temporal evolution of the magmatic system at tungurahua volcano ecuador detected by geodetic observations abstract changes in the pathway and timescale of magma ascent can be responsible for variations in eruptive style during long lived eruptions but are only documented at a small number of well instrumented systems here we integrate ps insar from high resolution terrasar x radar imagery with continuous gps data from 4 sites at tungurahua volcano ecuador our results show long term uplift between 2011 and 2014 associated with a continuously inflating prolate spheroid reservoir at a depth of 10 km beneath the summit comparisons with eruptive flux taking compressibility into account suggest that during this time period slightly over half the magma supplied to the system was erupted the observations span three distinct phases of eruption and in 2012 2013 an increase in eruptive activity was accompanied by uplift on the volcano s western flank similar episodes have previously been observed during large vulcanian eruptions and we attribute them to intrusions into an area of mechanical weakness a localised patch of subsidence mid way up the tungurahua s western flank is co located with a swarm of shallow long period seismicity and may represent a potential site for a development of a lateral vent this study demonstrates that satellite geodetic techniques are capable of characterising the geodetic signature of transitions in eruptive style during long lived andesitic eruptions even where deformation is low magnitude and measurements are challenging

use of terrestrial laser scanning tls for monitoring and modelling of geomorphic processes and phenomena at a small and medium spatial scale in polar environment scott river spitsbergen abstract the application of terrestrial laser scanning tls for precise modelling of land relief and quantitative estimation of spatial and temporal transformations can contribute to better understanding of catchment forming processes experimental field measurements utilising the 3d laser scanning technology were carried out within the scott river catchment located in the nw part of the wedel jarlsberg land spitsbergen the measurements concerned the glacier free part of the scott river valley floor with a length of 3 5 km and width from 0 3 to 1 5 km and were conducted with a state of the art medium range stationary laser scanner a leica scan station c10 a complex set of measurements of the valley floor were carried out from 86 measurement sites interrelated by the application of 82 common target points during scanning from 5 to 19 million measurements were performed at each of the sites and a point cloud constituting a model space was obtained by merging individual model spaces a digital surface model dsm of the scott river valley was obtained with a co registration error not exceeding 9 mm the accuracy of the model permitted precise measurements of dimensions of landforms of varied scales on the main valley floor and slopes and in selected sub catchments the analyses verified the efficiency of the measurement system in polar meteorological conditions of spitsbergen in mid summer

the influence of erosional processes on the visibility of permanent scatterers features from sar remote sensing on mount etna e sicily abstract analysis of 1549 dinsar interferograms covering the period from 2003 to 2010 has highlighted significant motion along the entire set of the active faults identified by advanced dinsar analyses i e permanent scatterers features psf affecting the mount etna volcano in eastern sicily in the analysed period the absence of significant seismicity producing co seismic ground deformation suggests that the overall deformation that has been recognized on the interferograms is to be associated with interseismic almost continuous creep which is well documented along most of the active faults according to field evidence the structures should accumulate displacements resulting in their permanent visibility on the interferograms progressively increases through time this expected behaviour has been recognised only for part of the entire set of structures other tectonic features in fact show episodic appearances alternating with periods of absence of ground displacement on the interferograms simulating a stick slip mechanism of deformation conflicting with field evidence this apparently incongruous behaviour can be interpreted as the result of topographic changes due to the combination of the tectonic displacements with related amounts of the differential erosion and deposition across the fault line the comparison between the history of the appearances and the monthly rainfall in the region seems to demonstrate that these structures appear when one of the two interacting processes governing the topographic changes around the fault i e tectonic vs erosional prevails over the other otherwise the same structures are not evident on the interferograms when the two components are in balance

resolving three dimensional surface displacements from insar measurements a review abstract one dimensional measurement along the line of sight los direction has greatly limited the capability of insar technique in the investigation of surface displacements and their dynamics in recent years great efforts have been made to resolve complete three dimensional 3 d displacements from insar measurements this contribution is intended to provide a systematic review of the progress achieved in this field based on an analysis of the insar los measurements we first cover two commonly used techniques i e offset tracking and multi aperture insar mai with which the surface displacement in the azimuth direction can be measured together with the los displacement several methods for mapping 3 d displacements using insar measurements are subsequently presented and categorized into three groups i combination of multi pass los and azimuth measurements ii integration of insar and gps data and iii prior information assisted approaches the strengths and weaknesses of each method are analyzed to show the applicability of each method to specific 3 d displacement mapping cases in hope to provide a useful guidance in choosing a suitable approach accordingly finally suggestions for resolving the challenging issues and outlook of future research are given

geometry and kinematics of the fault systems controlling the unstable flank of etna volcano sicily abstract an updated tectonic framework of etna s unstable flank has been defined as a result of multidisciplinary analyses carried out by integrating geological and geophysical data the different typologies of datasets have been analyzed and correlated in order to constrain the geometry and kinematics of the fault systems controlling the unstable flank of etna volcano and to better understand their complex relationship with the offshore morphostructures of the continental margin in particular we have considered as the main structural elements the following four fault systems pernicana ragalna tremestieri trecastagni and timpe slip rates and kinematics have been estimated in both long and short terms respectively from geological and seismotectonic geodetic data data integration has allowed defining five kinematic domains in the sliding flank of etna 1 the ne block bordered by the pernicana fault and characterised by the highest deformation velocities ground velocity progressively diminishes toward south with a clockwise rotation of the vectors defining 2 the block embracing the central part of the timpe system 3 the giarre wedge 4 the medium east block bounded by the s tecla and trecastagni faults and 5 the se block bordered by the hidden belpasso ognina tectonic lineament the dynamics of these blocks takes place through discontinuous movements sudden short term accelerations related to the magma intrusion are superimposed to a fairly constant mid term ese sliding the proposed comprehensive model of the unstable flank provides the basic input parameters for applying analytical models to flank dynamics of etna volcano

gravitational sliding of the mt etna massif along a sloping basement geological field evidence and laboratory modelling indicate that volcanoes constructed on slopes slide downhill if this happens on an active volcano then the movement will distort deformation data and thus potentially compromise interpretation our recent gps measurements demonstrate that the entire edifice of mt etna is sliding to the ese the overall direction of slope of its complex rough sedimentary basement we report methods of discriminating the sliding vector from other deformation processes and of measuring its velocity which averaged 14 mm year 1 during four intervals between 2001 and 2012 though sliding of one sector of a volcano due to flank instability is widespread and well known this is the first time basement sliding of an entire active volcano has been directly observed this is important because the geological record shows that such sliding volcanoes are prone to devastating sector collapse on the downslope side and whole volcano migration should be taken into account when assessing future collapse hazard it is also important in eruption forecasting as the sliding vector needs to be allowed for when interpreting deformation events that take place above the sliding basement within the superstructure of the active volcano as might occur with dyke intrusion or inflation deflation episodes

