seasonality of dissolved rare earth elements in the lower mississippi river 1 dissolved rare earth element ree concentrations were determined in a 27 month time series of the lower mississippi river overall the results agree with limited previous investigations that is the river shows enrichment of heavy rees relative to light rees and also has a significant ce anomaly however the previous investigations relied on only single samples from the river this seasonal investigation reveals significant temporal variations in the river s ree chemistry in particular large approximately fivefold variations in light ree concentrations are observed the light rees follow a seasonality similar to particle reactive trace elements also the ce anomaly shows a corresponding seasonality with greatest fractionation when dissolved concentrations are lowest the time series encompassed a period of extreme flooding in the u s midwest however this event did not appear to affect dissolved ree concentrations the results of this study are compatible with previous observations of dissolved trace elements in the lower mississippi river which suggested the importance of redox processes within the river system in controlling seasonal concentration variability for many of these elements additionally speciation modeling indicates that carbonate complexes likely dominate the solution chemistry of rees in the lower mississippi the observed behavior of the dissolved rees is likewise compatible with this speciation

the january 1998 earthquake swarm at axial volcano juan de fuca ridge hydroacoustic evidence of seafloor volcanic activity on january 25 1998 at 11 33z an intense swarm of earthquakes began within the summit caldera of axial volcano central juan de fuca ridge jdfr the earthquake swarm was detected using the u s navy hydrophones in the northeast pacific ocean the earthquake swarm lasted 11 days and produced 8247 detected 1037 located earthquakes during the first two days of the swarm earthquake activity migrated from the summit caldera 50 km along the south rift zone of axial volcano at rates of 0 92 0 13 and 0 23 0 09 m s 1 earthquake epicenter migration is characteristic of a lateral magma dike injection the largest three swarm earthquakes occurred within the caldera their timing and mechanisms are consistent with adjustment of the caldera floor as magma is removed from beneath the summit earthquakes with short t wave rise times shallow focal depths cluster at two spots along the summit and south rift zone and are considered possible seafloor eruption sites in situ ground deformation and hydrothermal plume monitors and later shipboard observations confirmed the occurrence of a seafloor volcanic eruption at the volcano s summit

carbonate ion concentration in glacial age deep waters of the caribbean sea 1 on the basis of the whole foraminifera shell weights for g sacculifer and n dutertrei from caribbean cores it appears that the carbonate ion concentration of water at 1800 m depth in the open atlantic i e the depth of the caribbean sill was 14 mol kg greater during glacial time than during the holocene the sense of this difference is consistent with the observation that the 13c 12c ratio for benthic foraminifera from glacial age atlantic upper deep water was higher than that for their holocene equivalents it is also consistent with fragment to whole foraminifera results however as several questions regarding the assumptions involved in converting shell weights to paleocarbonate ion concentrations remain unanswered this reconstruction must be considered tentative critical in this regard are the assumptions that shell wall thicknesses were the same as today s at any given site during glacial time and that the 0 3 g per mol kg relationship between shell weight and carbonate ion concentration is applicable over the entire deep water column the records reported here reveal no evidence for an early holocene preservation event however that for core v28 122 documents a dissolution event close to the mis 5 4 boundary

active faulting at the eurasian north american and pacific plates junction abstract the active faults known and inferred in the area where the major pacific north american and eurasian plates come together group into two belts one of them comprises the faults striking roughly parallel to the pacific ocean margin the extreme members of the belt are the longitudinal faults of islands arcs in its oceanic flank and the faults along the continental margins of marginal seas in its continental flank the available data show that all these faults move with some strike slip component which is always right lateral we suggest that characteristic right lateral either partially or dominantly kinematics of the fault movements has its source in oblique convergence of the pacific plate with continental eurasian and north american plates the second belt of active faults transverses the extreme northeast asia as a continental extension of the active mid arctic spreading ridge the two active fault belts do not cross but come close to each other at the northern margin of the sea of okhotsk marking thus the point where the pacific north american and eurasian plates meet

