land sea interaction and morphogenesis of coastal foredunes a modeling case study from the southern baltic sea coast abstract coastal foredunes are developed as a result of the interplay of multi scale land sea processes basic driving mechanisms of coastal foredune morphogenesis as well as natural processes and factors involved in shaping the foredune geometry are quantitatively studied in this paper by a numerical model aeolian sediment transport and vegetation growth on the subaerial part of a beach is simulated by a cellular automata ca approach while the sediment budget in the subaqueous zone serving as a sediment source sink for the foredune ridges is estimated in a process based model the coupled model is applied to a 1 km long section of a barrier coast swina gate in the southern baltic sea for a 61 year 1951 2012 hindcast of its foredune development general consistency is shown between the observational data and simulation results indicating that the formation of an established coastal foredune results from a balance between wind wave impacts and vegetation growth driven by an effective onshore wind and a boundary sediment supply small scale dunes develop on the backshore and migrate landward they are then trapped in a narrow strip characterized by a large density gradient of vegetation cover which separates the hydrodynamically active zone and the vegetated zone continuous accumulation of sediment in this strip induces the development of a foredune ridge according to the simulations the formation of an established coastal foredune has to meet three preconditions 1 an effective onshore aeolian transport 2 a net onshore or lateral sediment supply and 3 a climate favoring vegetation growth the formation of a new foredune ridge in front of an already existing foredune is determined by a combination of the sediment supply rate the extreme wind wave event frequency and the vegetation growth rate simulation results demonstrate a remarkable variability in foredune development even along a small 1 km coast section implying that the medium to long term land sea interaction and foredune morphogenesis is quite sensitive to boundary conditions and various processes acting on multi temporal and spatial scales

volcano ice interactions precursory to the 2009 eruption of redoubt volcano alaska abstract in late summer of 2008 after nearly 20 years of quiescence redoubt volcano began to show signs of abnormal heat flow in its summit crater in the months that followed the excess heat triggered melting and ablation of redoubt s glaciers beginning at the summit and propagating to lower elevations as the unrest accelerated a variety of morphological changes were observed including the creation of ice cauldrons areas of wide spread subsidence punctures in the ice carved out by steam and deposition from debris flows in this paper we use visual observations satellite data and a high resolution digital elevation model of the volcanic edifice to calculate ice loss at redoubt as a function of time our aim is to establish from this time series a proxy for heat flow that can be compared to other data sets collected along the same time interval our study area consists of the drift glacier which flows from the summit crater down the volcano s north slope and makes up about one quarter of redoubt s total ice volume of 4 km 3 the upper part of the drift glacier covers the area of recent volcanism making this part of ice mass most susceptible to the effect of volcanic heating moreover melt water and other flows are channeled down the drift glacier drainage by topography leaving the remainder of redoubt s ice mantle relatively unaffected the rate of ice loss averaged around 0 1 m 3 s over the last four months of 2008 accelerated to over twenty times this value by february 2009 and peaked at greater than 22 m 3 s just prior to the first major explosion on march 22 2009 we estimate a cumulative ice loss over this period of about 35 million cubic meters m m 3

control on the emplacement of the andesite lava dome of the soufriere hills volcano montserrat by degassing induced crystallization lava solidification is controlled by two mechanisms external cooling and gas exsolution the latter inducing crystallization due to increasing liquidus temperature the andesite lava dome of the soufriere hills volcano montserrat is an extrusion dominated by crystallization caused by gas exsolution where cooling is unimportant in controlling emplacement in the magma chamber the magma has an estimated viscosity of 7 106 pa s during ascent gas exsolution caused the magma to extrude in a highly crystalline state with only 5 15 residual melt viscosities in the range 1013 1014 pa s and mechanical strength 1 mpa deformation can be heterogeneous with extrusion along shear zones rheological stiffening in the upper conduit also causes large overpressures shallow seismicity and cyclic patterns of dome extrusion gas rich porphyritic andesites tend to be the least mobile kind of lava because transition from magma into hot crystalline material was reached during ascent

repeated fracture and healing of silicic magma generate flow banding and earthquakes textures in an exceptionally preserved effusive rhyolite conduit at torfajokull iceland indicate that rising magma repeatedly fractured and healed at shallow levels in the conduit rfh process anastomosing tuffisite veins filled by fine grained juvenile clasts were generated by shear fracture of highly viscous magma in the glass transition interval welding of the particulate material during subsequent deformation led to thorough healing of veins allowing repeated fracture of the same body of magma we propose that the rfh process is a rechargeable trigger mechanism for hybrid seismicity and show that the time scale of the process and the fractures formed by it are consistent with the repeat time and magnitude of hybrid earthquakes during silicic eruptions the rfh process may also form the flow banding that is nearly ubiquitous in obsidian

the age petrogeneis and tectonic significance of the frontenac formation basalts northern new hampshire and western maine within plate basalts are present across the connecticut valley gaspe trough in new england and canada proposed mechanisms for the extensional magmatism include back arc basin extension slab breakoff and extensional collapse the age and composition of the bimodal frontenac formation of northern new england and southern quebec has bearing on the topic we analyzed zircons from the meta felsic rocks of the formation and determined a silurian age of 432 8 ma we also analyzed the frontenac rocks for major and trace elements and compared their compositions to the other mafic rocks along strike in the connecticut valley gaspe trough these include the comerford intrusive suite and the standing pond volcanic member of the waits river formation of vermont the silurian chaleur group and the early devonian dalhousie group of new brunswick and the gaspe peninsula and to the piscataquis belt rocks of northern maine all these rocks are post taconic within plate tholeiites that span an age range from 432 ma frontenac formation to 419 ma comerford intrusive suite in spite of their similar tectonic setting subtle differences in trace element compositions are evident indicating a multiplicity of sources in the production of the siluro devonian magmas ce yb versus la ta values suggest that the frontenac magmas were derived from spinel peridotite sources in the asthenospheric mantle we suggest that slab rollback and back arc basin extension permitted asthenospheric mantle upwelling to the spinel peridotite stability field causing the frontenac partial melting event at depths as low as 35 km sediments of the frontenac formation were deposited as turbidite successions into a developing trough resulting from extension the coeval influx of sediment and intrusion of basalt produced a sediment sill complex because the upward migration of the basaltic magmas was hindered by the rapidly thickening sediment overburden subsequently slab breakoff may have opened an asthenospheric window generating the younger within plate magmas that occurred from 425 to 418 ma across the connecticut valley gaspe trough

evaluation of depth of closure using data from duck nc usa using 12 years of frequent high precision profiles collected on a wave dominated sandy oceanic beach to 8 m depth the characteristics and interpretation of depth of closure or the seaward limit of significant profile change is critically examined this includes evaluation of the predictive capability of d1 the seaward boundary of the littoral zone as originally defined by hallermeier 1981 hallermeier r j 1981 a profile zonation for seasonal sand beaches from wave climate coastal eng 4 253 277 depth of closure during major erosional events is usually produced by the seaward limit of offshore bar movement following the original recommendation of hallermeier 1981 d1 based on 12 h exceeded wave height and a reference depth of mean low water provides a robust limit to the observations using a 6 cm change criterion empirically the observed depth of closure is 69 of d1 although the scatter is large this scatter is partly controlled by pre event profile shape most particularly bar configuration depth of closure under accretional conditions can also be measured but it is time scale dependent as accretion is a slow steady process d1 underpredicts closure for accretional situations time interval e g annual depth of closure represents the integral effect of erosional and accretional events an important observation of the data is that depth of closure increases with time scale however the full population of time interval observations is not resolved at duck due to the measurement limit 8 m depth as time interval increases from 1 year to 8 years less cases close most non closing time interval cases coincide with the periods influenced by the most energetic wave events however time interval closures are generally deeper than the biggest event closure in the period showing that it represents more than the largest event the frequency distribution of the data suggests that most if not all of these missing data simply represent closures deeper than 8 m depth up to a 4 year time interval d1 t appears to provide a reasonable limit to the quantified observations it is an interesting result that d1 an event based approach might provide a limit to closure over periods up to 4 years as these time interval closures are generally larger than those produced by single storms therefore the general applicability of this result for more complete data sets or on rapidly evolving i e eroding or accreting coasts is uncertain the present data also suggest that on swell dominated coastlines where accretional processes are dominant d1 may underpredict closure suggesting an important limitation to this approach but as sediment would be moving onshore this may not be a practical problem therefore within the limits of the data set hallermeier s 1981 approach is found to define robust estimates of depth of closure particularly for individual erosional events this useful result is expected to find widespread application in coastal geology and engineering

gas emissions from failed and actual eruptions from cook inlet volcanoes alaska 1989 2006 cook inlet volcanoes that experienced an eruption between 1989 and 2006 had mean gas emission rates that were roughly an order of magnitude higher than at volcanoes where unrest stalled for the six events studied mean emission rates for eruptions were 13 000 t d co2 and 5200 t d so2 but only 1200 t d co2 and 500 t d so2 for non eruptive events failed eruptions statistical analysis suggests degassing thresholds for eruption on the order of 1500 and 1000 t d for co2 and so2 respectively emission rates greater than 4000 and 2000 t d for co2 and so2 respectively almost exclusively resulted during eruptive events the only exception being two measurements at fourpeaked while this analysis could suggest that unerupted magmas have lower pre eruptive volatile contents we favor the explanations that either the amount of magma feeding actual eruptions is larger than that driving failed eruptions or that magmas from failed eruptions experience less decompression such that the majority of h2o remains dissolved and thus insufficient permeability is produced to release the trapped volatile phase or both in the majority of unrest and eruption sequences increases in co2 emission relative to so2 emission were observed early in the sequence with time all events converged to a common molar value of c s between 0 5 and 2 these geochemical trends argue for roughly similar decompression histories until shallow levels are reached beneath the edifice i e from 20 35 to 4 6 km and perhaps roughly similar initial volatile contents in all cases early elevated co2 levels that we find at these high latitude andesitic arc volcanoes have also been observed at mid latitude relatively snow free basaltic volcanoes such as stromboli and etna typically such patterns are attributed to injection and decompression of deep co2 rich magma into a shallower chamber and open system degassing prior to eruption here we argue that the c s trends probably represent tapping of vapor saturated regions with high c s and then gradual degassing of remaining dissolved volatiles as the magma progresses toward the surface at these volcanoes however c s is often accentuated due to early preferential scrubbing of sulfur gases the range of equilibrium degassing is consistent with the bulk degassing of a magma with initial co2 and s of 0 6 and 0 2 wt respectively similar to what has been suggested for primitive redoubt magmas

stochastic simulation of volcanic tremor from ruapehu abstract the most common volcanic tremor produced by ruapehu is a continuous signal with a dominant frequency of about 2 hz this signal has a sharply peaked spectrum and an autocorrelation function with a high degree of coherence even for lags of over 20 seconds these characteristics strongly suggest that the cause of this tremor is a single resonator probably a fluid filled cavity resonating in an organ pipe mode the stochastic simulation of such a resonator uses the equation of motion of a simple harmonic oscillator which applies to an organ pipe fundamental resonance with either the characteristics of the oscillator or the forcing function containing a random element a white noise forcing function which would be appropriate for excitation of the cavity by a high pressure gas input gave good agreement with the observed spectra and autocorrelation functions another possible model used an oscillator with a damping factor which varied randomly and was sometimes negative so oscillations built up rather than decayed this also gave a reasonable simulation of ruapehu tremor the third excitation model used a poisson process in which during each time interval there was a certain probability of applying a fixed impulse to the resonator it was found that the impulses had to be frequent i e several times a second to match the characteristics of ruapehu tremor it has been suggested that tremor is composed of a succession of low frequency b type earthquakes the results of this simulation show that at ruapehu tremor could be produced by a resonator with positive feedback just sustaining oscillation or by a resonator excited by external impulses the most promising model for low frequency earthquakes describes them as the result of a major external disturbance of the resonator

