time reverse imaging for far field tsunami forecasting 2011 tohoku earthquake case study this paper describes a new method for forecasting far field tsunamis by combining aspects of least squares tsunami source inversion lsq with time reverse imaging tri this method has the same source representation as lsq but uses tri to estimate initial sea surface displacement we apply this method to the 2011 japan tsunami and the results show that the method produces tsunami waveforms of excellent agreement with observed waveforms at both near and far field stations not used in the source estimation the spatial distribution of cumulative sea surface displacement agrees well with other models obtained in more sophisticated inversions but resolve source kinematics are not well resolved the method has potential for application in tsunami warning systems as it is computationally efficient and can be used to estimate the initial source model by applying precomputed green s functions in order to provide more accurate and realistic tsunami predictions

preliminary sensitivity study of eruption source parameters for operational volcanic ash cloud transport and dispersion models a case study of the august 1992 eruption of the crater peak vent mount spurr alaska abstract ash clouds are one of the major hazards that result from volcanic eruptions once an eruption is reported volcanic ash transport and dispersion vatd models are used to forecast the location of the ash cloud these models require source parameters to describe the ash column for initialization these parameters include eruption cloud height and vertical distribution particle size distribution and start and end time of the eruption further if downwind concentrations are needed the eruption mass rate and or volume of ash need to be known upon notification of an eruption few constraints are typically available on many of these source parameters recently scientists have defined classes of eruption types each with a set of pre defined eruption source parameters esp we analyze the august 18 1992 eruption of the crater peak vent at mount spurr alaska which is the example case for the medium silicic eruption type we have evaluated the sensitivity of two of the esp the grain size distribution gsd and the vertical distribution of ash on the modeled ash cloud hysplit and puff vatd models are used to simulate the ash clouds from the different sets of source parameters we use satellite data processed through the reverse absorption method as reference for computing statistics that describe the modeled to observed comparison with the grain size distribution the three options chosen 1 an estimated distribution based on past eruption studies 2 a distribution with finer particles and 3 the national oceanic and atmospheric administration hysplit gsd have little effect on the modeled ash cloud for the initial vertical distribution both linear uniform concentration throughout the vertical column and umbrella shapes were chosen for hysplit the defined umbrella distribution no ash below the umbrella apparently underestimates the lower altitude portions of the ash cloud and as a result has a worse agreement with the satellite detected ash cloud compared to that with the linear vertical distribution for this particular eruption the puff model with a poisson function to represent the umbrella cloud gave similar results as for a linear distribution both having reasonable agreement with the satellite detected cloud further sensitivity studies of this eruption as well as studies using the other source parameters are needed

estimating volcanic ash hazard in european airspace abstract the widespread disruption of european air traffic in late april 2010 during the eruption of eyjafjallajokull showed the importance of early assessment of volcanic hazard from explosive eruptions in this study we focus on the short term hazard of airborne ash from a climatological perspective focusing on eruptions on iceland by studying eruptions of different intensity and frequency we estimate the overall probability that ash concentration levels considered hazardous to aviation are exceeded over different parts of europe the method involves setting up a range of eruption scenarios based on the eruptive history of icelandic volcanoes and repeated simulation of these scenarios for 2 years worth of meteorological data simulations are conducted using meteorological data from the era interim reanalysis set which is downscaled using the weather research and forecasting wrf model the weather data are then used to drive the lagrangian particle dispersion model flexpart wrf for each of the eruption scenarios a set of threshold values commonly used in volcanic ash advisories are used to analyze concentration data from the dispersion model we see that the dispersion of ash is highly dominated by the mid latitude westerlies and mainly affect northern uk and the scandinavian peninsula the occurrence of high ash levels from icelandic volcanoes is lower over continental europe but should not be neglected for eruptions when the release rate of fine ash m is in the order of 10 7 kg s 1 or higher there is a clear seasonal variation in the ash hazard during the summer months the dominating dispersion direction is less distinct with some plumes extending to the northwest and greenland in contrast during the winter months the strong westerly winds tend to transport most of the emissions eastwards the affected area of a winter time eruption is likely to be larger as high concentrations can be found at a further distance downwind from the volcano effectively increasing the probability of hazardous levels of ash reaching the european continent the concentration thresholds for aviation which were adopted after the eyjafjallajokull eruption in 2010 have strong influence on the hazard estimates for weaker eruptions but is less important for larger eruptions thus ash forecasts for weaker eruptions are likely more uncertain in comparison to larger eruptions

hydrometeor enhanced tephra sedimentation constraints from the 18 may 1980 eruption of mount st helens 1 uncertainty remains on the origin of distal mass deposition maxima observed in many recent tephra fall deposits in this study the link between ash aggregation and the formation of distal mass deposition maxima is investigated through reanalysis of tephra fallout from the mount st helens 18 may 1980 msh80 eruption in addition we collate all the data needed to model distal ash sedimentation from the msh80 eruption cloud four particle size subpopulations were present in distal fallout with modes at 2 2 4 2 5 9 and 8 3 settling rates of the coarsest subpopulation closely matched predicted single particle terminal fall velocities sedimentation of particles 100 m was greatly enhanced predominantly through aggregation of a particle subpopulation with modal diameter 5 9 0 2 19 3 m mammatus on the msh80 cloud provided a mechanism to transport very fine ash particles with predicted atmospheric lifetimes of days to weeks from the upper troposphere to the surface in a matter of hours in this mechanism ash particles initiate ice hydrometeor formation high in the troposphere subsequently the volcanic cloud rapidly subsides as mammatus develop from increased particle loading and cloud base sublimation rapid fallout occurs as the cloud passes through the melting level in a process analogous to snowflake aggregation aggregates sediment en masse and form the distal mass deposition maxima observed in many recent volcanic ash fall deposits this work provides a data resource that will facilitate tephra sedimentation modeling and allow model intercomparisons

volcanic ash hazard climatology for an eruption of hekla volcano iceland abstract ash produced by a volcanic eruption on iceland can be hazardous for both the transatlantic flight paths and european airports and airspace in order to begin to quantify the risk to aircraft this study explored the probability of ash from a short explosive eruption of hekla volcano 63 98 n 19 7 w reaching european airspace transport dispersion and deposition of the ash cloud from a three hour explosive eruption with an initial plume height of 12 km was simulated using the met office s numerical atmospheric dispersion modelling environment name the model used operationally by the london volcanic ash advisory centre eruptions were simulated over a six year period from 2003 until 2008 and ash clouds were tracked for four days following each eruption results showed that a rapid spread of volcanic ash is possible with all countries in europe facing the possibility of an airborne ash concentration exceeding international civil aviation organization icao limits within 24 h of an eruption an additional high impact low probability event which could occur is the southward spread of the ash cloud which would block transatlantic flights approaching and leaving europe probabilities of significant concentrations of ash are highest to the east of iceland with probabilities exceeding 20 in most countries north of 50 n deposition probabilities were highest at scottish and scandinavian airports there is some seasonal variability in the probabilities ash is more likely to reach southern europe in winter when the mean winds across the continent are northerly ash concentrations usually remain higher for longer during summer when the mean wind speeds are lower

a multidisciplinary effort to assign realistic source parameters to models of volcanic ash cloud transport and dispersion during eruptions during volcanic eruptions volcanic ash transport and dispersion models vatds are used to forecast the location and movement of ash clouds over hours to days in order to define hazards to aircraft and to communities downwind those models use input parameters called eruption source parameters such as plume height h mass eruption rate duration d and the mass fraction m63 of erupted debris finer than about 4 or 63 m which can remain in the cloud for many hours or days observational constraints on the value of such parameters are frequently unavailable in the first minutes or hours after an eruption is detected moreover observed plume height may change during an eruption requiring rapid assignment of new parameters this paper reports on a group effort to improve the accuracy of source parameters used by vatds in the early hours of an eruption we do so by first compiling a list of eruptions for which these parameters are well constrained and then using these data to review and update previously studied parameter relationships we find that the existing scatter in plots of h versus yields an uncertainty within the 50 confidence interval of plus or minus a factor of four in eruption rate for a given plume height this scatter is not clearly attributable to biases in measurement techniques or to well recognized processes such as elutriation from pyroclastic flows sparse data on total grain size distribution suggest that the mass fraction of fine debris m63 could vary by nearly two orders of magnitude between small basaltic eruptions 0 01 and large silicic ones 0 5 we classify eleven eruption types four types each for different sizes of silicic and mafic eruptions submarine eruptions brief or vulcanian eruptions and eruptions that generate co ignimbrite or co pyroclastic flow plumes for each eruption type we assign source parameters we then assign a characteristic eruption type to each of the world s 1500 holocene volcanoes these eruption types and associated parameters can be used for ash cloud modeling in the event of an eruption when no observational constraints on these parameters are available