dike propagation energy balance from deformation modeling and seismic release magma is transported in the crust mainly by dike intrusions in volcanic areas dikes can ascend towards the free surface and also move by lateral propagation eventually feeding flank eruptions understanding dike mechanics is a key to forecasting the expected propagation and associated hazard several studies have been conducted on dike mechanisms and propagation however a less in depth investigated aspect is the relation between measured dike induced deformation and the seismicity released during its propagation we individuated a simple equation that can be used as a proxy of the expected mechanical energy released by a propagating dike and is related to its average thickness for several intrusions around the world afar japan mt etna we correlate such mechanical energy to the seismic moment released by the induced earthquakes we obtain an empirical law that quantifies the expected seismic energy released before arrest the proposed approach may be helpful to predict the total seismic moment that will be released by an intrusion and thus to control the energy status during its propagation and the time of dike arrest

tomographic images and 3d earthquake locations of the seismic swarm preceding the 2001 mt etna eruption evidence for a dyke intrusion 1 on july 12 2001 mt etna experienced a sudden increase of seismic activity heralding one of the most intense eruptions of the past 30 years between july 12 and july 18 when the eruption started thousands of small magnitude earthquakes occurred and were recorded by a dense seismic network run by the istituto nazionale di geofisica e vulcanologia sezione di catania ingv ct hypocentral depths of earthquakes were very shallow mostly located above 3 km b s l and clustered near the summit area the high quality seismic dataset gives us the unique opportunity to study the process of magma migration before the eruption in this study we present the three dimensional earthquake locations and the velocity structure obtained by a tomographic inversion the shallowness of seismicity allowed us to enhance the details of the structure beneath the summit craters in a volume poorly defined by previous tomographic studies the presence of a high vp body previously observed at mt etna is confirmed at shallow depth beneath the southeastern part of the summit area the earthquakes preceding the eruption onset concentrated at its western border a low vp vs anomaly is found at 0 1 km depth just at the top of the volume where the magma intruded before the eruption this anomalous zone can be considered as molten material wealthy in gas the relocated seismicity occurs in a cylinder below the vents activated along the fracture system and exhibited an upward migration until the eruption all these results show evidence for the emplacement of a near vertical dyke striking about n s and a few kilometres south of the summit craters

surface deformation and coherence measurements of kilauea volcano hawaii from sir c radar interferometry the shuttle imaging radar c x synthetic aperture radar sir c x sar radar on board the space shuttle endeavor imaged kilauea volcano hawaii in april and october 1994 for the purpose of measuring active surface deformation by the methods of repeat pass differential radar interferometry observations at 24 cm l band and 5 6 cm c band wavelengths were reduced to interferograms showing apparent surface deformation over the 6 month interval and over a succession of 1 day intervals in october a statistically significant local phase signature in the 6 month interferogram is coincident with the pu u o o lava vent interpreted as deformation the signal implies centimeter scale deflation in an area several kilometers wide surrounding the vent peak deflation is roughly 14 cm if the deformation is purely vertical centered southward of the pu u o o caldera delays in the radar signal phase induced by atmospheric refractivity anomalies introduce spurious apparent deformation signatures at the level of 12 cm peak to peak in the radar line of sight direction though the phase observations are suggestive of the wide area deformation measured by global positioning system gps methods the atmospheric effects are large enough to limit the interpretation of the result it is difficult to characterize centimeter scale deformations spatially distributed over tens of kilometers using differential interferometry without supporting simultaneous spatially distributed measurements of refractivity along the radar line of sight studies of the interferometric correlation of images acquired at different times show that l band is far superior to c band in the vegetated areas even when the observations are separated by only 1 day these results imply longer wavelength instruments are more appropriate for studying surfaces by repeat pass observations

