broadband recording of strombolian explosions and associated very long period seismic signals on mount erebus volcano ross island antarctica in december 1996 and january 1997 broadband seismometers were deployed on the summit plateau of mount erebus at radial distances of 0 7 1 4 and 1 9 km from the central crater and lava lake strombolian explosions at erebus previously have been observed to produce seismic and acoustic energy between 1 and 6 hz new observations document significant energy with spectral peaks as grave as 20 s nearly identical very long period vlp signals begin 1 5 s prior to explosions have dilatational onsets and persist for up to 150 s similar vlp waveforms were recorded at all three stations indicating that the seismograms are essentially source dominated particle motions suggest an initial depth for the vlp source of up to several hundred meters migrating deeper in the course of 15 s such explosion associated vlp signals may indicate a nondestructive lossy resonance or nonlinear fluid flow excitation within the shallow magmatic system

broadband seismic experiment at merapi volcano java indonesia very long period pulses embedded in multiphase earthquakes abstract multiphase mp and low frequency lf earthquakes with spectral peak amplitudes at 3 4 and 1 hz respectively are two common types of shallow volcanic earthquakes previously recognized at merapi volcano their mechanisms are poorly understood but mps have been temporally associated with lava dome growth we conducted a seismic experiment in january february 1998 using four broadband seismographs to investigate the nature of seismic activity associated with dome growth during our experiment merapi experienced mild dome growth with low level seismic activity we compare our data to that recorded on a local short period sp network with the following preliminary results mp and lf events as recorded and classified on the short period network instruments were recognized on the broadband network frequency spectrograms revealed similar patterns in the near summit region at widely separated broadband stations higher frequency spectra than previously recognized were identified for both mp and lf events and were strongly attenuated as a function of radial distance from the source thus the spectral characteristics of these events as recorded on far field stations are not fully indicative of the source processes in particular many events classified as lf type appear to have much high frequency energy near the source this aspect of these so called lf earthquakes and their association with very long period vlp pulses suggests that many events identified in the far field as lf events are in actuality a variety of the mp event and involve similar source processes broadband records indicated that simple large amplitude vlp pulses were embedded in mp and lf wavetrains from event to event these pulses were similar in their waveforms and had periods of 4 s vlp events embedded in lf and mp earthquakes were located using particle motions the epicenters were clustered in a central region of the dome complex and preliminary source depths were within about 100 m of the dome surface suggesting a source region deep within the dome or the uppermost conduit a similar source location was established by study of mp high frequency onsets our broadband data suggests that we have recorded both elastic seismic waves and a simple embedded pulse that is interpreted to represent a surface tilt at the seismometer site the inferred tilt indicates an inflation and subsequent deflation possibly caused by a gas pressure pulse or episodic shallow magma transport with stick slip movement of the conduit wall

the origin of the sierra de aracena hollows in the sierra morena huelva andalucia spain hollows in the sierra de aracena part of western sector of sierra morena region huelva spain are geoecologically unusual macroforms they are underlain by deeply weathered bedrock but have eutrophic soils with distinctive vegetation paleosols with very dark colours a predominance of smectites and large amounts of total and free iron occur on the floors on the hollows an evolutionary model is proposed for the hollows involving differential weathering during the mesozoic on plutonic and amphibolitic rocks alpine tectonic activity followed by quaternary erosion and exhumation leading to formation of erosional terraces

late pleistocene relic ultisols and alfisols in an alluvial fan complex in coastal tuscany detailed stratigraphic sedimentary facies and palaeosol analyses were performed on an outcrop on late quaternary deposits in the coastal area of tuscany the outcrop was selected as representative of one of the major quaternary alluvial fan complexes of central italy the ancient cecina river fan and as showing contrasting if related palaeosols the oldest relic palaeosol was identified as an ultisol representative of the most developed soil type normally found as relic soil in italy and about whose possible ages only approximate interpretations presently exist osl dating set the whole succession of sediments palaeosols and geomorphic surfaces into a firm chronological setting as a result evolution of the cecina fan complex in late pleistocene could be fully reconstructed assessment of the age of the relic ultisol produced results contrasting with current interpretations showing how such a soil type can have developed in italian conditions in a relatively short time i e since about mis 5d

broadband measurements of the sources of explosions at stromboli volcano italy during september october 1997 21 three component broadband seismometers were deployed on stromboli volcano at radial distances of 0 3 2 2 km from the active crater to investigate the source mechanisms of strombolian explosions in the 2 50 s band the very long period vlp signals associated with explosions are consistent with two stationary sources repeatedly activated in time vlp particle motions are essentially linear and analyses of semblance and particle motions are consistent with a source centroid offset 300 m beneath and 300 m northwest of the active vents similar vlp waveforms are observed at all 21 stations indicating that the seismograms are source dominated the vlp ground displacement response to each explosion may be qualitatively interpreted as 1 pressurization of the conduit associated with the ascent of a slug of gas 2 depressurization of the conduit in response to mass withdrawal during the eruption and 3 repressurization of the conduit associated with the replenishment of the source with fluid