satellite detection long range transport and air quality impacts of volcanic sulfur dioxide from the 2014 2015 flood lava eruption at barðarbunga iceland the 2014 2015 bar arbunga vei ivotn fissure eruption at holuhraun produced about 1 5 km3 of lava making it the largest eruption in iceland in more than 200 years over the course of the eruption daily volcanic sulfur dioxide so2 emissions exceeded daily so2 emissions from all anthropogenic sources in europe in 2010 by at least a factor of 3 we present surface air quality observations from across northern europe together with satellite remote sensing data and model simulations of volcanic so2 for september 2014 we show that volcanic so2 was transported in the lowermost troposphere over long distances and detected by air quality monitoring stations up to 2750 km away from the source using retrievals from the ozone monitoring instrument omi and the infrared atmospheric sounding interferometer iasi we calculate an average daily so2 mass burden of 99 49 kilotons kt of so2 from omi and 61 18 kt of so2 from iasi for september 2014 this volcanic burden is at least a factor of 2 greater than the average so2 mass burden between 2007 and 2009 due to anthropogenic emissions from the whole of europe combining the observational data with model simulations using the united kingdom met office s numerical atmospheric dispersion modelling environment model we are able to constrain so2 emission rates to up to 120 kilotons per day kt d during early september 2014 followed by a decrease to 20 60 kt d between 6 and 22 september 2014 followed by a renewed increase to 60 120 kt d until the end of september 2014 based on these fluxes we estimate that the eruption emitted a total of 2 0 0 6 tg of so2 during september 2014 in good agreement with ground based remote sensing and petrological estimates although satellite derived and model simulated vertical column densities of so2 agree well the model simulations are biased low by up to a factor of 8 when compared to surface observations of volcanic so2 on 6 7 september 2014 in ireland these biases are mainly due to relatively small horizontal and vertical positional errors in the simulations of the volcanic plume occurring over transport distances of thousands of kilometers although the volcanic air pollution episodes were transient and lava dominated volcanic eruptions are sporadic events the observations suggest that i during an eruption volcanic so2 measurements should be assimilated for near real time air quality forecasting and ii existing air quality monitoring networks should be retained or extended to monitor so2 and other volcanic pollutants

a review of the inferred geodynamic evolution of the dharwar craton over the ca 3 5 2 5 ga period and possible implications for global tectonics the geological history and evolution of the dharwar craton from ca 3 5 2 5 ga is reviewed and briefly compared with a second craton kaapvaal to allow some speculation on the nature of global tec

numerical modelling of tsunami generation and propagation from submarine slumps the 1998 papua new guinea event summary deep and large submarine slumps may generate tsunamis as disastrous as tsunamis of tectonic origin such a landslide is likely to be the origin of the 1998 july 17 tsunami of papua new guinea the deadliest tsunami in the last 50 years water waves devastated a 20 km stretch of coastline wiping out three villages and killing more than 2200 people a numerical model has been developed to study the efficiency of deep slumps in producing tsunamis and has been applied to the papua new guinea event the landslide is treated as the flow of a homogeneous gravity driven continuum governed by a rheological law water waves are generated by sea bottom displacements induced by the landslide the shallow water approximation is adopted for both the landslide and the associated water waves the resulting differential equations are solved by a finite difference method based on shock capturing the shallow water hypothesis is tested by comparison with a model solving navier stokes equations for a mixture of water and sediments sensitivity tests carried out for a 2 d simplified geometry show that the water surface profile depends strongly on the constitutive law of the landslide the 1998 event is simulated numerically by the shallow water model testing different friction laws the observed inundation height distribution is well reproduced by the model for a volume of 4 km3 with its top located at a water depth of 550 m and sliding with a coulomb type friction law over a distance of 5 km

resolution analysis of finite fault source inversion using one and three dimensional green s functions 2 combining seismic and geodetic data using numerical tests for a prescribed heterogeneous earthquake slip distribution we examine the importance of accurate green s functions gf for finite fault source inversions which rely on coseismic gps displacements and leveling line uplift alone and in combination with near source strong ground motions the static displacements while sensitive to the three dimensional 3 d structure are less so than seismic waveforms and thus are an important contribution particularly when used in conjunction with waveform inversions for numerical tests of an earthquake source and data distribution modeled after the 1994 northridge earthquake a joint geodetic and seismic inversion allows for reasonable recovery of the heterogeneous slip distribution on the fault in contrast inaccurate 3 d gfs or multiple 1 d gfs allow only partial recovery of the slip distribution given strong motion data alone likewise using just the gps and leveling line data requires significant smoothing for inversion stability and hence only a blurred vision of the prescribed slip is recovered although the half space approximation for computing the surface static deformation field is no longer justifiable based on the high level of accuracy for current gps data acquisition and the computed differences between 3 d and half space surface displacements a layered 1 d approximation to 3 d earth structure provides adequate representation of the surface displacement field however even with the half space approximation geodetic data can provide additional slip resolution in the joint seismic and geodetic inversion provided a priori fault location and geometry are correct nevertheless the sensitivity of the static displacements to the earth structure begs caution for interpretation of surface displacements particularly those recorded at monuments located in or near basin environments

using simple plume models to refine the source mass flux of volcanic eruptions according to atmospheric conditions abstract a simple three dimensional volcanic plume model that incorporates the effects of moisture and ambient wind is presented and used iteratively to refine the source mass flux obtained from an empirical relationship between the plume rise height and source mass flux according to the prevailing atmospheric conditions it is applied to the eruption of eyjafjallajokull in may 2010 using realistic atmospheric profiles appropriate to the time of the eruption it is shown that the ambient wind has the largest effect on the refined source mass flux with moisture playing a secondary though still important role it is also shown that significant differences in the values of the revised source mass fluxes can arise when the realistic atmospheric profiles are approximated by idealised profiles the revised source mass flux is used to initialise a long range dispersion model of ash in the atmosphere

sediment effect on tsunami generation of the 1896 sanriku tsunami earthquake the 1896 sanriku earthquake was one of the most devastating tsunami earthquakes which generated an anomalously larger tsunami than expected from its seismic waves previous studies indicate that the earthquake occurred beneath the accretionary wedge near the trench axis it was pointed out recently that sediments near a toe of an inner trench slope with a large horizontal movement due to the earthquake might have caused an additional uplift in this paper the effect of the additional uplift to tsunami generation of the 1896 sanriku tsunami earthquake is quantified we estimate the slip of the earthquake by numerically computing tsunamis and comparing their waveforms with those recorded at three tide gauges the estimated slip for the model without the additional uplift is 10 4 m and those with the additional uplift are 5 9 6 7 m this indicates that the additional uplift of the sediments near the trench has a large effect on the tsunami generation

ash3d a finite volume conservative numerical model for ash transport and tephra deposition 1 we develop a transient 3 d eulerian model ash3d to predict airborne volcanic ash concentration and tephra deposition during volcanic eruptions this model simulates downwind advection turbulent diffusion and settling of ash injected into the atmosphere by a volcanic eruption column ash advection is calculated using time varying pre existing wind data and a robust high order finite volume method our routine is mass conservative and uses the coordinate system of the wind data either a cartesian system local to the volcano or a global spherical system for the earth volcanic ash is specified with an arbitrary number of grain sizes which affects the fall velocity distribution and duration of transport above the source volcano the vertical mass distribution with elevation is calculated using a suzuki distribution for a given plume height eruptive volume and eruption duration multiple eruptions separated in time may be included in a single simulation we test the model using analytical solutions for transport comparisons of the predicted and observed ash distributions for the 18 august 1992 eruption of mt spurr in alaska demonstrate to the efficacy and efficiency of the routine

a review of tephra transport and dispersal models evolution current status and future perspectives abstract tephra transport models try to predict atmospheric dispersion and sedimentation of tephra depending on meteorology particle properties and eruption characteristics defined by eruption column height mass eruption rate and vertical distribution of mass models are used for different purposes from operational forecast of volcanic ash clouds to hazard assessment of tephra dispersion and fallout the size of the erupted particles a key parameter controlling the dynamics of particle sedimentation in the atmosphere varies within a wide range largest centimetric to millimetric particles fallout at proximal to medial distances from the volcano and sediment by gravitational settling on the other extreme smallest micrometric to sub micrometric particles can be transported at continental or even at global scales and are affected by other deposition and aggregation mechanisms different scientific communities had traditionally modeled the dispersion of these two end members volcanologists developed families of models suitable for lapilli and coarse ash and aimed at computing fallout deposits and for hazard assessment in contrast meteorologists and atmospheric scientists have traditionally used other atmospheric transport models dealing with finer particles for tracking motion of volcanic ash clouds and eventually for computing airborne ash concentrations during the last decade the increasing demand for model accuracy and forecast reliability has pushed on two fronts first the original gap between these different families of models has been filled with the emergence of multi scale and multi purpose models second new modeling strategies including for example ensemble and probabilistic forecast or model data assimilation are being investigated for future implementation in models and or modeling strategies this paper reviews the evolution of tephra transport and dispersal models during the last two decades presents the status and limitations of the current modeling strategies and discusses some emergent perspectives expected to be implemented at operational level during the next few years improvements in both real time forecasting and long term hazard assessment are necessary to loss prevention programs on a local regional national and international level

uncertainty analysis of a model of wind blown volcanic plumes mathematical models of natural processes can be used as inversion tools to predict unobserved properties from measured quantities uncertainty in observations and model formulation impact on the efficacy of inverse modelling we present a general methodology history matching that can be used to investigate the effect of observational and model uncertainty on inverse modelling studies we demonstrate history matching on an integral model of volcanic plumes that is used to estimate source conditions from observations of the rise height of plumes during the eruptions of eyjafjallajokull iceland in 2010 and grimsvotn iceland in 2011 sources of uncertainty are identified and quantified and propagated through the integral plume model a preliminary sensitivity analysis is performed to identify the uncertain model parameters that strongly influence model predictions model predictions are assessed against observations through an implausibility measure that rules out model inputs that are considered implausible given the quantified uncertainty we demonstrate that the source mass flux at the volcano can be estimated from plume height observations but the magmatic temperature exit velocity and exsolved gas mass fraction cannot be accurately determined uncertainty in plume height observations and entrainment coefficients results in a large range of plausible values of the source mass flux our analysis shows that better constraints on entrainment coefficients for volcanic plumes and more precise observations of plume height are required to obtain tightly constrained estimates of the source mass flux