monitoring velocity variations in the crust using earthquake doublets an application to the calaveras fault california we present a technique that greatly improves the precision in measuring temporal variations of crustal velocities using an earthquake doublet or pair of microearthquakes that have nearly identical waveforms and the same hypocenter and magnitude but occur on different dates we compute differences in arrival times between seismograms recorded at the same station in the freqency domain by cross correlation of short windows of signal a moving window analysis of the entire seismograms including the coda gives t the difference in arrival times versus running time along the seismogram the time resolution of the method is an order of magnitude better than the digitization interval the t technique is illustrated with a pair of microearthquakes m 1 7 and 2 0 that occurred before and after the coyote lake california earthquake m 5 9 of august 6 1979 and on the same segment of the calaveras fault that ruptured during the earthquake the coda wave arrivals for some stations are progressively delayed for the second earthquake in the doublet so that its seismogram appears as a stretched version of the earlier event we interpret this systematic variation in t along the coda as a change in the average s velocity in the upper crust in the time interval between the two doublets s wave velocities appear to have decreased by 0 2 in an oblong region 5 10 km in radius at the south end of the aftershock zone

deep fault plane geometry inferred from multiplet relative relocation beneath the south flank of kilauea dense microearthquake swarms occur in the upper south flank of kilauea providing multiplets composed of hundreds of events the similarity of their waveforms and the quality of the data have been sufficient to provide accurate relative relocations of their hypocenters a simple and efficient method has been developed which allowed the relative relocation of more than 250 events with an average precision of about 50 m horizontally and 75 m vertically relocation of these events greatly improves the definition of the seismic image of the fault that generates them indeed relative relocations define a plane dipping about 6 northward although corresponding absolute locations are widely dispersed in the swarm a composite focal mechanism built from events providing a correct spatial sampling of the multiplet also gives a well constrained northward dip of about 5 to the near horizontal plane this technique thus collapses the clouds of hypocenters of single event locations to a plane coinciding with the slip plane revealed by previous focal mechanism studies we cannot conclude that all south flank earthquakes collapse to a single plane there may locally be several planes perhaps with different dips and depths throughout the south flank volume the 6 northward dipping plane we found is too steep to represent the overall flexure of the oceanic crust under the load of the island of hawaii this plane is probably an important feature that characterizes the basal slip layer below the upper south flank of kilauea volcano differences in seismicity rate and surface deformations between the upper and lower south flank could be related to the geometry of this deep fault plane the present work illustrates how high precision relative relocations of similar events in dense swarms combined with the analysis of geodetic measurements can help to describe deep fault plane geometry systematic selection and extensive relative relocation of similar earthquakes could be attempted in other well instrumented highly seismic areas to provide reliable basic information especially useful for understanding of earthquake generation processes

hidden dykes detected on ultra long period seismic signals at piton de la fournaise volcano broadband seismic data enable us to test whether ultra long period ulp signals can be used to investigate magma chamber pressure state and to monitor volcanic eruptions by systematically investigating seismic signals at geoscope station rer we find ulp signals associated with volcanic events during the last 2 decades we tentatively propose to interpret these signals as events highlighting the activity of the upper magma feeding system of the piton de la fournaise volcano and as being related to the deep magma chamber some of these unusual signals were previously detected and usually interpreted in term of tilt battaglia j aki k montagner j j p tilt signals derived from a geoscope vbb station on the piton de la fournaise volcano geophys res lett 27 5 2000 605 608 they are detected using sts1 seismometers sensitive in the bandwidth 10 3 to 10 2 hz this alternative model enables to quantify each event in terms of a pressure drop in the upper magma reservoir of the volcano two kinds of seismic waveforms can be associated with two types of fracturing events the first one is related to the fast rise of a magma batch coming from the deep magma chamber and the second is the result of a slow rise in pressure inside a shallow reservoir in both cases we are able to detect these events on very long period seismic data the interpretation of these signals supports the idea of a single magma source at the sea level thus we propose to classify all the eruptions occurring during the last two decades into two groups corresponding to the two primary pressure states of the magma chamber 2007 elsevier b v all rights reserved

present day dune environment dynamics on the coast of the świna gate sandbar polish west coast abstract in present day polish coastal dunes development heavy storms and human activity play a significant role natural or almost natural dune processes and accumulation of the coast is observed only in a few places such as the wina gate sandbar also called barrier as far as the spit number and morphology of the youngest ridges is concerned they are different in the western the middle and the eastern part in the western part ridges are smaller and closer to each other thus depressions between them are narrower moreover beach is widely covered by small hillocks in the middle part ridges are higher but narrower likewise depressions between them are wider the beach is wide and covered by large numbers of plants and dune hillocks in the eastern part dunes are also high but tend to be narrow with steep seaside slope having the most frequent occurrence depressions and beach are narrow the number of plants is not considerable compared with other parts since 1997 an increase of the new dune ridge on the still developing beach has been observed each year the beach is becoming wider and covered by larger number of plants plants lead to the development of new dunes and increase of the sandbar the new foredune ridge consists of several hillocks joined into irregular ridge this new first ridge is also shaped by storm waves but still becomes a real ridge this development may be caused by continuous sand supply and by very strong north and west winds a lot of different dune psammophyties on the beach are in favour of sand fixing on the increasing beach far from the first ridge only on part of spit with a tendency to erosion accumulation of the dunes is not to be observed additionally human activity stops aeolian accumulation and plant growth on the beach

simulation of large scale coastal change using a morphological behaviour model abstract quantitative simulation of large scale coastal behaviour lscb is possible using a model based only on principles of sand mass conservation and geometric rules for shoreface and active sand body morphology dynamic processes are subsumed into a set of parameters that define the geometry of the active cross shore profile which in turn can represent an entire coastal cell the parameters together with a set of local behaviour rules governing adjustments at discrete points along the profile provide a simple formulation that is constrained by sediment mass balance to yield emergent numerical solutions for profile kinematics the emergent qualities of this shoreface translation model are exemplified in simulation experiments on changes to sand deposits on the southeastern australian coast and shelf during the post glacial marine transgression in another example the model is used to simulate lscb over engineering time scales at an idiosyncratic site both examples illustrate the over riding importance of small residual sand movements that accumulate through time to cause lscb in comparison to gross sand movements the residuals are too small to measure directly or predict on the basis of available theory exploratory inverse simulation provides a quantitative method for side stepping these limitations the shoreface translation model therefore is used as a tool to explore possible forms of coastal behaviour through an approach that incorporates available data along with theoretical considerations validation is not strictly possible for this type of inverse approach so the degree to which a simulation reproduces observed features in nature is a measure of its success

location of eruption related earthquake clusters at augustine volcano alaska using station pair differential times summary families of similar earthquakes at shallow depths occurring over multiple timescales have been identified prior to and during the 2005 2006 eruption of augustine volcano the use of conventional and double difference location methods failed to result in stable locations due primarily to noisy site conditions as well as unfavourable station geometry for the alaska volcano observatory stations previous work found that relatively robust estimates of the median arrival time difference between station pairs could be determined and used a constant velocity half space model true station elevations and a variant of the method of hyperbolas to estimate locations for four of the clusters we have carried out a more extensive location analysis including data from nine clusters and incorporating a linear gradient velocity model obtained from preliminary forward modelling of the data our location results show a progressive shallowing of the clusters with time clusters prior to 2005 december lie near sea level whereas those in 2005 december and 2006 january concentrate about 500 m above sea level asl prior to the explosive eruptions and about 500 and 1200 m asl respectively essentially at the surface afterwards these results are consistent with geodetic observations and modelling

taconian orogenesis sedimentation and magmatism in the southern quebec northern vermont appalachians stratigraphic and detrital mineral record of iapetan suturing cambrian ordovician units of the southern quebec appalachians oceanic domain include obducted ophiolites and an overlying syncollisional sedimentary basin represented by the saint daniel melange and flysch units of the magog group these terrains were thrust onto the laurentian continental margin during the taconian orogeny and are unconformably overlain by silurian devonian successor basins this contribution presents and discusses new stratigraphic data acquired in the oceanic domain as well as u pb and 40ar 39ar geochronological data on detrital zircons and muscovites sampled at various stratigraphic levels from the base of the sedimentary units of the oceanic domain and the silurian devonian units of the gaspe belt this work combined with the compilation of existing data for southern quebec and western new england allows a better definition of the tectono stratigraphic evolution of the area and are used to propose correlations with different rock units of the northern new england appalachians which represents a collage of laurentian margin and oceanic units it is shown that cambrian ordovician rocks of southern quebec and northern vermont have undergone a similar tectonic evolution the ophiolites were obducted onto the laurentian margin as a more or less coherent slab of oceanic lithosphere both the ophiolites and continental margin rocks were uplifted eroded and unconformably overlain by middle to late ordovician units of the saint daniel melange and magog group in a forearc setting the presence of mafic and felsic volcanic flows that are interstratified within the saint daniel melange can be correlated with an episode of delamination and slab breakoff during the final stages of obduction and exhumation of the orogenic wedge the magog group was deposited during the emplacement of the taconian nappes as the outboard volcanic arc was still active but progressively shutting down the provenances suggested by the age of the dated detrital minerals can be entirely reconciled with the peri laurentian context of the studied rock units and testify of the tectonic evolution and sedimentary recycling of the taconian orogen from ophiolite obduction onto the laurentian margin to the collapse of the orogenic belt and the formation of successor basins

coastline evolution at different time scales examples from the pomeranian bight southern baltic sea sedimentological and morphological changes on the upper and lower shoreface during relatively stable sea level highstand conditions have been investigated in the pomeranian bight southern baltic sea at time scales ranging from storm events to millennia in order to cover that variety of time scales different methods have been applied seasonal variations in the morphology of the upper shoreface were measured accurately using the tracer stick method the ratio of breaking waves and energy dissipation due to wave breaking are the main forces controlling redeposition on the upper shoreface with the depth of disturbance up to three times the net change the impact of single storm events can be observed from sidescan sonar mosaics to remain on the decadal scale aerial photographs covering the upper shoreface show that the location of gates channel like systems where water masses move offshore created during storm events also remain stable over decades sedimentological and geomorphological variations and changes on the lower shoreface are only measurable on the century to millennium scale because the main driving forces are longlasting processes like sea level fluctuations or neotectonics data on these scales have much more uncertainty in their relationship to forcing functions than data at shorter time scales because the effects of coastal processes active on different time scales can interact comprehensive understanding of large scale coastal behavior requires investigations from short events to long term processes c 2002 elsevier science b v all rights reserved

modelling storm impacts on beaches dunes and barrier islands a new nearshore numerical model approach to assess the natural coastal response during time varying storm and hurricane conditions including dune erosion overwash and breaching is validated with a series of analytical laboratory and field test cases innovations include a non stationary wave driver with directional spreading to account for wave group generated surf and swash motions and an avalanching mechanism providing a smooth and robust solution for slumping of sand during dune erosion the model performs well in different situations including dune erosion overwash and breaching with specific emphasis on swash dynamics avalanching and 2dh effects these situations are all modelled using a standard set of parameter settings the results show the importance of infragravity waves in extending the reach of the resolved processes to the dune front the simple approach to account for slumping of the dune face by avalanching makes the model easily applicable in two dimensions and applying the same settings good results are obtained both for dune erosion and breaching