simulation and observations of stratospheric aerosols from the 2009 sarychev volcanic eruption 1 we used a general circulation model of earth s climate to conduct simulations of the 12 16 june 2009 eruption of sarychev volcano 48 1 n 153 2 e the model simulates the formation and transport of the stratospheric sulfate aerosol cloud from the eruption and the resulting climate response we compared optical depth results from these simulations with limb scatter measurements from the optical spectrograph and infrared imaging system osiris in situ measurements from balloon borne instruments lofted from laramie wyoming 41 3 n 105 7 w and five lidar stations located throughout the northern hemisphere the aerosol cloud covered most of the northern hemisphere extending slightly into the tropics with peak backscatter measured between 12 and 16 km in altitude aerosol concentrations returned to near background levels by spring 2010 after accounting for expected sources of discrepancy between each of the data sources the magnitudes and spatial distributions of aerosol optical depth due to the eruption largely agree in conducting the simulations we likely overestimated both particle size and the amount of so2 injected into the stratosphere resulting in modeled optical depth values that were a factor of 2 4 too high modeled optical depth due to the eruption shows a peak too late in high latitudes and too early in low latitudes suggesting a problem with stratospheric circulation in the model the model also shows a higher decay rate in optical depth than is observed showing an inaccuracy in stratospheric removal rates in some seasons the modeled removal rate of sulfate aerosols from the sarychev eruption is higher than the rate calculated for aerosols from the 1991 eruption of mt pinatubo

long term stress strain analysis of volcano flank instability the eastern sector of etna from 1980 to 2012 1 we investigated the evolution of seismicity and deformation in the unstable eastern flank of etna volcano over a 30 year period from 1980 to 2012 a significant temporal correlation has been revealed between periods of flank acceleration and intensified seismic activity by comparing seismicity along the northern border pernicana fault system of the sliding flank and the deformation of the eastern flank two marked phases have been observed in 1984 1986 and in the years following 2002 these two phases are separated by an intermediate phase from 1987 to 2001 in which the flank sliding slowed down and the seismicity dropped drastically this common temporal evolution in the deformation rate and seismic release supports the hypothesis that the seismicity in the northern border can be viewed as a marker of the response to accommodate the stress exerted by the traction of the eastern flank sliding this interplay has also been corroborated by finite element method numerical computations that highlight a good correlation between the seismicity pattern and areas of positive stress changes induced by the sliding surface the two intense phases of flank acceleration are representative of two main different sources volcano flank instability stretching the eastern sector in the first 1984 1986 phase and magmatic intrusions pushing the eastern flank seaward since the 2002 2003 eruption establishing the relationship between flank acceleration and seismic activation therefore contributes to understanding etna s mechanical behavior and provides insights into the processes regulating the unstable flank response

geological evolution of mount etna volcano italy from earliest products until the first central volcanism between 500 and 100 ka ago inferred from geochronological and stratigraphic data we present an updated geological evolution of mount etna volcano based on new 40ar 39ar age determinations and stratigraphic data integrating the previous k ar ages volcanism began at about 500 ka ago through submarine eruptions on the gela catania foredeep basin about 300 ka ago fissure type eruptions occurred on the ancient alluvial plain of the simeto river forming a lava plateau from about 220 ka ago the eruptive activity was localised mainly along the ionian coast where fissure type eruptions built a shield volcano between 129 and 126 ka ago volcanism shifted westward toward the central portion of the present volcano val calanna moscarello area furthermore scattered effusive eruptions on the southern periphery of etna edifice occurred until about 121 ka ago the stabilization of the plumbing system on the valle del bove area is marked by the building of two small polygenic edifices tarderia and rocche volcanoes their eruptive activity was rather coeval ending 106 and 102 ka ago respectively during the investigated time span volcanism in etna region was controlled by a main e w extensional tectonic related to the reactivation of malta escarpment fault system in eastern sicily

geometric and kinematic variations along the active pernicana fault implication for the dynamics of mount etna ne flank italy abstract geological and structural analyses and ground deformation measurements performed along the eastern portion of the pernicana fault system and its splay segments allow the structural setting and the kinematic behaviour of the fault to be defined in addition the interrelationship between the deformation style of fault segments and the variations of the volcanic pile thickness along the fault strike are investigated using detailed sedimentary basement data brittle deformation dominates the n105 fault segment where the volcanic pile is more than 200 m thick with the development of a well defined fault plane characterised by main left lateral kinematics the transtensive deformation of the n105 fault is partitioned eastward at rocca campana to a main n120 segment here this segment crosses a culmination of the sedimentary basement close to vena village where the deformation pattern of the thin volcanic pile less than 100 m thick is influenced by the more ductile behaviour of the basement generating local short structures with different orientation and kinematics in the southern block of the fault on the northern one short e w trending faults show left lateral displacements with a minor reverse component on south dipping planes this kinematics is related to the oblique orientation of the n120 segment with respect to the seaward motion of the ne flank of etna on the whole the compressive component of the deformation affecting the n120 segment of the pernicana fault system generates a positive flower structure

coseismic displacements and creeping along the pernicana fault etna italy in the last 17 years a detailed study of a tectonic structure on a volcano abstract the pernicana fault is a tectonic fault located on mt etna sicily movements across this structure have been monitored over the last 17 years by a levelling network operated by the osservatorio vesuviano during the monitoring period the network has recorded coseismic displacements associated with earthquakes of magnitude 4 5 as well as aseismic displacements we present a detailed analysis of the displacement data aimed at modelling the geometry and mechanism of this fault as well as the size and mechanisms of individual earthquakes we use for interpreting the displacement data two types of inverse methods the first is able to determine from ground deformation data the geometry mechanism and location of a system rectangular faults with homogeneous dislocation the second finds for a fixed fault system geometry the heterogeneous slip distribution giving the best fit to the data the total recorded displacements during the last 17 years are well described by a single homogeneous rectangular normal fault with dislocation and size corresponding to a magnitude 5 7 earthquake thus revealing intense dynamics along such a fault coseismic displacements for individual earthquakes of considerable magnitude account for about 30 of the total deformation when interpreted in terms of an homogenous slip fault as inferred from total deformation some aspects of the data are not well explained thus calling for heterogeneous slip models it is hence possible with a certain approximation to distinguish the slip distributions associated with individual earthquakes from the almost homogeneous slip resulting from the sum of coseismic and aseismic movements the inferred seismic moments for the two larger earthquakes that occurred along this fault are considerable higher than reported in seismic bulletins about 1 degree of magnitude the results obtained here support the important role of levelling data for the detailed study of a peculiar kind of tectonic structure on a volcano aimed at understanding the complex interaction between volcano dynamics and induced movements along well defined structures