inversion of tsunami waveforms for the estimation of heterogeneous fault motion of large submarine earthquakes the 1968 tokachi oki and 1983 japan sea earthquakes waveform inversion of tsunami data provides independent and reliable information on earthquake source processes the propagation effects of tsunamis are accounted for by computing green s functions using a finite difference method and using the known bathymetry which is much better constrained than the seismic velocity structure the observed tsunami waveforms are corrected for the response of the tide gage system by using the results of in situ measurements using green s functions computed from bathymetric data on a 2 5 km grid and the observed waveforms digitized at 1 min intervals the spatial resolution of the faulting heterogeneity by the present method is as small as 30 km this method is applied to the 1968 tokachi oki and 1983 japan sea earthquakes the slip is concentrated at the northwestern part of the fault plane for the 1968 event for the 1983 event the slip on the fault just north of the epicenter is twice that of the other parts these asperity distributions are similar to those inferred from seismic wave analysis however the recovered total seismic moments are smaller the present method is shown to be a useful technique for estimating heterogeneous fault motion especially for historical events with no or poor seismic records and tsunami earthquakes in which the excitations of seismic and tsunami waves are different

a case study of observations of volcanic ash from the eyjafjallajokull eruption 2 airborne and satellite radiative measurements 1 an extensive set of airborne and satellite observations of volcanic ash from the eyjafjallajokull icelandic eruption are analyzed for a case study on 17 may 2010 data collected from particle scattering probes and backscatter lidar on the facility for airborne atmospheric measurements faam bae 146 aircraft allow estimates of ash concentration to be derived using radiative transfer simulations we show that airborne and satellite infrared radiances can be accurately modeled based on the in situ measured size distribution and a mineral dust refractive index furthermore airborne irradiance measurements in the 0 3 1 7 m range are well modeled with these properties retrievals of ash mass column loading using infrared atmospheric sounding interferometer iasi observations are shown to be in accord with lidar derived mass estimates giving for the first time an independent verification of a hyperspectral ash variational retrieval method the agreement of the observed and modeled solar and terrestrial irradiances suggests a reasonable degree of radiative closure implying that the physical and optical properties of volcanic ash can be relatively well constrained using data from state of the science airborne platforms such as the faam bae 146 aircraft comparisons with iasi measurements during recent grimsvotn and puyehue volcanic eruptions demonstrate the importance of accurately specifying the refractive index when modeling the observed spectra

rupture process of the 2004 sumatra andaman earthquake from tsunami waveform inversion the aim of this work is to infer the slip distribution and rupture velocity along the rupture zone of the 26 december 2004 sumatra andaman earthquake from available tide gage records of the tsunami we selected waveforms from 14 stations distributed along the coast of the indian ocean then we subdivided the fault plane into 16 subfaults both along strike and downdip following the geometry and mech anism proposed by banerjee et al 2005 and computed the corresponding green s functions by numerical solution of the shallow water equations through a finite difference method the slip distribution and rupture velocity were determined simul taneously by means of a simulated annealing technique we compared the recorded and synthetic waveforms in the time domain using a cost function that is a trade off between the l1 and l2 norms preliminary tests on a synthetic dataset together with a posteriori statistical analysis of the model ensemble enabled us to assess the ef fectiveness of the method and to quantify the model uncertainty the main finding is that the best source model features a nonuniform distribution of coseismic slip with high slip values concentrated into three main patches the first is located in the southern part of the fault off the coast of the aceh province the second between 6 5 n and 11 n and the third at depth between 11 n and 14 n furthermore we estimated that the rupture propagated at an average speed of 2 0 km sec

simulated volcanic ash imagery a method to compare name ash concentration forecasts with seviri imagery for the eyjafjallajokull eruption in 2010 1 during volcanic eruptions that eject ash into the atmosphere volcanic ash advisory centers issue statements on the forecast dispersion of the ash so that the aviation industry can manage airspace to avoid aircraft encountering volcanic ash observations such as those from satellites are compared with the forecasts from an atmospheric dispersion model to assess the quality of the ash forecasts a method has been developed to enable like with like comparison between satellite imagery of volcanic ash and simulated imagery using the forecast ash concentration data from an atmospheric dispersion model the ash concentration and numerical weather prediction data are used as inputs to a radiative transfer model to simulate radiances simulated satellite images are created from these simulated radiances here spinning enhanced visible and infrared imager volcanic ash images based on infrared brightness temperatures for the eyjafjallajokull eruption in 2010 are simulated in addition to providing a useful tool for forecasters in a volcanic ash advisory center the simulated images can be used to aid the understanding of how the ash affects the satellite imagery and also the physical properties of the ash

operational prediction of ash concentrations in the distal volcanic cloud from the 2010 eyjafjallajokull eruption 1 during the 2010 eruption of eyjafjallajokull improvements were made to the modeling procedure at the met office uk enabling peak ash concentrations within the volcanic cloud to be estimated in this paper we describe the ash concentration forecasting method its rationale and how it evolved over time in response to new information and user requirements the change from solely forecasting regions of ash to also estimating peak ash concentrations required consideration of volcanic ash emission rates the fraction of ash surviving near source fall out and the relationship between predicted mean and local peak ash concentrations unresolved by the model to validate the modeling procedure predicted peak ash concentrations are compared against observations obtained by ground based and research aircraft instrumentation this comparison between modeled and observed peak concentrations highlights the many sources of error and the uncertainties involved despite the challenges of predicting ash concentrations the ash forecasting method employed here is found to give useful guidance on likely ash concentrations predicted peak ash concentrations lie within about one and a half orders of magnitude of the observed peak concentrations a significant improvement in the agreement between modeled and observed values is seen if a buffer zone accounting for positional errors in the predicted ash cloud is used sensitivity of the predicted ash concentrations to the source properties e g the plume height and the vertical distribution of ash at the source is assessed and in some cases seemingly minor uncertainties in the source specification have a large effect on predicted ash concentrations

millimeter scale tsunami detected by a wide and dense observation array in the deep ocean fault modeling of an mw 6 0 interplate earthquake off sanriku ne japan

a simple inversion method for determining optimal dispersion model parameters from satellite detections of volcanic sulfur dioxide a simple inversion scheme for optimizing volcanic emission dispersion model parameters with respect to satellite detections is presented in this paper in this scheme multiple dispersion model simulations obtained by varying relevant model parameters are created and compared against satellite detections using pattern correlation as a measure of model agreement with observations it is shown that the scheme is successful in inferring emission source parameters such as those describing the vertical extent of the nascent sulfur dioxide emissions in the november 2010 mount merapi eruption in java indonesia these optimal parameter values then become a basis for improved forecasts of the transport of volcanic emissions

investigating the use of the saharan dust index as a tool for the detection of volcanic ash in seviri imagery abstract despite the similar spectral signatures of ash and desert dust relatively little has been done to explore the application of dust detection techniques to the problem of volcanic ash detection the saharan dust index sdi is routinely implemented for dust monitoring at some centres and could be utilised for volcanic ash detection with little computational expense thereby providing a product that forecasters already have some familiarity with to complement the suite of existing ash detection tools we illustrate one way in which the index could be implemented for the purpose of ash detection by applying it to three scenes containing volcanic ash from the 2010 eyjafjallajokull eruption iceland and the 2011 eruption of puyehue chile it was also applied to an image acquired over etna in january 2011 where a volcanic plume is clearly visible but is unlikely to contain any ash these examples demonstrate the potential of the sdi as a tool for ash monitoring under different environmental and atmospheric conditions in addition to presenting a valuable qualitative product to aid monitoring this work includes a quantitative assessment of the detection skill using a manually constructed expert ash mask the optimum implementation of any technique is likely to be dependent on both atmospheric conditions and on the properties of the imaged ash which is often unknown in a real time situation here we take advantage of access to a truth rarely available in a real time situation and calculate an ash mask based on the optimum threshold for the specific scene which is then used to demonstrate the potential of the sdi the sdi mask is compared to masks calculated from a simplistic implementation of the more traditional split window method again exploiting our access to the truth to set the most appropriate threshold for each scene and to a probabilistic method that is implemented without reference to the truth and which provides useful insights into the likely cloud ash contamination of each pixel since the sensitivity of the sdi and split window methods to the tailored thresholds was not tested such tailoring is unlikely to be possible in a real situation this study presents the maximum anticipated skill for the sdi in the context of the maximum skill anticipated for the split window method although both are likely to be lower in a real time situation the results for the sdi are comparable to those of the other methods with a true skill score of 80 02 for the eyjafjallajokull night time scene compared to 88 81 and 46 63 for the split window and probabilistic method respectively and 90 06 for the eyjafjallajokull day time scene compared to 97 61 and 56 96 for the puyehue image the sdi resulted in a true skill score of 74 85 while the split window approach achieved 99 62 these results imply that the sdi which is already implemented operationally at some centres for dust detection could be a useful complement to existing ash monitoring techniques

