two mode ionospheric response and rayleigh wave group velocity distribution reckoned from gps measurement following mw 7 8 nepal earthquake on 25 april 2015 the coseismic induced ionospheric total electron content tec perturbations were analyzed following the mw 7 8 nepal earthquake 28 147 n 84 708 e depth 15 km that occurred on 25 april 2015 at 06 11 26 utc the ionospheric response is due to both the modes i e shock acoustic waves slow mode and rayleigh wave induced fast mode the continuous global positioning system gps data at about 60 sites from various gps networks have been used in the present study all the sites within epicentral distance of 2400 km and 70 170 azimuth recorded the rayleigh wave induced tec response while the sites within 400 2200 km in the same azimuth recorded the response from both the modes the maximum coseismic induced peak to peak tec amplitude is 1 2 total electron content unit 1 tecu 1016 el m 2 from hodochron plot the apparent rayleigh wave velocity has been determined as 2400 m s on the average and the acoustic wave velocity as 1180 m s both these waves being discernible beyond 1200 km of epicentral distance as also evident from hodochron plot and wavelet spectrographs we reckoned the rayleigh wave group velocities using ionospheric response at selected radial pairs of stations and validated the ionospheric response distribution seen mainly depending on the epicentral distance satellite geometry directivity of radiation pattern and the upper crustal heterogeneity this study highlights the characteristics of ionospheric response consequent to the 2015 nepal earthquake

cooling mechanisms and an approximate thermal budget for the 1991 1993 mount etna lava flow the 1991 1993 eruption of mount etna sicily built a 7 2 km aa lava flow field within the valle del bove this letter provides estimates of the power losses associated with various cooling mechanisms operating during the development of the flow field derived from time series analysis of nighttime satellite remote sensing data unlike sensors used in many previous remote sensing studies of active lava the ers 1 along track scanning radiometer atsr provides unsaturated measurements of spectral radiance from even very hot surfaces this allows for more accurate solution of the lava flow endmember thermal components we find that radiative and conductive processes dominated with our model suggesting energy losses of similar magnitude radiative losses peaked about one month into the eruption when lava flowed in open channels conductive losses peaked after two months with a marked decline caused by a significant decrease in the horizontal spreading rate of lava by the end of the eruption the 235 106 m of erupted lava is estimated to have lost only 28 of its initial thermal energy a further 6 5 1017 j must be lost before the lava reaches ambient temperature

imaging and modeling the ionospheric airglow response over hawaii to the tsunami generated by the tohoku earthquake of 11 march 2011 1 although only centimeters in amplitude over the open ocean tsunamis can generate appreciable wave amplitudes in the upper atmosphere including the naturally occurring chemiluminescent airglow layers due to the exponential decrease in density with altitude here we present the first observation of the airglow tsunami signature resulting from the 11 march 2011 tohoku earthquake off the eastern coast of japan these images are taken using a wide angle camera system located at the top of the haleakala volcano on maui hawaii they are correlated with gps measurements of the total electron content from hawaii gps stations and the jason 1 satellite we find waves propagating in the airglow layer from the direction of the earthquake epicenter with a velocity that matches that of the ocean tsunami the first ionospheric signature precedes the modeled ocean tsunami generated by the main shock by approximately one hour these results demonstrate the utility of monitoring the earth s airglow layers for tsunami detection and early warning

harmonic excitation of mantle rayleigh waves by the 1991 eruption of mount pinatubo philippines an unusually long at least two hours seismic wave train having periods of about 230 sec was recorded at many worldwide seismic stations during the major eruption of mount pinatubo in the philippines on june 15 1991 this wave train exhibits two sharp spectral peaks at 228 and 270 sec the group velocity phase velocity and the particle motion of this wave train indicate that it is a rayleigh wave the most probable excitation mechanism is acoustic coupling of atmospheric oscillations that were set off by continuous thermal energy flux from the volcano the two spectral peaks correspond to the characteristic periods of acoustic and gravity modes of the earth s atmosphere the magnitude of the vertical single force equivalent to the acoustic coupling is 1 6 10 17 dynes over a frequency band of 0 003 to 0 01 hz the results suggest the possibility of using acoustically coupled rayleigh waves for detection characterization and quantification of volcanic eruptions acoustic coupling of the atmosphere and the solid earth provides a unique seismic source with long duration

a new crater near insight implications for seismic impact detectability on mars a new 1 5 m diameter impact crater was discovered on mars only 40 km from the insight lander context camera images constrained its formation between 21 february and 6 april 2019 follow up high resolution imaging science experiment images resolved the crater during this time period three seismic events were identified in insight data we derive expected seismic signal characteristics and use them to evaluate each of the seismic events however none of them can definitively be associated with this source atmospheric perturbations are generally expected to be generated during impacts however in this case no signal could be identified as related to the known impact using scaling relationships based on the terrestrial and lunar analogs and numerical modeling we predict the amplitude peak frequency and duration of the seismic signal that would have emanated from this impact the predicted amplitude falls near the lowest levels of the measured seismometer noise for the predicted frequency hence it is not surprising this impact event was not positively identified in the seismic data finding this crater was a lucky event as its formation this close to insight has a probability of only 0 2 and the odds of capturing it in before and after images are extremely low we revisit impact seismic discriminators in light of real experience with a seismometer on the martian surface using measured noise of the instrument we revise our previous prediction of seismic impact detections downward from a few to tens to just 2 per earth year still with an order of magnitude uncertainty

propagation of acoustic waves in a viscoelastic two phase system influence of gas bubble concentration abstract volcanic explosions generate pressure perturbations in the atmosphere and a seismic wavefield in the ground the source is therefore well coupled with the atmosphere and the ground the acoustic and elastic wavefields reflect dynamical processes at the source and the viscoelastic properties of the magma gas medium at low pressure 70 strongly affect the propagation properties of the acoustic wavefield we found that the amplitude of the infrasonic wavefield in the atmosphere typically recorded in case of strombolian explosions 2 105 pa can be explained by a deep 50 m source embedded in the magma conduit only if a very large unrealistic pressure drop 1013 pa is assumed the strong damping linked to the poor elastic properties of the shallow magma gas mixture prevents the efficient propagation of the acoustic waves in the magma gas mixture and resonance of body waves cannot occur infrasonic waves can be transmitted from the magma to the atmosphere only when the source is very shallow

fossils or sedimentary structures carbonaceous spheroids from the shale of the cryogenian nantuo formation in shengnongjia area south china abstract black shale of the cryogenian nantuo formation shennongjia area south china contains spheroids which co occur with fossils of macroalgae these three dimensional structures occur sparsely as isolated specimens or abundantly as clusters which show different types of boundaries between individuals they are generally circular on bedding surfaces and elliptical on transecting sections and range up to several millimeters in diameter both petrographic thin sections and scanning electron microscopy sem reveal that these spheroids are mostly organic carbon in composition and exhibit sharp well rounded external margins composed of microcrystalline clay minerals the carbonaceous nature of these spheroids and different elemental abundances between spheroids and matrix are also confirmed by raman spectroscopy and energy dispersive x ray spectroscopy eds organic carbon isotopic values of individual spheroids range from 28 55 to 28 83 with an average of 28 72 which show indistinguishable 13corg values with the surrounding sedimentary matrix but exhibit statistically significant difference to those of contemporaneous macroalgae a range of physical origins for these spheroids including concretions fluid escape structures raindrop impressions or bubble impressions are considered and cannot be entirely rejected alternatively biogenic origin is also a possible interpretation from observations of their morphological mineralogical geochemical and sedimentological characteristics although their nature remains unresolved the documentation of these new carbonaceous spheroids from the nantuo formation of shennongjia area adds to a growing list of fossil like structure records in the cryogenian period