dynamics of the eastern flank of mt etna volcano italy investigated by a dense gps network abstract mount etna has developed at the intersection of two regional tectonic lineaments the nnw sse trending hybleo maltese escarpment which separates the thick inland continental crust of the african platform from the ionian mesozoic oceanic crust and the ne sw messina fiumefreddo fault that marks a rift zone between south calabria and north eastern sicily extending as far as the mt etna area all tectonic features affect with outstanding surface features the eastern side of the volcano the eastern flank of the volcano is affected by a long term motion toward ese in 1997 in order to increase the detail of the ground deformation pattern on the lower eastern flank of mt etna a new gps network the ionica network was installed on this sector of the volcano this gps network consists of 24 stations and covers the lower eastern flank of the volcano from the town of catania to taormina and from the coastline up to an altitude of about 1300 m all the new stations consist in self centring benchmarks this kind of benchmark allows all station set up errors to be avoided before the merging of the ionica network to the frame of the global gps network of mt etna in june 2001 three surveys were carried out on this network in september 1997 august 1998 and january 2001 from the ground deformation pattern it is possible to distinguish two different sectors showing different characteristics of deformation the southern part of the network shows a more uniform distribution of the vertical motion with a mean se ward horizontal component while the northern one shows an heterogeneous vertical motion with a ese ward horizontal component furthermore a higher velocity is detected between 1997 and 1998 due to the additional stress induced by a shallow intrusion on the nw flank of the volcano the model resulting from data inversions defines a wide sliding plane beneath the entire eastern flank of the volcano with a low dip angle the expected velocity vectors fit well the observed ones even if the measured velocities are still quite higher than expected at lowermost stations the vertical inclination of the velocity vectors measured during the 1998 2001 period gradually decreases from west to east suggesting a sort of rotational movement of the south eastern flank interrupted by some anomalous vectors on the lower part that show higher vertical velocities these anomalies being located on a wedge defined by the intersection of the main nnw sse and ne sw fault systems and near the timpe faults are probably due to the activity of the vertical faults cutting the lower eastern flank of mt etna stations lying on the hanging wall and on the footwall of the timpe fault system are affected by similar horizontal displacements meaning that these structures are moving eastwards together with the sliding flank this evidence suggests that the timpe faults are probably second order structures with respect to the detachment surface these results depict a structural framework of the eastern flank of mt etna in which the low angle dislocation can be considered as a first order approximation of an actual listric plane and the current active part of the timpe fault system is confined above the detachment surface

very shallow dyke intrusion and potential slope failure imaged by ground deformation the 28 december 2014 eruption on mount etna on 28 december 2014 eruptive activity resumed at mount etna with fire fountain activity feeding two lava flows on the eastern and southwestern upper flanks of the volcano unlike all previous summit activity this eruption produced clear deformation at the summit of the volcano gps displacements and sentinel 1a ascending interferograms were calculated in order to image the ground deformation pattern accompanying the eruption the displacements observed by gps depict a local ground deformation pattern affecting only the upper part of the volcano despite snow cover on the summit differential interferometry synthetic aperture radar dinsar data allowed obtaining more detail on the ground deformation pattern on the upper eastern side of the volcano three dimensional gps displacements inversion located a very shallow ne sw intrusion just beneath the new southeast crater however this model cannot justify all the deformation observed by dinsar thus revealing a gravitational failure of the lava flow field

increase in background stratospheric aerosol observed with lidar at mauna loa observatory and boulder colorado 1 the stratospheric aerosol layer has been monitored with lidars at mauna loa observatory in hawaii and boulder in colorado since 1975 and 2000 respectively following the pinatubo volcanic eruption in june 1991 the global stratosphere has not been perturbed by a major volcanic eruption providing an unprecedented opportunity to study the background aerosol since about 2000 an increase of 4 7 per year in the aerosol backscatter in the altitude range 20 30 km has been detected at both mauna loa and boulder this increase is superimposed on a seasonal cycle with a winter maximum that is modulated by the quasi biennial oscillation qbo in tropical winds of the three major causes for a stratospheric aerosol increase volcanic emissions to the stratosphere increased tropical upwelling and an increase in anthropogenic sulfur gas emissions in the troposphere it appears that a large increase in coal burning since 2002 mainly in china is the likely source of sulfur dioxide that ultimately ends up as the sulfate aerosol responsible for the increased backscatter from the stratospheric aerosol layer the results are consistent with 0 6 0 8 of tropospheric sulfur entering the stratosphere

how to cope with volcano flank dynamics a conceptual model behind possible scenarios for mt etna abstract volcano flank dynamics poses a serious hazard also involving the inhabited lower slopes mt etna is a well studied unstable volcano and a significant amount of data has been collected on the dynamics of its eastern and southern flanks we first propose a conceptual model to describe and explain flank dynamics at etna we identify the preconditions as due to the differential unbuttressing conditions at the volcano base and the triggering factors as shallow magmatic sources dikes reservoirs evidence and parameters and or observations for flank dynamics are listed summarizing the 1994 2010 period of activity based on this we then propose a set of scenarios possibly occurring in case of unrest of the unstable flanks of mt etna flank unrest is a variation in the steady state condition of the volcano flanks possibly accompanied by significant ground deformation seismicity and eruptions the scenarios may provide a general reference and recommendation in case of five types of multi hazard processes related either as a cause or effect to flank dynamics 1 edifice inflation 2 emplacement of dikes along the ne and or s rifts 3 seismicity along pernicana fault system 4 seismicity on the s sector 5 seismicity along timpe fault system each scenario is analyzed and recommendations are given the scenarios may or may not be related to each other in the sense that the probability of occurrence of one scenario may or may not be contingent or dependent upon the prior occurrence of another these scenarios provide a qualitative analysis of the multi hazard processes related to flank dynamics a more quantitative i e probabilistic characterization is under consideration

complete three dimensional coseismic deformation field of the 2016 central tottori earthquake by integrating left and right looking insar observations with the improved sm vce method

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

fem based inversion for heterogeneous fault mechanisms application at etna volcano by dinsar data summary a procedure based on the finite element method fem for high resolution geodetic data inversion was developed to estimate non uniform slip distribution during the 2002 september 22 m3 7 earthquake rupture occurring only one month before the 2002 2003 eruption of etna volcano fem generated synthetic green s functions are combined with an inverse algorithm to simulate deformation of the earthquake for a 3 d problem domain that takes into account heterogeneity of material properties in the volcanic edifice the inversion of dinsar data shows complex kinematics of the northeastern flank of the etna volcano involving the pernicana fault system we detailed the coseismic shear rupture mechanism and highlighted a tensile mechanism never observed before related to a first attempt of magma intrusion which preceded the following october 26 eruption