propagation of distant tsunamis over slowly varying topography 1 a new two dimensional finite difference numerical scheme is developed to simulate the propagation of distant tsunamis over slowly varying topography with improved dispersion effect of waves the new scheme solves the shallow water equations on a uniform grid system however the actual computation is made on a hidden grid system whose grid size is adjustable according to the condition required to satisfy local dispersion relationships of waves for varying water depth the present model is tested for the cases of two dimensional propagation of an initial gaussian hump over various uniform water depth regions for a varying topography a one dimensional test is conducted the tests show that accuracy of the numerical model is improved significantly over that of the conventional finite difference models finally the present model is applied to the simulation of a historical tsunami event the numerical result shows that the submerged rise and ridge play an important role of a waveguide for the tsunamis propagating over that topography

the 1989 1990 eruption of redoubt volcano alaska impacts on aircraft operations abstract the december 1989 june 1990 eruption of redoubt volcano affected commercial and military air operations in the vicinity of anchorage alaska these effects were due to the direct impact of volcanic ash on jet aircraft as well as to the rerouting and cancellations of flight operations owing to eruptive activity between december and february five commercial jetliners were damaged from ash encounters the most serious incident took place on december 15 1989 when a boeing 747 400 aircraft temporarily lost power of all four engines after encountering an ash cloud as the airplane descended for a landing in anchorage while there were no injuries to passengers the damage to engines avionics and aircraft structure from this encounter is estimated at 80 million four additional encounters between jet aircraft and redoubt ash clouds occurred in the anchorage area on december 15 and 16 1989 and february 21 1990 none resulted in engine failure two additional encounters took place on december 17 1989 when jet airliners encountered the redoubt cloud over west texas at the time of these encounters the cloud was up to 55 hours old and had traveled in excess of 2 900 nautical miles 5 300 km following the december 15 encounters anchorage international airport remained open however most airline companies canceled operations for up to several days as communications between federal agencies and airlines improved and as a better understanding of the nature and behavior of ash rich eruption clouds was achieved most airlines resumed normal service by early january 1990 the resulting loss of revenue at anchorage international airport during several months following the eruption is estimated to total 2 6 million the impact on general aviation and military operations consisted mostly of cancellation and rerouting of flights

composition of the middle and late archaean upper continental crust as sampled from the kaldurga conglomerate dharwar craton india abstract the greywacke matrix of the polymict kaldurga conglomerate kcm of the bababudan schist belt has preserved the composition of the upper continental crust exposed during the middle and late archaean the boulder to pebble size clasts are of tonalitic and trondhjemitic gneisses ttg cross bedded quartzites amphibolites banded iron formations bif vein quartz and carbonates the recrystallized matrix mainly amphibolitic and quartzofeldspathic also includes heavy minerals such as kyanite derived from older schist belts geochemical parameters such as k 2 o na 2 o mgo fe 2 o 3 mgo k 2 o cr zr zr ti la lu eu eu and lree hree indicate that the conglomerate and its matrix were derived from a multicomponent source area a mixing model of provenance consisting of about 50 ttg 35 ultramafic rocks 10 mafic rocks and 5 sediments is consistent with the average composition of the kcm the exposure ratio of 90 10 of ttg and mafic ultramafic rocks older than 2 6 ga suggest that during the middle and late archaean the exposed crust had a relatively high proportion of mafic ultramafic components similar characteristics of multicomponent mixing are indicated by a large variation in ree abundances and eu anomalies it is inferred that the kaldurga conglomerate represents a transitional stage in unidirectional crustal evolution from dominantly mafic to felsic composition

in situ observations of volcanic ash clouds from the faam aircraft during the eruption of eyjafjallajokull in 2010 1 during april may 2010 the uk facility for airborne atmospheric measurements faam bae 146 aircraft flew 12 flights targeting volcanic ash clouds around the uk the aircraft observed ash layers between altitudes of 2 8 km with peak mass concentrations typically between 200 2000 g m3 as estimated from a cloud and aerosol spectrometer cas a peak value of 2000 5000 g m3 was observed over scotland on 14 may 2010 although with considerable uncertainty due to the possible contamination by ice aerosol size distributions within ash clouds showed a fine mode 0 1 0 6 m associated with sulphuric acid and or sulphate and a coarse mode 0 6 35 m associated with ash the ash mass was dominated by particles in the size range 1 10 m volume equivalent diameter with a peak typically around 3 5 m electron microscope images and scattering patterns from the sid 2h small ice detector probe showed the highly irregular shape of the ash particles ash clouds were also accompanied by elevated levels of so2 10 100 ppbv strong aerosol scattering 50 500 10 6 m 1 and low angstrom exponents 0 5 to 0 4 from the 3 wavelength nephelometer coarse mode mass specific aerosol extinction coefficients kext based on the cas size distribution varied from 0 45 1 06 m2 g a representative value of 0 6 m2 g is suggested for distal ash clouds 1000 km downwind from this eruption

dispersive tsunami of the 2010 chile earthquake recorded by the high sampling rate ocean bottom pressure gauges 1 cabled ocean bottom pressure gauges deployed offshore japan recorded the pressure change associated with the 2010 chile earthquake tsunami over a wider frequency range than that of coastal tide gauges or hydrophones although it was difficult to recognize the dispersive features in the original records the spectrograms clearly showed wave dispersion a low frequency tsunami 1 mhz arrived after an elapsed time of 24 hr from the earthquake origin time while a high frequency tsunami 9 mhz arrived after an elapsed time of 48 hr the arrival times can be explained by assuming a constant water depth of 4 km however the calculated waveform does not correctly reproduce the number of wave packets appearing in the observations cabled ocean bottom pressure gauges deployed offshore can record broadband tsunami signals reflecting the wide wavenumber range spatial spectrum for sea bottom deformation caused by the earthquake

charge mechanism of volcanic lightning revealed during the 2010 eruption of eyjafjallajokull 1 volcanic lightning has intrigued observers through the centuries several likely processes have been proposed to explain the electrification of volcanic plumes including quenching magma water interactions the fracturing or internal friction of fine grained ash and the freezing of plume water at height scarce measurements of volcanic lightning have not been able to distinguish between proposed ideas the eyjafjallajokull volcanic eruption in iceland in april may 2010 may have revealed its charge mechanism during its 39 days the eruption went through a few phases while the conditions of the ambient atmosphere also changed but at different times the most surprising change in the lightning activity occurred on 11 may with no obvious change in the physical eruption character or strength during 3 10 may there was no lightning recorded by long range networks followed by intense activity 11 20 may the change in lightning activity coincided with a change in the conditions of the ambient atmosphere at this time the altitude of the isotherms for droplet freezing about 20 c dropped drastically below the plume top therefore it appears that the atmospheric conditions around the plume were influencing or even controlling some of the lightning activity the critical plume top temperature which appears to have turned on and off the observed lightning activity during the eyjafjallajokull eruption is estimated to be between 20 and 24 c we conclude that a significant charge generation process of the observed volcanic lightning is probably analogous to processes in meteorological thunderclouds

three dimensional simulation of the electromagnetic fields induced by the 2011 tohoku tsunami the motion of seawater induces electromotive force of significant intensity due to faraday s law and the resulting electromagnetic em field can be recorded by instruments installed on land or on the ocean bottom however few studies have successfully made a quantitative interpretation to obtain geophysical information from observations of tsunami induced em signals by an exact and accurate application of maxwell equations we built a scheme for three dimensional numerical simulation to calculate em fields due to ocean tidal flow and tested the system s accuracy by using the source currents in the ocean as expected from a tohoku tsunami simulation here we show examples of a comparison of data from one land observatory in the tohoku district one island observatory in the izu bonin arc and one seafloor station in the northwest pacific ocean the water motion that generates source current in the sea consists of both the primary poloidal and toroidal magnetic modes our numerical simulation shows that the field of the primary toroidal magnetic mode can be effective for seafloor observations but only when the seafloor is highly conductive we examined how the conductivity of the shallower part of the seabed composed of sediments can be constrained by the tsunami induced em field observations which is difficult in case of using ordinary seafloor magnetotelluric signals we also defined the motional impedance just as the case of ordinary magnetotellurics and showed that both modeled and observed impedances approximately indicate the phase velocity of the long wave as predicted by a simple theory

interaction between volcanic plumes and wind during the 2010 eyjafjallajokull eruption iceland 1 estimates of volcanic source mass flux currently deduced from observations of plume height are crucial for ash dispersion models for aviation and population hazard this study addresses the role of the atmospheric wind in determining the height at which volcanic plumes spread in the atmosphere and the relationship between source mass flux and plume height in a wind field we present a predictive model of volcanic plumes that describes the bending over of the plume trajectory in a crosswind and show that model predictions are in accord with a dataset of historic eruptions if the profile of atmospheric wind shear is described the wind restricts the rise height of volcanic plumes such that obtaining equivalent rise heights for a plume in a windy environment would require an order of magnitude increase in the source mass flux over a plume in a quiescent environment our model calculations are used to calibrate a semi empirical relationship between the plume height and the source mass flux that explicitly includes the atmospheric wind speed we demonstrate that the model can account for the variations in plume height observed during the first explosive phase of the 2010 eyjafjallajokull eruption using independently measured wind speeds and show that changes in the observed plume height are better explained by changing meteorology than abrupt changes in the source mass flux this study shows that unless the wind is properly accounted for estimates of the source mass flux during an explosive eruption are likely to be very significant underpredictions of the volcanic source conditions