inflation model of uzon caldera kamchatka constrained by satellite radar interferometry observations 1 we analyzed radarsat 1 synthetic aperture radar sar data to compute interferometric sar insar images of surface deformation at uzon caldera kamchatka russia from 2000 to 2003 approximately 0 15 m of inflation occurred at uzon caldera extending beneath adjacent kikhpinych volcano this contrasts with insar data showing no significant deformation during either the 1999 to 2000 or 2003 to 2004 time periods we performed three sets of numerical source inversions to fit insar data from three different swaths spanning 2000 to 2003 the preferred source model is an irregularly shaped pressurized crack dipping 20 to the nw 4 km below the surface the geometry of this solution is similar to the upper boundary of the geologically inferred magma chamber extension of the surface deformation and source to adjacent kikhpinych volcano without an eruption suggests that the deformation is more likely of hydrothermal origin possibly driven by recharge of the magma chamber

the effects of topography on magma chamber deformation models application to mt etna and radar interferometry we have used a three dimensional elastic finite element model to examine the effects of topography on the surface deformation predicted by models of magma chamber deflation we used the topography of mt etna to control the geometry of our model and compared the finite element results to those predicted by an analytical solution for a pressurized sphere in an elastic half space topography has a significant effect on the predicted surface deformation for both displacement profiles and synthetic interferograms not only are the predicted displacement magnitudes significantly different but also the map view patterns of displacement it is possible to match the predicted displacement magnitudes fairly well by adjusting the elevation of a reference surface however the horizontal pattern of deformation is still significantly different thus inversions based on constant elevation reference surfaces may not properly estimate the horizontal position of a magma chamber we have investigated an approach where the elevation of the reference surface varies for each computation point corresponding to topography for vertical displacements and tilts this method provides a good fit to the finite element results and thus may form the basis for an inversion scheme for radial displacements a constant reference elevation provides a better fit to the numerical results

magmatic inflation at a dormant stratovolcano 1996 1998 activity at mount peulik volcano alaska revealed by satellite radar interferometry 1 a series of ers radar interferograms that collectively span the time interval from july 1992 to august 2000 reveal that a presumed magma body located 6 6 0 5 km beneath the southwest flank of the mount peulik volcano inflated 0 051 0 005 km3 between october 1996 and september 1998 peulik has been active only twice during historical time in 1814 and 1852 and the volcano was otherwise quiescent during the 1990s the inflation episode spanned at least several months because separate interferograms show that the associated ground deformation was progressive the average inflation rate of the magma body was 0 003 km3 month from october 1996 to september 1997 peaked at 0 005 km3 month from 26 june to 9 october 1997 and dropped to 0 001 km3 month from october 1997 to september 1998 an intense earthquake swarm including three ml 4 8 5 2 events began on 8 may 1998 near becharof lake 30 km northwest of peulik more than 400 earthquakes with a cumulative moment of 7 15 1017 n m were recorded in the area through 19 october 1998 although the inflation and earthquake swarm occurred at about the same time the static stress changes that we calculated in the epicentral area due to inflation beneath peulik appear too small to provide a causal link the 1996 1998 inflation episode at peulik confirms that satellite radar interferometry can be used to detect magma accumulation beneath dormant volcanoes at least several months before other signs of unrest are apparent this application represents a first step toward understanding the eruption cycle at peulik and other stratovolcanoes with characteristically long repose periods

kizimen volcano kamchatka a future mount st helens we studied the tectonic setting morphology geologic structure history of eruptive activity and evolution of the composition of the erupted material of kizimen volcano kamchatka from the moment of its origination 11 12 thousand years ago to the present time four cycles each 2 3 5 thousand years long were distinguished that characterize the activity of the volcano all of the largest eruptions were dated and their parameters determined we also estimated the volume and the mass of the erupted products the volcanic intensity of eruption of material during periods of high activity and the amount of material the volcano ejected at different stages of its formation it has been shown that the evolution of the composition of the rocks erupted from dacite to basaltic andesite takes place as a result of mixing of dacitic and basaltic magma it is suggested that future eruptions that may take place at kizimen may be similar to those at bandai 1888 and mount st helens 1980 volcanoes