fault creep and kinematics of the eastern segment of the pernicana fault mt etna italy derived from geodetic observations and their tectonic significance abstract aseismic fault displacements related to numerous fast slipping active faults are frequently observed on mt etna but the characteristics and the rate of displacements along with the behaviour of individual fault segments are poorly constrained to resolve this we installed two local geodetic networks in 1997 along the eastern segment of the pernicana fault one of the most active structures in the geodynamic framework of the volcano the networks are based on the electroptical distance measurements edm and global positioning system gps techniques and consist of four and six benchmarks respectively geodetic data confirm that the tectonic activity of the eastern pernicana fault is controlled by fault creep i e a near continuous stable sliding at a mean slip rate of 2 8 cm yr punctuated by aseismic displacement episodes the analysis of the strain tensor calculated from the edm and gps data indicates that deformation in the fault zone is related to a clear sinistral strike slip movement a more complete picture is obtained from the gps measurements for the rocca campana area where the main structure branches out eastward into a splay fault the inversion of 3d displacement vectors suggests a deformation model consisting of two principal sinistral strike slip faults with an oblique component of movement the maximum observed displacement 6 1 cm measured in the period april 1997 february 1999 is accommodated by the splay fault this finding corroborates the hypothesis that as proposed by the tectonic models in the literature the movement of the eastern segment of the pernicana fault is transferred easterly towards structures at a lower altitude along the same strike e g the fiumefreddo fault as a consequence the pernicana fault may constitute part of a continuous left lateral trans current zone which displaces the whole north eastern flank of mt etna

ground deformation modeling of flank dynamics prior to the 2002 eruption of mt etna on 22 september 2002 1 month before the beginning of the flank eruption on the ne rift an m 3 7 earthquake struck the northeastern part of mt etna on the westernmost part of the pernicana fault in order to investigate the ground deformation pattern associated with this event a multi disciplinary approach is presented here just after the earthquake specific gps surveys were carried out on two small sub networks aimed at monitoring the eastern part of the pernicana fault and some baselines belonging to the northeastern edm monitoring network of mt etna were measured the leveling route on the northeastern flank of the volcano was also surveyed furthermore an investigation using sar interferometry was performed and also the continuous tilt data recorded at a high precision sensor close to the epicenter were analyzed to constrain the coseismic deformation the results of the geodetic surveys show a ground deformation pattern that affects the entire northeastern flank of the volcano clearly shaped by the pernicana fault but too strong and wide to be related only to an m 3 7 earthquake leveling and dinsar data highlight a local strong subsidence up to 7 cm close to the pernicana fault significant displacements up to 2 cm were also detected on the upper part of the ne rift and in the summit craters area while the displacements decrease at lower altitude suggesting that the dislocation did not continue further eastward three dimensional gps data inversions have been attempted in order to model the ground deformation source and its relationship with the volcano plumbing system the model has also been constrained by vertical displacements measured by the leveling survey and by the deformation map obtained by sar interferometry

magma uprising and flank dynamics on mount etna volcano studied using gps data 1994 1995 1 ground deformation occurring on mount etna from 1994 to 1995 is analyzed in this paper this period was characterized by intense volcanic activity at the four summit craters with frequent strombolian activity fire fountains and emplacement of several new lava flows four gps surveys were carried out during this time two as routinely planned each year and an additional two in 1995 to acquire more data to follow the activity at the ne crater the comparisons between gps surveys are reported in terms of horizontal and vertical displacements of each station and in terms of areal dilatation and principal strain axes during the period considered in this work a trend of increasing areal dilatation of the volcano at a rate of about 5 strain yr was recognized it was briefly interrupted by a small contraction about 2 strain in the autumn of 1995 when volcanic activity at the summit craters began in detail the strain distribution of the network is analyzed it allows the detection of areas showing anomalous behavior such as the summit zone or the pernicana fault inversions of the ground displacement vectors have been performed by appropriately combining numerical and analytical approaches results of the inversions suggest structures defining an eastward and southward sliding of the eastern and southeastern sectors of mount etna

feeding system and magma storage beneath mt etna as revealed by recent inflation deflation cycles 1 ground deformation at mt etna detected by three gps surveys carried out in 2004 2005 and 2006 is analyzed the data set encompasses the 2004 2005 eruptions and foreruns those of 2006 a wide deflation of the entire volcano was detected from 2004 to 2005 accompanying the 2004 2005 eruption conversely an evident inflation phase from 2005 to 2006 followed this eruption and preceded the 2006 one in both cases the deflation inflation cycle was accompanied by a continuous seaward motion of the eastern flank we inverted both data sets 2004 2005 deflation and 2005 2006 inflation using an optimization algorithm based on the genetic algorithm ga in order to detect the ground deformation sources the wide contraction measured during the eruption reveals the drainage of a sill shaped magma reservoir located by data inversions at a depth of about 4 5 km b s l the pressurizing source modeled for the 2005 2006 time interval indicates a refilling of the shallower near vertical plumbing system of the volcano this could indicate a change in the geometry of the feeding system active after the 2004 2005 eruption with a new and shallower magma storage that could have enabled the resumption of volcanic activity that was observed at summit craters in 2006 these results improve the imaging of the plumbing system of mt etna volcano

dynamics of mount etna before during and after the july august 2001 eruption inferred from gps and differential synthetic aperture radar interferometry data we acknowledge the istituto nazionale di geofisica e vulcanologia the italian dipartimento per la protezione civile and the european community contract ingv dpc ur v3 6 36 and volume project for their economic contribution to this research the sar data are provided by esa esrin

importance of gravitational spreading in the tectonic and volcanic evolution of mount etna the interaction between gravity and thermal effects largely determines the structural and magmatic evolution of volcanic constructs at scales spanning several orders of magnitude from small cones to the oceanic crust1 3 although gravitational spreading is a direct consequence of this interaction and a fundamental process in volcano growth it is rarely recognized as such here we describe a striking example of this process at etna volcano in italy the volcano and its clay rich substratum are slowly spreading towards the east and south driven by gravity spreading produces extensional structures in the summit region and contpressional structures at the base of the volcano eastward movement of the volcanic edifice over a stationary magma supply may be the cause of an apparent westward migration of volcanic activity as gravitational spreading seems to control the location and magnitude of shallow seismicity and flank eruptions an appreciation of its effects could become an essential element of future volcanic hazard evaluation our model proposed here for etna may also be relevant to a reinterpretation of the geological history of a number of other volcanoes

structural assessment of mount etna volcano from permanent scatterers analysis a study of the deformation pattern of mount etna volcano based on the results from the permanent scatterers ps technique is reported ground motion data provided by the interferometric synthetic aperture radar insar ps technique from 1995 to 2000 are compared and validated by gps data an analysis of the ascending and descending line of sight los components of ground velocities has yielded detailed ground deformation maps and cross sections this analysis allows detection and constraint of discontinuities in the surface velocity field los velocities have then been combined to calculate the vertical and horizontal e w ground velocities a wide inflation of the edifice has been detected on the western and northern flanks over an area of about 350 km2 a seaward motion of the eastern and southern flanks has also been measured ps data allows the geometry and kinematics of the several blocks composing the unstable flanks to be defined even in the highly urbanized areas and their displacement rates have been measured with millimeter precision this analysis reveals the extension of some features beyond their field evidences and defines new important features the results of this work depict a new comprehensive kinematic model of the volcano highlighting the gravitational reorganization of the unbuttressed volcanic pile on its slippery clay basement on the southern flank but an additional drag force due to a strong subsidence of the continental margin facing the etna volcano is necessary to explain the ps velocity field observed on the eastern flank