environmental interpretation and a sequence stratigraphic framework for the terminal proterozoic ediacara member within the rawnsley quartzite south australia abstract fossils of the ediacara biota are confined to preservational windows in the ediacara member of the rawnsley quartzite pound subgroup from the flinders ranges south australia the base of the ediacara member is a type 1 sequence boundary incised into the partly lithified chace quartzite member of the rawnsley quartzite the ediacara member and the upper half of the rawnsley quartzite comprise the rawnsley depositional sequence bounded above by the early cambrian uratanna depositional sequence the rawnsley sequence developed over an erosional surface cut into the chace quartzite member with some 250 m of relief southeasterly directed palaeovalleys are filled with a sequence of massive sandstone and laminated siltstone passing up into well bedded sandstone at lowstand local channels were filled by massive sand the highstand systems tract consists of several parasequence sets of laminated siltstone and channelized amalgamated massive sandstone overlain by interbedded siltstone and sandstone grading up into well bedded clean sandstone impressions of soft bodied ediacaran organisms are preserved above the valley fill facies on sandstone partings within upward shoaling delta front environments between storm and fairweather wavebase the ediacara member is in places conformably overlain by up to 500 m of sandstone of the same lithofacies as those underlying the member distinctive microbial mat bound sand laminae described as petee structures are characteristic of the rawnsley quartzite above and below the ediacara member during deposition of the ediacara member colonization of the deeper substrates by microbial mat communities enabled preservation of the ediacara biota the erosional surface at the base of the ediacara member is one of at least four incision events recorded in the terminal proterozoic and early cambrian succession of the adelaide geosyncline the similarity of incision filling lithofacies of the rawnsley and uratanna sequences has in condensed sections led to confusion between the depositional sequences characteristic trace and body fossil assemblages provide the only clear distinction between depositional cycles spanning the proterozoic cambrian boundary

spatiotemporal variability of active lava surface radiative properties using ground based multispectral thermal infrared data abstract active lava surfaces emplaced during effusive eruptions are typically observed in the form of lava flows lakes or domes there are numerous volcanoes on earth that regularly produce active lava including k lauea volcano in hawai i which had a continually active lava flow field from the 1980s until the end of the last eruptive phase in 2018 during the last decade of that period it also had a persistent lava lake at the summit this study used a new ground based miniature multispectral thermal camera mmt cam imaging system to acquire high spatiotemporal data of active lava surfaces at k lauea volcano in 2018 the goal was to quantify the short term variability of the radiative properties e g emissivity kinetic temperature and heat flux of molten lava during cooling and propagation using concurrent in situ multispectral thermal infrared tir measurements as expected there was a strong positive correlation between kinetic temperature fraction of exposed melt and heat flux importantly there is also a negative or inverse correlation found for the emissivity of lava surfaces with temperature during cooling immediately following emplacement the temporal results reveal low and high frequency 10s of minutes to seconds changes in radiative properties up to 25 and 5 variability respectively the spatial analysis provided insights into emplacement dynamics and activity potential through the interpretation of the improved heat flux measurements for example these data highlighted lava lake over turning subsurface supply pathways and lava flow breakout zones additionally the first calibrated in situ emissivity measurements of actively emplaced lava indicated a lower efficiency of radiant heat flux from molten lava surfaces prior to a viscoelastic crust forming which results in lower calculated heat fluxes than previous estimates this implies that prior heat budget calculations and lava flow propagation models may have overestimated heat flux by at least 20 from the molten lava prior to cooling and crust formation therefore the results of this study allow for more accurate calibration of prior calculations and models resulting in more accurate values and a reduction in the uncertainty of hazard models reliant on these values

surface cooling advection and the development of different surface textures on active lavas on kilauea hawai i the validity of lava flow cooling models were investigated using data from a high resolution high frame rate thermal imaging camera on kilauea hawai i during august 2004 once the surface temperature data for small lava flow and lobes were corrected for emissivity viewing distance humidity and viewing angle it was clear that their upper surfaces were thermally stratified on eruption the interior of a stationary lava lobe was exposed by removing the crust and its cooling rate was measured at 30 hz for this flow the measured cooling trend was successfully modelled using a finite difference cooling model however modelled and measured cooling rates of a pahoehoe lobe and a small channelised lava flow were only in agreement until the crust began to deform the departure from the modelled trend at this point is attributed to two factors one is the complex cooling regime of a highly deformed ropy crust in which exposed lava at the crests of the ropes radiates in all directions compared with lava in the troughs where radiative cooling is less effective the second and more important reason for the difference is the reduced flow rate of the crust once it begins to be compressed the underlying visco elastic zone beneath the crust flows more rapidly than the crust and consequently advective heat flow significantly reduces cooling rates variations in heat loss from different flow textures and the incorporation of different advective heat components is clearly important in future flow models one of the critical parameters in such models is the temperature at which different surface textures develop temperature profiles along lobes and flows also revealed that rope textures developed on pahoehoe lavas when temperatures were in the range of 700 800 c brittle deformation of pahoehoe crust occurred when temperature dropped below 700 c and small pahoehoe lobes stopped advancing at temperatures of 600 650 c it is important to recognise that the flow front temperatures at which these flows stop advancing will be significantly greater than for larger flows on similar gradients the higher internal and basal shear stresses of large lava flows will allow the flow to advance until the visco elastic layer at the front of a front is significantly cooler than the temperatures recorded on these small flows on kilauea

textured organic surfaces associated with the ediacara biota in south australia abstract the ediacaran period takes its name from the fossils of the ediacara biota which represent the first appearance of large and diverse assemblages of organisms in the fossil record although the global record of these distinctive body fossils is now well known a previously unrecognized megascopic organic record of textured organic surfaces tos occurs in the ediacara biota however tos is also a feature over a wider range of paleoenvironmental settings where body fossils are unknown in ediacaran siliciclastic successions that have been studied in australia namibia and western north america paleoecological analysis of successive bedding planes of strata from the late ediacaran rawnsley quartzite in the flinders ranges of south australia reveals that tos represent the most common organic features in bedding surface assemblages of the ediacara biota the tos consist of preserved patterned assemblages of textured organic mats fibers and simple tubular body fossils complex ediacara body fossils while striking for their distinctive body plans and dominating some of the beds are relatively minor components of combined overall surface area many elements of tos have previously been miss diagnosed as trace fossils which are in practice limited to two or at most three morphotypes that indicate the presence of bilateria although tos represent a simpler grade of organismic construction than discrete and more complex ediacara body fossils they were preserved in a similar manner marked variability in all components of the biota between successive surfaces suggests that ediacara ecologies fluctuated at short intervals despite an apparently consistent sedimentary regime

assemblage palaeoecology of the ediacara biota the unabridged edition fossils of the ediacara biota offer our earliest insight into diverse macroscopic life on this planet in particular given the diversity and range of exquisite soft bodied preservation the potential for unraveling aspects of the paleobiology and paleoecology is great clearly however there can be a taphonomic overprint that dictates how complete the assemblage is new diversity data including richness and evenness from south australia is compared to previously published data from newfoundland and the white sea and is within the range of values for both modern and phanerozoic assemblages however missing from our current understanding of ediacaran ecosystems is a full description and interpretation of the many problematica structures and organic surfaces

three dimensional ionospheric tomography of post seismic perturbations produced by the denali earthquake from gps data summary the coupling between the solid earth and its atmosphere is responsible for vertically propagating infrasonic waves generated by seismic surface waves these pressure waves are amplified as they propagate upward and produce perturbations of ionospheric electron density the electron density perturbations above california due to the seismic surface waves generated by the denali earthquake on 2002 november 3 have been imaged from gps data by a tomographic method the integrated electron content along gps ray paths presents a noise level that is lower in the acoustic wave frequency band than in the gravity wave frequency band therefore the filtered gps data from californian networks are inverted for a tomographic reconstruction of electron density perturbations in the acoustic frequency band the inversion is properly resolved only in a small number of areas due to the geometry of gps ray paths in these areas a wave propagating upward at 1 2 0 3 km s 1 and horizontally at 4 1 km s 1 is observed with a timing consistent with an infrasonic wave generated by the path of seismic surface waves the discrepancies between the observed electron density perturbation structure and the expected infrasonic wave can be explained by the poor resolution of the inverse problem or by a simple model of interactions between the neutral wave and the plasma future development of dense gps networks and the advent of the galileo system will overcome the resolution problems and allow us to relate ionospheric perturbations to the seismic signal such a relation can be used to constrain the source and propagation of seismic waves as well as upper atmosphere characteristics

goce the first seismometer in orbit around the earth the first in situ sounding of a post seismic infrasound wavefront is presented using data from the goce mission the atmospheric infrasounds following the great tohoku earthquake on 11 march 2011 induce variations of air density and vertical acceleration of the goce platform these signals are detected at two positions along the goce orbit corresponding to a crossing and a doubling of the infrasonic wavefront created by seismic surface waves perturbations up to 11 of air density and 1 35 10 7 m s2 of vertical acceleration are observed and modeled with two different solid atmosphere coupling codes these perturbations are a due to acoustic waves creating vertical velocities up to 130 m s amplitudes and arrival times of these perturbations are reproduced respectively within a factor 2 and within a 60 s time window waveforms present a good agreement with observed data the vertical acceleration to air density perturbation ratio is higher for these acoustic waves than for gravity waves combining these two pieces of information offers a new way to distinguish between these two wave types this new type of data is a benchmark for the models of solid atmosphere coupling amplitude and frequency content constrain the infrasound attenuation related to atmosphere viscosity and thermal conductivity observed time shifts between data and synthetics are ascribed to lateral variations of the seismic and atmospheric sound velocities and to the influence of atmospheric winds these effects should be included in future modeling this validation of our modeling tools allows to specify more precisely future observation projects