improving the amplitude source location asl method using multicomponent seismic data an assessment with active source seismic dataimproving the asl method using multicomponent seismic data an assessment with active source seismic data improving the amplitude source location asl method using multi component seismic data an assessment with active source seismic data

source characterization for an explosion during the 2009 eruption of redoubt volcano from very long period seismic waves abstract the 2009 eruption of redoubt produced several very long period vlp signals associated with explosions we invert for the source location and mechanism of an explosion at redoubt volcano using waveform methods applied to broadband recordings such characterization of the source carries information on the geometry of the conduit and the physics of the explosion process inversions are carried out assuming the volcanic source can be modeled as a point source with mechanisms described by a a set of 3 orthogonal forces b a moment tensor consisting of force couples and c both forces and moment tensor components we find that the source of the vlp seismic waves during the explosion is well described by either a combined moment force source located northeast of the crater and at an elevation of 1 6 km asl or a moment source at an elevation of 800 m to the southwest of the crater the moment tensors for the solutions with moment and force and moment only share similar characteristics the source time functions for both moment tensors begin with inflation pressurization and execute two cycles of deflation reinflation depressurization repressurization although the moment force source provides a better fit to the data we find that owing to the limited coverage of the broadband stations at redoubt the moment only source is the more robust and reliable solution based on the moment only solution we estimate a volume change of 19 000 m3 and a pressure change of 7 mpa in a dominant sill and an out of phase volume change of 5000 m3 and pressure change of 1 8 mpa in a subdominant dike at the source location these results shed new light on the magmatic plumbing system beneath redoubt and complement previous studies on vulcanian explosions at other volcanoes

source mechanism of very long period signals accompanying dome growth activity at merapi volcano indonesia 1 very long period vlp pulses with period of 6 7s displaying similar waveforms were identified in 1998 from broadband seismographs around the summit crater these pulses accompanied most of multiphase mp earthquakes a type of long period event locally defined at merapi volcano source mechanisms for several vlp pulses were examined by applying moment tensor inversion to the waveform data solutions were consistent with a crack striking 70 and dipping 50 sw 100m under the active dome suggest pressurized gas transport involving accumulation and sudden release of 10 60 m3 of gas in the crack over a 6s interval

kaolinitic paleosols in the south west of the iberian peninsula sierra morena region spain paleoenvironmental implications abstract this paper studies the physical and chemical characteristics of eight different soil profiles with paleohorizons rich in kaolinites and developed on different lithologies along the southern border of the hercinian iberian peninsula sierra morena region the paleohorizons of four of these soils are defined by low ph levels desaturation of the exchange complex and proportions of kaolinite of over 75 these characteristics are associated with subtropical pedogenic conditions during the pliocene period a further two soil profiles are contemporary and defined by the following features they occupy depression areas the clay fraction is dominated by kaolinites and smectites the exchange complex is saturated and the ph is above neutral values the last two soil profiles are developed on pliocene continental deposits and have more moderate pedogenic features their kaolinite levels are around 50 and their evolution is associated with shorter periods of exposure to these subtropical alteration conditions

source mechanisms of explosions at stromboli volcano italy determined from moment tensor inversions of very long period data 1 seismic data recorded in the 2 30 s band at stromboli volcano italy are analyzed to quantify the source mechanisms of strombolian explosions during september 1997 to determine the source centroid location and source mechanism we minimize the residual error between data and synthetics calculated by the finite difference method for a point source embedded in a homogeneous elastic medium that takes topography into account two source centroids are identified each representative of the distinct event types associated with explosive eruptions from two different vents the observed waveforms are well reproduced by our inversion and the two source centroids that best fit the data are offset 220 and 260 m beneath and 160 m northwest of the active vents the source mechanisms include both moment tensor and single force components the principal axes of the moment tensor have amplitude ratios 1 1 2 which can be interpreted as representative of a crack if one assumes the rock matrix at the source to have a poisson ratio n 1 3 a value appropriate for hot rock both imaged cracks dip 60 to the northwest and strike northeast southwest along a direction parallel to the elongation of the volcanic edifice and a prominent zone of structural weakness as expressed by lineaments dikes and brittle structures for our data set the volume changes estimated from the moments are 200 m 3 for the largest explosion from each vent together with the volumetric source is a dominantly vertical force with a magnitude of 10 8 n consistent with the inferred movement of the magma column perched above the source centroid in response to the piston like rise of a slug of gas in the conduit index terms 7215 seismology earthquake parameters 7280 seismology volcano seismology 8419 8414 volcanology eruption mechanisms keywords very long period seismicity moment tensor inversions eruption mehanics