environmental magnetism of pleistocene sediments in the north pacific and ontong java plateau temporal variations of detrital and biogenic components 1 an environmental magnetic study was conducted to investigate temporal variations of the sources of magnetic minerals in the pacific ocean using sediment cores of pleistocene age the proportion of interacting i to noninteracting n i single domain components was estimated from first order reversal curve diagrams and the proportion of middle m to low l coercivity components was determined from decomposition of isothermal remanent magnetization irm acquisition curves the i and m components are interpreted to be carried by terrigenous maghemite while the n i and l components represent biogenic magnetite an inverse correlation between the ratio of anhysteretic remanent magnetization susceptibility arm to saturation irm sirm and the i n i ratio was confirmed for sediments across wide expanses in the pacific ocean this implies that arm sirm can be used to estimate the relative abundances of biogenic and terrigenous components in sediments in the north pacific the relative abundance of the i and m components increases in glacial periods variations of arm sirm and s ratio s 0 1t resemble each other and decrease in the same time intervals these variations reflect increases of terrigenous input in glacial periods as eolian dust on the ontong java plateau in the western equatorial pacific on the other hand minima in arm sirm and s 0 1t occur at glacial to interglacial transitions and the relative abundance of the i and m components increases in these periods terrigenous material in this region is considered to be transported mainly from the new guinea and solomon islands by the equatorial undercurrent the higher proportion of the terrigenous component at glacial to interglacial transitions is coeval with carbonate preservation maxima reported from the ontong java plateau suggesting a linkage between the two

deflation of mount etna monitored by spaceborne radar interferometry ground based measurements of volcano deformation can be used to assess eruptive hazard but require the costly and often hazardous installation and maintenance of an instrument network here we show that spaceborne radar interferometry which has already shown its utility in mapping earthquake related deformation1 can be used to monitor long term volcano deformation two families of synthetic aperture radar images acquired from ascending and descending orbits by the satellite ers 1 and looking at mount etna from opposite sides cover the time period from 17 may 1992 to 24 october 1993 and include the second half of etna s most recent eruption despite artefacts of the interferometric technique we can observe a volcano wide deflation which is an expected consequence of the eruption but which had not previously been appreciated we quantify it using a simple model based on the change of pressure in a sphere located in an elastic half space the modelled deformation increases linearly with time until the end of the eruption our results show that it will be possible to use this technique to detect the inflation of volcanic edifices that usually precedes eruptions

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

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

a process based model of pre eruption seismicity patterns and its use for eruption forecasting at dormant stratovolcanoes abstract using long term data sets the eruptive size timing and style can typically be successfully forecast for dormant volcanoes using current monitoring data and knowledge of precursory eruptive patterns the usaid usgs volcano disaster assistance program vdap utilizes seismic data over multiple eruption cycles and across volcano types to successfully forecast eruption size style and onset times as well as changes within ongoing eruptions from millions of seismic event observations we show that seismic data a proxy for rate dependent strain changes in the magmatic system combined with a process based conceptual geologic model enables eruption forecasting especially for stratovolcanoes dormant 20 years we show that this model often works for some open systems ones that sufficiently reseal to plug the conduit and also where a deep intrusion occurs after phreatic or phreatomagmatic explosions have begun this model is divided into four seismicity and geologic stages we describe each of the four stages of seismicity in detail and how they relate to the ongoing geologic process of that stage stage 1 deep intrusion and seismicity occurring at 10 to 40 km depth below the volcanic edifice stage 2 distal vt seismicity induced at distances from 2 to 30 km laterally from the summit by magma intruding into and inflating the upper crustal magma storage region stage 3 vent clearing seismicity associated with the initial vent creation and clearing phase of eruptive activity stage 4 repetitive event seismicity associated with the final ascent of magma from 2 km to the surface we present 36 examples of this seismic progression from 26 volcanoes we believe that this progression generally correlates with the magma flux and the eventual explosivity and is invaluable for forecasting eruptions