textural evidence of peperites inside pillow lavas at acicastello castle rock mt etna sicily globular and microglobular peperites with mingled sediment in millimetric to decimetric domains are described from inside pillow lavas at acicastello castle rock mt etna sicily for the first time the peperites now comprise basalt and minor remnants of fine grained detrital material with smectite and zeolite crystallised during late hydrothermal activity we propose that peperites formed when the magma ascending towards the surface intruded and intermixed with the unconsolidated wet pleistocene bluish marly clays of the substrate subsequently they were transported by the uprising magma from the source region towards the surface where they are preserved in pillow lavas

the apparent british sea slope is caused by systematic errors in the levelling based vertical datum the spirit levelling based british vertical datum ordnance datum newlyn implies a south north apparent slope in mean sea level of up to 53 mm deg 1 latitude due to the datum falling on heading northwards although this apparent slope has been investigated since the 1960s explanations of its origin have remained inconclusive it has also been suggested that rather than a slope the british vertical datum includes a step of about 240 mm affecting all sites north of about 53 n in either case the british vertical datum may be of limited use for any study requiring accurate heights or changes in heights such as testing geoid models groundwater and hydrocarbon extraction the calibration and validation of satellite based digital terrain models and the unification of vertical datums internationally within the last decade however based on an apparent reduction in the slope to only 12 mm deg 1 latitude with respect to recent geoid models it has been claimed that the british vertical datum does provide a physically meaningful surface for use in scientific applications in this paper we reinvestigate the presence of apparent south north sea slopes around britain and reported slopes in the vertical datum using the egm2008 global gravitational model together with mean sea level and gps data from british tide gauges gps ellipsoidal heights of 178 fundamental benchmarks across mainland britain and vertical deflection observations at 192 stations we demonstrate a south north slope in the british vertical datum of 20 25 mm deg 1 latitude with respect to both mean sea level corrected for the ocean s mean dynamic topography and the inverse barometer response to atmospheric pressure loading and the egm2008 quasigeoid model while egm2008 is shown to exhibit a negligible slope of 2 4 mm deg 1 with respect to mean sea level it is clear therefore that the slope can only arise from systematic errors in the levelling although we are unable to isolate their exact origin using an offset detection method based on a penalized likelihood maximization using the schwarz information criterion we do not detect a step in the vertical datum affecting all sites north of 53 n but do identify regional distortions that we attribute to the inhomogeneity in both the levelling data used and the least squares adjustment procedures used to realize the datum we conclude that the british vertical datum remains unsuitable for scientific purposes

a multidisciplinary study of an active fault crossing urban areas the trecastagni fault at mt etna italy abstract the trecastagni fault is a nnw sse tectonic structure in the densely inhabited southern flank of mt etna characterised by evident morphological scarps and movements of normal and right lateral type that directly affect roads and buildings the fault is affected by continuous dynamics with intermittent accelerations accompanied with shallow seismicity it has an important role in the instability affecting mt etna s south eastern flank and represents part of the southern boundary of the unstable sector the motion of the fault between 2005 and 2011 has been analysed by using a multi disciplinary approach involving terrestrial and satellite ground deformation data active monitoring systems able to investigate the fault in detail are extensometers a levelling network and insar two episodes of acceleration were recorded at the end of 2009 and during 2010 data evidences that the acceleration episodes affected only portions of the fault and that stress may accumulate and be periodically released although both magmatic processes inflation or intrusive episodes and flank dynamics influence the occurrence of the tf acceleration episodes the dragging effect of the overall seaward sliding of the south eastern flank is evident and it causes the subsidence of the hangingwall accumulating stress on the fault that is periodically seismically released

3d displacement maps of the 2009 l aquila earthquake italy by applying the sistem method to gps and dinsar data terra nova 25 79 85 2013 abstract we present an application of the novel sistem approach to obtain the dense 3d ground deformation pattern produced by the april 6 2009 mw 6 3 l aquila earthquake this event characterized by a sw dipping normal fault with thousands of foreshocks and aftershocks located in the depth range 5 15 km is the most destructive to have struck the abruzzo region since the major 1703 seismic sequence the surface deformation revealed by the sistem through the integration of gps with interferometric measurements from the envisat and alos satellites shows a deformed area extending towards se along the aterno valley in agreement with seismological and other geodetic observations we inverted the sistem results using an optimization algorithm based on the genetic algorithm providing an accurate spatial characterization of ground deformation our results improve previous kinematic solutions for the paganica fault and allow identification of additional faults that have contributed to the observed complex ground deformation pattern

implications of extinction due to meteoritic smoke in the upper stratosphere 1 recent optical observations of aerosols in the upper stratosphere and mesosphere show significant amounts of extinction at altitudes above about 40 km where the stratospheric sulfate aerosol layer ends recent modeling of this region reveals that meteoritic smoke settling from the mesosphere and its interaction with the upper part of the sulfate aerosol layer is the origin of the observed extinction extinction in this region has major implications for the interpretation and analysis of several kinds of aerosol data satellite and lidar we compare observations from the sage ii satellite and from noaa s lidar located at mauna loa hawaii to extinction profiles derived from the whole atmosphere community climate model waccm coupled with the community aerosol and radiation model for atmospheres carma our results show that a major source of extinction exists in the region above about 30 km that must be addressed by all remote sensing instruments that have traditionally used the stratosphere above about 30 km as an aerosol free region to estimate the molecular component of their total extinction it is also shown that meteoritic smoke not only contributes to but also becomes the dominant source of aerosol extinction above 35 km and poleward of 30 degrees in latitude as well as above 40 km in the tropics after addressing the concerns described here current and past observations of this region could be reanalyzed to further our understanding of meteoritic dust in the upper stratosphere

stick slip vs stable sliding fault behaviour a case study using a multidisciplinary approach in the volcanic region of mt etna italy abstract in active volcanic zones fault dynamics is considerably fast but it is often difficult to separate the pattern of nearly continuous large scale volcanic processes inflation deflation processes flank instability from impulsive episodes such as dyke intrusions or coseismic fault displacements at etna multidisciplinary studies on active faults whose activity does not strictly depend on volcanic processes are relatively few here we present the case study of the san leonardello fault an active structure located in the eastern flank of mt etna characterised by a well known seismic history this fault saw renewed activity in may 2009 when pre seismic creeping along the southern segment preceded an mw 4 0 earthquake in the northern segment followed by some twenty five aftershocks later in march april 2016 creep events reactivated the southern section of the same fault both the seismic and aseismic phenomena were recorded by the seismic and gnss networks of ingv osservatorio etneo and produced surface faulting that left a footprint in the pattern of ground deformation detected by the insar measurements we demonstrate that the integration of multidisciplinary data collected for volcano surveillance may shed light on different aspects of fault dynamics and allow understanding how coseismic slip and creep alternate in space and time along the strike moreover we use findings from our independent datasets to propose a conceptual model of the san leonardello fault taking into account behaviour and previous constraints from fault based seismic hazard analyses although the faulting mechanisms described here occur at a very small scale compared with those of a purely tectonic setting this case study may represent a perfect natural lab for improving knowledge of seismogenic processes also in other fault zones characterised by stick slip vs stable sliding fault behaviour