from sumatra 2004 to tohoku oki 2011 the systematic gps detection of the ionospheric signature induced by tsunamigenic earthquakes the recent tsunamigenic earthquake in tohoku 11 march 2011 strongly affirms one more time after the sumatra event 26 december 2004 the necessity to open new paradigms in oceanic monitoring detection of ionospheric anomalies following the sumatra tsunami demonstrated that ionosphere is sensitive to the tsunami propagation observations supported by modeling proved that tsunamigenic ionospheric anomalies are deterministic and reproducible by numerical modeling via the ocean neutral atmosphere ionosphere coupling mechanism in essence tsunami induces internal gravity waves propagating within the neutral atmosphere and detectable in the ionosphere most of the ionospheric anomalies produced by tsunamis were observed in the far field where the tsunami signature in the ionosphere is clearly identifiable in this work we highlight the early signature in the ionosphere produced by tsunamigenic earthquakes and observed by gps measuring the total electron content close to the epicenter we focus on the first hour after the seismic rupture we demonstrate that acoustic gravity waves generated at the epicenter by the direct vertical displacement of the source rupture and the gravity wave coupled with the tsunami can be discriminated with theoretical support we illustrate the systematic nature of those perturbations showing several observations nominally the ionospheric perturbation following the tsunamigenic earthquakes in sumatra on 26 december 2004 and 12 september 2007 in chile on 14 november 2007 in samoa on 29 september 2009 and the recent catastrophic tohoku oki event on 11 march 2011 based on the analytical description we provide tracks for further modeling efforts and clues for the interpretation of complex and thus often misleading observations the routine detection of the early ionospheric anomalies following the rupture highlights the role of ionospheric sounding in the future ocean monitoring and tsunami detection

detecting atmospheric perturbations produced by venus quakes 1 the possibility to detect seismic activity on venus by using the mechanical coupling of the solid atmosphere system is investigated first the atmospheric attenuation of infrasonic waves produced by quakes is theoretically determined from a pure co2 atmospheric model demonstrating that frequencies below 0 1 hz are amplified by a factor of 10 000 above 120 km altitude with a simple quake model an upper limit of infrasonic adiabatic temperature and density perturbations above the source is estimated then we demonstrate that the temperature increase due to high altitude acoustic energy dissipation above a quake is large enough to be measured by remote sensing methods finally the expected post seismic effects are analyzed in the framework of the virtis instrument on board the esa venus express mission

ionospheric remote sensing of the denali earthquake rayleigh surface waves 1 using the global positioning system we have detected ionospheric disturbances associated with the long period rayleigh waves from the 2002 denali earthquake ms 7 9 the dense california gps networks allowed us to map the ionospheric perturbations and to compute the group velocity with a high spatial resolution above the pacific coasts due to a low sampling rate a large error in the velocity determination remains nonetheless it demonstrates that bi static remote sensing measurements of seismic waves with gps networks can be performed monostatic measurements with a dedicated satellite could possibly be used to record in the ionosphere surface waves originating from large earthquakes such a space based remote sensing of the local group velocity of rayleigh surface waves would effectively complement the seismic networks for high resolution global tomography of the earth s lithosphere

the thermal signature of volcanic eruptions on io and earth abstract we investigate a spectrum based technique to identify the style of active volcanic eruptions on jupiter s moon io thermal remote sensing of io has had to rely primarily on low spatial resolution data similar to low spatial resolution satellite data applied to detecting and charting the temporal evolution of terrestrial hot spots these terrestrial analyses use data from sensors designed to monitor the weather and sea surface temperature on io such low spatial resolution data are used to classify eruption styles modes of emplacement by means of several criteria related to the temporal evolution of the infrared spectrum associated with the eruptive activity at each hot spot which we term thermal signature we find that the ratio of the emission at 2 and 5 m and how this ratio changes with time is often diagnostic of eruption style even in low spatial resolution data tests using thermal data for terrestrial ground truth cases show that our classification system is valid on earth the results of our analysis can be used to aid in the design of future space based instruments that can be used for volcano monitoring on io as well as earth

paleoecology of the enigmatic tribrachidium new data from the ediacaran of south australia abstract tribrachidium is a monospecific genus of the ediacara biota found globally in the ediacara member of the rawnsley quartzite flinders ranges of south australia the spatial distribution of tribrachidium across the seafloor is best described as patchy although tribrachidium is the dominant fossil on two of the twenty six beds currently excavated and is present in large numbers on another the genus most commonly occurs as no more than a handful of specimens on a bed tribrachidium size frequency distributions of each of the three beds with more than 5 specimens are all statistically distinguishable from one another additionally the size range on any given bed is smaller than the overall size range observed for the genus these patterns suggest that these organisms lived in populations composed of single generations the beds with numerous tribrachidium come from different facies and are characterized by the presence of dissimilar mixes of taxa and textured organic surfaces indicating that tribrachidium was a generalist able to adapt to a variety environments uniquely the base or internal structure of tribrachidium is also found preserved in both positive and negative relief as a sequence of concentric ridges on beds where tribrachidium is the dominant genus the most parsimonious explanation for the presence of these concentric ridge fossils is that they are the fossilized form of a tribrachidium preserved when the organism was buried upside down flipped over or dead and partially decayed prior to burial

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

surface textures and dynamics of the 2005 lava dome at shiveluch volcano kamchatka shiveluch is one of the largest and most active andesitic volcanoes of the kuril kamchatka arc it commonly alternates between vulcanian explosive eruptions and periods of dome growth and subsequent dome collapse driven block and ash flows the volcano was in an extended period of heightened activity for most of the period 2004 2010 we examined this activity in detail using thermal infrared tir remote sensing as part of the urgent request protocol urp program of the advanced spaceborne thermal emission and reflection radiometer aster instrument and confirmed the results with ground based photography and airborne tir camera data high spatial resolution tir images were collected during both daytime and nighttime satellite overpasses prior to and following the large explosive event eruption of 27 february 2005 and the dome growth that followed during a field campaign in august 2005 a helicopter overflight designed to acquire visible and tir data of the active dome was performed this was a nadir looking low altitude overflight and the first ever of shiveluch volcano involving non russian scientists the image data revealed an active crease structure in the center of the dome with a distinctly different crescent shaped high temperature 380 c zone roughly perpendicular to the crease in order to provide a time context and estimate extrusion rates the airborne data were compared to the spaceborne aster data and long distance ground based photography of the dome acquired by our russian colleagues the presence of a crease structure and the complex thermal pattern on the surface were both unexpected discoveries that reveal the way in which exogenous dome growth was occurring at the time this highly active period at shiveluch provides a unique example to better understand silicic lava dome growth using tir data the results also demonstrate a straightforward approach for fusing ground air and spaceborne image data which could be applied to other active domes around the world

infrasound and gravity waves over the andes observed by a pressure sensor on board a stratospheric balloon the study of infrasound acoustic and gravity waves sources and propagation in the atmosphere of a planet gives us precious insight on atmosphere dynamics climate and even internal structure the implementation of modern pressure sensors with high rate sampling on stratospheric balloons is improving their study we analyzed the data from the national aeronautics and space administration ultra long duration balloon mission 16 may to 30 june 2016 here we focus on the balloon s transit of the andes mountains we detected gravity waves that are associated to troposphere convective activity and mountain waves an increase of the horizontal wavelengths from 50 to 70 km with increasing distance to the mountains is favoring the presence of mountain waves we also report on the detection of infrasounds generated by the mountains in the 0 01 0 1 hz range with a pressure amplitude increase by a factor 2 relative background signal besides we characterized the decrease of microbaroms power when the balloon was flying away from the ocean coast these observations suggest in a way similar to microseisms for seismometers that microbaroms are the main background noise sources recorded in the stratosphere even far from the ocean sources finally we observed a broadband signal above the andes between 0 45 and 2 hz probably associated with a thunderstorm the diversity of geophysical phenomena captured in less than a day of observation stresses the interest of high rate pressure sensors on board long duration balloon missions