imaging the dynamics of dyke propagation prior to the 2000 2003 flank eruptions at piton de la fournaise reunion island 1 the relationship between shallow magma storage and flank injections in volcanic edifices is rarely documented we analyse the time series of geodetic and seismic data collected at piton de la fournaise volcano la reunion during 9 flank eruptions from 2000 to 2003 the data depicts how magma injections supplied flank eruptions at piton de la fournaise volcano and allows to precisely determine the direction and duration of dike intrusions indicating a two phases pattern consistent over all the eruptions 1 fast vertical migration of the dyke 2 m s from the magma chamber to the surface in 10 to 50 minutes and 2 slower lateral migration 0 2 0 8 m s in tens of minutes to hours controlled by the rift zone geometry

multiple inflation and deflation events at kenyan volcanoes east african rift the presence or absence of magma exerts a fundamental control on the distribution of strain in continental rift zones yet the time scales of magma intrusion remain unconstrained using more than a decade of measurements from interferometric synthetic aperture radar insar we detected geodetic activity at four of the eleven central rift volcanoes in the kenyan sector of the east african rift subsidence of 2 5 cm occurred at suswa and menengai over the period 1997 2000 9 cm of uplift was recorded at longonot in 2004 2006 and 21 cm of uplift occurred at paka during 2006 2007 the deformation is episodic and no deformation was observed at these volcanoes during other time periods preceding the infl ation at paka we observed transient uplift and subsidence of a second nearby source likely associated with fl ow through a complex plumbing system the best fi tting source models for each episode include infl ation or defl ation of a horizontal penny shaped crack at a depth of 2 5 km the episodic nature of the activity its lack of correlation with seasons and the preferred source geometry are all consistent with activity in the volatile rich cap to a crystal rich magma chamber beneath each of the four volcanoes the presence of active magmatic systems beneath more than 40 of the volcanoes and the 2007 2008 explosive eruptions at nearby oldoinyo lengai volcano have implications for models of continental rifting caldera volcanoes geothermal resources and volcanic and seismic hazard in rift zones

volcano tectonic earthquakes a new tool for estimating intrusive volumes and forecasting eruptions abstract we present data on 136 high frequency earthquakes and swarms termed volcano tectonic vt seismicity which preceded 111 eruptions at 83 volcanoes plus data on vt swarms that preceded intrusions at 21 other volcanoes we find that vt seismicity is usually the earliest reported seismic precursor for eruptions at volcanoes that have been dormant for decades or more and precedes eruptions of all magma types from basaltic to rhyolitic and all explosivities from vei 0 to ultraplinian vei 6 at such previously long dormant volcanoes because large eruptions occur most commonly during resumption of activity at long dormant volcanoes vt seismicity is an important precursor for the earth s most dangerous eruptions vt seismicity precedes all explosive eruptions of vei 5 and most if not all vei 4 eruptions in our data set surprisingly we find that the vt seismicity originates at distal locations on tectonic fault structures at distances of one or two to tens of kilometers laterally from the site of the eventual eruption and rarely if ever starts beneath the eruption site itself the distal vt swarms generally occur at depths almost equal to the horizontal distance of the swarm from the summit out to about 15 km distance beyond which hypocenter depths level out we summarize several important characteristics of this distal vt seismicity including swarm like nature onset days to years prior to the beginning of magmatic eruptions peaking of activity at the time of the initial eruption whether phreatic or magmatic and large non double couple component to focal mechanisms most importantly we show that the intruded magma volume can be simply estimated from the cumulative seismic moment of the vt seismicity from log10 v 0 77 log moment 5 32 with volume v in cubic meters and seismic moment in newton meters because the cumulative seismic moment can be approximated from the size of just the few largest events and is quite insensitive to precise locations the intruded magma volume can be quickly and easily estimated with few short period seismic stations notable cases in which distal vt events preceded eruptions at long dormant volcanoes include nevado del ruiz 1984 1985 pinatubo 1991 unzen 1989 1995 soufriere hills 1995 shishaldin 1989 1999 tacana 1985 1986 pacaya 1980 1984 rabaul 1994 and cotopaxi 2001 additional cases are recognized at frequently active volcanoes including popocateptl 2001 2003 and mauna loa 1984 we present four case studies pinatubo soufriere hills unzen and tacana in which we demonstrate the above mentioned vt characteristics prior to eruptions using regional data recorded by neic we recognized in near real time that a huge distal vt swarm was occurring deduced that a proportionately huge magmatic intrusion was taking place beneath the long dormant sulu range new britain island papua new guinea that it was likely to lead to eruptive activity and warned rabaul volcano observatory days before a phreatic eruption occurred this confirms the value of this technique for eruption forecasting we also present a counter example where we deduced that a vt swarm at volcan cosiguina nicaragua indicated a small intrusion insufficient to reach the surface and erupt finally we discuss limitations of the method and propose a mechanism by which this distal vt seismicity is triggered by magmatic intrusion