estimating the total mass emitted by the eruption of eyjafjallajokull in 2010 using plume rise models abstract the volcanic plume rise model of devenish 2013 is applied to the duration of the 39 day eruption of eyjafjallajokull in 2010 to produce a time series of the estimated source mass flux this in turn is integrated to give the total emitted mass which is found to lie within the error bounds of an observational estimate made by gudmundsson et al 2012 the calculation uses realistic profiles of key atmospheric variables such as wind speed temperature and humidity taken from a numerical weather prediction model and appropriate to the time of the eruption the sensitivity of the model results to changes in the values of the entrainment coefficients is discussed it is shown that including the radius of the plume when it is strongly affected by the wind in the comparison of the modelled and observed rise heights not only improves the accuracy of the estimated total emitted mass compared with neglecting the radius but also reduces the sensitivity of this estimate to the value of the entrainment coefficient associated with velocity differences normal to the plume axis

tsunami sources of the november 2006 and january 2007 great kuril earthquakes abstract along the northern kuril trench a great interplate earthquake occurred in november 2006 followed by an outer rise normal fault event in january 2007 surface wave magnitudes m s 7 8 and 8 2 indicate that the 2007 event was larger while the global cmt solutions m w 8 3 and 8 1 indicate that the 2006 event was larger tsunamis from both events were recorded at tide gauge stations in japan russia and the united states as well as deep ocean assessment and reporting of tsunamis dart systems and cabled tsunami sensors installed on deep ocean bottom inversion of 52 tsunami waveforms indicates that the 2006 tsunami source was about 200 km long extending from the epicenter to northeast the largest slips of 4 7 m are estimated on the northeastern subfaults for the 2007 event inversion of 32 waveforms shows that the tsunami source was about 120 km long with the largest slip of 3 5 m on the northeastern subfault the agreements between the observed and synthetic tsunami waveforms are generally good for both events not only within the inversion time windows but also for the later phases which were not used in inversions the slip distributions yield the seismic moment of m w 8 1 for the 2006 event and m w 7 9 for the 2007 event the seismic moment of the 2006 event was larger than the 2007 event from comparison of tsunami data regardless of fault model

determining the contribution of volcanic ash and boundary layer aerosol in backscatter lidar returns a three component atmosphere approach 1 a solution of the lidar equation is discussed that permits combining backscatter and depolarization measurements to quantitatively distinguish two different aerosol types with different depolarization properties the method has been successfully applied to simultaneous observations of volcanic ash and boundary layer aerosol obtained in exeter united kingdom on 16 and 18 april 2010 permitting the contribution of the two aerosols to be quantified separately first a subset of the atmospheric profiles is used where the two aerosol types belong to clearly distinguished layers for the purpose of characterizing the ash in terms of lidar ratio and depolarization these quantities are then used in a three component atmosphere solution scheme of the lidar equation applied to the full data set in order to compute the optical properties of both aerosol types separately on 16 april a thin ash layer 100 400 m deep is observed average and maximum estimated ash optical depth 0 11 and 0 2 it descends from 2800 to 1400 m altitude over a 6 hour period on 18 april a double ash layer 400 m deep is observed just above the morning boundary layer average and maximum estimated ash optical depth 0 19 and 0 27 in the afternoon the ash is entrained into the boundary layer and the latter reaches a depth of 1800 m average and maximum estimated ash optical depth 0 1 and 0 15 an additional ash layer with a very small optical depth was observed on 18 april at an altitude of 3500 4000 m by converting the lidar optical measurements using estimates of volcanic ash specific extinction derived from other works the observations seem to suggest approximate peak ash concentrations of 1500 and 1000 g m3 respectively on the two observations dates

tsunami source of the 2004 sumatra andaman earthquake inferred from tide gauge and satellite data tsunami source of the 2004 sumatra andaman earthquake was esti mated from a joint inversion of tsunami waveforms recorded on tide gauges and sea surface heights captured by satellite altimetry measurements the earthquake the largest in the past 40 years caused devastating tsunami damage to countries around the indian ocean but the tsunami source in particular its northern end was not well resolved although aftershocks and crustal deformation extended from off north western sumatra island through the nicobar islands to the andaman islands some seismic wave analyses indicated a shorter source length several hundred kilometers we used tsunami waveforms recorded at 12 tide gauge stations around the source and the sea surface heights measured by three satellites jason1 topex poseidon and envisat we numerically computed tsunami propagation using realistic bathym etry more than 66 000 depth points were digitized from nautical charts and combined with the etopo2 data inversion of satellite data indicates that the tsunami source extended to the andaman islands with a total length of 1 400 km but such a model produces much larger tsunami waveforms than observed at indian tide gauge stations inversion of tide gauge records and the joint inversion indicate that the tsunami source was about 900 km long the largest slip about 13 to 25 m was located off sumatra island and the second largest slip up to 7 m near the nicobar islands the slip distribution is similar for different rupture velocities and rise times with a slow velocity of 1 km sec and a rise time of 3 min yielding the largest variance reduction

a case study of observations of volcanic ash from the eyjafjallajokull eruption 1 in situ airborne observations on 17 may 2010 the faam bae 146 aircraft made remote and in situ measurements of the volcanic ash cloud from eyjafjallaja kull over the southern north sea the falcon 20e aircraft operated by deutsches zentrum fa r luft und raumfahrt dlr also sampled the ash cloud on the same day while no a wingtip to wingtipa co ordination was performed the proximity of the two aircraft allows worthwhile comparisons despite the high degree of inhomogeneity e g column ash loadings varied by a factor of three over 100 km the range of ash mass concentrations and the ratios between volcanic ash mass and concentrations of so2 o3 and co were consistent between the two aircraft and within expected instrumental uncertainties the data show strong correlations between ash mass so2 concentration and aerosol scattering with the faam bae 146 data providing a specific extinction coefficient of 0 6a 0 8 m2 g 1 there were significant differences in the observed ash size distribution with faam bae 146 data showing a peak in the mass at 3 5 mm volume equivalent diameter and dlr data peaking at 10 mm differences could not be accounted for by refractive index and shape assumptions alone the aircraft in situ and lidar data suggest peak ash concentrations of 500a 800 mg m 3 with a factor of two uncertainty comparing the location of ash observations with the ash dispersion model output highlights differences that demonstrate the difficulties in forecasting such events and the essential nature of validating models using high quality observational data from platforms such as the faam bae 146 and the dlr falcon

sensitivity analysis of dispersion modeling of volcanic ash from eyjafjallajokull in may 2010 1 we analyze the sensitivity of a mathematical model of volcanic ash dispersion in the atmosphere to the representation of key physical processes these include the parameterization of subgrid scale atmospheric processes and source parameters such as the height of the eruption column the mass emission rate the size of the particulates and the amount of ash that falls out close to the source by comparing the results of the mathematical model with satellite and airborne observations of the ash cloud that erupted from eyjafjallajokull volcano in may 2010 we are able to gain some insight into the processes and parameters that govern the long range dispersion of ash in the atmosphere the structure of the ash cloud particularly its width and depth appears to be sensitive to the source profile i e whether ash is released over a deep vertical column or not and to the level of subgrid diffusion of central importance to the quantitative estimates of ash concentration in the distal ash cloud is the fallout of ash close to the source by comparing the mass of the ash and the column loadings in the modeled and observed distal ash cloud we estimate the fraction of fine ash that survives into the distal ash cloud albeit with considerable uncertainty the processes that contribute to this uncertainty are discussed

dispersion and nonlinear effects in the 2011 tohoku oki earthquake tsunami this study reveals the roles of the wave dispersion and nonlinear effects for the 2011 tohoku oki earthquake tsunami we conducted tsunami simulations based on the nonlinear dispersive equations with a high resolution source model the simulations successfully reproduced the waveforms recorded in the offshore deep sea and focal areas the calculated inundation area coincided well with the actual inundation for the sendai plain which was the widest inundation area during this event by conducting sets of simulations with different tsunami equations we obtained the followings insights into the wave dispersion nonlinear effects and energy dissipation for this event although the wave dispersion was neglected in most studies the maximum amplitude was significantly overestimated in the deep sea if the dispersion was not included the waveform observed at the station with the largest tsunami height 2 m among the deep ocean stations also verified the necessity of the dispersion it is well known that the nonlinear effects play an important role for the propagation of a tsunami into bays and harbors additionally nonlinear effects need to be considered to accurately model later waves even for offshore stations in particular including nonlinear terms rather than the inundation was more important when precisely modeling the waves reflected from the coast

a model for wet aggregation of ash particles in volcanic plumes and clouds 2 model application 1 the occurrence of particle aggregation has a dramatic effect on the transport and sedimentation of volcanic ash the aggregation process is complex and can occur under different conditions and in multiple regions of the plume and in the ash cloud in the companion paper costa et al develop an aggregation model based on a fractal relationship to describe the rate particles are incorporated into ash aggregates the model includes the effects of both magmatic and atmospheric water present in the volcanic cloud and demonstrates that the rate of aggregation depends on the characteristics of the initial particle size distribution the aggregation model includes two parameters the fractal exponent df which describes the efficiency of the aggregation process and the aggregate settling velocity correction factor e which influences the distance at which distal mass deposition maxima form both parameters are adjusted using features of the observed deposits here this aggregation model is implemented in the fall3d volcanic ash transport model and applied to the 18 may 1980 mount st helens and the 17 18 september 1992 crater peak eruptions for both eruptions the optimized values for df 2 96 3 00 and e 0 27 0 33 indicate that the ash aggregates had a bulk density of 700 800 kg m 3 the model provides a higher degree of agreement than previous fully empirical aggregation models and successfully reproduces the depositional characteristics of the deposits investigated over a large range of scales including the position and thickness of the secondary maxima