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

characterization of controls on high resolution stratigraphic architecture in wave dominated shoreface shelf parasequences using inverse numerical modeling abstract a new inverse numerical modeling method is used to constrain the environmental parameters e g relative sea level sediment supply and wave climate histories that control stratigraphic architecture in wave dominated shallow marine deposits the method links a process response forward stratigraphic model that simulates wave and storm processes barsim to a combination of inverse methods formulated in a bayesian framework that allows full characterization of uncertainties this method is applied for the first time to a real geologic dataset collected at outcrop from two shoreface shelf parasequences in the aberdeen member blackhawk formation of the book cliffs east central utah usa the environmental parameters that controlled the observed stratigraphic architecture are quantified and key aspects of stratigraphic architecture are successfully predicted from limited data stratigraphic architecture at parasequence stacking and intra parasequence scales was driven principally by relative sea level varying by up to about 55 m and sediment supply varying by up to 70 m2 yr whose interplay determines the shoreline trajectory within zones of distinctive shoreline trajectory variations in wave climate of up to about 3 m in fairweather wave height controlled superimposed variations in sandstone and shale content e g the development of upward coarsening and upward fining bedsets the modeling results closely match the observed stratigraphic architecture but their quality is limited by 1 the formulation and assumptions of the forward modeling algorithms and 2 the observed data distribution and quality which provide poor age constraint

constraints on unrest in the tolbachik volcanic zone in kamchatka prior the 2012 13 flank fissure eruption of plosky tolbachik volcano from local seismicity and gps data abstract a new fissure eruption began on 27 november 2012 on the southern slope of plosky tolbachik volcano which is located in central kamchatka russia and is part of the klyuchevskoy volcano group we analyzed the displacement of the earth surface and the seismicity during several months before the eruption onset according to seismic and gps data the eruption was preceded by about 4 5 months july november 2012 of synchronous crustal deformation and seismicity the seismic anomaly comprises low energy level seismicity mainly m 1 2 2 3 under plosky tolbachik volcano at a depth of less than 5 km in the 2 3 weeks immediately preceding the eruption the rate of seismicity and the amount of radiated seismic energy exceeded the long term average values 2000 2011 by more than 40 times the deformation anomaly was recorded by displacement of the gps points at distances from 20 to 60 km to the north of tolbachik the principal axis of the compressive strain was approximately directed towards the tolbachik eruption site the permanent gps network detected radial compression and tangential stretching the compressive strain reached about 10 7 prior to eruption onset the comparable duration of seismic and deformation anomalies 4 5 months before the eruption is consistent with a common origin connected to magma rising from depth and is interpreted as indicating that they were medium term precursors to the eruption data recorded during this unrest episode of the tolbachik volcanic zone will contribute to understanding of the reawakening of volcanic activity in this region and others worldwide with similar characteristics

ground deformation associated with the precursory unrest and early phases of the january 2006 eruption of augustine volcano alaska 1 on january 11 2006 augustine volcano erupted after nearly 20 years of quiescence global positioning system gps instrumentation at augustine consisting of six continuously recording telemetered receivers measured clear precursory deformation consistent with a source of inflation or pressurization beneath the volcano s summit at a depth of around sea level deformation began in early summer 2005 and was preceded by a subtle but distinct increase in seismicity which began in may 2005 after remaining more or less constant deformation rates accelerated on at least three stations beginning in late november 2005 after this date gps data suggest the upward propagation of a small dike into the edifice which based on the style of deformation and high levels of gas emission appears to have ascended to shallow levels by mid december 2005 about four weeks before the eruption began

constraints on dike propagation from continuous gps measurements the january 1997 east rift zone eruption on kilauea volcano hawaii occurred within a network of continuous global positioning system gps receivers the gps measurements reveal the temporal history of deformation during dike intrusion beginning 8 hours prior to the onset of the eruption the dike volume as a function of time estimated from the gps data using elastic green s functions for a homogeneous half space shows that only two thirds of the final dike volume accumulated prior to the eruption and the rate of volume change decreased with time these observations are inconsistent with simple models of dike propagation which predict accelerating dike volume up to the time of the eruption and little or no change thereafter deflationary tilt changes at kilauea summit mirror the inferred dike volume history suggesting that the rate of dike propagation is limited by flow of magma into the dike a simple lumped parameter model of a coupled dike magma chamber system shows that the tendency for a dike to end in an eruption rather than intrusion is favored by high initial dike pressures compressional stress states large compressible magma reservoirs and highly conductive conduits linking the dike and source reservoirs comparison of model predictions to the observed dike volume history the ratio of erupted to intruded magma and the deflationary history of the summit magma chamber suggest that most of the magma supplied to the growing dike came from sources near to the eruption through highly conductive conduits interpretation is complicated by the presence of multiple source reservoirs magma vesiculation and cooling as well as spatial variations in dike normal stress reinflation of the summit magma chamber following the eruption was measured by gps and accompanied a rise in the level of the pu u o o lava lake for a spheroidal chamber these data imply a summit magma chamber volume of 20 km3 consistent with recent estimates from seismic tomography continuous deformation measurements can be used to image the spatiotemporal evolution of propagating dikes and to reveal quantitative information about the volcanic plumbing systems

storm driven bottom sediment transport on a high energy narrow shelf nw iberia and development of mud depocenters bottom sediment transport on the nw iberian shelf was monitored during a downwelling storm in september 2014 collected data was analyzed and fed into a 3d coastal ocean model to understand storm driven sediment transport on the shelf and its impact on mid shelf mud depocenters mdcs a significantly enhanced level of bottom sediment resuspension nearly two orders of magnitude higher than that in the pre storm period was recorded at the mooring site field data analysis reveals that it was induced by a short lasting strong bottom current in combination with enhanced wave current interaction simulation results indicate that this strong current was part of a coastal jet resulted from downwelling an across shelf horizontal density gradient as high as 0 32 g m4 occurred at the interface between the downwelling and the bottom waters forming a remarkable front due to buoyancy effect the downwelling water was mostly confined to the coast with a depth limit of 80 m in the south and 120 m in the north of the region resulting in a northward directed coastal jet simulation results suggest that during the storm local near bottom sediment suspensions with concentrations on the order of 10 kg m3 would be triggered by wave current interaction and flow convergence associated with the front direct impact on the development of mdcs by transport and deposition of concentrated sediment suspensions is indicated by model results the seaward limit of the front coincided with the shoreward edge of the mdc nucleus suggesting the front as a primary control on the deposition of fine grained sediment this article is protected by copyright all rights reserved

models of ground deformation from vertical volcanic conduits with application to eruptions of mount st helens and mount etna we present simple analytical models of ground deformation from inflation of vertical volcanic conduits or pipes we compare three cases corresponding to 1 a pressurized pipe with closed end at the top that resists the internal pressure 2 a pressurized pipe with top open for which the internal deformation is mainly dislocation of the cylindrical walls and 3 a pipe shaped region that dilates for the closed pipe we use eshelby s inclusion theory to model deformation from a thin pressurized elongated prolate ellipsoid in a full space which we express in terms of double forces to satisfy surface boundary conditions we superimpose image solutions by using double forces derived from mindlin s half space solution for the point force for the open pipe we apply the volterra integral to dislocation across a cylindrical surface and generalize it to the half space using mindlin s point force solution these two solutions show marked differences from the line of dilatation solution ratios of maximum horizontal deformation to maximum vertical deformation for the pipe models are significantly greater than values for the center or line of dilatation models this and the more gradual fall off of the deformation with distance may be used as diagnostics for discriminating between pipe like sources and dilatational sources on volcanoes where both components of the deformation field are available as examples we compare the closed pipe model with deformation associated with dome building on mount st helens volcano and tilt predicted by the open pipe model with tilt measured during a period of explosive eruptive activity on mount etna sicily in 1995 comparison between model values and the measurements suggests that the effective elastic moduli of the volcanic cones are very low

dynamics of seismogenic volcanic extrusion at mount st helens in 2004 05 the 2004 05 eruption of mount st helens exhibited sustained near equilibrium behaviour characterized by relatively steady extrusion of a solid dacite plug and nearly periodic shallow earthquakes here we present a diverse data set to support our hypothesis that these earthquakes resulted from stick slip motion along the margins of the plug as it was forced incrementally upwards by ascending solidifying gas poor magma we formalize this hypothesis with a dynamical model that reveals a strong analogy between behaviour of the magma plug system and that of a variably damped oscillator modelled stick slip oscillations have properties that help constrain the balance of forces governing the earthquakes and eruption and they imply that magma pressure never deviated much from the steady equilibrium pressure we infer that the volcano was probably poised in a near eruptive equilibrium state long before the onset of the 2004 05 eruption

repeating coupled earthquakes at shishaldin volcano alaska since it last erupted in 1999 shishaldin volcano aleutian islands alaska has produced hundreds to thousands of longperiod 1 2 hz lp earthquakes every day with no other sign of volcanic unrest in 2002 the earthquakes also exhibited a short period 4 7 hz sp signal occurring between 3 and 15 s before the lp phase although the sp phase contains higher frequencies than the lp phase its spectral content is still well below that expected of brittle failure events the sp phase was never observed without the lp phase although lp events continued to occur in the absence of the precursory signal the twophased events are termed bcoupled eventsq reflecting a triggered relationship between two discrete event types both phases are highly repetitive in time series suggestive of stable non destructive sources waveform cross correlation and spectral coherence are used to extract waveforms from the continuous record and determine precise p wave arrivals for the sp phase although depths are poorly constrained the sp phase is believed to lie at shallow b4 km depths just west of shishaldin s summit the variable timing between the sp and lp arrivals indicates that the trigger mechanism between the phases itself moves at variable speeds a model is proposed in which the sp phase results from fluid moving within the conduit possibly around an obstruction and the lp phase results from the coalescence of a shallow gas bubble the variable timing is attributed to changes in gas content within the conduit the destruction of the conduit obstacle on november 21 2002 resulted in the abrupt disappearance of the sp phase published by elsevier b v

lithospheric geometry of the wopmay orogen from a slave craton to bear province magnetotelluric transect 1 two dimensional inversions of lithospheric probing magnetotelluric mt data at a total of 20 sites acquired along an approximately east west 300 km long profile across the wopmay orogen in the northwest territories canada provide electrical resistivity models of the boundary between the archean slave craton and the adjacent proterozoic bear province an analysis of distortion effects and structural dimensionality indicates that the mt responses are primarily one dimensional or only weakly two dimensional with a depth independent geoelectric strike angle of n32 e consistent with regional structural geology the regional scale model generated from the longer period responses from all of the sites along the profile reveals significant lateral variations in the lithospheric mantle resistive cratonic roots are imaged to depths of 200 km beneath both the slave craton and the hottah terrane of the bear province these are separated by a less resistive region beneath the great bear magmatic zone which is speculatively interpreted as a consequence of a decrease in the grain size of olivine in the wopmay mantle caused by localized shearing compared to its neighboring cratonic roots focused two dimensional models from higher frequency responses at sites on specific sections of the profile reveal the resistivity structure at crustal depths beneath the region these suggest that the root of the slave craton crosses beneath the wopmay orogen and that the wopmay fault zone does not penetrate into the lower crust a comparison of these results with those obtained during the lithoprobe project farther south shows striking along strike variations in the conductivity structure associated with the wopmay orogen