strain accommodation by slow slip and dyking in a youthful continental rift east africa continental rifts begin and develop through repeated episodes of faulting and magmatism but strain partitioning between faulting and magmatism during discrete rifting episodes remains poorly documented in highly evolved rifts tensile stresses from far field plate motions accumulate over decades before being released during relatively short time intervals by faulting and magmatic intrusions1 2 3 these rifting crises are rarely observed in thick lithosphere during the initial stages of rifting here we show that most of the strain during the july august 2007 seismic crisis in the weakly extended natron rift tanzania was released aseismically deformation was achieved by slow slip on a normal fault that promoted subsequent dyke intrusion by stress unclamping this event provides compelling evidence for strain accommodation by magma intrusion in addition to slip along normal faults during the initial stages of continental rifting and before significant crustal thinning

ground surface deformation patterns magma supply and magma storage at okmok volcano alaska from insar analysis 1 intereruption deformation 1997 2008 eruption magma storage had increased by 3 7 5 2 1 0 7 m 3 or 85 100 of the 1997 eruption volume we propose that the supply rate decreased in response to the diminishing pressure gradient between the shallow storage zone and a deeper magma source region eventuallytheeffectsofcontinuingmagmasupplyandvesiculationofstoredmagmacaused acriticalpressurethresholdtobeexceeded triggeringthe2008eruption asimilarpatternof initially rapid inflation followed by oscillatory but generally slowing inflation was observed prior to the 1997 eruption in both cases withdrawal of magma during the eruptions depressurized the shallow storage zone causing significant volcano wide subsidence and initiating a new intereruption deformation cycle

assessing the altitude and dispersion of volcanic plumes using misr multi angle imaging from space sixteen years of volcanic activity in the kamchatka peninsula russia abstract volcanic eruptions represent a significant source of atmospheric aerosols and can display local regional and global effects impacting earth systems and human populations in order to assess the relative impacts of these events accurate plume injection altitude measurements are needed in this work volcanic plumes generated from seven kamchatka peninsula volcanoes shiveluch kliuchevskoi bezymianny tolbachik kizimen karymsky and zhupanovsky were identified using over 16 years of multi angle imaging spectroradiometer misr measurements eighty eight volcanic plumes were observed by misr capturing 3 25 of reported events at individual volcanoes retrievals were most successful where eruptive events persisted over a period of weeks to months compared with existing ground and airborne observations and alternative satellite based reports compiled by the global volcanism program gvp misr plume height retrievals show general consistency the comparison reports appear to be skewed towards the region of highest concentration observed in misr constrained plume vertical extent the report observations display less discrepancy with misr toward the end of the analysis period 2013 2016 with improvements in the suborbital data likely the result of the deployment of new instrumentation conversely the general consistency of misr plume heights with conventionally reported observations supports the use of misr in the ongoing assessment of volcanic activity globally especially where ground based observations are unavailable differences between the northern shiveluch kliuchevskoi bezymianny and tolbachik and southern kizimen karymsky and zhupanovsky volcanoes broadly corresponding to the central kamchatka depression ckd and eastern volcanic front evf geological sub regions of kamchatka respectively are distinguished by varying magma composition for example by comparison with reanalysis model simulations of local meteorological conditions ckd plumes were generally less constrained by mid tropospheric