piecing together the puzzle of the ediacara biota excavation and reconstruction at the ediacara national heritage site nilpena south australia abstract patterns of origination and evolution of early complex life on this planet are interpreted largely from the fossils of the precambrian soft bodied ediacara biota excavation and reconstruction of beds of the ediacara member of the rawnsley quartzite at the national heritage ediacara fossil site nilpena in the flinders ranges of south australia has exposed nearly 300 square meters of fossiliferous bedding planes as a result the taphonomy and sedimentology of the succession are well constrained rendering it possible to disentangle ecological from environmental and taphonomic signals the fossil record that is preserved on these beds is a function of a number of factors including 1 sedimentary environment 2 initial colonization 3 nature of textured organic surfaces 4 duration of time between episodes of disturbance and 5 biostratinomic processes the excavation and reconstruction of beds at nilpena yield an exceptional and unique opportunity to examine not only the taxonomic composition of ediacara communities but also their ecological character at various stages of development preserved ecological snapshots of fossil assemblages range from immature communities of small bodied individuals associated with poorly developed organic mats to communities characterized by a high diversity of macrofaunal taxa wide range of body sizes and the presence of dense textured organic surfaces

a method for estimating eruption rates of planetary lava flows abstract a model that accounts for radiative losses from a partially crusted hotter core can be used to constrain eruption rates of single lobed planetary lava flows by assuming thermal characteristics are similar to terrestrial flows eruption rate can be expressed as a function of the area fraction of core exposed initial core temperature core temperature when the flow stops advancing crust thickness flow thickness and the density and heat capacity of the lava

lava effusion rates from hand held thermal infrared imagery an example from the june 2003 effusive activity at stromboli a safe easy and rapid method to calculate lava effusion rates using hand held thermal image data was developed during june 2003 at stromboli volcano italy we used a forward looking infrared radiometer flir to obtain images of the active lava flow field on a daily basis between may 31 and june 16 2003 during this time the flow field geometry and size where flows typically a few hundred meters long were emplaced on a steep slope meant that near vertical images of the whole flow field could be captured in a single image obtained from a helicopter hovering at an altitude of 750 m and 1 km off shore we used these images to adapt a thermally based effusion rate method previously applied to low and high spatial resolution satellite data to allow automated extraction of effusion rates from the hand held thermal infrared imagery a comparison between a thermally derived 0 23 0 87 m3 s 1 and dimensionally derived effusion rate 0 56 m3 s 1 showed that the thermally derived range was centered on the expected value over the measurement period the mean effusion rate was 0 38 0 25 m3 s 1 which is similar to that obtained during the 1985 86 effusive eruption and the time averaged supply rate calculated for normal non effusive strombolian activity a short effusive pulse reaching a peak of 1 2 m3 s 1 was recorded on june 3 2003 one explanation of such a peak would be an increase in driving pressure due to an increase in the height of the magma contained in the central column we estimate that this pulse would require the magma column to attain a height of 190 m above the effusive vent which is approximately the elevation difference between the vent and the floor of the ne crater our approach gives an easy to apply method that has the potential to provide effusion rate time series with a high temporal resolution

magma budgets and steady state activity of vulcano and stromboli we present three models for magma budget during steady state volcanic activity by which non erupted magma is emplaced as dykes or cumulates or crystallises in place using gas and thermal data we apply our models at vulcano to calculate degassing cooling and crystallisation of magma at a rate of 40 375 kg s 1 within a magma body with an upper surface at a 2 km depth at stromboli we calculate a steady magma supply of 300 1300 kg s 1 to shallow 1 km depths

improved general circulation models of the martian atmosphere from the surface to above 80 km we describe a set of two new generation general circulation models of the martian atmosphere derived from the models we originally developed in the early 1990s the two new models share the same physical parameterizations but use two complementary numerical methods to solve the atmospheric dynamic equations the vertical resolution near the surface has been refined and the vertical domain has been extended to above 80 km these changes are accompanied by the inclusion of state of the art parameterizations to better simulate the dynamical and physical processes near the surface boundary layer scheme subgrid scale topography parameterization etc and at high altitude gravity wave drag in addition radiative transfer calculations and the representation of polar processes have been significantly improved we present some examples of zonal mean fields from simulations using the model at several seasons one relatively novel aspect previously introduced by wilson 1997 is that around northern winter solstice the strong pole to pole diabatic forcing creates a quasi global angular momentum conserving hadley cell which has no terrestrial equivalent within such a cell the coriolis forces accelerate the winter meridional flow toward the pole and induce a strong warming of the middle polar atmosphere down to 25 km this winter polar warming had been observed but not properly modeled until recently in fact thermal inversions are generally predicted above one and often both poles around 60 70 km however the mars middle atmosphere above 40 km is found to be very model sensitive and thus difficult to simulate accurately in the absence of observations

rayleigh wave signature in ionograms induced by strong earthquakes 1 after the magnitude 9 0 earthquake off the pacific coast of tohoku near the east coast of honshu japan which occurred on 11 march 2011 an unusual multiple cusp signature mcs was observed in ionograms at three ionosonde stations across japan to investigate the general characteristics of mcss we examined ionograms obtained during the period 1957 to 2011 from five ionosonde stations in japan after earthquakes with a seismic magnitude of 8 0 or greater a total of 43 such earthquakes occurred after 1957 as recorded in the database of the united states geological survey mcss were observed in 8 of 43 earthquakes allowing us to investigate the specific conditions of mcs appearance the appearance of mcss at different epicentral distances exhibits traveling characteristics at a velocity of 4 0 km s which is in the range of rayleigh waves there is a 7 min offset in delay time after the earthquake at each epicentral distance in the travel time diagram this offset is consistent with the propagation time of acoustic waves from the ground to the ionosphere launched by rayleigh waves mcss in ionograms provide a snapshot of vertical disturbances induced by a wave because the sweep time for the whole ionospheric echo traces is much shorter than the propagation time of acoustic waves the vertical scale of the disturbances is 10 30 km which corresponds to an acoustic wave period of 20 50 s at ionospheric heights

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

lava effusion a slow fuse for paroxysms at stromboli volcano questo lavoro ha analizzato i risultati del monitoraggio termico delle eruzioni di stromboli del 2002 2003 e 2007 ed ha mostrato come prima di ogni parossisma il volume di lava eruttato nel corso dell attivita effusiva sia stato confrontabile questa osservazione ha fatto ipotizzare l esistenza di una decompressione critica nel sistema di alimentazione superficiale del vulcano raggiungibile anche lentamente che innesca la veloce risalita del magma ricco in gas responsabile dei parossismi durante l attivita effusiva a questa decompressione critica e associabile una soglia di volume di magma emesso che diventa la misura discriminante per valutare la fase critica del vulcano e predire il parossisma

from source to surface dynamics of etna s lava fountains investigated by continuous strain magnetic ground and satellite thermal data we investigated the eruptive episodes that occurred at etna volcano on 15 november 2011 and 18 march 2012 using different types of data we present novel data from two recently installed strainmeters that recorded unique signals during the lava fountain phases of these events the strainmeter data integrated with those recorded by the magnetic network and with satellite and ground thermal data allowed us to follow the path of a gas rich magma batch from the source inside the volcano to the surface and atmosphere the amplitude ratio of the volumetric strain changes constrained the storage depth of the magma feeding the lava fountains above 1 5 km below sea level magnetic data revealed an attempted shallow lateral intrusion whereas ground and satellite thermal data furnished a quantification of the total erupted volumes of 2 2 106 m3 for the 15 november event and 3 0 106 m3 for the 18 march event despite different durations of the explosive and effusive phases of the two lava fountain events the total erupted volume was quite similar suggesting the emptying of a shallow storage system displaying a steady behaviour

detection and modeling of rayleigh wave induced patterns in the ionosphere 1 global positioning system gps allows the detection of ionospheric disturbances associated with the vertical displacements of most of the major shallow seismic events we describe a method to model the time and space distributions of rayleigh wave induced total electron content tec patterns detected by a dense gps array we highlight the conditions for which a part of the ionospheric pattern can be directly measured at teleseismic distance and above the epicenter in particular a satellite elevation angle lower than 40 is a favorable condition to detect rayleigh wave induced ionospheric waves the coupling between the solid earth and its atmosphere is modeled by computing the normal modes of the solid earth atmosphere system we show the dependency of the coupling efficiency on various atmospheric conditions by summation of the normal modes we model the atmospheric perturbation triggered by a given earthquake this shows that a part of the observation is a rayleigh induced radiation pattern and therefore characteristic of the seismic rupture through atmosphere ionosphere coupling we model the ionospheric perturbation after the description of the local geomagnetic field anisotropic effects we show how the observation geometry is strongly affecting the radiation pattern this study deals with the related data for two earthquakes with far field and near field observations using the japanese gps network geonet after the 12 may 2008 wenchuan earthquake china and after the 25 september 2003 tokachi oki earthquake japan respectively waveforms and patterns are compared with the observed tec perturbations providing a new step toward the use of ionospheric data in seismological applications

high resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption at redoubt volcano alaska abstract a combination of satellite and airborne high resolution visible and thermal infrared tir image data detected and measured changes at redoubt volcano during the 2008 2009 unrest and eruption the tir sensors detected persistent elevated temperatures at summit ice melt holes as seismicity and gas emissions increased in late 2008 to march 2009 a phreatic explosion on 15 march was followed by more than 19 magmatic explosive events from 23 march to 4 april that produced high altitude ash clouds and large lahars two or three lava domes extruded and were destroyed between 23 march and 4 april after 4 april the eruption extruded a large lava dome that continued to grow until at least early july 2009

gps detection of ionospheric perturbations following the january 17 1994 northridge earthquake sources such as atmospheric or buried explosions and shallow earthquakes producing strong vertical ground displacements are known to produce pressure waves that propagate at infrasonic speeds in the atmosphere at ionospheric altitudes low frequency acoustic waves are coupled to ionospheric gravity waves and induce variations in the ionospheric electron density using global positioning system gps data recorded by the permanent gps network operating in southern california we computed ionospheric electron content time series for several days preceding and following the january 17 1994 mw 6 7 northridge earthquake we observe an anomalous signal beginning several minutes after the earthquake with time delays that increase with distance from the epicenter the signal frequency and phase velocity are consistent with results from numerical models of atmospheric ionospheric acoustic gravity waves excited by seismic sources as well as previous electromagnetic sounding results we believe that these perturbations are caused by the ionospheric response to the strong ground displacement associated with the northridge earthquake

two mode long distance propagation of coseismic ionosphere disturbances 1 using gps total electron content tec measurements we analyzed ionosphere response to the great kurile earthquake of 4 october 1994 high spatial resolution of the japanese dense array of gps receivers geonet provided us the unique opportunity to observe the evolution of coseismic ionospheric disturbances cid which propagated for more than 1800 km away from the epicenter plotting a traveltime diagram for the cid and using an array processing technique within the approximation of a spherical cid wavefront we observed a phenomenon of cid separation into two modes and we found that characteristics of the cid depend on the distance from the epicenter the maximum of the cid amplitude was observed at 500 km from the epicenter within the first 600 700 km the cid propagation velocity was about 1 km s which is equal to the sound speed at the height of the ionospheric f layer starting from 600 to 700 km out from the epicenter the disturbance seems to divide into two separate perturbations with each propagating at a different velocity about 3 km s for the one and about 600 m s for the other apparently the tec response in the far field of the cid source is a mixture of signals that further splits into two modes because of the difference in their velocities our observations are in good agreement with the results of space time data processing in the approximation of a spherical wavefront of cid propagation

a quantitative look at the demise of a basaltic vent the death of kupaianaha kilauea volcano hawai i the kupaianaha vent the source of the 48th episode of the 1983 to present pu u o o kupaianaha eruption erupted nearly continuously from july 1986 until february 1992 this investigation documents the geophysical and geologic monitoring of the final 10 months of activity at the kupaianaha vent detailed very low frequency vlf electromagnetic profiles across the single lava tube transporting lava from the vent were used to determine the cross sectional area of the molten lava within the tube combined with measurements of lava velocity these data provide an estimate of the lava output of kupaianaha in addition lava temperatures calculated from analysis of quenched glass and bulk rock chemistry were obtained for samples taken from the tube at the same site the combined data set shows the lava flux from kupaianaha vent declining linearly from 250 000 m3 day in april 1991 to 54 000 m3 day by november 1991 during that time surface breakouts of lava from weak points along the tube occurred progressively closer to the vent consistent with declining efficiency in lava transport there were no significant changes in lava temperature or in bulk mgo content during this period another eruptive episode the 49th began uprift of kupaianaha on 8 november 1991 and erupted lava concurrently with kupaianaha for 18 days lava flux from kupaianaha decreased in response to this new episode but the response was delayed by approximately 1 day after 14 november 1991 lava velocities were no longer measurable in the tube because the lava stream beneath the skylight had crusted over however the vlf derived electrical conductances documented the decreasing flux of molten lava through the tube kupaianaha remained active but output continued to decrease until early february 1992 when the last active surface flows were seen in november 1991 we used the linearly decreasing effusion rate to accurately predict the date for the death of the kupaianaha vent the linear nature of the decline in lava tube conductance and the delayed and slow response of the waha ula tube conductances to the 49th eruptive episode led us to speculate that a the kupaianaha vent shut down because of a decrease in driving pressure and not because of a freeze up of the vent and b that pu u o o episode 49 and kupaianaha were fed nearly vertically from a source deep within the rift zone

seismic observations of meteors coupling theory and observations to date coupling of acoustic waves directly with the earth s surface represents the bulk of the observed meteor related seismic signals while precursory and impact related seismic waves remain an observational rarity with proliferation of infrasound and seismic monitoring systems new opportunities exist to explore the relationship between earth s atmosphere andsurface continued studyofmeteorseismologywillleadto new methods to constrain energies sizes and fluxes for moderately cm to m sized meteoroids on earth and potentially on mars

rheology of basaltic ash from stromboli volcano inferred from intermittent compression experiments abstract after ash dominated strombolian eruption considerable amount of ash falls back to the volcanic conduit by the fallback ash the formation of a dense near surface region is expected because it is compacted by weights of its own and other fallback clasts the dense cap causes the gas pressure inside the conduit to increase which promotes a forthcoming eruption under such conditions the rheology of the fallback ash plays an important role in this cyclical eruption mechanism however little attention has been given to the point we examined the rheology of ash collected at stromboli volcano via intermittent compression experiments changing temperature and compression time rate the elastic modulus the viscosity and the relaxation time were estimated by a viscoelastic maxwell model the results show that the elasticity and the viscosity dominantly depend on the compression rate and the temperature respectively although both of them vary with time thus the ash behaves either elastically or viscously depending on the external conditions and time the viscoelastic characteristics can be explained by magnitude relationships between the characteristic relaxation time and times for compression and rest processes this indicates that the balance of the time scales is key to determining the rheological characteristics

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

nostradamus the radar that wanted to be a seismometer 1 surface waves emitted after large earthquakes are known to induce by dynamic coupling atmospheric infrasonic waves propagating upward through the neutral and ionized atmosphere those waves have been detected in the past at ionospheric heights using a variety of techniques such as hf doppler sounding or gps receivers the hf doppler technique particularly sensitive to the ionospheric signature of rayleigh waves is used here to show ionospheric perturbations consistent with the propagation of rayleigh wave phases r1 and r2 following the sumatra earthquake on the 28 march 2005 m 8 6 this is in our knowledge the first time that the phase r2 is detected by ionospheric sounding in addition we prove here that the ionospheric signature of r2 is also observed by over the horizon oth radar the latter was never used before to detect seismic signature in the ionosphere adding the oth radar to the list of the ionospheric seismometers we discuss and compare the performances of the three different instruments mentioned above namely hf doppler sounding gps receivers and oth radar

infrasonic sounds excited by seismic waves of the 2011 tohoku oki earthquake as visualized in ionograms after the m 9 0 tohoku oki earthquake in 2011 strong deformation of ionogram echo traces forming multiple cusp signatures mcss were observed at three stations 790 1880 km from the epicenter the vertical structure of the ionospheric disturbances was determined by true height analysis and compared with broadband seismograph records at stations close to the ionosondes these ionospheric disturbances were caused by vertically propagating acoustic waves excited by the up down ground motion of seismic waves numerical simulations have shown that acoustic waves with a period of 15 40 s and amplitude of order 1 mm s at the ground level were sufficient to create mcss as sharp as those observed these acoustic wave parameters are consistent with the seismic records if the motion of the air mass on the ground level is assumed to be the same as the ground motion the travel time diagram of the seismic records along the line connecting the epicenter and ionosondes showed that the first mcs ionogram detected at each station was caused by p waves while the others were caused by rayleigh waves