sediment soil sequences in the granada basin as evidence for long and short term climatic changes during the pliocene and quaternary in the western mediterranean abstract since the tortonian the carbonate dominated granada basin has received various terrestrial sediments late miocene pliocene early and mid pleistocene alluvial fans and late pleistocene slope deposits and loesses these deposits include many paleosols two hundred and forty samples of paleosols and sediments in 20 representative pliocene and pleistocene profiles were analysed by standard methods the long sequences with up to 85 paleosols indicate climatic cycles over at least 5 ma erosion and sedimentation occurred under dry conditions without vegetation cover during periods of geomorphodynamic activity soil formation occurred under wet conditions with closed vegetation during periods of geomorphodynamic stability the pedogenetically effective climate has been subtropical mediterranean since the early pliocene decreasing soil formation intensity indicates decreases of humidity in the mid late pliocene and late pleistocene

climate and biomes in the west mediterranean area during the pliocene a new pollen derived method of climatic quantification based on the mutual climatic range of plant taxa has been applied to 17 pliocene pollen sequences in the west mediterranean area the latitudinal gradient observed in the pollen data was confirmed by the climatic reconstructions there is a gradient from north to south both for temperatures and precipitation at the beginning of the pliocene 5 32 5 ma the climate in the north mediterranean area was on average warmer and more humid than today respectively 1 4oc and 400 700 mm in the south mediterranean region the climate was both warmer and drier than today respectively equal to or 5oc higher and drier or equal humidity the pollen based climate estimates were then used to reconstruct biomes for the region the results show the occurrence of three biomes the broad leaved evergreen warm mixed forest the xerophytic woods scrub biome and the warm grass shrub biome these biomes are still represented today in the mediterranean region despite different thermic and water conditions

spatial extent of a hydrothermal system at kilauea volcano hawaii determined from array analyses of shallow long period seismicity 2 results we present a probabilistic method to locate the source of seismic events using seismic antennas the method is based on a comparison of the event azimuths and slownesses derived from frequency slowness analyses of array data with a slowness vector model several slowness vector models are considered including both homogeneous and horizontally layered half spaces and also a more complex medium representing the actual topography and three dimensional velocity structure of the region under study in this latter model the slowness vector is obtained from frequency slowness analyses of synthetic signals these signals are generated using the finite difference method and include the effects of topography and velocity structure to reproduce as closely as possible the behavior of the observed wave fields a comparison of these results with those obtained with a homogeneous half space demonstrates the importance of structural and topographic effects which if ignored lead to a bias in the source location we use synthetic seismograms to test the accuracy and stability of the method and to investigate the effect of our choice of probability distributions we conclude that this location method can provide the source position of shallow events within a complex volcanic structure such as kilauea volcano with an error of 200 m

imaging magma storage below teide volcano tenerife using scattered seismic wavefields summary tenerife canary islands spain is a volcanic island dominated by the teide pico viejo complex with a summit height of 3718 m after renewed signs of activity starting in 2004 an active seismic experiment was performed in 2007 to derive a tomographic model and identify seismic anomalies possibly associated with the magmatic system to complement the tomography a double beam forming analysis is applied on two orthogonal 2 d profiles crossing the island to look for evidence of the existence of a magma chamber numerical tests allow us to investigate the best measure of coherency between traces and show that the correlation and nth root semblance methods give better results than the classical semblance they also demonstrate that the technique is reliable for locating scattering structures at depth even when the velocity model is imperfect applying this technique to the tenerife data set two main anomalies can be identified one at approximately 7 9 km b s l depth in the northern part of the island and one shallower 1 4 km b s l beneath the main summit these structures could be linked to the magmatic system in good agreement with previous studies the shallowest one may be the phonolitic storage area feeding the teide pico viejo complex while the deepest structure may be related to the basaltic system