deformation patterns magma supply and magma storage at karymsky volcanic center kamchatka russia 2000 2010 revealed by insar abstract under a complex geological region influenced by the subduction of the pacific plate kamchatka peninsula is one of the most active volcanic arcs in the pacific rim due to logistical difficulty in instrumentation shallow magma plumbing systems beneath some of the kamchatkan volcanoes are poorly understood insar offers a safe and quick method for monitoring volcanic deformation with a high spatial resolution in this study a group of satellite radar interferograms that span the time interval from 2000 to 2010 shows eruptive and non eruptive deformation at karymsky volcanic center kvc kamchatka russia all the interferograms provide details of the activity around the kvc during 2000 2010 as follows 1 from 2000 to 2004 the karymsky an akademia nauk area deflated and the ms maly semyachik area inflated 2 from 2004 to 2006 the karymsky an area deflated with ongoing eruption while the ms area subsided without eruption 3 from 2006 to 2008 as with 2000 2004 the karymsky an area deflated and the ms area inflated 4 from 2008 to 2010 the karymsky an area inflated up to 3 cm and the ms area subsided point source models suggest that two magma reservoirs provide a good fit to the observed deformation one source is located beneath the area between karymsky and an at a depth of approximately 7 0 km and the other one is situated beneath ms at a depth of around 5 8 km synchronous deformation patterns suggest that two magma systems are fed from the same deep magma source and connected by a fracture zone the insar results are consistent with gps ground deformation measurements seismic data and petrological constraints

the 1996 mw 6 6 lijiang earthquake application of jers 1 sar interferometry on a typical normal faulting event in the northwestern yunnan rift zone sw china abstract the northwestern yunnan rift zone in the yunnan province of china is a seismically active region located along the western boundary of the sichuan yunnan block on the eastern margin of the qinghai tibetan plateau an earthquake with a magnitude of 6 6 mw occurred in this region on february 3 1996 the lijiang earthquake was the largest normal faulting event to occur along the western boundary of the sichuan yunnan block in the last 40 years in this study we used l band jers 1 japanese earth resources satellite 1 sar data sets from two descending orbits to detect surface deformation signals surrounding the epicentral region in order to estimate the source parameters through an inversion of the displacement fields the results indicated that the earthquake can be explained by slip along two segments of the n s trending listric normal fault named the lijiang daju fault coseismic deformation patterns and slip distributions revealed that the earthquake consisted of two sub events which were also suggested by seismological results based on an analysis of the static coulomb stress change the second sub event was likely triggered by the first sub event the central segment of the lijiang daju fault which has an eastward convex geometry did not rupture during the earthquake this phenomenon was probably related to a geometrical discontinuity at the fault bend area of the lijiang daju fault

widespread uplift and trapdoor faulting on galapagos volcanoes observed with radar interferometry volcanic uplift caused by the accumulation of magma in subsurface reservoirs is a common precursor to eruptions1 2 but for some volcanoes uplift of metres or more has not yet led to an eruption3 here we present displacement maps of volcanoes in the galapagos islands constructed using satellite radar interferometry that might help explain this dichotomy we show that all but one of the seven volcanoes on the islands of isabela and fernandina deformed during 1992 99 cerro azul and fernandina erupted4 5 6 during the observation period and show evidence of inflation co eruptive deflation and shallow dyke intrusion in contrast the largest volcano sierra negra has not erupted yet exhibits spatially and temporally variable deformation with a maximum uplift of 2 7 m between 1992 and 1999 which can be modelled by a shallow inflating sill inflation during 1997 98 however was accompanied by trapdoor faulting on a steeply dipping fracture system within the caldera repeated trapdoor faulting over geological time has formed an arcuate intra caldera ridge within sierra negra and may have acted to relax stresses above the magma chamber inhibiting summit eruptions similar processes may help explain large uplift unaccompanied by eruptive activity at other volcanoes