bichromatic excitation of long period rayleigh and air waves by the mount pinatubo and el chichon volcanic eruptions we have detected a new powerful source of low frequency seismic energy which is associated with some violent volcanic eruptions for the two eruptions for which we have identified this new source the spectrum is bichromatic consisting of two narrow phase coherent spectral lines these bands were centered on 3 76 and 5 14 mhz for the april 4 1982 el chichon eruption and on 3 68 and 4 44 mhz for the june 15 1991 mt pinatubo eruption during the latter 8 hour long eruption the resonance frequencies varied by less than 20 hz the strength of the source is sufficient to excite globe circling surface waves we conclude from these observations that volcanoes can excite harmonic tremors at much longer periods than previously observed our preferred source model involves feedback between local atmospheric oscillations and the eruption process the physics responsible for this feedback remains subject to speculations

numerical simulation of the atmospheric signature of artificial and natural seismic events the mechanical coupling between solid planets and their atmospheres enables seismically induced acoustic waves to propagate in the atmosphere we numerically simulate this coupled system for two application cases active seismic experiments ases and passive seismic experiments a recent ase krishnamoorthy et al 2018 https doi org 10 1002 2018gl077481 observed the infrasonic signals produced by a seismic hammer to measure the sensitivity of observations to seismic parameters we attempt to reproduce the results from this experiment at short range by considering a realistic unconsolidated subsurface and an idealized rock solid subsurface at long range we investigate the influence of the source by using two focal mechanisms we found surface waves generate an infrasonic plane head wave in the ase case of the rock solid material for the passive seismic experiments the amplitude of atmospheric infrasound generated by seismic surface waves is investigated in detail despite some limitations the simulations suggest that balloon measurement of seismically induced infrasound might help to constrain ground properties

separating the thermal fingerprints of lava flows and simultaneous lava fountaining using ground based thermal camera and seviri measurements uring effusive eruptions thermal satellite monitoring has proved well suited to map thethermal flux from lava flows however during lava fountaining events thermal contributions from active flows and from the fountain itself cannot be separated in low resolution satellite data here using photogrammetry and atmospheric modeling techniques we compare radiance estimates from long range ground based thermal camera data from which the fountain can be excluded with those from seviri satellite images for a fountaining event at mount etna 12 august 2011 the radiant heat flux determined from the ground based camera showed similar behavior to values retrieved from spinning enhanced visible and infrared imager seviri thus the seviri signal is interpreted to be dominated by the lava flows with minimal contribution from the fountain furthermore by modeling the cooling phase of each pixel inundated by lava the mean thickness and lava volume 2 4 10 6 m3 derived from camera images are comparable with those calculated from seviri 2 8 10 6 m3

magma emission rates from shallow submarine eruptions using airborne thermal imaging abstract the effusion rate is the most important parameter to gather when a volcanic eruption occurs because it controls the way in which a lava body grows extends and expands influencing its dimensional properties calculation of lava flow volume from thermal images collected by helicopter surveys has been largely used during the last decade for monitoring subaerial effusive eruptions however due to the depths where volcanic activity occurs monitoring submarine volcanic eruptions is a very difficult task the 2011 2012 submarine volcanic eruption at el hierro canary islands has provided a unique and excellent opportunity to monitor eruptive processes occurring on the seabed the use of a hand held thermal camera during daily helicopter flights allowed us to estimate for the first time the daily and total erupted magma volumes from a submarine eruption the volume of magma emitted during this eruption has been estimated at 300 mm3 giving an average effusion rate of 25 m3 s 1 thermal imagery by helicopter proved to be a fast inexpensive safe and reliable technique of monitoring volcanic eruptions when they occur on the shallow seabed

seismoacoustic coupling induced by the breakup of the 15 february 2013 chelyabinsk meteor on 15 february 2013 around 03 20 00 utc the largest meteor reported since the 1908 tunguska event was observed as a fireball traveling through the earth s atmosphere exploding in an air burst near the city of chelyabinsk russia the rarity of such an event provides a unique window on the physics of meteoroid collision we report the fine seismic detection of rayleigh waves produced by the coupling of ground motion with the incident shock wave at distances up to 4000 km from the event combining information from seismic beam forming analysis recon structed trajectory from casual video records and remote sensing we identify the rayleigh waves as being initiated by the shock wave produced by the main blast that occasioned damages and injuries in chelyabinsk from the rayleigh wave observations we report a magnitude ms 3 7 seismic source

multi dimensional distribution of near field ionospheric disturbances produced by the 2015 mw7 8 nepal earthquake abstract ionospheric anomalies possibly associated with large earthquakes particularly coseismic ionospheric disturbances have been detected by global positioning system gps a large nepal earthquake with magnitude mw7 8 occurred on april 25 2015 in this paper we investigate the multi dimensional distribution of near field coseismic ionospheric disturbances cids using total electron content tec and computerized ionospheric tomography cit from regional gps observational data the results show significant ionospheric tec disturbances and interesting multi dimensional structures around the main shock regarding the tec changes coseismic ionospheric disturbances occur approximately 10 20 min after the earthquake northeast and northwest of epicentre the maximum ridge to trough amplitude of cids is up to approximately 0 90 tecu min propagation velocities of the tec disturbances are 1 27 0 06 km s and 1 91 0 38 km s it is believed that the ionospheric disturbances are triggered by acoustic and rayleigh waves tomographic results show that the three dimensional distribution of ionospheric disturbances obviously increases at an altitude of 300 km above the surrounding epicentre predominantly in the entire region between 200 km and 400 km significant ionospheric disturbances appear at 06 30 ut from tomographic images this study reveals characteristics of an ionospheric anomaly caused by the nepal earthquake

detection of a new summit crater on bezymianny volcano lava dome satellite and field based thermal data an explosive eruption occurred at the summit of bezymianny volcano kamchatka peninsula russia on 11 january 2005 which was initially detected from seismic observations by the kamchatka volcanic eruption response team kvert this prompted the acquisition of 17 advanced spaceborne thermal emission and reflection radiometer aster satellite images of the volcano over the following 10 months visible and infrared data from aster revealed significant changes to the morphology of the summit lava dome later seen with field based thermal infrared tir camera surveys in august 2005 the morphology of the summit lava dome was observed to have changed from previous year s observations and historical accounts in august 2005 the dome contained a new crater and two small lava lobes stepped scarps within the new summit crater suggest a partial collapse mechanism of formation rather than a purely explosive origin hot pyroclastic deposits were also observed to have pooled in the moat between the current lava dome and the 1956 crater wall the visual and thermal data revealed a complex eruption sequence of explosion s viscous lava extrusion and finally the formation of the collapse crater based on this sequence the conduit could have become blocked pressurized which could signify the start of a new behavioural phase for the volcano and lead to the potential of larger eruptions in the future

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 discharge rate estimates from thermal infrared satellite data for pacaya volcano during 2004 2010 abstract pacaya is one of the most active volcanoes in central america and has produced lava flows frequently since 1961 all effusive activity between 1961 and 2009 was confined by an arcuate collapse scarp surrounding the northern and eastern flanks however the recent breaching of this topographic barrier and the eruption of a large lava flow outside of the main center of activity have allowed lava to extend into nearby populated areas indicating the need for assessment and monitoring of lava flow hazards we investigated whether a commonly used satellite based model could produce accurate lava discharge rates for the purpose of near real time assessment of hazards during future eruptions and to assess the dynamics of this persistently degassing system the model assumes a linear relationship between active lava flow area and time averaged discharge rate tadr via a simple conversion factor we calculated the conversion factor via two methods 1 best fitting of satellite derived flow areas to ground based estimates of lava flow volume and 2 theoretically via a parameterized model that takes into account the physical properties of the lava to apply the latter method we sampled four lava flows and measured density vesicularity crystal content and major element composition we found the best agreement of conversion factors in the eruption with the most complete satellite coverage and used data for these flows to define the linear relationship between area and discharge rate the physical properties of the sampled flows were essentially identical so that any discrepancy between the two methods of calculating conversion factors must be due to modeling errors or environmental factors unaccounted for by the parameterized model however our best fitting method provides a new means to set the conversion appropriately and to obtain self consistent tadrs we identified two distinct types of effusive activity at pacaya type 1 activity characterized by initially high tadrs of about 1 10 m 3 s 1 followed by a waning phase and type 2 activity characterized by low scattered tadrs of about 0 1 1 m 3 s 1 the risk associated with type 1 activity is much higher so identifying the type 1 radiance signature in satellite imagery is useful for monitoring an ongoing eruption