location of long period events below kilauea volcano using seismic amplitudes and accurate relative relocation 1 we present methods for improving the location of long period lp events deep and shallow recorded below kilauea volcano by the permanent seismic network lp events might be of particular interest to understanding eruptive processes as their source mechanism is assumed to directly involve fluid transport however it is usually difficult or impossible to locate their source using traditional arrival time methods because of emergent wave arrivals at kilauea similar lp waveform signatures suggest the existence of lp multiplets the waveform similarity suggests spatially close sources while catalog solutions using arrival time estimates are widely scattered beneath kilauea s summit caldera in order to improve estimates of absolute lp location we use the distribution of seismic amplitudes corrected for station site effects the decay of the amplitude as a function of hypocentral distance is used for inferring lp location in a second stage we use the similarity of the events to calculate their relative positions the analysis of the entire lp seismicity recorded between january 1997 and december 1999 suggests that a very large part of the lp event population both deep and shallow is generated by a small number of compact sources deep events are systematically composed of a weak high frequency onset followed by a low frequency wave train aligning the low frequency wave trains does not lead to aligning the onsets indicating the two parts of the signal are dissociated this observation favors an interpretation in terms of triggering and resonance of a magmatic conduit instead of defining fault planes the precise relocation of similar lp events based on the alignment of the high energy low frequency wave trains defines limited size volumes

dmodels a matlab software package for modeling crustal deformation near active faults and volcanic centers abstract we have developed a matlab software package for the most common models used to interpret deformation measurements near faults and active volcanic centers the emphasis is on analytical models of deformation that can be compared with data from the global positioning system gps insar tiltmeters and strainmeters source models include pressurized spherical ellipsoidal and sill like magma chambers in an elastic homogeneous flat half space dikes and faults are described following the mathematical notation for rectangular dislocations in an elastic homogeneous flat half space all the expressions have been checked for typographical errors that might have been present in the original literature extended to include deformation and strain within the earth s crust as opposed to only the earth s surface and verified against finite element models a set of gps measurements from the 2006 eruption at augustine volcano alaska is used to test the software package the results show that the best fit source to the gps data is a spherical intrusion v 5 10 4 km3 about 880 m beneath the volcano s summit

determining the seismic source mechanism and location for an explosive eruption with limited observational data augustine volcano alaska 1 waveform inversions of the very long period components of the seismic wavefield produced by an explosive eruption that occurred on 11 january 2006 at augustine volcano alaska constrain the seismic source location to near sea level beneath the summit of the volcano the calculated moment tensors indicate the presence of a volumetric source mechanism systematic reconstruction of the source mechanism shows the source consists of a sill intersected by either a sub vertical east west trending dike or a sub vertical pipe and a weak single force the trend of the dike may be controlled by the east west trending augustine seldovia arch the data from the network of broadband sensors is limited to fourteen seismic traces and synthetic modeling confirms the ability of the network to recover the source mechanism the synthetic modeling also provides a guide to the expected capability of a broadband network to resolve very long period source mechanisms particularly when confronted with limited observational data

observations of hybrid seismic events at soufriere hills volcano montserrat july 1995 to september 1996 swarms of small repetitive events with similar waveforms and magnitudes are often observed during the emplacement of lava domes over 300 000 such events were recorded in association with the emplacement of the lava dome at soufriere hills volcano montserrat from august 1995 through august 1996 these events originated 2 3 km deep they exhibited energy ranging over 1 5 4 5 hz and were broader band than typical long period events we term the events hybrid between long period and volcano tectonic the events were more impulsive and broader band prior to compared with during and after periods of inferred increased magma flux rate individual swarms contained up to 10 000 events often exhibiting very similar magnitudes and waveforms throughout the swarm swarms lasted hours to weeks during which inter event intervals generally increased then decreased often several times long duration swarms began about every two months starting in late september 1995 we speculate that the events were produced as the magma column degassed into adjacent cracks

observations of volcanic tremor at mount st helens volcano digital recordings of ground motion during tremor episodes accompanying eruptions at mount st helens volcano in the state of washington on august 7 and october 16 18 1980 are studied the spectra of the vertical component waveforms contain at least two dominant peaks at 1 0 and 1 3 hz for all events recorded during both eruptions that were studied spectra of horizontal ground motion show peaks at 0 9 and 1 1 hz the relative amplitude of the two peaks changes between tremor episodes and during single tremor episodes and shows no consistent relation to amplitude of ground motion spectra of long period earthquakes are very similar to those of tremor events suggesting that tremor is composed of many long period earthquakes that occur over a period of time the unique waveform of tremor events observed at mount st helens must be due to a source effect since the relative amplitude of the two dominant peaks changes during tremor episodes the path effect on tremor waveforms is small since there are no peaks in the spectra of waveforms recorded during tectonic earthquakes occurring in the vicinity of mount st helens the consistency of the location of the spectral peaks for the wide range of tremor amplitudes means that there must be a physical length at the source that is constant independent of the amplitude of motion at the source variations in amplitude of motion generated during tremor events must be due to variations in the force driving the tremor amplitudes of ground motion varies between 0 11 and 4 7 m seismic moment rates during the two eruptions are calculated using the model of aki et al 1977 and found to vary between 6 1018 and 1 1020 dynes cm s 1 which are larger than values found by aki et al 1977 who studied amplitudes of shallow tremor events recorded during the october 1963 eruption of kilauea volcano in hawaii study of tremor amplitudes recorded at corvallis oregon leads to the conclusion that tremor accompanying the cataclysmic may 18 1980 eruption was at least one order of magnitude larger in amplitude than tremor during august and october

long period seismicity during magma movement at volcan de colima during the period from february to september 2005 volcan de colima produced 30 vulcanian explosions of sufficient magnitude to produce pyroclastic flows of variable size with a total volume of at least 2 5 106 m3 swarms of long period events were associated with each event their duration ranging from about 6 h to 3 days and each swarm containing up to 886 events the characteristics of the swarms have been studied to understand the source mechanism and their relationship with the vulcanian explosions in total 12 548 long period events were analysed using various comparative and statistical methods patterns were not apparent in the data with no correlation between different properties of the swarms duration magnitude or frequency of occurrence of lp events and the magnitude of the associated vulcanian explosion whether recorded by seismicity volume of pyroclastics or altitude of the eruption column this along with other characteristics of the swarms such as the continuation of the swarm after the explosion with an increase in long period event amplitude in some cases suggests that the mechanism is not merely associated with the pressurization under an impermeable cap and resulting pressure differentials between adjacent volumes within the system it is more likely that the production of long period events is dominated by brittle fracturing on the margins of an ascending magma body a model is proposed whereby the unloading above the ascending magma column produced by a vulcanian explosion resulted in an increase in ascent rate reflected in the increasing amplitude of long period events the results reflect the complexity of non linear processes involved during magma ascent degassing crystallization and rupture of the impermeable plug during the vulcanian process at volcan de colima as at many volcanoes long period events represent a useful precursor for eruptive activity for monitoring this paper highlights some useful analyses that can be carried out which could illustrate certain characteristics of an eruptive episode a preliminary model is presented of the conduit processes at work during the cyclic extrusive and explosive activity during 2005

a coupled modeling scheme for longshore sediment transport of wave dominated coasts a case study from the southern baltic sea abstract a modeling scheme based on dynamic coupling of a high resolution 1d cross shore model to a 2dh area model is developed to calculate the total longshore sediment transport lst rate in wave dominated coasts the purpose of this coupling strategy aims at resolving the lst with a high resolution both temporally and spatially inside the surf zone and with a coarser spatial resolution seaward of the surf zone the 2dh area model operates on a fixed pre designed regional grid parent grid and the 1d cross shore model is dynamically coupled to the boundary of the parent grid with a time varying domain starting from the first wave breaking point and ending at the maximum wave set up point the time varying domain is generated in the 1d model by resolving the landward wave propagation from the offshore conditions provided by the 2dh area model at every time step with a high resolution cell size the 1d model resolves the wave propagation processes and resulting lst along the profile the coupled model is applied to study the lst in the pomeranian bight at the southern baltic sea simulation results are compared with three other different hierarchical modeling methods from empirical formulas such as cerc and kamphuis to a 2dh area simulation the comparative study indicates that the dynamically coupled model can be a reliable tool in practical applications especially for the areas where hydrodynamics is controlled by complex bathymetry e g multiple longshore bars or morphologically induced circulation patterns

volcano geodesy recent developments and future challenges abstract ascent of magma through earth s crust is normally associated with among other effects ground deformation and gravity changes geodesy is thus a valuable tool for monitoring and hazards assessment during volcanic unrest and it provides valuable data for exploring the geometry and volume of magma plumbing systems recent decades have seen an explosion in the quality and quantity of volcano geodetic data new datasets some made possible by regional and global scientific initiatives as well as new analysis methods and modeling practices have resulted in important changes to our understanding of the geodetic characteristics of active volcanism and magmatic processes from the scale of individual eruptive vents to global compilations of volcano deformation here we describe some of the recent developments in volcano geodesy both in terms of data and interpretive tools and discuss the role of international initiatives in meeting future challenges for the field

long term morphodynamic evolution of estuaries an inverse problem abstract a new technique for predicting long term variations in estuary morphology is developed using a morphological evolution equation that isolates diffusive and non diffusive processes in estuaries the contribution from non diffusive processes to the morphological changes of the estuary is incorporated in the governing equation by a source function the source function is derived by solving an inverse problem using historic survey data of the humber estuary uk covering a period of 150 years source functions derived for the consecutive pairs of bathymetry surveys show a significant structure persistent throughout the entire data set large scale features such as tidal channels tidal flats and linear banks in the outer estuary are persistently visible in the source function empirical orthogonal function eof analysis is used to analyse the spatial and temporal variation in the source function the first spatial eigenfunction which corresponds to the time mean value of the source function captures over 92 of the mean square of the data over 65 of the data variance is captured by the first six eigenfunctions the first temporal eigenfunction which corresponds to the mean value of the source function is almost constant as expected

a unifying framework for shoreline migration 2 application to wave dominated coasts 1 the bruun rule widely used to predict transgression due to sea level rise on decade to century timescales based on a fixed nearshore profile neglects the influence of inland topography and substrate lithology leading to physically unreasonable predictions on longer timescales we use a new approach the shoreline exner equation to model shoreline transgression on wave dominated coasts over timescales of decades to millennia our results show that interactions between nearshore processes and inland topography neglected by bruun style models drive morphologic evolution which modulates shoreline retreat analytical solutions suggest that while short term shoreline retreat will sometimes follow the bruun rule long term transgression will always follow the slope of the inland topography moreover our results show that the slope of the inland landscape relative to the nearshore slope exerts a first order control on coastal morphology such that steep coasts tend to form cliff backed beaches while gentle coasts tend to form barrier island lagoon systems however compositional variations between the inland landscape and nearshore system can alter this pattern