pliocene sequence stratigraphy climatic trends and sapropel formation in the northern apennines italy abstract the pliocene stratigraphy of the romagna northern apennines foredeep has been reconstructed through mapping and measuring the different lithostratigraphic units the physically correlated sedimentary bodies have been chronologically calibrated through biostratigraphic analyses analysis of facies and fossil content allowed reconstructing the main depositional systems and their evolution the co occurrence of shallow to deep water environments and carbonate to siliciclastic systems allowed understanding fully the role of eustasy and climate vs continuous tectonic deformation controlling the accommodation and basin morphology following a limited sea level lowering at 4 2 ma associated with the first signal of cooling in the early pliocene a fast growing subtropical type carbonate platform developed in response to warm and oligotrophic surface waters furthermore a significant drop in sea level at 3 75 ma points to an important pliocene continental glaciation in the northern hemisphere during the subsequent transgression warm and possibly humid climate favoured the deposition of the first pliocene sapropel around 3 3 ma the growth of a second generation of carbonate platform between 3 3 and 3 042 ma suggests a renewed warm period and limited runoff at the top of this highstand thick sapropels developed which can easily be correlated across the mediterranean the platform abruptly drowned was overwhelmed by bio erosion and was covered by iron phosphate crusts whereas in the adjacent basins numerous sapropel layers occurred rich of biosiliceous forms documenting the shift from ccarb to corg deposition strong oscillations of climate due to precessionally controlled seasonality and increased precipitation and runoff are considered as the main causes of the increase of surface water fertility after the 2 87 ma sea level drop again very significant the sapropel rapidly disappears in conjunction to the development of the lowstand wedge after this cold period which ended around 2 6 ma carbonate platforms never recovered due to the enduring cooler surface waters and the onset of an active drainage on the apenninic range this study documents the role of the eustatic variations on the pliocene deposition of the actively deforming northern apennines foredeep the abrupt lithostratigraphic changes appear also controlled by palaeoproductivity variations associated with climate and runoff

insights into fluid transport mechanisms at white island from analysis of coupled very long period vlp long period lp and high frequency hf earthquakes the august 2012 to october 2013 white island unrest sequence included 5 explosive volcanic eruptions and emplacement of a small dome these events were linked to an overall increase in so2 and h2s gas flux and rsam seismic tremor which began in late 2011 prior to this unrest a small swarm of 25 events was observed on 19 21 august 2011 and captured on a temporary seismic array including 14 broadband sensors each event comprised coupled pulses having distinct high frequency hf 2 5 hz long period lp 0 5 1 1 hz and very long period vlp 0 03 0 125 hz or 8 30 s earthquakes for each coupled event we compute the source locations origin times and related uncertainties by application of standard arrival time locations for the hf earthquakes and waveform semblance for the lp and vlp earthquakes results suggest that the events are centred beneath the active vent at depths generally 1 5 km the hf and lp earthquakes have shallow depths 1 km while vlp have slightly deeper source locations 0 8 1 5 km emergent onsets for lp and vlp sources make an analysis of the absolute origin times problematic but waveform matching of vlp to lp and hf components suggests that the main vlp pulse precedes the hf and lp source processes waveform inversion for the vlp source is consistent with the rupture of a high angle east west oriented crack opening either in a purely tensile or shear tensile manner the moment of the isotropic component is estimated at 1 2 1012 nm and the corresponding volumetric change is in the range 145 450 m3 results are interpreted as an upward migration of fluids which first excite the vlp from a high angle crack in the magma carapace followed by the excitation of lp and hf source processes in the overlying hydrothermal system

distinguishing high surf from volcanic long period earthquakes repeating long period lp earthquakes are observed at active volcanoes worldwide and are typically attributed to unsteady pressure fluctuations associated with fluid migration through the volcanic plumbing system nonvolcanic sources of lp signals include ice movement and glacial outburst floods and the waveform characteristics and frequency content of these events often make them difficult to distinguish from volcanic lp events we analyze seismic and infrasound data from an lp swarm recorded at pagan volcano on 12 14 october 2013 and compare the results to ocean wave data from a nearby buoy we demonstrate that although the events show strong similarity to volcanic lp signals the events are not volcanic but due to intense surf generated by a passing typhoon seismo acoustic methods allow for rapid distinction of volcanic lp signals from those generated by large surf and other sources a critical task for volcano monitoring

application of near real time radial semblance to locate the shallow magmatic conduit at kilauea volcano hawaii 1 radial semblance is applied to broadband seismic network data to provide source locations of very long period vlp seismic energy in near real time with an efficient algorithm and adequate network coverage accurate source locations of vlp energy are derived to quickly locate the shallow magmatic conduit system at kilauea volcano hawaii during a restart in magma flow following a brief pause in the current eruption the shallow magmatic conduit is pressurized resulting in elastic radiation from various parts of the conduit system a steeply dipping distribution of vlp hypocenters outlines a region extending from sea level to about 550 m elevation below and just east of the halemaumau pit crater the distinct hypocenters suggest the shallow plumbing system beneath halemaumau consists of a complex plexus of sills and dikes an unconstrained location for a section of the conduit is also observed beneath the region between kilauea caldera and kilauea iki crater