large scale ground deformation of etna observed by gps between 1994 and 2001 we have processed thirty global positioning system gps campaigns carried out at etna from 1994 to early 2001 between the last two main flank eruptions of the mt etna sicily italy this rest period allowed us to investigate the deep magma plumbing system of the mt etna the temporal dynamics of twenty three points observed three times or more were analyzed all the time series show a first order linear trend during the five years period it suggests that the volcano was continuously deformed by the action of a deep source while a discrete activity of the volcano was observed at the summit we have interpreted the residual deformation field as the result of an major eastward motion of the eastern flank of the volcano

bayesian inversion of 1994 1998 vertical displacements at mt etna evidence for magma intrusion summary we have developed a bayesian method for the inversion of static ground deformations at volcanic areas the method allows inference of the conditional probability density on the location and mechanism of point sources representing volcanic phenomena isotropic strain nuclei tensile faults embedded in homogeneous elastic media the method has been tested with simulated and real data from volcanic areas we have then analysed vertical displacements recorded at mt etna southern italy from 1994 to 1998 by high precision levelling measurements in this period had been carried out yearly so resulting displacements have been analysed both in consecutive periods and in the cumulative one measurement periods 1994 1995 and 1997 1998 show significant uplift of several centimetres the maximum cumulative displacement amounts to 6 5 cm with a trend similar to each of the two periods 1994 1995 and 1997 1998 the shape of displacement is well approximated by a circular symmetry thus allowing one to hypothesize an isotropic overpressure model as the source simulating magma intrusion at shallow depth the application of the inverse method gives the most probable location at about 4 5 km of depth b s l at about 1 5 km north of the central craters the 95 per cent of probability density is concentrated within a radius of about 0 5 km on the horizontal 1 km on depth the obtained results give important insight on the interpretation of recent eruptive episodes

structural features of an active strike slip fault on the sliding flank of mt etna italy abstract the strike slip pernicana fault system pfs was activated along the eastern flank of mt etna during an earthquake in september 2002 and one month later during the eruption of the ne rift structural and volcanological data suggest that the pfs was activated as a result of the slide of the ne flank of etna this activation produced surface fracturing on walls and on paved and unpaved roads the segments of the pfs arranged in a right stepping en echelon configuration show a an inverse proportion between length and frequency b fractal behavior over scales of 10 2 10 1 m between their length overstep and overlap c consistent strike with regard to their fault array and d a progressive eastward decrease in the displacement along the smallest faults the consistent geometric and kinematic features of the pfs related to the sector collapse of etna are similar to those of faults in strike slip settings

satellite data for a rapid assessment of tsunami inundation areas after the 2011 tohoku tsunami the mw 9 0 earthquake that occurred off the coast of japan s tohoku region produced a great tsunami causing catastrophic damage and loss of life within hours of the tsunami event satellite data were readily available and massive media coverage immediately circulated thousands of photographs and videos of the tsunami satellite data allow a rapid assessment of inundated areas where access can be difficult either as a result of damaged infrastructure e g roads bridges ports airports or because of safety issues e g the hazard at nuclear power plant at fukushima in this study we assessed in a day tsunami inundation distances and runup heights using satellite data very high resolution satellite images from the geoeye1 satellite and from the digitalglobe worldview srtm and aster gdem of the tohoku region northeast japan field survey data by japanese and other international scientists validated our results this study focused on three different locations site selection was based on coastal morphologies and the distance to the tsunami source epicenter study sites are rikuzentakata oyagawahama and yagawahama in the oshika peninsula and the sendai coastal plain sendai city to yamamoto city maximum inundation distance 6 km along the river and maximum runup 39 m at rikuzentakata estimated from satellite data agree closely with the 39 7 m inundation reported in the field here the ria coastal morphology and horn shaped bay enhanced the tsunami runup and effects the sendai coastal plain shows large inundation distances 6 km and lower runup heights natori city and wakabayashi ward on the sendai plain have similar runup values 12 and 16 m respectively obtained from srtm data these are comparable to those obtained from field surveys 12 and 9 5 m however at yagawahama and oyagawahama miyagi prefecture both srtm and aster data provided maximum runup heights 41 to 45 m and 33 to 34 m respectively which are higher than those measured in the field about 27 m this difference in dem and field data is associated with aster and srtm dem s pixel size and vertical accuracy the latter being dependent on ground coverage slope aspect and elevation countries with less access to technology and infrastructure can benefit from the use of satellite imagery and freely available dems for an initial pre field surveys rapid estimate of inundated areas distances and runup and for assisting in hazard management and mitigation after a natural disaster

seismo tectonic behavior of the pernicana fault system mt etna a gauge for volcano flank instability 1 flank instability at basaltic volcanoes is often related to repeated dike intrusions along rift zones and accompanied by surface fracturing and seismicity these processes have been mostly studied during specific events and the lack of longer term observations hinders their better understanding here we analyze 20 years of deformation of the pernicana fault system pfs the key structure controlling the instability of the eastern flank of mt etna we exploit east west and vertical components of mean deformation velocity as well as corresponding time series computed from ers envisat 1992 2010 and cosmo skymed 2009 2011 satellite radar sensors via synthetic aperture radar interferometry techniques we then integrate and compare this information with field seismic and leveling data collected between 1980 and 2012 we observe transient displacements accompanied by seismicity overprinted on a long term background eastward motion 2 cm yr in the last decades these transient events were preceded by a constant amount of accumulated strain near the pfs the time of strain accumulation varies between a few years and a few decades also depending on magma emplacement within the nearby north east rift which may increase the strain along the pfs these results suggest that the amount of deformation near the pfs may be used as a gauge to forecast the occurrence of instability transients on the eastern flank of etna in this context the pfs may provide an ideal small scale structure to test the relations between strain accumulation stress loading and seismic energy release