a long term decadal scale evolution model for microtidal barrier systems abstract a model is presented to simulate the long term decadal evolution of microtidal spit barrier systems the model has been derived from the analysis of coastal processes taking place along the trabucador la banya complex in the ebro delta spanish mediterranean coast it is composed of two submodels to simulate the evolution of the seaside and bayside barrier shorelines the outer coast submodel is of the one line type but formulated in curvilinear coordinates to reproduce the evolution of strongly curved coasts which is a common configuration for spits the model makes use of a long term parameterization of the longshore sediment transport rate which is formulated in terms of a morphological wave and a local transport constant the inner coast submodel is based on a morphological equilibrium approach it considers the overwash transport to be the dominant driving term contributing to the sediment budget of the inner coast it makes use of the concept of critical barrier width to estimate the conditions under which overwash is able to contribute to bayside shoreline accretion the model has been verified calibrated for the trabucador la banya system and it has been used to simulate its evolution under different climatic scenarios

evolution of the december 14 1989 precursory long period event swarm at redoubt volcano alaska abstract the intermittency pattern and evolution in waveforms of long period lp seismic events during the intense 23 h swarm that preceded the december 14 1989 eruption of redoubt volcano are investigated utilizing cross correlation to exploit the high degree of similarity among waveforms a substantially more complete event catalog is generated than was available from near realtime detection based on short term long term amplitude ratios which was saturated by the high rate of activity the temporal magnitude distribution of the predominant lp events is found to have an unusual banded structure in which the average magnitude of each band slowly increases and then decreases through time a bifurcation that appears in the uppermost band shortly after the peak in magnitudes is characterized by a quasi periodicity in intermittency and magnitude that is reminiscent of one of the classic routes to chaotic behavior in some non linear systems the waveforms of the predominant events evolve slowly but unsteadily through time these gradual changes appear to result from variations in the relative amplitudes of spectral peaks that remain stable in frequency which suggests that they are due to differential excitation of a single resonant source two other previously unrecognized repetitive waveforms are also identified but the signals from these secondary events are not clearly recorded at distances beyond the closest station similarities among the spectra of the predominant and secondary events suggest that the signals from these events also could represent different modes of exciting the same source significant changes in the rates and the sizes of the largest of these secondary events appear to coincide with the peak in the size distribution of the predominant lps at least some of the non repetitive lp waveforms in the swarm appear to be the result of the superposition of signals from the rapid repetition of predominant lp source thus placing a constraint on the repeat time of the triggering mechanism for this source a lone hybrid event which has a waveform character intermediate between the predominant lp events and high frequency volcano tectonic events was also identified in the swarm the occurrence of this event provides important evidence that the low frequency character of the lp events is a source rather than a path or site effect

geochemistry and origin of metamorphosed mafic rocks from the lower paleozoic moretown and cram hill formations of north central vermont delamination magmatism in the western new england appalachians

seismicity patterns prior to the 2011 el hierro eruption abstract the first fully monitored volcanic eruption in the canary islands started on 10 october 2011 2 km south of the island of el hierro this submarine eruption was preceded by various precursory signals the most evident of which were the seismic series that started in july 2011 consisting of almost 10 000 low magnitude earthquakes located by manual picking this seismicity revealed a 20 km horizontal migration from the north of the island to the south at depths of between 10 and 17 km the deeper events occurring further south we applied a relative location algorithm hypodd to improve hypocentral locations the resulting distribution is more compact slightly shallower and reveals a clearer difference in depths from north to south tests performed to check the reliability of the results gave maximum uncertainties of 400 m in the relocations furthermore new features were found including the origin of the seismicity in the center of the island and the presence of two alternating seismogenic zones in the north of the island during the first month of activity online material figures of waveforms from cross correlation data statistics stereogram of ray parameters ray tracing tests and table of hypodd relocations

high precision relative locations of earthquakes at mount st helens washington several earthquake sequences have occurred at mount st helens as clusters of shallow events with nearly identical waveforms multiplets we present a technique that allows the relative relocation of events within a multiplet to at least an order of magnitude higher precision than is typically possible with traditional techniques a multiplet is studied in pairs of events called doublets each doublet is made up of a reference event and one other event from the multiplet the cross spectrum of a short window beginning just before the p arrival is used to compute differences in arrival times between seismograms from the same station for each doublet these time differences computed with a precision of 1 2 ms are then used to locate each earthquake relative to the reference event engineering explosions with well known locations are used to test the relocation technique explosions can be relocated with accuracy better than 20 m for events within 250 m of the reference explosion the relocation technique is applied to earthquakes preceding the september 10 1984 and the may june 1985 dome building eruptions of mount st helens forty events that occurred during a 12 hour period in september 1984 are located in a volume approximately 30 m in diameter beneath the lava dome the earthquakes following the extrusion do not occur in multiplets and appear to be distributed over a much larger volume in the may june 1985 eruption we recognize three multiplet sets that took place successively in time the multiplets are interpreted as repeated failure or slip within a relatively small volume due to high strain rates around the magma supply conduit

rockfalls at augustine volcano alaska the influence of eruption precursors and seasonal factors on occurrence patterns 1997 2009 abstract rockfalls have been recorded in seismic data at augustine volcano from 1997 to the present typical events last about 30 s and have frequencies 4 hz on stations within 5 km of the summit many rockfalls are well recorded on summit seismic stations suggesting that they originate from the steep summit dome typical background years such as 2003 or 2004 had several dozen events in the summer and fall june to november that were strong enough to trigger an automatic event detection system for example 17 rockfalls were recorded in 2003 mostly in late summer when air temperatures were warm and rainfall rates were highest and 28 events were recorded in 2004 also in late summer in 2005 about eight months before the onset of the eruption of augustine in january 2006 there was a significant increase in the number of rockfalls detected this increase of surface rockfall activity occurred at nearly the same time as precursory earthquake activity increased beneath augustine overall there were more than 340 rockfalls in 2005 consisting of both short less than 30 s and long greater than 30 s duration events the high rate of rockfalls in 2005 constitutes a new class of precursory signal that needs to be incorporated into long term monitoring strategies at augustine and elsewhere during the eruption numerous rockfalls continued to occur and block and ash flows dominated the seismic records when the volcano began a phase of dome growth and collapse the high rates of rockfalls continued after the eruption ended due the new unstable lava dome and adjacent tephra at the summit as of 2009 the rockfall rates are still high but are declining steadily

magma fracture and hybrid earthquakes in the conduit of augustine volcano 1 we exploit subtle but systematic shifts in seismic waveforms to examine a 2 h cluster of repeating hybrid volcanic earthquakes preceding the first magmatic explosions at augustine volcano in january 2006 we extract differential p wave traveltimes of 0 01 s to determine that the source locations migrated downward by approximately 35 m waveform characteristics gps observations and visual reports of lava effusion at the summit suggest that the earthquakes were sourced by fracturing magma in the upper conduit as the lava cooled and degassed at the surface the conditions in the upper conduit changed causing the zone in which magma fracture could occur to move downward through the magma column these changes may also have been the first indicators that the conduit was becoming choked causing a buildup in pressure that resulted in the large magmatic explosions that followed 36 h later

seismic signals preceding the explosive eruption of mount st helens washington on 18 may 1980 abstract the intense seismic activity which preceded the 18 may 1980 eruption of mount st helens washington released 2 to 3 10 18 ergs day in earthquakes that did not correlate temporally with phreatic eruptions which occurred during the same period although the b value and amplitude ratios long period short period of the earthquakes vary with time there are no definitive precursors to the 18 may earthquake and eruption a mogi type ii frequency magnitude relation with critical magnitude mc 4 6 constrains the characteristic dimension of the highly stressed region under mount st helens to approximately 3 km preceding the eruption a major increase in seismic energy release and a decrease in b value around 1 april 1980 may indicate the first major influx of magma into the upper portion of the volcano seismic waves from low frequency volcanic earthquake have large periods at all epicentral distances recordings of volcanic earthquakes from 2 to 4 april 1980 at sites 4 to 9 km from mount st helens show two predominant periods of 0 55 and 1 0 sec we speculate that seismic signals from the low frequency volcanic earthquakes have a tectonic origin but may be modified by pressure oscillations in nearby magma

the augustine magmatic system as revealed by seismic tomography and relocated earthquake hypocenters from 1994 through 2009 1 we incorporate 14 years of earthquake data from the alaska volcano observatory with data from a 1975 controlled source seismic experiment to obtain the three dimensional p and s wave velocity structure and the first high precision earthquake locations at augustine volcano to be calculated in a fully three dimensional velocity model velocity tomography shows two main features beneath augustine a narrow high velocity column beneath the summit extending from 2 km depth to the surface and elevated velocities on the south flank our relocation results allow a thorough analysis of the spatio temoral patterns of seismicity and the relationship to the magmatic and eruptive activity background seismicity is centered beneath the summit at an average depth of 0 6 km above sea level in the weeks leading to the january 2006 eruption of augustine seismicity focused on a nw se line along the trend of an inflating dike a series of drumbeat earthquakes occurred in the early weeks of the eruption indicating further magma transport through the same dike system during the six months following the onset of the eruption the otherwise quiescent region 1 to 5 km below sea level centered beneath the summit became seismically active with two groups of earthquakes differentiated by frequency content the deep longer period earthquakes occurred during the eruption and are interpreted as resulting from the movement of magma toward the summit and the post eruptive shorter period earthquakes may be due to the relaxation of an emptied magma tube the seismicity subsequently returned to its normal background rates and patterns

seismic velocity structure of the crust and shallow mantle of the central and eastern united states by seismic surface wave imaging seismic surface waves from the transportable array of earthscope s usarray are used to estimate phase velocity structure of 18 to 125 s rayleigh waves then inverted to obtain three dimensional crust and upper mantle structure of the central and eastern united states ceus down to 200 km the obtained lithosphere structure confirms previously imaged ceus features e g the low seismic velocity signature of the cambrian reelfoot rift and the very low velocity at 150 km depth below an eocene volcanic center in northwestern virginia new features include high velocity mantle stretching from the archean superior craton well into the proterozoic terranes and deep low velocity zones in central texas associated with the late cretaceous travis and uvalde volcanic fields and beneath the south georgia rift which contains jurassic basalts hot spot tracks may be associated with several imaged low velocity zones particularly those close to the former rifted laurentia margin

global mapping functions for the atmosphere delay at radio wavelengths i have developed expressions for calculating the ratios mapping functions of the line of sight hydrostatic and wet atmospheric path delays to their corresponding zenith delays at radio wavelengths for elevation angles down to 3 the coefficients of the continued fraction representation of the hydrostatic mapping function depend on the latitude and height above sea level of the observing site and on the day of the year the dependence of the wet mapping function is only on the site latitude by comparing with mapping functions calculated from radiosonde profiles for sites at latitudes between 43 s and 75 n the hydrostatic mapping function is seen to be more accurate than and of comparable precision to mapping functions currently in use which are parameterized in terms of local surface meteorology when the new mapping functions are used in the analysis of geodetic very long baseline interferometry vlbi data the estimated lengths of baselines up to 10 400 km long change by less than 5 mm as the minimum elevation of included data is reduced from 12 to 3 the independence of the new mapping functions from surface meteorology while having comparable accuracy and precision to those that require such input makes them particularly valuable for those situations where surface meteorology data are not available