location and mechanism of very long period tremor during the 2008 eruption of okmok volcano from interstation arrival times 1 we describe continuous very long period vlp tremor that occurred during the 2008 eruption of okmok volcano alaska due to its low frequency content in band from the 0 2 0 4 hz the wave field of the vlp tremor is relatively free of path effects from continuous recordings of the vlp tremor on 2 three component broadband and 3 single component short period instruments we devise a method to locate the epicenter of the tremor based on interstation arrival times computed with cross correlation we find the epicenter since the vertical and radial components of the vlp tremor wave field are dominated by rayleigh waves and the time shifts are related to lateral propagation over the 4 h period studied this procedure yields a location nnw of cone d close to the new cone built over the course of the eruption similar analysis using the transverse horizontal components from the 2 three component broadband instruments yields strong constraints on the source mechanism of the vlp tremor we observe an anomalous interstation arrival time due to the existence of a nodal plane in the love wave radiation pattern the orientation of a compensated linear vector dipole clvd source estimated from the transverse components closely aligns with the regional maximum horizontal stress direction the depth of the clvd source is constrained by matching the vertical components to the rayleigh wave radiation pattern at all five stations we find the vlp tremor source depth to be 2 km bsl positioned between the magma chamber at okmok 3 km bsl and the surface

highlights from a seismic broadband array on stromboli volcano an array of nine three component broadband seismometers was deployed in two different configurations on stromboli volcano the analysis of the seismic wavefield related to volcanic explosions revealed some observations which offer a completely new insight into the internal dynamics of a volcano these new observations are restricted to the low frequency range below 1 hz and underline therefore the superiority of broadband recordings over conventional short period observations surprisingly simple wavelets indicate an initially contracting source mechanism gas jets that could not be seen in a short period seismic record at all generate a clear dilatational wavelet in a broadband recording suggesting the same contracting source mechanism the analysis of particle motion and seismic array techniques permits a location of the seismic source we find low frequency signals of 3s and 6s period that are not related to eruptions and do not share a common source with the eruption related events a video recording of visible volcanic activity at the crater region allows one to correlate precisely eruptive features with seismic signals

monitoring very long period seismicity at kilauea volcano hawaii 1 on 19 march 2008 eruptive activity returned to the summit of kilauea volcano hawaii with the formation of a new vent within the halemaumau pit crater the new vent has been gradually increasing in size and exhibiting sustained degassing and the episodic bursting of gas slugs at the surface of a lava pond 200 m below the floor of halemaumau the spectral characteristics source location obtained by radial semblance and hidden markov model pattern recognition of the degassing burst signals are consistent with an increase in gas content in the magma transport system beginning in october 2007 this increase plateaus between march september 2008 and exhibits a fluctuating pattern until 31 january 2010 suggesting that the release of gas is slowly diminishing over time

performance of the radial semblance method for the location of very long period volcanic signals we investigate the performance of a source location method that com bines multichannel semblance and particle motions and is being increasingly used to obtain estimates of the source locations of very long period vlp seismic signals recorded on volcanoes the method makes use of the radial particle motions and large wavelengths that characterize the vlp events to assess the capabilities of this radial semblance method and to better understand its limitations we quantify the effects of window length noise contents of the signal inaccurate velocity models receiver coverage and orientation errors in the horizontal components of the receiv ers our results show that the semblance method performs best when 1 the noise level is low enough to allow a good characterization of the waveforms 2 the sources are located at distances between one half of the average receiver spacing and about two times the network aperture and 3 the orientations of the horizontal components of the seismometers are known with relative accuracy when these requirements are met the radial semblance method constitutes an adequate tool to obtain preliminary locations of vlp volcanic signals recorded by broadband networks moreover we provide a formula to determine the radial semblance level that should be used to define error regions associated to the estimated source locations

mechanism of phreatic eruptions at aso volcano inferred from near field broadband seismic observations broadband seismometers deployed at aso volcano in japan have detected a hydrothermal reservoir 1 to 1 5 kilometers beneath the crater that is continually resonating with periods as long as 15 seconds when phreatic eruptions are observed broadband seismograms elucidate a dynamic interplay between the reservoir and discharging flow along the conduit gradual pressurization and long period 20 seconds pulsations of the reservoir during the 100 to 200 seconds before the initiation of the discharge followed by gradual deflation of the reservoir concurrent with the discharging flow the hydrothermal reservoir where water and heat from the deeper magma chamber probably interact appears to help control the surface activity at aso volcano

