reservoir of degassing magma drives liquid magma up the conduit causing the lake to fill as the magmastatic pressure in the lake increases the upward supply of magma driven by the gas bubbles falls eventually the upflow becomes unstable and liquid drains downwards from the lake driven by the magmastatic pressure of the overlying lake suppressing the ascent of any more bubbles from the chamber at a later stage once the lake has drained sufficiently the descent speed of liquid through the conduit decreases below the ascent speed of the bubbles and the recharge cycle resumes application of a quantitative model of the experiments to the natural system is broadly consistent with field data

static and cyclic liquefaction potential of fraser delta sand in simple shear and triaxial tests the potential for static and cyclic liquefaction of the sand that underlies the highly seismic fraser delta is assessed under simple shear test conditions typical of an earthquake shaking a comparison of liquefaction potential is also made between simple shear and conventional triaxial stress conditions it is shown that the liquefaction potential of sand is profoundly influenced by the stress path the reduction factors currently applied to the cyclic triaxial resistance for representing simple shear response may involve a large degree of conservatism in design a direct measurement of soil behaviour under stress conditions typical of earthquake loading may thus have large economic benefits key words sand liquefaction static cyclic triaxial simple shear

continuous gravity measurements reveal a low density lava lake at kīlauea volcano hawai i abstract on 5 march 2011 the lava lake within the summit eruptive vent at k lauea volcano hawai i began to drain as magma withdrew to feed a dike intrusion and fissure eruption on the volcano s east rift zone the draining was monitored by a variety of continuous geological and geophysical measurements including deformation thermal and visual imagery and gravity over the first 14 hours of the draining the ground near the eruptive vent subsided by about 0 15 m gravity dropped by more than 100 gal and the lava lake retreated by over 120 m we used gps data to correct the gravity signal for the effects of subsurface mass loss and vertical deformation in order to isolate the change in gravity due to draining of the lava lake alone using a model of the eruptive vent geometry based on visual observations and the lava level over time determined from thermal camera data we calculated the best fit lava density to the observed gravity decrease to our knowledge the first geophysical determination of the density of a lava lake anywhere in the world our result 950 300 kg m 3 suggests a lava density less than that of water and indicates that k lauea s lava lake is gas rich which can explain why rockfalls that impact the lake trigger small explosions knowledge of such a fundamental material property as density is also critical to investigations of lava lake convection and degassing and can inform calculations of pressure change in the subsurface magma plumbing system

fifteen years of thermal activity at vanuatu s volcanoes 2000 2015 revealed by mirova abstract the vanuatu archipelago consists of 80 islands and hosts 5 subaerial volcanoes yasur lopevi ambrym aoba and gaua that have shown sign of activity during the past decade in this contribution we provide a 15 years long datasets 2000 2015 of the thermal activity recorded at these active volcanoes by means of mirova middle infrared observation of volcanic activity a new volcanic hotspot detection system based on modis data the analyzed volcanoes are characterized by a spectrum of volcanic activities whose thermal signature has been tracked and carefully analyzed these include strombolian vulcanian explosions at yasur lava flows at lopevi lava lakes at ambrym surtseyan type eruptions within the voui crater lake of aoba and ash dominated eruptions with strong degassing at gaua the collected data reveal several details of the long term eruptive dynamics at single sites such as a monthly long pulse in thermal emissions at yasur volcano as well as at the two active craters of ambrym benbow and marum heating cycles within aoba crater lake and intermittent pressurized eruptions at lopevi volcano has also been detected and shed light in the eruptive dynamics of the analyzed volcanoes in addition we were able to track a two years long intensification of thermal output at benbow crater ambrym that preceded the occurrence of the first intra caldera eruptions of this volcano since 1989 we emphasize how the data provided by mirova represent a new safe and affordable method for monitoring in near real time a large spectrum of volcanic activities taking place at vanuatu and other volcanic areas

insights into shallow magmatic processes at kīlauea volcano hawaiʻi from a multiyear continuous gravity time series continuous gravity data collected near the summit eruptive vent at k lauea volcano hawai i during 2011 2015 show a strong correlation with summit area surface deformation and the level of the lava lake within the vent over periods of days to weeks suggesting that changes in gravity reflect variations in volcanic activity joint analysis of gravity and lava level time series data indicates that over the entire time period studied the average density of the lava within the upper tens to hundreds of meters of the summit eruptive vent remained low approximately 1000 1500 kg m3 the ratio of gravity change adjusted for earth tides and instrumental drift to lava level change measured over 15 day windows rose gradually over the course of 2011 2015 probably reflecting either 1 a small increase in the density of lava within the eruptive vent or 2 an increase in the volume of lava within the vent due to gradual vent enlargement superimposed on the overall time series were transient spikes of mass change associated with inflation and deflation of k lauea s summit and coincident changes in lava level the unexpectedly strong mass variations during these episodes suggest magma flux to and from the shallow magmatic system without commensurate deformation perhaps indicating magma accumulation within and withdrawal from void space a process that might not otherwise be apparent from lava level and deformation data alone continuous gravity data thus provide unique insights into magmatic processes arguing for continued application of the method at other frequently active volcanoes