high rate gps data on active volcanoes an application to the 2005 2006 mt augustine alaska usa eruption volcanic eruptions are usually preceded by measurable signals of growing unrest the most evident of which are the increase in seismicity and ground deformation it is also important to identify precursors of a possible renewal of the volcanic activity and to distinguish between an eruptive activity characterized by an intrusion with the related destructive power and a migration of magma stored in the main conduits the 2005 2006 eruption at mt augustine alaska usa is a good example of a massive migration of magmatic fluids from depth about 1 km b s l under the effect of gas overpressure the movements recorded by high rate gps hrgps data 15 s of sampling and processing rate from the stations deployed on the volcano define the dimensions and the characteristics of the shallow plumbing system in this study we propose a model of the different stages preceding the effusive phase the precursory phase where gas overpressure in the body of the volcano opens the terminal conduit

long term morphological modeling of a tidal inlet the arcachon basin france abstract the arcachon lagoon on the french atlantic coast is a triangular shaped lagoon of 20 km on a side connected to the ocean by a 3 km wide inlet between the mainland and an elongated sand spit this tidal inlet exhibits a particularly active morphology due to locally strong tidal currents and rough wave conditions during the past 300 years minimum and maximum spatial extents of the cap ferret sand spit have varied by 8 km while one or two channels have alternately allowed circulation between the lagoon and the ocean these impressive morphological changes have never prevented regular flushing of the lagoon eventhough the spit came as close as 300 m from the coast during the 18th century according to bruun s concept of tidal inlet stability theory and engineering 1978 510 pp the balance between longshore littoral transport and the tidal prism ensures the perpetuity of the inlet process modeling was believed to give better insight into the respective roles of tides and waves in driving the long term morphological changes of the inlet a two dimensional horizontal morphodynamic model was therefore developed combining modules for hydrodynamics waves sediment transport and bathymetry updates the use of process models at a scale of decades requires a schematization of the input conditions we defined representative mean annual wave and tide conditions with respect to sediment transport i e conditions that induce the same annual transport as measured in the field driven by these representative conditions simulations run from the 1993 bathymetry show that the tide is responsible for the opening of a new channel at the extremity of the sand spit where tidal currents are the strongest while waves induce a littoral transport responsible for the longshore drift of sand bodies across the inlet one particular simulation consisted in running the model from a hypothetical initial topography where the channels are filled with sand and the entire inlet is set to a constant depth 3 m the results show the reproduction of a channel and bar system comparable to historical observations which supports the idea that the lagoon is unlikely to be disconnected from the ocean provided tide and wave conditions remain fairly constant in the following decades

a numerical investigation of choked flow dynamics and its application to the triggering mechanism of long period events at redoubt volcano alaska we use numerical simulations of transonic flow through a crack to study the dynamics of the formation of shock waves downstream from a nozzle like constriction inside the crack the model solves the full set of navier stokes equations in two dimensions via an explicit multifield finite difference representation the crack walls are assumed to be perfectly rigid and elastic coupling to the solid is not considered the simulations demonstrate how the behavior of unsteady shock waves near the walls can produce recurring step like pressure transients in the flow which in turn induce resonance of the fluid filled crack the motion of the shock waves is governed primarily by smooth low amplitude pressure fluctuations at the outlet of the crack the force induced on the walls scales with the amplitude of the shock which is a function of the magnitude of the inlet pressure aperture of the constriction and thickness of the boundary layer the applied force also scales in proportion to the spatial extent of the shock excursion which depends on the fluctuation rate of outlet pressure using the source parameters of long period lp events at redoubt volcano alaska as a guide for our simulations we infer that coupling of the shock to the walls occurs for crack inlet to outlet pressure ratios pi po 2 31 and that the position of the shock front becomes most sensitive to outlet pressure fluctuations for flow regimes with pi po 2 48 for such regimes fluctuations of outlet pressure of up to 0 5 mpa at rates up to 3 mpa s are sufficient to induce pressure transients with magnitudes up to 12 5 mpa over 0 1 2 5 m of the walls within 0 5 s these flow parameters may be adequate for triggering the lp events in the precursory swarm to the december 14 1989 eruption of redoubt according to the flow model the recurrence rate and amplitudes of l p events are inferred to be a manifestation of the response of a shallow hydrothermal reservoir to the sustained injection of superheated steam from a magma column roofing below this reservoir

characterising the relaxation distance of nearshore submarine morphology a southern baltic sea case study abstract a method for defining the length of coast with alongshore uniformity of nearshore submarine morphology is required in many shore normal nearshore profile modelling approaches here we introduce a new variable the relaxation distance to describe the alongshore spacing between two adjacent shore normal profiles characterised by distinct morphologies within this distance alongshore morphological changes are too small to distinguish so the nearshore submarine morphology is regarded as uniform along the coast we apply a semi variogram approach which expresses decreased spatial correlation of the nearshore submarine morphology with alongshore distance to quantify relaxation distances we apply this morphological variable to analyse 225 measured shore normal submarine profiles at 500 m intervals in three distinct sites of the tideless wave dominated southern baltic coast swina eba and hel the relaxation distances of these three sites are approximately 4500 m 3000 m and 2200 m of the three sites swina has the smoothest nearshore submarine morphology and the weakest wave energy the relaxation distances of different quasi straight segments at each site appear similar but those at different sites decrease with enlarged morphological perturbations which are residuals resulting from detrending the shore normal profiles the standard deviations of these morphological perturbations are correlated with the incidence wave angles and wave energy we also found that large perturbations such as longshore bars and channels have a significant impact on the estimation of underwater volume using shore normal profile trends therefore relaxation distance can indicate morphological smoothness the length of shore parallel uniform nearshore submarine morphology and the impact of local processes on submarine morphology

precursory swarms of long period events at redoubt volcano 1989 1990 alaska their origin and use as a forecasting tool abstract during the eruption of redoubt volcano from december 1989 through april 1990 the alaska volcano observatory issued advance warnings of several tephra eruptions based on changes in seismic activity related to the occurrence of precursory swarms of long period lp seismic events dominant period of about 0 5 s the initial eruption on december 14 occurred after 23 years of quiescence and was heralded by a 23 hour swarm of lp events that ended abruptly with the eruption after a series of vent clearing explosions over the next few days dome growth began on december 21 another swarm with lp events similar to those of the first began on the 26th and ended in a major tephra eruption on january 2 eruptions continued over the next two weeks and then ceased until february 15 when a large eruption initiated a long phase of repetitive dome building and dome destroying episodes that continued into april warnings were issued before the major events on december 14 and january 2 but as the eruptive sequence continued after january 2 the energy of the swarms decreased and forecasting became more difficult a significant but less intense swarm preceded the february 15 eruption which was not forecast this eruption destroyed the only seismograph on the volcanic edifice and stymied forecasting until march 4 when the first of three new stations was installed within 3 km of the active vent from march 4 to the end of the sequence on april 21 there were eight eruptions six of which were preceded by detectable swarms of lp events although weak these swarms provided the basis for warnings issued before the eruptions on march 23 and april 6 the initial swarm on december 13 had the following features 1 short duration 23 hours 2 a rapidly accelerating rate of seismic energy release over the first 18 hours of the swarm followed by a decline of activity during the 5 hours preceding the eruption 3 a magnitude range from 0 4 to 1 6 4 nearly identical lp signatures with a dominant period near 0 5 s 5 dilatational first motions everywhere and 6 a stationary source location at a depth of 1 4 km beneath the crater this occurrence of long period events suggests a model involving the interaction of magma with groundwater in which magmatic gases steam and water drive a fixed conduit at a stationary point throughout the swarm the initiation of that sequence of events is analogous to the failure of a pressure relief valve connecting a lower supercharged magma dominated reservoir to a shallow hydrothermal system a three dimensional model of a vibrating fluid filled crack recently developed by chouet is found to be compatible with the seismic data and yields the following parameters for the lp source crack length 280 380 m crack width 140 190 m crack thickness 0 05 0 20 m crack stiffness 100 200 sound speed of fluid 0 8 1 3 km s compressional wave speed of rock 5 1 km s density ratio of fluid to rock 0 4 and ratio of bulk modulus of fluid to rigidity of rock 0 03 0 07 the fluid filled crack is excited intermittently by an impulsive pressure drop that varies in magnitude within the range of 0 4 to 40 bar such disturbance appears to be consistent with a triggering mechanism associated with choked flow conditions in the crack

estimates of eruption velocity and plume height from infrasonic recordings of the 2006 eruption of augustine volcano alaska abstract the 2006 eruption of augustine volcano alaska began with an explosive phase comprising 13 discrete vulcanian blasts these events generated ash plumes reaching heights of 3 14 km the eruption was recorded by a dense geophysical network including a pressure sensor located 3 2 km from the vent infrasonic signals recorded in association with the eruptions have maximum pressures ranging from 13 111 pa eruption durations are estimated to range from 55 350 s neither of these parameters however correlates with eruption plume height the pressure record however can be used to estimate the velocity and flux of material erupting from the vent assuming that the sound is generated as a dipole source eruptive flux in turn is used to estimate plume height assuming that the plume rises as a buoyant thermal plume heights estimated in this way correlate well with observations events that exhibit strongly impulsive waveforms are underestimated by the model suggesting that flow may have been supersonic

ocean noise triggering of rhythmic long period events at deception island volcano 1 we report on swarms of repeating long period lp events with remarkably periodic occurrence at deception island volcano antarctica the lp events show dominant frequencies near 2 hz and characteristic inter event times that range from 10 s to 20 s for individual swarms we observe that lp inter event times are approximate integer multiples of the dominant periods of the oceanic microseism indicating a synchronization of lp activity with the phase of ocean noise we attribute lp periodicity to the coincidence of sustained lp activity in an unstable hydrothermal system and external forcing by ocean noise that introduces periodic pressure variations in volcano fluids we estimate the volumetric strain change generated by the oceanic microseism at the source location and conclude that strain of order 10 7 is sufficient to introduce clear periodicity in the lp sequences and that periodicity increases with increasing strain

temporal variations of repeating low frequency volcanic earthquakes at ngauruhoe volcano new zealand abstract a persistent swarm of micro earthquakes was observed at ngauruhoe volcano new zealand from 2005 to 2010 marking the first unrest episode at the volcano since 1975 detailed waveform and spectral analysis of the continuous seismic record revealed eight earthquake families f1 f8 within a sequence of 8561 low frequency earthquakes an analysis of stacked waveforms of each family allowed the families to be linked systematically into four super families that may indicate four different mechanisms and or source locations or geometries the first super family mostly occurred in 2005 and showed stable waveforms and no significant evolution the second super family was dominant over a two year period starting in mid 2006 and displayed a slow evolution with progressively higher frequency the third super family emerged from early 2008 with intermittent occurrence and high seismicity and progressed to higher peak frequency in 2010 the fourth super family was mainly observed from late 2008 to mid 2009 and had the highest peak frequency in 2009 the observed evolutionary pattern may be driven by a modest multi year input of gas and heat from a deeper relict magmatic zone into the shallow volcano hydrothermal system the interplay of gas from below and seasonal meltwater from above may have modulated the seismic activity and may relate to repeated over pressurization and failure of constricted evolving pathways within a pervasive crack system