paleoenvironmental evolution of the pliocene villarroya lake northern spain a multidisciplinary approach abstract the pliocene villarroya basin fill consists of lacustrine and alluvial deposits over 100 m thick the lacustrine deposits up to 30 m thick comprise three sequences the two lower sequences consist of profundal laminated deposits formed by mostly terrigenous facies that are overlain by charophytic carbonates and varves the uppermost third sequence made up of massive bioturbated mudstones corresponds to a very shallow lacustrine palustrine environment bulk mineralogy comprises carbonates clay minerals quartz and feldspars the carbonates are exogenic biogenic calcite and biogenic aragonite biogenic calcite constitutes ostracod shells and charophyte stem encrustations whereas aragonite forms gastropod shells and in some varve intervals charophyte encrustations the clay minerals are illite kaolinite palygorskite chlorite and paragonite which are inherited from source rocks and smectite and interstratified clays which are probably formed in the soils of the source area variations in clay mineralogy reflect the interplay between the climate tectonic rejuvenation and the paleogeography of the basin the pollen assemblages indicate significant variations in climate a first phase of varying climate was followed by cool temperate and sub humid phases that culminated in a temperate and dry episode which is recorded in the lower part of the second lacustrine sequence this was succeeded by a marked warm and humid episode which may be correlated with the mid pliocene warmth about 3 0 ma and the subsequent cooling phase which is recorded in the upper third sequence in the two lower sequences profundal lacustrine deposits ostracods indicate oligosaline to mesosaline waters with salinity variations and some warm and na cl episodes molluscs are characterized by hydrobiids suggesting a salinity stress in the upper palustrine deposits the ostracods and aquatic mollusc assemblages indicate fresh cold waters faunal records indicate that changes in salinity do not correlate with climate suggesting phases of significant saline inputs to the lake which were recorded in the lower first sequence and in the upper part of the second sequence the lacustrine sequence of villarroya record pronounced variations in climate and in the lacustrine environment however there are no consistent relationships between the climate conditions inferred from the pollen data and the sedimentary record of the environmental changes showing that other factors especially tectonics have exerted an influence on the paleoenvironmental evolution and on the sedimentary record of the pliocene villarroya lake

very long period signals associated with vulcanian explosions at popocatepetl volcano mexico very long period vlp seismic signals associated with large summit eruptions of popocatepetl volcano in the last four years are investigated using data from a broadband seismometer 0 04 120 s deployed on the north flank of the volcano at a radial distance of 5 km from the active crater the vlp signals associated with individual eruptions share similar waveforms discrete vlp signals accompanying long period lp events also share similar signatures and have dominant periods that are nearly identical to those observed in the vlp waveforms of explosions the vlp particle motions for eruption onsets consistently point to a source located a few km beneath the crater the vlp ground displacement response to each explosion is marked by a compression followed by a dilatation and terminating with another compression suggesting a sequence of pressurization depressurization repressurization of the conduit the repetitive nature of the waveforms points to a non destructive source process which has remained active in the magmatic system of popocatepetl at least since april 1997

properties of the near field term and its effect on polarisation analysis and source locations of long period lp and very long period vlp seismic events at volcanoes abstract seismicity that originates within volcanic magmatic and hydrothermal plumbing systems is characterised by wavelengths that are often comparable to or longer than the source receiver distance the effect of such a near field configuration must be explored when analysing these signals herein we summarise properties of near field observations for both a single force and moment tensor seismic sources we show radiation patterns of the near intermediate and far field terms for the source types that are most likely candidates for long lp and very long period vlp volcanic seismicity including a single force compensated linear vector dipole clvd a tensile crack and a pipe like source we find that the deviation of the first motion polarisation from the radial direction is significant in all planes except one whose normal is parallel to the symmetry axis if there is one of the source mechanism however this deviation is less pronounced or even negligible when there is a considerable volumetric component in the source as in the case of a tensile crack or pipe our location test shows that the accuracy of locations obtained using the semblance or cross correlation techniques is very significantly affected by the near field geometry this effect is especially pronounced for shallow sources such as often encountered on volcanoes and decreases with increasing source depth hence in practical applications on volcanoes 3d full waveform numerical simulation including topography and structural heterogeneities should be used in order to both validate location techniques and as an interpretational aid to reduce misinterpretations of location results

apparent migration of tremor source synchronized with the change in the tremor amplitude observed at aso volcano japan at aso volcano kyushu japan several different types of volcanic tremor have been observed for many years one of them is the continuous tremor the ground vibration which has dominant frequency between 3 and 10 hz and has approximately constant amplitudes without any clear beginning and ending we observed the continuous tremor at aso using short period seismometer arrays for 3 days in 1999 we locate the source of the continuous tremor by seismic array data processing we use the semblance coefficients in order to estimate the arrival azimuth and apparent slowness by grid search the epicenters of the continuous tremor are located around the currently active crater and the source depths are likely to be shallower than 600 m we find that the estimated epicenter clearly migrates synchronized with the change in the tremor amplitude the migration often occurs periodically with a period of about 80 s but aperiodic occurrence of the migration is also often seen in both cases the epicenter is located southeastward northwestward when the amplitude is larger smaller we propose that there are two or more independent tremor sources with fixed locations and that their amplitudes modulate either aperiodically or periodically with periods nearly 80 s the tremor signals from those sources are mixed at the arrays and the estimated epicenter parameters vary according to which signal dominates the seismograms the simplest model is that there are two point sources one at west and the other at south of the crater we call the two sources as nw source and se source respectively and the amplitude of the se source changes with time consequently the se source dominates the seismogram when the observed amplitude is larger whereas the nw source dominates when the amplitude is smaller we generate synthetic seismograms and apply the location technique to them to verify the validity of the two point source model and to search the locations of two sources which can explain the observed synchronization between the amplitude and the apparent epicenter location we find that the distance between the two sources needs to be more than 400 m to agree with the observation we also analyze the seismic array data observed in 2001 and infer that the nw source in 1999 may be identical to the tremor source of the 2001 data