analysis of satellite and in situ ground deformation data integrated by the sistem approach the april 3 2010 earthquake along the pernicana fault mt etna italy case study abstract etna is known worldwide as one of the most studied and monitored active volcanoes flank instability along the eastern and southern portions of mt etna has been observed and measured thanks to geodetic networks and insar data analysis the spreading area is bordered to the north by the east west pernicana fault system pfs whose dynamics is often linked with the eruptive activity as recently observed during the 2002 2003 eruption a seismic sequence occurred from april 2 3 2010 along the pfs with very shallow a few hundred meters mainshocks of magnitude 4 3 and 3 6 explosions and ash emissions at the summit craters followed this swarm culminating a few days later april 7 8 despite their small magnitude the earthquakes caused damage and significant surface fracturing along the pfs in order to investigate and measure the deformations in the near field of the earthquakes the sistem integration approach has been exploited the sistem enabled integrating geodetic in situ ground deformation measurements gps and leveling with satellite interferometric measurements envisat and alos in order to obtain high resolution 3d displacement maps allowing to overcome the limitations of each technique and take advantage of the particular features of each of them the integrated ground deformation field evidenced that the medium behave elastically we inverted the sistem results using an optimization algorithm based on the genetic algorithm ga in order to model the kinematics of the pfs associated to seismic swarm the results are in good agreement with the field evidence and improved the knowledge on the kinematics of the pfs and mt etna s unstable flank

the role of the pernicana fault system in the spreading of mt etna italy during the 2002 2003 eruption flank instability and collapse are observed at many volcanoes among these mt etna is characterized by the spreading of its eastern and southern flanks the eastern spreading area is bordered to the north by the e w trending pernicana fault system pfs during the 2002 2003 etna eruption ground fracturing along the pfs migrated eastward from the ne rift to as far as the 18 km distant coastline the deformation consisted of dextral en echelon segments with sinistral and normal kinematics both of these components of displacement were one order of magnitude larger 1 m in the western previously known portion of the pfs with respect to the newly surveyed 9 km long eastern section 0 1 m this eastern section is located along a pre existing but previously unknown fault where displaced man made structures give overall slip rates 1 1 9 cm year only slightly lower than those calculated for the western portion 1 4 2 3 cm year after an initial rapid motion during the first days of the 2002 2003 eruption movement of the western portion of the pfs decreased dramatically while parts of the eastern portion continued to move these data suggest a model of spreading of the eastern flank of etna along the pfs characterized by eruptions along the ne rift instantaneous short lived meter scale displacements along the western pfs and more long lived centimeter scale displacements along the eastern pfs the surface deformation then migrated southwards reactivating one after the other the nnw sse trending timpe and trecastagni faults with displacements of 0 1 and 0 04 m respectively these structures along with the pfs mark the boundaries of two adjacent blocks moving at different times and rates the new extent of the pfs and previous activity over its full length indicate that the sliding eastern flank extends well below the ionian sea the clustering of seismic activity above 4 km b s l during the eruption suggests a deep decollement for the moving mass the collected data thus suggests a significant movement volume 1 100 km3 of the eastern flank of etna both on shore and off shore

interaction between magma intrusion and flank dynamics at mt etna in 2008 imaged by integrated dense gps and dinsar data 1 global positioning system gps and differential interferometric synthetic aperture radar dinsar data collected from july 2007 to july 2008 on mt etna are analyzed to define the dynamics preceding and accompanying the onset of the eruption on 13 may 2008 short and long term comparisons have been made on both gps and radar data covering similar time windows thanks to the availability of three gps surveys the year before the eruption onset an increase in the seaward movement of the ne flank of the volcano has been detected in the few months before the dike intrusion the gps ground deformation pattern also shows a slight inflation centered on the western side of the volcano in the preeruptive long term comparison from july 2007 to may 2008 the gps has been integrated with dinsar data by the sistem approach to take advantage of the different methodologies and provide high spatial sampling of the 3 d ground displacement pattern we inverted the sistem results to model the pressure source causing the observed preeruptive inflation the subsequent emplacement of the eruptive dike was imaged by two gps surveys carried out on a dense network over the uppermost part of the volcano on 6 and 13 may i e a few days before and a few hours after the beginning of the eruption we inverted this comparison to define the position geometry and kinematics of the dike the dike intrusion was also imaged by dinsar data with temporal baselines of 2 3 months which confirm strong displacements localized on the summit area rapidly decreasing toward the middle flanks of the volcano as detected by very short term gps data furthermore the comparison between dinsar and gps data highlighted the presence of a depressurizing source localized beneath the upper southwestern area acting just after the dike intrusion finally the long period 1 year gps and dinsar data were integrated by sistem to finely depict the 3 d ground deformation pattern with the highest spatial resolution the long period data allowed the complex kinematics of the volcano to be finely imaged and highlighting the interaction between flank dynamics and magma injection

modeling of alos and cosmo skymed satellite data at mt etna implications on relation between seismic activation of the pernicana fault system and volcanic unrest abstract we investigate the displacement induced by the 2 3 april 2010 seismic swarm the largest event being of ml 4 3 magnitude by means of dinsar data acquired over the volcano by the cosmo skymed and alos radar systems satellite observations combined with leveling data allowed us to perform a high resolution modeling inversion capable of fully capturing the deformation pattern and identifying the mechanism responsible for the pfs seismic activation the inversion results well explain high gradients in the radar line of sight displacements observed along the fault rupture the slip distribution model indicates that the fault was characterized by a prevailing left lateral and normal dip slip motion with no fault dilation and hence excludes that the april 2010 seismic swarm is a response to accommodate the stress change induced by magma intrusions but it is due to the tectonic loading possibly associated with sliding of the eastern flank of the volcano edifice these results provide a completely different scenario from that derived for the 22 september 2002 m3 7 earthquake along the pfs where the co seismic shear rupture was accompanied by a tensile mechanism associated with a first attempt of magma intrusion that preceded the lateral eruption occurred here a month later these two opposite cases provide hints into the behavior of the pfs between quiescence and unrest periods at etna and pose different implications for eruptive activity prediction and volcano hazard assessment the dense pattern of ground deformation provided by integration of data from short revisiting time satellite missions together with refined modeling for fault slip distribution can be exploited at different volcanic sites where the activity is controlled by volcano tectonic interaction processes for a timely evaluation of the impending hazards

dynamics of mount etna volcano inferred from static and kinematic gps measurements 1 ground deformations measured on mount etna from late 1995 to mid 1998 using gps observations are analyzed four gps surveys were carried out during the considered period in 1995 the gps network consisted of 18 stations on the volcanic edifice and 6 stations around it during the 1996 survey 22 new monuments were added along a n s profile crossing the summit craters area this profile was surveyed by a semikinematic method allowing greater spatial detail to be achieved on the uppermost part of the volcano the comparisons between the gps surveys are reported here in terms of horizontal and vertical displacements for each station and also in terms of areal dilatation and strain distribution this last parameter continues its ascending trend at a rate of 5 strain yr 1 already shown in the previous period after the end of the 1991 1993 flank eruption inversion of the ground deformation patterns permits investigation of the evolution of both the position and dynamics of magma reservoirs beneath the volcano consistently associated with a general eastward sliding of its eastern sector this study allows us to define the nonuniqueness of ground deformation sources through the investigated period suggesting that the plumbing system of the volcano is made up of a complex system of single intrusions occurring at different times