a multi scale hybrid long term morphodynamic model for wave dominated coasts abstract process based modules based on conservative equations to solve the transport of waves currents and sub aqueous sediment and behavior oriented modules based on empirical descriptions of cliff erosion bed load and terrestrial aeolian sand transport are coupled with up scaling measures and stability maintaining approaches in a parallel code to simulate decadal to millennial scale morphological evolution of wave dominated coasts an application to the southern baltic sea for a hindcast of holocene morphogenesis of the darss zingst peninsula demonstrates the robustness of the model the model is then used to investigate the morphogenesis and evolution of spits in an idealized fetch limited sandy coastal environment evolution of the spit system can be categorized into three periods according to the simulation results in the early period all initial coastline perturbations are amplified due to the high angle wave effects size competition between adjacent spits starts afterwards interaction between adjacent spits dominates the middle period smaller spits tend to retrogress due to unbalanced sediment budget and this sediment loss feeds further growth of their larger neighbors the retrograded spits are either smoothed or evolve into barrier lagoons and relatively stable large scale spits originating from larger spits are developed in the late period low frequency storms impinging from a regular high angle onto the coastline facilitate the development of spits in the early period but become a hindering factor afterwards terrestrial aeolian transport not only plays a key role in stabilizing the spits but is also revealed as an important factor for long term coastline erosion

seismological aspects of the 1989 1990 eruptions at redoubt volcano alaska the ssam perspective abstract ssam is a simple and inexpensive tool for continuous monitoring of average seismic amplitudes within selected frequency bands in near real time on a pc based data acquisition system during the 1989 1990 eruption sequence at redoubt volcano the potential of ssam to aid in rapid identification of precursory long period lp event swarms was realized and since this time ssam has been incorporated in routine monitoring efforts of the alaska volcano observatory in particular an eruption that occurred on april 6 was successfully forecast primarily on the basis of recognizing the precursory lp activity on ssam of twenty two significant eruptions that occurred between december 14 and april 21 eleven had precursory swarms longer than one hour in duration that could be detected on ssam for individual swarms the patterns of relative spectral amplitudes are distinct at each station and remain largely stationary through time thus indicating that one source may have been preferentially and repeatedly activated throughout the swarm typically a single spectral band dominates the signal at each seismic station for the vigorous one day swarm that preceded the first eruption on december 14 signals were sharply peaked in the 1 9 2 7 hz band at the closest station located 4 km from the vent but were dominated by 1 3 1 9 hz energy at three more distant stations located 7 5 22 km from the vent the tendency for the signals from different swarms recorded at the same station to be peaked in the same frequency band suggests that all of the sources are characterized by a predominant length scale signals from the precursory lp swarms became weaker as the eruption sequence progressed and swarms that occurred in march and april could only be detected at seismographs on the volcanic edifice onset times of precursory lp swarms prior to eruptions ranged from a few hours to about one week but after the initial vent clearing phase that ended december 19 these intervals tended to become progressively shorter for successive swarms these trends in the relative onset times and intensities of successive precursory lp swarms are consistent with an overall depressurization of the magmatic system through time in general each of the swarms had an emergent onset but the intensities did not always increase steadily until the eruptions instead as the time of an eruption approached the intensity usually increased more rapidly before peaking and then declining prior to the eruption for three of the swarms two distinct peaks in intensity were apparent the time intervals between final peaks in swarm intensity and ensuing eruptions ranged from about 2 hours to almost 2 days but the peaks always occurred closer to the eruptions than to the swarm onsets both the onset of lp swarm activity and a decline in intensity prior to an eruption may represent critical points in the process of pressurization that drives the flow of fluids and gas in a sealed magmatic system a notable exception to this pattern is the eruption of march 9 which lacked a detectable precursory lp swarm but was followed by an unusually long period of strong lp seismicity that may have been stimulated by a depressurization of the magmatic system resulting from dome failure on both december 14 and january 2 the spectra of early syn eruptive signals have peaked signatures much like those of the spectra of precursory lp activity from shortly before the eruptions these similarities may indicate that the source of precursory seismicity continued to be active during at least the early part of each eruption in syn eruptive signals from march and april recorded at stations on the volcanic edifice the dominant spectral energy progressively shifts with time during the eruption to lower frequencies at least part of the energy in these signals may have been generated by the debris flows associated with dome failures

late glacial and holocene depositional history in the eastern part of the szczecin lagoon great lagoon basin nw poland abstract analyses on 27 sediment cores taken from the bottom of the szczecin lagoon allowed environmental reconstruction of the postglacial main stages of basin development based on detailed sedimentological geochemical diatomological and malacological studies of selected key cores studies revealed that during the late glacial and holocene this area developed in several stages in the late glacial the whole study area constituted a low alluvial plain at the turn from younger dryas to holocene the alluvial plain was cut through by the odra river to a level of 10 11 m below sea level b s l along with the first phases of the holocene marine transgression at the southern baltic sea s coasts the accumulation of the limnic swampy deposits began in this lower part of the odra valley at ca 6 6 5 ka bp the transgression proceeded and littorina sea waters flooded the area at that time the szczecin lagoon constituted a marine embayment in which series of sands partly rich in malacofauna was deposited the development of the swina barrier resulted in the isolation of the embayment from the direct inflow of baltic sea waters

results from the broadband seismic network on montserrat a digital broadband seismic network has been installed around soufriere hills volcano on montserrat while several distinctive types of seismic events with frequencies ranging from 0 5hz to 30hz could be identified the emphasis is on two types of low frequency events which indicate the involvement of a fluid phase in the source mechanism the so called long period events and the hybrid events the latter occur in swarms with distinct periodicities of 4 to 12 hours and preceed major dome collapses and explosions the swarms correlate very well with the tilt observed at the flanks of the volcanic edifice and hence can be linked to the pressurization of the magmatic system occasionally separate hybrid events merge and form harmonic tremor which sometimes has a shifting spectral content this reveals temporary changes in the source parameters low frequency seismic signals on montserrat are considered to be key parameters for the monitoring of the internal dynamics of the volcano

volcano monitoring using gps developing data analysis strategies based on the june 2007 kīlauea volcano intrusion and eruption 1 the global positioning system gps is one of the most common techniques and the current state of the art used to monitor volcano deformation in addition to slow several centimeters per year displacement rates gps can be used to study eruptions and intrusions that result in much larger tens of centimeters over hours days displacements it is challenging to resolve precise positions using gps at subdaily time intervals because of error sources such as multipath and atmospheric refraction in this paper the impact of errors due to multipath and atmospheric refraction at subdaily periods is examined using data from the gps network on k lauea volcano hawai i methods for filtering position estimates to enhance precision are both simulated and tested on data collected during the june 2007 intrusion and eruption comparisons with tiltmeter records show that gps instruments can precisely recover the timing of the activity

seismic evolution of the 1989 1990 eruption sequence of redoubt volcano alaska abstract redoubt volcano in south central alaska erupted between december 1989 and june 1990 in a sequence of events characterized by large tephra eruptions pyroclastic flows lahars and debris flows and episodes of dome growth the eruption was monitored by a network of five to nine seismic stations located 1 to 22 km from the summit crater notable features of the eruption seismicity include 1 small long period events beginning in september 1989 which increased slowly in number during november and early december 2 an intense swarm of long period events which preceded the initial eruptions on december 14 by 23 hours 3 shallow swarms 0 to 3 km of volcano tectonic events following each eruption on december 15 4 a persistent cluster of deep 6 to 10 km volcano tectonic earthquakes initiated by the eruptions on december 15 which continued throughout and beyond the eruption 5 an intense swarm of long period events which preceded the eruptions on january 2 and 6 nine additional intervals of increased long period seismicity each of which preceded a tephra eruption hypocenters of volcano tectonic earthquakes suggest the presence of a magma source region at 6 10 km depth earthquakes at these depths were initiated by the tephra eruptions on december 15 and likely represent the readjustment of stresses in the country rock associated with the removal of magma from these depths the locations and time history of these earthquakes coupled with the eruptive behavior of the volcano suggest this region was the source of most of the erupted material during the 1989 1990 eruption this source region appears to be connected to the surface by a narrow pipe like conduit as inferred from the hypocenters of volcano tectonic earthquakes concentrations of shallow volcano tectonic earthquakes followed each of the tephra eruptions on december 15 these shocks may represent stress readjustment in the wall rock related to the removal of magma and volatiles at these depths this shallow zone was the source area of the majority of long period seismicity through the remainder of the eruption the long period seismicity likely reflects the pressurization of the shallow portions of the magmatic system

characterization of open and closed volcanic systems in indonesia and mexico using insar time series 1 we use 2007 2011 advanced land observing satellite alos data to perform an arc wide interferometric synthetic aperture radar insar time series survey of the trans mexican volcanic belt tmvb and to study time dependent ground deformation of four indonesian volcanoes selected following the 2007 2009 study of chaussard and amelung 2012 our objectives are to examine whether arc volcanoes exhibit long term edifice wide cyclic deformation patterns that can be used to characterize open and closed volcanic systems and to better constrain in which cases precursory inflation is expected we reveal deformation cycles at both regularly active and previously inactive indonesian volcanoes but we do not detect deformation in the tmvb reflecting a lower activity level we identify three types of relationships between deformation and activity inflation prior to eruption and associated with or followed by deflation kerinci and sinabung inflation without eruption and followed by slow deflation agung and eruption without precursory deformation merapi colima and popocatepetl at merapi no significant deformation is detected even during eruption the first two cases correspond to closed volcanic systems and suggest that the traditional model of magmatic systems and eruptive cycles do apply to andesitic volcanoes i e inflation and deflation episodes associated with magma accumulation or volatile exsolution in a crustal reservoir followed by eruptions or in situ cooling in contrast the last case corresponds to open volcanic systems where no significant pressurization of the magmatic reservoirs is taking place prior to eruptions and thus no long term edifice wide ground deformation can be detected we discuss these results in terms of insar s potential for forecasting volcanic unrest

equilibrium responses of cliffed coasts to changes in the rate of sea level rise abstract basic formulae have long been used to predict the effects of sea level rise on coastal recession for instance the geometric bruun rule and its modifications has often been applied to sandy coasts both low lying and steep however the behavior of rocky coasts whether strongly or poorly lithified should be significantly different than that of sandy coasts given that rocky coast evolution depends upon the irreversible breakdown of rock whereas sandy and depositional systems are controlled by the transport and related transport gradients of mobile sediment here we investigate the basis of a modeled relationship which suggests with a number of caveats that the equilibrium soft rock cliff recession rate can be estimated by the square root of the relative change in sea level rise rate although this relationship was derived using the numerical model scape soft cliff and platform erosion which simulates a broad soft rock cliffed coastal system driven by stochastic environmental forces here we show that a simplified modeling approach also reproduces the relationship we then extend this approach to develop a general theoretical framework within which it is possible to consider the potential responses of the different types of cliffed coasts to changes in the rate of sea level rise although a wide variety of processes affect different coastal settings this framework demonstrates how the strength and the nature of feedbacks within cliffed system control their response to sea level rise this suggests that cliffed environments controlled by different processes can still respond in similar ways to changes in the rate of sea level rise most rocky coasts would be expected to respond as a damped or negative feedback system between the extremes of a no feedback system that is unresponsive to sea level rise rate and an instant response system characterized by a linear response similar to the bruun rule this framework suggests that a potential inverse feedback case could also exist in which increased rates of sea level rise reduce the rate of coastal recession in almost all cases it is apparent that cliffed coast response to sea level rise depends not only upon the total elevation change of sea level but on the rate of the sea level rise these theoretical investigations and the classifications presented provide a framework to understand the behavior of systems affected by a wide array of processes and provide expectations that can be tested using more complex models of cliffed coast evolution in a variety of environments whether sandy or rocky hard or soft