a crust and upper mantle model of eurasia and north africa for pn travel time calculation abstract we develop a regional seismic travel time rstt model and method for use in routine seismic analysis the model parameterization is a global tessellation of nodes with a velocity profile at each node interpolation of the velocity profiles generates a 3d crust and laterally variable upper mantle velocity the upper mantle velocity profile at each node is represented as a linear velocity gradient which enables travel time computation in approximately 1 millisecond this computational speed allows the model to be used in routine analyses in operational monitoring systems we refine the model using a tomographic formulation that adjusts the average crustal velocity mantle velocity at the moho and the mantle velocity gradient at each node while the rstt model is inherently global our first rstt tomographic effort covers eurasia and north africa where we have compiled a data set of approximately 600 000 pn arrivals ten percent of the data set is randomly selected and set aside for testing purposes travel time residual variance for the validation data is reduced by 32 based on a geographically distributed set of validation events with epicenter accuracy of 5 km or better epicenter error using 16 pn arrivals is reduced by 46 from 17 3 km ak135 model to 9 3 km rstt model after tomography the median uncertainty ellipse area is reduced by 68 from 3070 km 2 ak135 to 994 km 2 rstt and the number of ellipses with area less than 1000 km 2 which is the area allowed for onsite inspection under the comprehensive nuclear test ban treaty is increased from 0 ak135 to 51 rstt

tsunami wave height estimation from gps derived ionospheric data large underwater earthquakes mw 7 can transmit part of their energy to the surrounding ocean through large seafloor motions generating tsunamis that propagate over long distances the forcing effect of tsunami waves on the atmosphere generates internal gravity waves that when they reach the upper atmosphere produce ionospheric perturbations these perturbations are frequently observed in the total electron content tec measured by multifrequency global navigation satellite systems gnss such as gps glonass and in the future galileo this paper describes the first inversion of the variation in sea level derived from gps tec data we used a least squares inversion through a normal mode summation modeling this technique was applied to three tsunamis in far field associated to the 2012 haida gwaii 2006 kuril islands and 2011 tohoku events and for tohoku also in close field with the exception of the tohoku far field case for which the tsunami reconstruction by the tec inversion is less efficient due to the ionospheric noise background associated to geomagnetic storm which occurred on the earthquake day we show that the peak to peak amplitude of the sea level variation inverted by this method can be compared to the tsunami wave height measured by a dart buoy with an error of less than 20 this demonstrates that the inversion of tec data with a tsunami normal mode summation approach is able to estimate quite accurately the amplitude and waveform of the first tsunami arrival

role of heat advection in a channeled lava flow with power law temperature dependent rheology 1 the cooling of a lava flow both in the transient and the steady state is investigated considering that lava rheology is pseudoplastic and dependent on temperature lava exits from the vent with constant velocity and flows down a slope under the effect of gravity force inside a channel of rectangular cross section we consider that cooling of lava is caused by thermal radiation into the atmosphere and thermal conduction at the channel walls and at the ground the heat equation is solved numerically in a 3 d computational domain and the solution is tested to evaluate the numerical errors we study the steady state and the initial transient period of lava cooling results indicate that the advective heat transport significantly modifies the cooling rate of lava slowing down the cooling process since the lava velocity depends on temperature the cooling rate depends on the effusion temperature velocity profiles are modified during cooling showing two marginal static zones where the crust can form and remain stable the fraction of crust coverage is calculated under the assumption that the solid lava is a plastic body with temperature dependent yield strength we numerically confirm that heat advection cannot be neglected in the mechanism of formation of lava tubes

modeling of atmospheric coupled rayleigh waves on planets with atmosphere from earth observation to mars and venus perspectives acoustic coupling between solid earth and atmosphere has been observed since the 1960s first from ground based seismic pressure and ionospheric sensors and since 20 years with various satellite measurements including with global positioning system gps satellites this coupling leads to the excitation of the rayleigh surface waves by local atmospheric sources such as large natural explosions from volcanoes meteor atmospheric air bursts or artificial explosions it contributes also in the continuous excitation of rayleigh waves and associated normal modes by atmospheric winds and pressure fluctuations the same coupling allows the observation of rayleigh waves in the thermosphere most of the time through ionospheric monitoring with doppler sounders or gps the authors review briefly in this paper observations made on earth and describe the general frame of the theory enabling the computation of rayleigh waves for models of telluric planets with atmosphere the authors then focus on mars and venus and give in both cases the atmospheric properties of the rayleigh normal modes and associated surface waves compared to earth the authors then conclude on the observation perspectives especially for rayleigh waves excited by atmospheric sources on mars and for remote ionospheric observations of rayleigh waves excited by quakes on venus

acoustic environment of the martian surface prompted by the mars microphone aboard the 1998 mars polar lander a theoretical study of the acoustical environment of the martian surface has been made to ascertain how the propagation of sound is attenuated under such conditions and to predict what sounds may be detectable by a microphone viscous and thermal relaxation termed classical absorption molecular relaxation and geometric attenuation are considered classical absorption is stronger under martian conditions resulting in sounds in the audible frequencies 20 hz to 20 khz being more strongly attenuated than in the terrestrial environment the higher frequencies 3000 hz will be severely attenuated as the absorption is frequency dependent at very low infrasound frequencies i e 10 hz attenuation will be mostly due to geometric spreading of the propagating wave front and will therefore be more similar to the terrestrial surface environment probable sound sources in the landed environment include wind blown dust and sand from large dust storms dust devils and possible associated electrostatic discharge the sounds most likely to be detected will be sounds generated by the lander itself and aeroacoustic noises generated by winds blowing against the lander and its instruments

a simple explanation for the space based calculation of lava eruption rates abstract knowing how lava effusion rates vary during basaltic eruptions can be of great significance when trying to provide preliminary forecasts regarding how far lava will flow however problems exist in accurately determining effusion rates using conventional field based techniques to ameliorate this problem harris et al j geophys res 102 1997 7985 8003 bull volcanol 59 1997 49 64 j volcanol geotherm res 102 2000 237 269 developed a method for determining effusion rates using infrared satellite data and showed how the method could be used to provide realistic estimates of effusion rates repeatedly during several eruptions at kilauea hawai i krafla iceland etna and stromboli italy harris et al j geophys res 102 1997 7985 8003 bull volcanol 59 1997 49 64 indicate that their method allows instantaneous lava effusion rates to be determined thermodynamically by equating the amount of heat lost by an active lava flow derived from the satellite data to the amount of heat liberated by the cooling mass of lava the purpose of this paper is to provide a simpler alternative explanation we find that rather than being used to calculate heat loss harris et al j geophys res 102 1997 7985 8003 bull volcanol 59 1997 49 64 j volcanol geotherm res 102 2000 237 269 actually use the satellite data to estimate the area of active lava present within the satellite s field of view at the movement of data acquisition thus changes in the effusion rates they present can only be proportional to changes in this area the active flow areas were then multiplied by a constant the value of which is obtained from a crude approximation of the lava flows heat balance crucially the absolute value of this term falls within the range of an empirically derived parameter that was found by pieri and baloga j volcanol geotherm res 30 1986 29 45 to explain strong linear correlations between eruption rate i e the time averaged effusion rate and lava flow area for 34 historic hawaiian flows as a result we find that the method of harris et al j geophys res 102 1997 7985 8003 does not yield instantaneous effusion rates but instead provides a valid and useful way to estimate average effusion rates i e the eruption rate from measurements of flow area

spatio temporal evolution of temperature and fluid flow through a new thermo lithological boundary the case of a pit crater of karthala volcano comoros archipelago refilled on january 13th 2007 by a lava flow on january 13 th 2007 the effusive eruption of karthala volcano in the comoros islands emitted a lava flow which has been perfectly constrained inside the cylindrical shape of the choungou chagnoumeni pit crater 225m in diameter and with a thickness of about 7m the good knowledge of the geometry of this lava flow allowed modeling its cooling with the rheolef code with a good accuracy the results of the thermal modeling were compared with other measurements performed on the field 1 a high resolution electrical resistivity tomography profile crossing the boundary of the crater and 2 the thermal monitoring of temperature with eleven sensors spaced 1 meter apart at 30 cm depth perpendicularly to the boundary of the crater thanks to this multidisciplinary approach it has been possible to display that in the first order the resistivity distribution in the soil 2 years and 5 months after the eruption is directly influenced by the residual temperature and not by the structural boundary during the first three years of cooling an inversion in the shallow lateral temperature gradient was observed in temperature data set collected at 30 cm depth