seismo volcano source localization with triaxial broad band seismic array summary seismo volcano source localization is essential to improve our understanding of eruptive dynamics and of magmatic systems the lack of clear seismic wave phases prohibits the use of classical location methods seismic antennas composed of one component 1c seismometers provide a good estimate of the backazimuth of the wavefield the depth estimation on the other hand is difficult or impossible to determine as in classical seismology the use of three component 3c seismometers is now common in volcano studies to determine the source location parameters backazimuth and depth we extend the 1c seismic antenna approach to 3cs this paper discusses a high resolution location method using a 3c array survey 3c music algorithm with data from two seismic antennas installed on an andesitic volcano in peru ubinas volcano one of the main scientific questions related to the eruptive process of ubinas volcano is the relationship between the magmatic explosions and long period lp swarms after introducing the 3c array theory we evaluate the robustness of the location method on a full wavefield 3 d synthetic data set generated using a digital elevation model of ubinas volcano and an homogeneous velocity model results show that the backazimuth determined using the 3c array has a smaller error than a 1c array only the 3c method allows the recovery of the source depths finally we applied the 3c approach to two seismic events recorded in 2009 crossing the estimated backazimuth and incidence angles we find sources located 1000 660 m and 3000 730 m below the bottom of the active crater for the explosion and the lp event respectively therefore extending 1c arrays to 3c arrays in volcano monitoring allows a more accurate determination of the source epicentre and now an estimate for the depth

seismic analysis of the 13 october 2012 te maari new zealand lake breakout lahar insights into flow dynamics and the implications on mass flow monitoring abstract on 6 august 2012 an eruption of the upper te maari vent tongariro volcano and subsequent debris flow in the mangatetipua channel created a debris dam and ephemeral lake the lake reached its maximum volume of 50 000 m3 by 13 october initiating dam breaching at 22 30 nzdt 11 30 utc after a period of intense rainfall the breach eventually grew to 29 12 m causing eroded debris flow sediment and water to remobilize as a lahar the event comprising multiple surges lasted 30 min and displaced 57 000 m3 of remobilized sediment up to 4 5 km downstream to determine the dynamics of the event the seismic signals generated by the lahar were compared with active seismic source data collected in february 2013 the comparison used a common frequency band range of 3 10 hz to compute amplitude for four near field seismic stations for periods with signal to noise ratios above 2 0 we obtained lahar amplitude distributions that match best the equivalent active source amplitudes within 0 5 km of the dam breakout the accumulated seismic energy of the lahar was estimated at 1 93 109 nm whereas the peak energy was 6 88 107 nm results of this work may improve the characterization of future mass flow events in the te maari mangatetipua area through the calibration of seismic stations used in this study

source process of very long period seismic events associated with the 1998 activity of iwate volcano northeastern japan we observed very long period seismic events that are associated with the 1998 activity of iwate volcano northeast japan the events show a dominant period of 10 s and duration of 30 60 s often with accompanying short period waves at the beginning and at the end of the long period signals by analyzing the broadband seismograms we find that the source elongates in the east west direction for 4 km at a depth of 2 km beneath the western part of iwate volcano results of moment tensor inversions show a source mechanism of mutual deflation and inflation of two chambers located at the western and eastern edges of the source region the source region coincides with the low seismic velocity zone detected by seismic tomography and is very close to the locations of pressure sources estimated from crustal deformation data on the basis of these results we infer that the very long period seismic events are generated by transportation and movement of magmatic fluid hot water and or magma in a shallow part of the volcano we further present a simple source model of very long period seismic events based on one dimensional flow dynamics and propose a new parameter to characterize the size of very long period event the energy flow rate which is obtained by dividing the seismic moment by the dominant period the energy flow rate was estimated as 3 1 1012 j s for the event on july 29 1998

very long period seismic signals and caldera formation at miyake island japan over a period of roughly 40 days starting on 8 july 2000 a caldera structure 1 7 kilometers in diameter developed by means of gradual depression and expansion of the summit crater at miyake island japan at the same time very long period vlp seismic signals were observed once or twice a day source mechanism analyses of the vlp signals show that the moment tensor solutions are smooth step functions over a time scale of 50 seconds with dominant volumetric change components we developed a model to explain the caldera and the vlp signals in which a vertical piston of solid materials in the conduit is intermittently sucked into the magma chamber by lateral magma outflow this model offers potential for making quantitative estimations of the characteristic physical properties of magma systems