pre eruption deformation caused by dike intrusion beneath kizimen volcano kamchatka russia observed by insar abstract interferometric synthetic aperture radar insar images reveal a pre eruption deformation signal at kizimen volcano kamchatka russia where an ongoing eruption began in mid november 2010 the previous eruption of this basaltic andesite to dacite stratovolcano occurred in 1927 1928 insar images from both ascending and descending orbital passes of envisat and alos palsar satellites show as much as 6 cm of line of sight shortening from september 2008 to september 2010 in a broad area centered at kizimen about 20 cm of opening of a nearly vertical dike provides an adequate fit to the surface deformation pattern the model dike is approximately 14 km long 10 km high centered 13 km beneath kizimen and strikes ne sw time series analysis of multi temporal interferograms indicates that 1 intrusion started sometime between late 2008 and july 2009 2 continued at a nearly constant rate and 3 resulted in a volume expansion of 3 2 107 m3 by september 2010 i e about two months before the onset of the 2010 eruption earthquakes located above the tip of the dike accompanied the intrusion eventually magma pressure in the dike exceeded the confining strength of the host rock triggering the 2010 eruption our results provide insight into the intrusion process that preceded an explosive eruption at a pacific rim stratovolcano following nearly a century of quiescence and therefore have implications for monitoring and hazards assessment at similar volcanoes elsewhere

constraints on magma chamber geometry at sierra negra volcano galapagos islands based on insar observations abstract we investigate the problem of estimating magma chamber geometry using insar observations of sierra negra volcano galapagos ascending and descending interferograms are combined to determine vertical and one horizontal component of displacement the ratio of maximum horizontal to vertical displacement suggests a sill like source spherical or stock like bodies are inconsistent with the data we estimate the geometry of the sill assuming a horizontal uniformly pressurized crack with unknown periphery and depth the sill is discretized into small elements that are either open and are subjected to the pressure boundary condition or remain closed we find the best fitting sill to be located beneath sierra negra s inner caldera at a depth of about 2 km using boundary element calculations we show that any magma chamber with a flat top coincident with the sill model fits the data equally well the data are insensitive to the sides and bottom of the magma chamber

trenching studies of active faults in kamchatka eastern russia palaeoseismic tectonic and hazard implications the central part of the kamchatka peninsula is characterized by a well defined depression associated with active volcanism aligned ne sw on the east the depression is bounded by a prominent system of active faults known as the east kamchatka fault zone ekfz in order to improve understanding of the behaviour and kinematic role of this fault zone a fieldwork programme including study of trenches was conducted in the north central part of this system aerial photograph analysis ground truthed indicates a westward fault dip with predominantly normal slip while lateral offsets of river terraces and stream channels demonstrate a combined dextral component over 20 excavated pits and natural exposures were examined to confirm a detailed tephra succession extending from the early holocene to recent historic eruptions this chronological framework then provided age control on five past faulting events recognised in three trenches these events took place at about 10 5 6 0 4 5 and in a two event succession within a short time span at 3 3 3 2 ka bp event clustering may be characteristic and fault length displacement values suggest earthquakes of m6 5 thus representing a significant new element in regional seismic hazard evaluations additional to events generated at the subduction interface the relatively long gap in faulting since the two most recent events may also be significant for hazard scenarios and there is a possible link between the faulting and volcanic activity in the depression overall the ekfz together with the nachiki transverse zone farther south is thought to define a regional scale block that is extending eastwards independently from the rest of kamchatka

broad accommodation of rift related extension recorded by dyke intrusion in saudi arabia volcanic fields at the eastern margin of the red sea rift were regarded as seismically quiet until a swarm of 30 000 earthquakes struck in 2009 geological analyses reveal the intrusion of a volcanic dyke and indicate that rift related extension is spread over a broad region far from the rift axis