using data insertion with the name model to simulate the 8 may 2010 eyjafjallajokull volcanic ash cloud a data insertion method where a dispersion model is initialized from ash properties derived from a series of satellite observations is used to model the 8 may 2010 eyjafjallajokull volcanic ash cloud which extended from iceland to northern spain we also briefly discuss the application of this method to the april 2010 phase of the eyjafjallajokull eruption and the may 2011 grimsvotn eruption an advantage of this method is that very little knowledge about the eruption itself is required because some of the usual eruption source parameters are not used the method may therefore be useful for remote volcanoes where good satellite observations of the erupted material are available but little is known about the properties of the actual eruption it does however have a number of limitations related to the quality and availability of the observations we demonstrate that using certain configurations the data insertion method is able to capture the structure of a thin filament of ash extending over northern spain that is not fully captured by other modeling methods it also verifies well against the satellite observations according to the quantitative object based quality metric sal structure amplitude location and the spatial coverage metric figure of merit in space

estimation of optimal dispersion model source parameters using satellite detections of volcanic ash in this paper we demonstrate how parameters describing the geometry of the volcanic ash source for a particular volcanic ash dispersion model hysplit may be inferred by the use of satellite data and multiple trial simulations the areas of space likely to be contaminated by ash are identified with the aid of various remote sensing techniques and polygons are drawn around these areas as they would be in an operational setting dispersion model simulations are initialized either by a cylindrical source or a specified ash distribution depending on the context parameters of interest such as the base and top height diameter and optimal release time of the cylindrical source or the height of the specified ash distribution are inferred by forming a parameter grid and running multiple simulations for each parameter grid point value optimal values of the parameter values are identified by calculating spatial correlations between the model simulations and observations we demonstrate that the methodology can be used to correctly infer various model parameters and improves volcanic ash forecasts in various eruption case studies

so2 as a possible proxy for volcanic ash in aviation hazard avoidance 1 airborne volcanic ash poses a significant danger to aircraft but is difficult to quantify accurately using satellite data while sulphur dioxide is much easier to detect accurately but is much less of a direct hazard to aviation this paper investigates the reliability of using so2 as a proxy for the location of volcanic ash using an so2 retrieval from the infrared atmospheric sounding interferometer iasi and ash detections from iasi and the advanced along track scanning radiometer aatsr using a numerical missed ash fraction applied to the eruptions of eyjafjallajokull in 2010 and puyehue cordon caulle in 2011 reveals that the so2 flag typically misses 30 of the detectable ash furthermore the missed ash fraction is found to be highly variable both between the two eruptions and over the course of each eruption with values of over 80 found on some days the detection threshold of the aatsr ash flag is also investigated using radiative transfer calculations allowing the threshold of the iasi flag to be inferred and these are related to the ash contamination levels

acoustic gravity waves from the source region of the 2011 great tohoku earthquake mw 9 0 1 atmospheric pressure waves were recorded within 5 h after the 2011 great tohoku earthquake mw 9 0 by sensitive microbarographs at four regional stations and eight international monitoring system stations at distances up to 6700 km while its apparent phase velocity between the regional stations is 341 m s the global stations indicate weak dispersive wave trains with low frequencies between 1 6 and 4 8 mhz propagating with an average phase velocity around 364 m s the low frequency waves may be interpreted as acoustic gravity waves excited by upheaval and depression of the sea surface in the source region due to coseismic uplift and subsidence of the sea bottom during this great thrust earthquake assuming the source dimension and the average coseismic vertical displacements of the sea surface with reference to tsunami observations we calculate synthetic waveforms for some of the far field stations by incorporating a standard sound velocity structure in the atmosphere up to an altitude of 220 km the synthetics provide reasonable explanations for the general features of the observed waveforms suggesting possible ranges for the source parameters generating these acoustic gravity waves our analysis suggests that the average initial upheaval of the sea surface in the central zones of the source region may exceed 4 6 m and that the risetime of the coseismic deformation may be in the range between 3 and 4 min in the eastern narrow zone adjacent to the japan trench the deformation has significantly higher initial amplitude and shorter risetime

tsunami waveform inversion including dispersive waves the 2004 earthquake off kii peninsula japan 1 long waves are often assumed to model tsunamis but the wavelength of the initial water height distribution produced by a large submarine earthquake particularly in the direction perpendicular to the fault strike is sometimes not much greater than the water depth the resulting tsunami may have a dispersive character that cannot be simulated based on a conventional long wave approximation the 2004 earthquake off kii peninsula m 7 4 on the southern coast of japan indeed produced a dispersive tsunami that was recorded at two stations located off shikoku for the foreshock m 7 1 on the contrary a dominant dispersive tsunami was not recognized at these stations because dispersive waves show strong directional dependence with respect to the fault strike the above difference indicates that the strikes of the main shock and the foreshock were different we conducted a tsunami waveform inversion analysis based on the dispersive tsunami equations to estimate the initial water height distribution of the main shock the estimated initial water height distribution overlapped with the aftershock region suggesting that the fault strike was perpendicular to the trough axis and the total displaced water volume was 1 7 2 0 109 m3 when we used the conventional long wave approximation the estimated initial water height distribution extended considerably from the aftershock area because artificial sources were needed outside the aftershock area to reproduce the observed dispersive waves

tsunami source of the 2011 tohoku oki earthquake japan inversion analysis based on dispersive tsunami simulations 1 the large tsunami of the 2011 tohoku oki earthquake was clearly recorded by the ocean bottom pressure and gps wave gauges deployed in and around japan we estimated the initial tsunami water height distribution by inversion analysis of the waveforms based on dispersive tsunami simulations the distribution is characterized by a peak height of 8 m located near the trench and the high water 2m region extending landward with a width of 100 km a series of numerical simulations suggests that a relatively steep peak located near the trench is necessary in order to simultaneously reproduce the dispersive wave at a far field station and the near field waveforms furthermore we estimated the coseismic slip distribution at the plate boundary which indicates that large slip 30 m occurred at a depth of 20 km which corresponds to a large slip deficit area in the interseismic period another slip 25 m occurred at the shallower part 10 km during the rupture

fdm simulation of seismic waves ocean acoustic waves and tsunamis based on tsunami coupled equations of motion we have developed a new unified modeling technique for the total simulation of seismic waves ocean acoustic waves and tsunamis resulting from earthquakes based on a finite difference method simulation of the 3d equations of motion using the equilibrium between the pressure gradient and gravity in these equations tsunami propagation is naturally incorporated in the simulation based on the equations of motion the performance of the parallel computation for the newly developed tsunami coupled equations using a domain partitioning procedure shows a high efficiency coefficient with a large number of cpu cores the simulation results show how the near field term associated with seismic waves produced by shallow earthquakes leads to a permanent coseismic deformation of the ground surface which gives rise to the initial tsunami on the sea surface propagation of the tsunami along the sea surface as a gravity wave and ocean acoustic waves in seawater with high frequency multiple p wave reflections between the free surface and sea bottom are also clearly demonstrated by the present simulations we find a good agreement in the tsunami waveform between our results and those obtained by other simulations based on an analytical model and the navier stokes equations demonstrating the effectiveness of the tsunami coupling simulation model based on this simulation we show that the ratio of the amplitude of ocean acoustic waves to the height of the tsunami both of which are produced by the earthquake strongly depends on the rise time of the earthquake rupture this ratio can be used to obtain a more detailed understanding of the source rupture processes of subduction zone earthquakes and for implementing an improved tsunami alert system for slow tsunami earthquakes

evaluating the structure and magnitude of the ash plume during the initial phase of the 2010 eyjafjallajokull eruption using lidar observations and name simulations 1 the eyjafjallajokull volcano in iceland erupted explosively on 14 april 2010 emitting a plume of ash into the atmosphere the ash was transported from iceland toward europe where mostly cloud free skies allowed ground based lidars at chilbolton in england and leipzig in germany to estimate the mass concentration in the ash cloud as it passed overhead the uk met office s numerical atmospheric dispersion modeling environment name has been used to simulate the evolution of the ash cloud from the eyjafjallajokull volcano during the initial phase of the ash emissions 14 16 april 2010 name captures the timing and sloped structure of the ash layer observed over leipzig close to the central axis of the ash cloud relatively small errors in the ash cloud position probably caused by the cumulative effect of errors in the driving meteorology en route result in a timing error at distances far from the central axis of the ash cloud taking the timing error into account name is able to capture the sloped ash layer over the uk comparison of the lidar observations and name simulations has allowed an estimation of the plume height time series to be made it is necessary to include in the model input the large variations in plume height in order to accurately predict the ash cloud structure at long range quantitative comparison with the mass concentrations at leipzig and chilbolton suggest that around 3 of the total emitted mass is transported as far as these sites by small 100 m diameter ash particles

a user friendly one dimensional model for wet volcanic plumes 1 this paper presents a user friendly graphically based numerical model of one dimensional steady state homogeneous volcanic plumes that calculates and plots profiles of upward velocity plume density radius temperature and other parameters as a function of height the model considers effects of water condensation and ice formation on plume dynamics as well as the effect of water added to the plume at the vent atmospheric conditions may be specified through input parameters of constant lapse rates and relative humidity or by loading profiles of actual atmospheric soundings to illustrate the utility of the model we compare calculations with field based estimates of plume height 9 km and eruption rate 4 105 kg s during a brief tephra eruption at mount st helens on 8 march 2005 results show that the atmospheric conditions on that day boosted plume height by 1 3 km over that in a standard dry atmosphere although the eruption temperature was unknown model calculations most closely match the observations for a temperature that is below magmatic but above 100 c