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

mt etna 2001 eruption new insights into the magmatic feeding system and the mechanical response of the western flank from a detailed geodetic dataset abstract in the last decades the increasing availability of comprehensive geodetic datasets has allowed for more detailed constraints on subsurface magma storage and conduits at several active volcanoes worldwide here by using a large dataset of geodetic measurements collected between early january 2001 and august 2001 we identified at least six different deformation stages that allow us to quantify the surface deformation patterns before during and after the 2001 mt etna volcanic eruption our results are largely in agreement with previous works e g the presence of a deep inflating source and a shallow dike located beneath the north western and upper southern flanks of the volcano respectively however we provide 1 finer resolution of the temporal activity of these magmatic sources leading to 2 new evidence related to the evolution of the magmatic system and the mechanical response of the western flank in particular during the pre eruptive phase results and analysis show a clear change in the ground deformation pattern of the volcano in response to the 20 24 april 2001 seismic swarm that occurred beneath the western flank evolving from a volcano wide inflation to a slight deflation of the summit area we suggest that the source responsible for the volcano wide inflation beginning in the fall of 2000 experienced a drastic reduction in the inflation rate in response to this seismic swarm moreover we provide evidence for the presence of a new inflating source located beneath the upper southern flank at a depth of 7 0 km bsl that triggered both the occurrence of the 20 24 april 2001 seismic swarm and led to the rapid ascent of magma upward to the surface after 12 july the lower vents system was fed by fresh magma rising from this source the presence of this inflating source is inferred by 1 seismological and volcanological observations coming from the 2001 eruption and 2 seismological constraints coming from a previous similar episode that occurred at etna during the 1993 1998 period furthermore both shallow deflations observed after the 20 24 april 2001 seismic swarm and during the first day of the eruption also could be due to the deflation of two adjacent portions of the same shallow 2 km bsl reservoir such reservoirs would feed the activity that occurred at the south east crater after january 2001 and the activity of the upper vents system during the july august eruption in agreement with petrochemical observations through an updated revision of the available data we shed some light on the relevance of pre eruptive activity patterns an important element for an effective volcano monitoring

an integrated method based on dinsar mai and displacement gradient tensor for mapping the 3d coseismic deformation field related to the 2011 tarlay earthquake myanmar abstract the satellite differential interferometric synthetic aperture radar dinsar technology has been widely applied for mapping the ground deformation associated with the geophysical events such as earthquakes however the conventional dinsar can measure only the one dimensional 1d ground displacement along the radar line of sight los and the crucial displacement measurements e g near the epicenter and along the surface ruptures are usually not available or degraded in quality due to the significant deformation gradients with availability of satellite sar images acquired along ascending and descending orbits this paper proposes an integrated method to map the three dimensional 3d coseismic deformation field by combining dinsar for detecting los displacements the multiple aperture interferometry mai for detecting along track displacements and the displacement gradient tensor dgt model for characterizing spatial correlation of ground displacements the proposed method termed as insar dgt was first tested through an experiment of recovering 3d displacements from a simulated coseismic deformation field we then applied the proposed method to map the 3d coseismic deformation field related to the 2011 tarlay earthquake myanmar by using the ascending and descending alos palsar images both the results derived for the simulated experiment and the 2011 tarlay earthquake show that the quality of the 3d coseismic displacements can be raised efficiently by the insar dgt method and the precisions in the east west e w north south n s and up down u d displacements for the 2011 tarlay earthquake are increased 22 36 and 24 respectively the validation indicates that the improved coseismic deformation field for the 2011 tarlay earthquake is in good agreement with the deformation field simulated from the existing optimized fault model the number of the missing data points in the 3d coseismic deformation field can be reduced significantly by the insar dgt method it is revealed that the causative fault i e the west part of the nam ma fault for the tarlay earthquake generated a left lateral slip that was accompanied by a minor normal dip slip component the careful interpretation demonstrates that the causative fault structures include the determined main fault segment and the two suspected branched segments at east of the tarlay town

detachment depth revealed by rollover deformation an integrated approach at mount etna this work was partially funded by ingv and the dpc ingv project flank and partially by the asi srv project

the spectrum of persistent volcanic flank instability a review and proposed framework based on kīlauea piton de la fournaise and etna abstract persistent motion of the south flank of k lauea volcano hawai i has been known for several decades but has only recently been identified at other large basaltic volcanoes namely piton de la fournaise la reunion and etna sicily thanks to the advent of space geodetic techniques nevertheless understanding of long term flank instability is based largely on the example of k lauea despite the large differences in the manifestations and mechanisms of the process when viewed through a comparative lens for example the rate of flank motion at k lauea is several times that of etna and piton de la fournaise and is accommodated on a slip plane several km deeper than is probably present at the other two volcanoes gravitational spreading also appears to be the dominant driving force at k lauea given the long term steady motion of the volcano s south flank regardless of eruptive intrusive activity whereas magmatic activity plays a larger role in flank deformation at etna and piton de la fournaise k lauea and etna however are both characterized by heavily faulted flanks while piton de la fournaise shows little evidence for flank faulting a helpful means of understanding the spectrum of persistent flank motion at large basaltic edifices may be through a framework defined on one hand by magmatic activity which encompasses both magma supply and edifice size and on the other hand by the structural setting of the volcano especially the characteristics of the subvolcanic basement or subhorizontal intravolcanic weak zones a volcano s size and magmatic activity will dictate the extent to which gravitational and magmatic forces can drive motion of an unstable flank and possibly the level of faulting of that flank while the volcano s structural setting governs whether or not a plane of weakness exists beneath or within the edifice and can facilitate flank slip considering persistent flank instability using this conceptual model is an alternative to using a single volcano as a type example especially given that the example is usually k lauea which defines an extreme end of the spectrum and can provide a basis for understanding why flank motion may or may not exist on other large basaltic volcanoes worldwide

lidar measurements of stratospheric aerosol over mauna loa observatory dual wavelength aerosol lidar backscatter measurements at mauna loa observatory are used to monitor and characterize the 15 30 km stratospheric aerosol layer the decay of aerosol loading following the el chichon mexico 17 n and pinatubo philippine islands 15 n volcanic eruptions of 1982 and 1991 respectively depends on the phase of the quasibiennial oscillation qbo in tropical stratospheric winds averaged over a 3 year period these effects are removed and an exponential decay with a characteristic e 1 decay time of about 1 year is observed for both eruptions by the end of 1996 about 5 years after the pinatubo eruption stratospheric aerosol levels at mauna loa had decayed to pre eruption levels approximately matching the lowest aerosol levels seen here in the past 17 years about 6 10 5 sr 1 at 694 nm integrated between 15 8 and 33 km however this background stratospheric aerosol level at mauna loa may depend on the qbo being slightly lower during the westerly phase analyses of aerosol backscatter backscatter wavelength dependence and trajectories provide evidence for a minor injection of aerosol from the rabaul eruption in papua new guinea 4 s in september of 1994