monitoring an effusive eruption at piton de la fournaise using radar and thermal infrared remote sensing data insights into the october 2010 eruption and its lava flows

ionospheric disturbances infrasound waves over the czech republic excited by the 2011 tohoku earthquake 1 a train of large amplitude infrasound wave packets was observed by multipoint continuous doppler sounding system in the ionosphere over the czech republic on 11 march 2011 it is shown that these infrasound wave packets originated from vertical motion of the ground surface that was caused by arrival of seismic waves generated by the strong tohoku earthquake the infrasound wave packets were observed in the ionosphere at heights of 210 220 km about 9 min after the detection of corresponding wave packets on the ground which is consistent with the calculated time for vertically propagating infrasound waves absolute values of cross correlation coefficients between ionospheric and ground measurements are typically higher than 0 9 for two wave packets 0 98 the individual wave packets recorded on the ground have different observed horizontal velocities and correspond to different types of seismic waves a comparison of vertical velocities of ground motion with oscillation velocities of air particles in the ionosphere indicates that almost 1 10 of the infrasound energy flux excited at the ground reached the altitudes of 210 220 km for wave periods longer than 30 s estimates of sound attenuation are performed it is also shown that it is necessary to consider the value of electron density gradient at the reflection height of the sounding radio wave and air plasma compression owing to the infrasound wave to get reasonable estimates of oscillation velocities of air particles from doppler shift frequencies

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

dickinsonia liftoff evidence of current derived morphologies abstract dickinsonia an iconic member of the ediacara biota is abundant in the ediacaran deposits found at the nilpena field site south australia despite exquisite fossil preservation at this site many specimens of dickinsonia appear to be incomplete with an apparently missing piece on the periphery orientation measurements from specimens on three fossil beds suggest that these so called missing pieces are aligned irrespective of the axial orientation of dickinsonia the nonrandom orientation of incomplete specimens matches that of other aligned structures found on two of these beds the preferred directionality of this feature suggests the molding of incomplete specimens under the influence of current activity prior to or during burial we propose that this feature originates where part of a dickinsonia was lifted off of the substrate during a storm event and that sand was deposited beneath this lifted portion this model suggests that dickinsonia was easily separated from the sea floor and was not attached to the substrate on which it lived this is consistent with the data from dickinsonia footprints suggesting that dickinsonia was mobile

volumetric observations during paroxysmal eruptions at mount etna pressurized drainage of a shallow chamber or pulsed supply abstract the october 17 to november 5 1999 eruption of mount etna s bocca nuova crater emplaced a 15 10 6 m 3 flow field the eruption was characterized by 11 paroxysmal events during which intense strombolian and lava fountain activity fed vigorous channelized a a flows at eruption rates of up to 120 m 3 s 1 each paroxysm lasted between 75 and 450 min and was separated by periods of less intense strombolian activity and less vigorous 3 s 1 effusion ground based satellite and model derived volumetric data show that the eruption was characterized by two periods during which eruption rates and cumulative volume showed exponential decay this is consistent with a scenario whereby the system was depressurized during the first eruptive period october 17 23 repressurized during an october 24 pause and then depressurized again during the second period october 25 28 the imbalance between the erupted and supplied volumes mean that the two periods involved the collection of 1 5 5 7 10 6 m 3 and 1 2 3 6 10 6 m 3 respectively or an increase in the time averaged supply to 11 6 13 6 m 3 s 1 and 12 5 14 9 m 3 s 1 two models are consistent with the observed episodic fountaining derived volumetric trends and calculated volume imbalance a magma collection model and a pulsed supply model in the former case depressurization of a shallow reservoir cause the observed volumetric trends and foam collapse at the reservoir roof powers fountaining in the pulsing case variations in magma flux account for pressurization depressurization and supply the excess volume increases in rise rate and volatile flux coupled with rapid exsolution during ascent trigger fountaining limiting equations that define critical foam layer volumes and magma rise rates necessary for hawaiian style fountaining favor the latter model

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

normal modes modelling of post seismic ionospheric oscillations since 1960 several experiments have shown strong perturbations of the ionosphere after earthquakes for the biggest quakes doppler ionospheric soundings have revealed displacements of several tens of meter of the ionized layers e and f an accurate modelling of these phenomena was however never described we present here synthetic displacements of such oscillations and compare it with experimental data realistic models of the atmosphere including viscosity are used as well as realistic earth and seismic source model these ionospheric oscillations are computed by normal modes summation taking explicitly into account the coupling between the solid earth and the open atmosphere they are associated to the rayleigh fundamental surface waves we obtain a good agreement between synthetics and observations so it should be possible to use this method to study the ionospheric post seismic perturbations and possibly the high altitude profile of the density and the viscosity of the atmosphere

gas bubble dynamics model for shallow volcanic tremor at stromboli volcanic tremor at stromboli aeolian islands italy is correlated to small infrasonic transients ripepe et al 1996 which repeat almost rhythmically in time in a range between 0 8 and 1 2 s we demonstrate that infrasonic transients are associated to small gas bubble 0 5 m burstings which produces no transients in the seismic signal tremor ground displacement attenuates with the inverse of the distance from the craters indicating that the source is shallow short term energy release shows that infrasonic and seismic signals are linked to the same dynamical process while at the long term scale it is evident that the two signals are controlled by two distinctive mechanisms we suggest that the possible physical model acts in two steps first gas coalescence and then gas bursting in our model the seismic signal is related to the coalescence of a gas bubble from a layer of small bubbles while the infrasonic signal is linked to the bursting of the bubble when it reaches the magma surface gas bubbles could form by free coalescence in magma or could be forced to coalesce by a structural barrier we calculate that forced coalescence induces in magma a pressure change 104 pa 2 orders of magnitude higher than free coalescence and it explains best the tremor ground displacement 10 5 m recorded at stromboli moreover forced coalescence evidences the role of a structural barrier such as a dike in volcanic tremor source dynamics in this gas dynamic process the delay time of 1 2 s between infrasonic pulses could reflect the gas nucleation interval of basaltic magma thomas et al 1993 manga 1996 we propose that the source function for the shallow volcanic tremor at stromboli could be the viscoelastic reaction of the magma to the pressure decrease induced by gas bubble growth rate under constant depressurization the spectrum of our source function is controlled by the time duration of the pressure pulse which represents the viscoelastic relaxation time of the magma and gas bubble growth rate the predicted asymptotic decay of the frequency contents fits the spectral behavior of the volcanic tremor ground displacement recorded at stromboli we show that the same spectral behavior can be found in ground displacement spectra of volcanic tremor recorded on different volcanoes

observations of the effect of wind on the cooling of active lava flows 1 we present the first direct observations of the cooling of active lava flows by the wind we confirm that atmospheric convective cooling processes i e the wind dominate heat loss over the lifetime of a typical pahoehoe lava flow in fact the heat extracted by convection is greater than predicted especially at wind speeds less than 5 m s and surface temperatures less than 400 c we currently estimate that the atmospheric heat transfer coefficient is about 45 50 w m 2 k 1 for a 10 m s wind and a surface temperature 500 c further field experiments and theoretical studies should expand these results to a broader range of surface temperatures and wind speeds

how well do fossil assemblages of the ediacara biota tell time patterns of origination evolution and extinction of early animal life on this planet are largely interpreted from the fossils of the precambrian soft bodied ediacara biota spanning nearly 40 m y of the terminal ediacaran period localities containing these fossils are loosely considered as part of either the avalon white sea or nama associations these associations have been interpreted to have temporal paleobiogeographic preservational and or paleoenvironmental significance surprisingly elements of all three associations occur within the ediacara member of the rawnsley quartzite of south australia an analysis of over 5000 specimens demonstrates that fossil distribution is strongly controlled by facies and taphonomy rather than time or biogeography and that individual taxa vary considerably in their environmental tolerance and taphonomic integrity the recognition that these taxa represent organisms living in various distinct environments both juxtaposed and shared holds strong implications for our interpretation of the record of early animal life on this planet and questions the biostratigraphic utility of the three associations furthermore although in situ soft bodied preservation provides a unique perspective on composition of benthic fossil assemblages the record should not be interpreted as a simple snapshot fossil beds represent a range of preservational modifications varying from current winnowed census samples of benthic communities at different depths and ecological maturity to entirely transported assemblages unless the appropriate environments and taphonomic conditions are present for certain taxa the absence of a particular taxon may or may not indicate its extinction in space or time