volcanic tremors at etna a model for hydraulic origin spectral analysis of volcanic tremors at etna reveals 2 characteristic features 1 the escaping vapor and gas streams drive the magma in random turbulent motion generating a seismic wave emission according toa f n exp m f k wherea amplitude f frequency n m k parameters 2 sudden transients in the boundary conditions of the piping system generate hydraulic pressure pulses which in the seismogram appear as wave packages their monochromatic frequency content suggests that their origin is associated with strong resonance phenomena it is conclusive that volcanic eruptions may be distinguished and classified according to different eigenfrequencies of the fissure and pipe network involved in the volcanic activity furthermore positions of active dykes may be traced following the amplitude distributions associated with pronounced spectral lines in the tremor spectra

earthquake classification location and error analysis in a volcanic environment implications for the magmatic system of the 1989 1990 eruptions at redoubt volcano alaska abstract determination of the precise locations of seismic events associated with the 1989 1990 eruptions of redoubt volcano posed a number of problems including poorly known crustal velocities a sparse station distribution and an abundance of events with emergent phase onsets in addition the high relief of the volcano could not be incorporated into the hypoellipse earthquake location algorithm this algorithm was modified to allow hypocenters to be located above the elevation of the seismic stations the velocity model was calibrated on the basis of a posteruptive seismic survey in which four chemical explosions were recorded by eight stations of the permanent network supplemented with 20 temporary seismographs deployed on and around the volcanic edifice the model consists of a stack of homogeneous horizontal layers setting the top of the model at the summit allows events to be located anywhere within the volcanic edifice detailed analysis of hypocentral errors shows that the long period lp events constituting the vigorous 23 hour swarm that preceded the initial eruption on december 14 could have originated from a point 1 4 km below the crater floor a similar analysis of lp events in the swarm preceding the major eruption on january 2 shows they also could have originated from a point the location of which is shifted 0 8 km northwest and 0 7 km deeper than the source of the initial swarm we suggest this shift in lp activity reflects a northward jump in the pathway for magmatic gases caused by the sealing of the initial pathway by magma extrusion during the last half of december volcano tectonic vt earthquakes did not occur until after the initial 23 hour long swarm they began slowly just below the lp source and their rate of occurrence increased after the eruption of 01 52 ast on december 15 when they shifted to depths of 6 to 10 km after january 2 the vt activity migrated gradually northward this migration suggests northward propagating withdrawal of magma from a plexus of dikes and or sills located in the 6 to 10 km depth range precise relocations of selected events prior to january 2 clearly resolve a narrow steeply dipping pencil shaped concentration of activity in the depth range of 1 7 km which illuminates the conduit along which magma was transported to the surface a third event type named hybrid which blends the characteristics of both vt and lp events originates just below the lp source and may reflect brittle failure along a zone intersecting a fluid filled crack the distribution of hybrid events is elongated 0 2 0 4 km in an east west direction this distribution may offer constraints on the orientation and size of the fluid filled crack inferred to be the source of the lp events

effects of earthquake ground motion on tracking characteristics of new global navigation satellite system receivers we use a shake table capable of large 7 g three dimensional accelerations with large payloads to simulate ground motion reconstructed from acceleration data collected during the february 2010 mw 8 8 maule chile earthquake the tracking performance of five modern geodetic gnss receiver and antenna combinations was investigated while undergoing simulated seismic shaking at three two levels of amplification individual system performance was characterized by the number of tracked gnss observations the l1 and l2 gps signal tracking was significantly impacted for the majority of the receiver models during simulations with maximum accelerations of 4 g and the tracking performance for all of the tested receiver types was significantly impaired during the 7 g simulations results show improved tracking when only the antenna was shaken suggesting that vibration induced oscillator phase noise may contribute significantly to tracking degradation during shaking

january 30 1997 eruptive event on kilauea volcano hawaii as monitored by continuous gps a continuous global positioning system gps network on kilauea volcano captured the most recent fissure eruption in kilauea s east rift zone erz in unprecedented spatial and temporal detail the short eruption drained the lava pond at pueu oeo leading to a two month long pause in its on going eruption models of the gps data indicate that the intrusion s bottom edge extended to only 2 4 km continuous gps data reveal rift opening 8 hours prior to the eruption absence of precursory summit inflation rules out magma storage overpressurization as the eruption s cause we infer that stresses in the shallow rift created by the continued deep rift dilation and slip on the south flank decollement caused the rift intrusion

long period and very long period events at mt etna volcano characteristics variability and causality and implications for their sources abstract almost 50 000 long period lp events were recorded at mt etna from november 2003 to may 2006 we analysed these events as well as very long period vlp events which were associated with some of them during some intervals the spectral and wavefield features of lp events remained steady with significant changes occurring between the intervals based on the times of the changes we distinguish five different sub periods in particular during sub period iii june november 2005 the wavefield at the stations nearest to the summit area was composed of p waves locations for 150 lp events occurring in sub period iii determined using radial semblance changed at the same time as the events spectral features changed it was during this sub period that many of the lp events were associated with vlp events based on similarity of the waveforms we distinguished two families of vlp events with gradually evolving waveforms the two families are located in slightly different places but near the sources of the lp events the change between the families occurred at the same time as the spectra of the lp events changed finally the source of the vlp events was investigated by performing complete waveform moment tensor inversion of stacks of the two families synthetic green s functions for the full moment tensor were calculated for a homogeneous half space for both families the source region with the highest variance reduction lies approximately beneath the active craters at 500 m below the altitudes of the stations the solutions for both families are very similar with sources that are between 60 and 70 isotropic attempts to determine deviatoric moment tensors produced consistently poorer fits the remaining energy is poorly constrained and is likely to be noise in conclusion these results highlight changes in the lp and vlp events at mt etna over time and the causal relationship between them

magma intrusion near volcan tancitaro evidence from seismic analysis abstract between may and june 2006 an earthquake swarm occurred near volcan tancitaro in mexico which was recorded by a temporary seismic deployment known as the mars network we located 1000 events from this seismic swarm previous earthquake swarms in the area were reported in the years 1997 1999 and 2000 we relocate and analyze the evolution and properties of the 2006 earthquake swarm employing a waveform cross correlation based phase repicking technique hypocenters from 911 events were located and divided into eighteen families having a correlation coefficient at or above 0 75 90 of the earthquakes provide at least sixteen phase picks we used the single event location code hypo71 and the p wave velocity model used by the jalisco seismic and accelerometer network to improve hypocenters based on the correlation adjusted phase arrival times we relocated 121 earthquakes which show clearly two clusters between 9 10 km and 3 4 km depth respectively the average location error estimates are

review of drones photogrammetry and emerging sensor technology for the study of dykes best practises and future potential abstract dykes play a major role in transporting magma through the crust to subsurface storage reservoirs or eruption sites at the surface the geometry connectivity and internal textures of dykes preserve an important record of dyke emplacement linkage and magma flow dynamics unravelling these facets of dyke evolution is critical to interpreting signals of magma migration in active volcanoes as well as tectonic processes including crust formation and continental break up during hazard assessment unfortunately our ability to develop new insights is limited by the continuity of high precision data that can be extracted from the field the emergence of unmanned aerial vehicles uavs a k a drones photogrammetry and other sensor techniques are set to greatly improve our field capabilities by collecting data at higher density and with greater precision here we present a workflow emphasising best practise in uav survey design the construction of photogrammetric models and standardised reporting of those models emphasis is given to the factors that should be considered in order to resolve the geological features of interest in any study e g wall rock fractures chilled margins magmatic breccias dyke apertures etc a point to raster technique is documented that measures spatial error in the rasters that are derived from photogrammetric models e g orthomosaics and digital elevation models using three case studies we show how dyke swarms can be mapped accurately over areas approaching 1 km2 at sub centimetre resolution the data illustrate how questions about dyke induced deformation host rock controls on segmentation and aperture variation may be addressed and we present a method for the high density high precision measurement of dyke apertures in 3d we also review semi automated mapping tools and emerging uav sensing techniques including hyperspectral and aeromagnetic sensors and the potentially important contributions they will make to the study of intrusive systems and volcanology more broadly

a numerical approach for approximating the historical morphology of wave dominated coasts a case study of the pomeranian bight southern baltic sea abstract comparison between historical maps from the 1900s 1980s and a modern map from the 2000s of the pomeranian bight at the southern baltic sea indicates that a major part of the coastline has been suffering continuous erosion this also holds for a major part of other coasts on a global scale quantifying coastal geomorphological changes on a decadal to centennial temporal scale thus needs to be intensified for coastal protection activities and integrated coastal zone management this study applies an estimation of sediment mass balance including the investigation of sediment source to sink transport in the case of absent historical survey data a numerical approach namely the dynamic equilibrium shore model desm is developed to approximate the historical morphology and to estimate sediment budget of wave dominated coasts based on the information of historical coastline configuration derived from maps a high resolution modern digital elevation model dem and relative sea level change the basic concept of the model is a dynamic equilibrium of the coastal cross shore profiles adapting to sediment mass balancing of a semi enclosed coastal area in which the unknown parameters of the cross shore profile shapes are calculated by numerical iterations the model is applied at the pomeranian bight in order to validate its capability in reflecting the pattern of bed level change and estimating sediment mass volume two tests of the model are conducted in approximating historical dems in 1980s and ca 1900 the changes of approximated dems from past to present are then respectively compared with the ones derived from a nautical sea chart in 1980s and the ones produced by a complex morphodynamic model that uses the approximated dem at ca 1900 as a starting point to hindcast the coastal morphological evolution of the research area the deposition erosion patterns along the coastline are consistent in both comparisons the pre conditions and limitations of the model are discussed in detail the model proposed here can serve as a useful tool for coastal morphological studies and potential applications for the future projection of coastal morphogenesis

ophiolite obduction in the quebec appalachians canada 40 ar 39 ar age constraints and evidence for syn tectonic erosion and sedimentation 1 2 3 detailed field work conducted in the dunnage zone of the quebec appalachians is herein combined with 40 ar 39 ar dating on a series of ophiolitic massifs crosscutting granites and associated metamorphic rocks occurring along the baie verte brompton line the taconian suture between laurentia and lower paleozoic peri laurentian oceanic terranes studied massifs are the lac brompton ophiolite and the riviere des plante ultramafic complex in southern quebec and the nadeau ophiolitic melange in the gaspe peninsula our work suggests that these massifs form remnants of eroded ophiolitic nappes which are unconformably overlain by the saint daniel and riviere port daniel melanges and correlate with the thetford mines and mont albert ophiolitic complexes our 40 ar 39 ar data and compiled regional age constraints indicate that ophiolite obduction was diachronous along the strike of the orogen the timing of obduction and melange formation varies according to the irregular geometry of the early paleozoic laurentian margin with earlier collision occurring along or at the margins of promontories obduction was initiated with the formation of infraophio litic metamorphic soles between ca 479 and 472 ma in southern quebec and the nadeau ophiolitic melange and pos sibly as late as ca 470 466 ma for the mont albert complex these sole rocks were later exhumed and translated onto the laurentian margin with the overlying ophiolites between 475 and 460 457 ma the uplifting and erosion of the orogenic wedge during the waning stages of obduction has resulted in the sedimentation of olistostromal melanges and onlapping flysch units above the ophiolitic nappes as well as foredeep flysch successions during the latest arenig to earliest caradoc