formation of an archaean continent about 30 of the earth is covered by continents but only about 10 small kernels of these continentsae known as archaean cratonsae are continental fragments formed before 2 5 gyr ago the kaapvaal craton of south africa which formed and stabilized between 3 7 and 2 7 gyr ago is one of the oldest reasonably sized examples of these continental fragments it consists of a mosaic of subdomains that have been welded together by processes similar to those of modern day plate tectonics the earliest subdomains may have owed their origin to the onset of efficient recycling from the earth s hydrosphere into the mantle

three dimensional tsunami generation simulation due to sea bottom deformation and its interpretation based on the linear theory summary the present study investigates the tsunami generation process by using 3 d numerical simulations and the linear potential theory first we evaluate the relation between sea bottom elevation and sea surface elevation as function of source size l sea depth h and source duration t based on 3 d numerical simulations the surface elevation decreases with increasing sea depth and source duration the difference between the sea bottom and the sea surface elevation appears when the source size is smaller than approximately 10 times the sea depth for a short source duration the linear potential theory can precisely predict the numerical simulation results based on the theory we can consider the tsunami generation as two spatial lowpass filter processes in which the cut off wavenumbers are given by the sea depth and the source duration the criteria for small source size and short source duration are given as l 13h and t l 8c respectively where c is the phase velocity of the tsunami we then simulate the tsunami generation of the 1896 sanriku tsunami earthquake japan the simulated sea surface elevation is significantly different from the sea bottom elevation which suggests the need for correction of the sea depth and source duration for the precise evaluation of the initial water height distribution to include these effects in 2 d simulations we can use the impulse response function and add the fractional sea surface uplift within the time step to the sea surface for each time step

spatial distribution of volcanic ash deposits of 2011 puyehue cordon caulle eruption in patagonia as measured by a perturbation in ndvi temporal dynamics abstract volcanic ash fallout is a recurrent environmental disturbance in forests arid and semi arid rangelands of patagonia south america the ash deposits over large areas are responsible for several impacts on ecological processes agricultural production and health of local communities public policy decision making needs monitoring information of the affected areas by ash fallout in order to better orient social economic and productive aids the aim of this study was to analyze the spatial distribution of volcanic ash deposits from the eruption of puyehue cordon caulle in 2011 by identifying a sudden change in the normalized difference vegetation index ndvi temporal dynamics defined as a perturbation located in the time series we applied a sparse wavelet transform using the basis pursuit algorithm to ndvi time series obtained from the moderate resolution image spectroradiometer modis sensor to identify perturbations at a pixel level the spatial distribution of the perturbation promoted by ash deposits in patagonia was successfully identified and characterized by means of a perturbation in ndvi temporal dynamics results are encouraging for the future development of a new platform in combination with data from forecasting models and tracking of ash cloud trajectories and dispersion to inform stakeholders to mitigate impact of volcanic ash on agricultural production and to orient public intervention strategies after a volcanic eruption followed by ash fallout over a wide region

quantification of volcanic cloud top heights and thicknesses using a train observations for the 2008 chaiten eruption new evidence of vertically thin 10 km ash clouds from the may 2008 chaiten eruption in southern chile is presented a train remote sensors were used to measure high resolution volcanic cloud top heights vcths during the explosive phase 2 10 may 2008 of the eruption ash clouds were identified using a reverse absorption technique applied to hyperspectral measurements taken by the atmospheric infrared sounder once identified heights and thicknesses were derived from the cloud aerosol lidar with orthogonal polarization caliop instrument as these two instruments are part of the same constellation of satellites coincident retrievals are routinely possible collocation of the data allowed for detection of volcanic ash within caliop profiles using a simple thresholding algorithm vcth and thickness were derived from the caliop profiles a total of 12 vcth measurements ranging from 3 7 to 16 6 km have been derived back trajectories from the hybrid single particle lagrangian integrated trajectory dispersion model were used as a check on volcanic origin of the detected ash clouds ensemble forward trajectories were generated to demonstrate how the new data could be used to improve volcanic ash advisory center operations the findings reported here demonstrate several cases where low level ash was not recorded previously and include observations of thin ash clouds at large distances 4000 km from the volcano

high precision slip distribution of the 1944 tonankai earthquake inferred from tsunami waveforms possible slip on a splay fault abstract inversion of tsunami waveforms is a well established technique for estimating the slip distributions of subduction zone earthquakes with some of the most detailed results having been obtained for earthquakes in the nankai trough sw japan the present study although it uses a method and tsunami waveform data set almost identical to previous study aims to improve on previous work by using a more precise specification of initial conditions for the calculation of tsunami green s functions specifically we incorporated four improvements in the present study 1 we used a realistic plate model based only on seismic survey results and assumed it to be the fault plane of the 1944 tonankai earthquake 2 the smallest subfaults consistent with the long wavelength approximation were used in the tsunami inversion analysis 3 we included the effect of horizontal displacement of the ocean bottom on tsunami generation and 4 we performed a checkerboard resolution test as obtained in previous studies a zone of high slip 2 0 m was resolved off the shima peninsula however the more precise calculation of tsunami green s functions has revealed additional detail that was not evident in previous studies which we demonstrate is resolvable and correlates with the position of known faults in the accretionary prism while there was little or no slip near the trench axis in the eastern part of the rupture zone there was up to 1 5 m of slip resolved within 30 km of the trough axis in the western part along the coast of the kii peninsula this troughward slip zone coincides with the position of a large splay fault mapped in multichannel reflection surveys furthermore it is also clear that the upper edge of the enshu fault off shima and atsumi peninsulas is consistent with the up dip limit of slip in the eastern part of our model we tested the possibility that slip occurred on the former splay fault instead of on the plate interface during the 1944 tonankai earthquake and find that slip on this splay fault is also consistent with the data although we cannot distinguish whether slip was dominant on the splay fault or on the plate interface we further suggest that the position of the enshu fault may be determined by the subduction of topographic highs and that such faults may have an important influence on the up dip rupture limit of the 1944 tonankai and potentially other subduction zone earthquakes

configuration of the late paleoproterozoic supercontinent columbia insights from radiating mafic dyke swarms abstract remnants of 2 1 1 8 ga orogens can be recognized in nearly every craton assembled within reconstructions of the rodinia supercontinent although no particular pattern of laterally extensive orogenic belts emerges these cratons may be the fragments of an older supercontinent formed in response to the collision and accretion of even older cratons during the early earth history paleomagnetic constraints have played a limited role in many previous reconstructions of the early precambrian supercontinent mainly because of the poor age control and a large scatter of the paleomagnetic poles the geometry of giant radiating dyke swarms and orogenic belts provide important constraints for the reconstruction of the pre rodinian supercontinent some early unmetamorphosed and undeformed mafic dyke swarms in north china southern peninsular india and north america share coeval age of 1 85 ga if these continents are assembled the overall pattern exhibited by the mafic dyke swarms appears to constitute a giant radiating swarm with a piercing point between the cuddapah rift in south india and the xiong er aulacogen in north china this suggests that the north china craton indian craton and canadian shield may be fragmented from the same landmass the reconstruction of 1 85 ga giant radiating dyke swarm attempted in this paper suggests that the north china craton india craton and canadian shield were united together to form a landmass within the columbia supercontinent before its extension and break up the 1 90 1 85 ga andean style north orogenic belt suggests that a subduction zone existed on the northern margin of the north china craton wopmay orogenic belt developed in a 1 88 1 84 ga continental volcano plutonic arc which is interpreted as the product of eastward subduction of oceanic lithosphere the transantarctica orogenic belt in east antarctica may be another candidate to be linked with the subduction zone the north orogenic wopmay orogenic and transantarctica orogenic belts could be connected to form a continuous subduction zone the orogenic comparison strengthens the configuration of the columbia supercontinent proposed by the reconstruction of the giant radiating dyke swarm the laurentia west australia and east antarctica were relatively stable from 1 85 ga to 1 20 ga as inferred from the data on dyke swarms magmatism and the paleomagnetism these continents constituted the core of the columbia supercontinent in the late paleoproterozoic time the north china craton and indian craton were however separated from the columbia supercontinent during the mesoproterozoic time

satellite and radar analysis of the volcanic cumulonimbi at mount pinatubo philippines 1991 1 several observers reported interesting convective phenomena in the months and years following the 15 june 1991 climactic eruption of mount pinatubo philippines the observed phenomena included deep convection resulting from 1 lower level eruptions 2 secondary phreatic explosions and 3 enhanced surface heating we have compared radar records and satellite imagery to obtain a more coherent understanding of these volcanic cumulonimbi from 17 june to 30 september 1991 and to identify observational challenges for future events geostationary satellite imagery analysis for the period shows that the dominant localized effect on convection following the eruption was to bring the afternoon evening peak in the diurnal convective cycle over the mountain forward by 2 3 hours we examined four cases in detail and identified a number of possible interactions between the volcano and the meteorological environment for three of these cases the volcanic emissions apparently mixed with cumulonimbi developing around the volcano on 21 june 1991 microphysical analyses clearly show a strong reduction in cloud top effective particle radius caused by the additional aerosols in the cloud while on the two other occasions there was a slight or barely detectible reduction in the fourth case for a cumulonimbus developing above a major secondary phreatic explosion no unusually small cloud top effective radii were found perhaps because the ash injected into the cloud was dominated by giant cloud condensation nuclei these cases verify that volcanic emissions can be released through the depth of the troposphere and lower stratosphere from relatively small eruptions future major tropical eruptions and their aftermaths should be studied using intensive ground and satellite based observations to explore these phenomena further

simulation of a dispersive tsunami due to the 2016 el salvador nicaragua outer rise earthquake m w 6 9 the 2016 el salvador nicaragua outer rise earthquake mw 6 9 generated a small tsunami observed at the ocean bottom pressure sensor dart 32411 in the pacific ocean off central america the dispersive observed tsunami is well simulated using the linear boussinesq equations from the dispersive character of tsunami waveform the fault length and width of the outer rise event is estimated to be 30 and 15 km respectively the estimated seismic moment of 3 16 1019 nm is the same as the estimation in the global cmt catalog the dispersive character of the tsunami in the deep ocean caused by the 2016 outer rise el salvador nicaragua earthquake could constrain the fault size and the slip amount or the seismic moment of the event

complex earthquake rupture and local tsunamis 1 in contrast to far field tsunami amplitudes that are fairly well predicted by the seismic moment of subduction zone earthquakes there exists significant variation in the scaling of local tsunami amplitude with respect to seismic moment from a global catalog of tsunami runup observations this variability is greatest for the most frequently occurring tsunamigenic subduction zone earthquakes in the magnitude range of 7 mw 8 5 variability in local tsunami runup scaling can be ascribed to tsunami source parameters that are independent of seismic moment variations in the water depth in the source region the combination of higher slip and lower shear modulus at shallow depth and rupture complexity in the form of heterogeneous slip distribution patterns the focus of this study is on the effect that rupture complexity has on the local tsunami wave field a wide range of slip distribution patterns are generated using a stochastic self affine source model that is consistent with the falloff of far field seismic displacement spectra at high frequencies the synthetic slip distributions generated by the stochastic source model are discretized and the vertical displacement fields from point source elastic dislocation expressions are superimposed to compute the coseismic vertical displacement field for shallow subduction zone earthquakes it is demonstrated that self affine irregularities of the slip distribution result in significant variations in local tsunami amplitude the effects of rupture complexity are less pronounced for earthquakes at greater depth or along faults with steep dip angles for a test region along the pacific coast of central mexico peak nearshore tsunami amplitude is calculated for a large number n 100 of synthetic slip distribution patterns all with identical seismic moment mw 8 1 analysis of the results indicates that for earthquakes of a fixed location geometry and seismic moment peak nearshore tsunami amplitude can vary by a factor of 3 or more these results indicate that there is substantially more variation in the local tsunami wave field derived from the inherent complexity subduction zone earthquakes than predicted by a simple elastic dislocation model probabilistic methods that take into account variability in earthquake rupture processes are likely to yield more accurate assessments of tsunami hazards

seismic and tsunami wave propagation of the 2011 off the pacific coast of tohoku earthquake as inferred from the tsunami coupled finite difference simulation abstract the 2011 tohoku earthquake m 9 0 caused significant hazards including strong ground motion coseismic ground deformation and tsunamis for a deeper understanding of these phenomena we conducted a large scale parallel computer simulation by means of the finite difference method fdm with newly developed tsunami coupled equations of motion this method is based on the equations of motion for an elastic medium treating seawater as elastic material having zero s wave velocity tsunami waves are included by taking into account gravity and their equilibrium with the pressure gradient an effective method of fdm simulation using the state of the art massively parallelized k computer is also studied with the use of a 3d layered velocity structure that includes topography and bathymetry basement structure moho depth and plate boundaries and use of the appropriate source rupture model based on joint inversion of seismic waves and geodetic observations the simulated seismic waves demonstrate anomalous seismic wave propagation by the thick 3d basin structure inland we also found that the sea column acts as a strong absorber of seismic waves for shallow up dip slip on the ocean side coseismic deformation and tsunamis are dynamically generated in this simulation tsunami attacks on the subsided pacific coast are simulated without any additional assumptions we also modeled the tsunami and seismic records of ocean bottom pressure gauges above the fault because sea bottom tsunami and seismic observation is powerful but very complex recording both seismic and tsunami waves the use of these coupled numerical simulations has great potential for resolving complex source fault rupture processes in a 3d heterogeneous structure online material mpeg movies of fault slip seismic wave propagation seafloor and ground displacement and tsunamic propagation

the impact of particle shape on fall velocity implications for volcanic ash dispersion modelling abstract modelling atmospheric volcanic ash dispersion is a critical tool in mitigating the impact of large explosive eruptions it is also useful for understanding and reconstructing past events most atmospheric dispersion models include a sedimentation velocity term that is sensitive to the physical properties of the particle but many do not use particle shape as an input parameter instead particles are assumed to be spherical there are many empirical and semi empirical shape dependent drag laws we measure the velocity of scaled analogue particles over the range of flow conditions anticipated for volcanic ash dispersion to test published formulae against an independent dataset we use a semi empirical formula we determined to be accurate for non spheres to investigate the sensitivity of the modelled transport of an ash cloud to particle shape using the atmospheric dispersion model name and a shape parameter we measure for non spherical ash particles from katla volcano iceland we find that model particle trajectories are sensitive to particle shape for particles 1 3 m diameter the sedimentation velocity of smaller particles is low compared to atmospheric vertical velocities sensitivity to shape increases with size such that 100 m particles can travel 44 further from the source when they are highly non spherical sphericity 0 5 despite the sensitivity of the fall velocity of large particles to their shape however forecasts of distal ash concentration using particle size distributions of 0 1 100 m and 0 1 250 m show relatively good agreement between a spherical and non spherical case for the first 36 h after an eruption the vertical structure of an ash cloud is more sensitive to particle shape than the horizontal extent model particle trajectories are also sensitive to particle size and we find a discrepancy between different particle size parameters for non spherical ash particle long axis l used in cryptotephra studies was on average twice the equivalent volume sphere diameter dv used in dispersion modelling for tephra samples from katla volcano iceland this discrepancy in size measurements could explain the observed travel distance of large distal cryptotephra shards

simulation of tsunami induced by dynamic displacement of seabed due to seismic faulting in conventional tsunami simulation techniques simplifications have been employed by neglecting the dynamic seabed displacement resulting from fracturing of a seismic fault and considering only the static contribution the water layer is also assumed to be incompressible regardless of its acoustic effects they should be reconsidered in light of the state of the art technology because considerable discrepancies between numerical simulations and actual observation have been pointed out regarding for example arrival time and wave height in the present study tsunami simulation is conducted without using these kinds of simplification taking into account both the dynamic displacement and acoustic effects as a result thus simulated tsunamis are found to be remarkably larger in the wave height especially in the near fault area where these two effects are superposed in far field however tsunamis thus simulated are likely to show little difference in the wave height but show considerable difference in the arrival time in addition the present dynamic analysis is capable of simulating the water wave induced by the rayleigh wave propagated along the seabed

three dimensional simulation of tsunami generation and propagation application to intraplate events 1 a parallel finite difference numerical simulation program based on the navier stokes ns equations is developed for simulating 3 d tsunami generation and propagation we can simulate tsunami propagation over more than 1000 km using this program although such tsunami propagation over long distances has usually been conducted on the basis of on 2 d simulations some 2 d simulations have assumed that the initial tsunami distribution is identical to the sea bottom deformation caused by the earthquake the 3 d simulations however indicate that this assumption is inappropriate when the source width 2ax is less than 10 times the sea depth h 2ax 10h for a source process time of 20 s dispersion of tsunami appears when the source is of small size and the dispersion is more apparent in a direction perpendicular to the fault strike we also conduct tsunami simulations for two intraplate events the 2004 off kii peninsula m 7 4 and the 2007 off kuril islands m 8 1 events the 3 d tsunami simulation has successfully simulated the offshore tsunami and we obtained good agreement between the observations and the calculations for both events in particular for the 2004 off kii peninsula event although the 2 d linear long wave theory cannot simulate important characteristics in the record such as the arrival time of the peak amplitude and the dispersive tsunami the 3 d ns simulation is well able to model those characteristics

investigation of the complex dynamics and structure of the 2010 eyjafjallajokull volcanic ash cloud using multispectral images and numerical simulations 1 we investigated the structure and evolution of the 2010 eyjafjallajokull volcanic cloud and its dispersal over iceland and europe integrating satellite multispectral images and numerical simulations data acquired by medium resolution imaging spectrometer meris and advanced spaceborne thermal emission and reflection radiometer aster have been analyzed to quantify the cloud extent and composition the vol calpuff dispersal code was applied to reconstruct the transient and 3 d evolution of the cloud source parameters estimated on the base of available a posteriori volcanological data sets have been used quantitative comparisons between satellite retrievals and modeling results were performed for two selected instants of time during the first and third eruptive phases on a regional scale sensitivity of the model to initial volcanological conditions has been analyzed at continental scale several complex non intuitive features of cloud dynamics have been highlighted and strengths and limitations of the adopted methods identified the main findings are the level of quantitative agreement between satellite observations and numerical results depends on ash cloud composition particle sizes and concentration with better agreement for smaller particles and higher concentrations the agreement between observations and modeling outcomes also depends on the temporal stability of volcanological conditions and the complexity of the meteorological wind field the irregular dispersion of ash as reconstructed from satellite data and numerical modeling can be well explained by the different response of particle sizes to strong vertical wind shear and by resuspension processes acting at ground level eruptive source conditions are the main source of uncertainty in modeling especially during an ongoing crisis and at long range scales