moment tensor analysis of near field broadband waveforms observed at aso volcano japan abstract locations and focal mechanisms of long period volcanic events observed at aso volcano japan are determined by waveform inversion near field broadband three component seismograms of four to seven stations are simultaneously inverted in the time domain in order to find the six component seismic moment tensor a linear inversion is performed at each point of a 3d grid located under the volcano in order to constrain the centroid position and the focal mechanism of the source the complete displacements including near field waves in a homogeneous half space for a general point source are taken into account inversions of 43 long period tremors and six phreatic eruptions exhibit mainly an isotropic mechanism with a minor deviatoric component that may originate from a north south trending crack these events are all located in a small region at about 1 3 km depth beneath the active crater the high accuracy both of locations a few hundred meters and of focal mechanisms given by the inversion is partly attributed to the rapid variation of the amplitude of the static displacement seen in the long period part of the near field seismograms

array analysis using circular wave front geometry an application to locate the nearby seismo volcanic source summary the zero lag cross correlation technique used for array analysis in the hypothesis of plane waves has been modified to allow the wave front to be circular synthetic tests have been performed to check the capability of the method which returns the input test data when the source array distances are not greater than two or three times the array aperture for this distance range the method furnishes an estimate of the apparent velocity and the epicentral coordinates of the source for more distant sources the method becomes equivalent to that based on the planar wave approximation which gives an estimate of the backazimuth to the source and the apparent velocity the method has been applied to seismic data recorded at the active volcano located at deception island antarctica 35 volcanic long period events occurring in a small swarm were selected results show that the epicentres are close to the array between 0 4 and 2 km and aligned in a sw direction in agreement with one of the main directions of the fracture system of deception volcano

detailed analysis of wave propagation beneath the campi flegrei caldera italy we investigate the complex propagation of seismic waves beneath the campi flegrei caldera italy using multichannel recordings of artificial explosions the sources consisted of air gun explosions shot in the gulf of pozzuoli at offsets ranging between 3 and 7 km a multichannel recording device was deployed in the solfatara crater and consisted of ten vertical component and two three component short period seismometers with a maximum aperture of about 150 m the zero lag correlation zlc technique was adopted to estimate horizontal slowness and backazimuth of coherent waves crossing the array for sources located in the northern sector of the gulf with maximum offset 5 km ray parameters and backazimuths are in agreement with those predicted for the 1d velocity model used for routine locations for sources at offsets larger than 5 km the zlc curves depict prominent maxima associated with a secondary phase propagating with a lower velocity than the first arrival p wave using finite difference synthetic seismograms generated for a 2d realistic velocity model we explain these late arrivals in terms of a lateral velocity variation located at depths of about 1 km such discontinuity would correspond to a positive vp anomaly imaged by a recent 3d tomographic study and interpreted as the submerged southern rim of campi flegrei caldera collapsed during the explosive eruption of 12 ky b p the small spacing among adjacent shot points allowed simultaneous wave field decomposition at the source and receiver arrays using a modified version of the double beam method we retrieve the independent variation of horizontal slowness at both the source and receiver regions for both cases we found azimuthal deviations as large as 50 with respect to the great circle path at the source region these discrepancies may be interpreted in terms of ray bending at the interface of the aforementioned positive anomaly at the receiver array the observed anomalies may be attributed to either velocity variations marking the solfatara crater rim or to a near receiver low velocity body whose position would coincide with negative gravimetric anomalies and a high vp vs ratio region inferred by independent geophysical and seismological studies

the soils and ages of the rana surfaces related to the villuercas and altamira mountain ranges western spain summary the soils of rana surfaces related to the sierra de las villuercas and the sierra de altamira western spain were studied with reference to vegetation cover and geomorphic position these soils were highly weathered with kaolinite dominant in the clay fraction and almost no weatherable minerals in the sand fraction iron oxides were segregated in some of the horizons giving a formation of pseudoplinthite this high degree of weathering and the patina of their quartzite stones are comparable to those of soils developed on the oldest ran a surfaces studied in central spain the soils classified as palehumults and palexerults are given tentatively a middle upper pliocene age

characterizing complex eruptive activity at santiaguito guatemala using infrasound semblance in networked arrays abstract we implement an infrasound semblance technique to identify acoustic sources originating from volcanic vents and apply the technique to the generally low amplitude infrasound

magmatic dike resonances inferred from very long period seismic signals very long period vlp signals showing simple decaying harmonic oscillations with periods near 10 seconds and lasting for about 300 seconds were observed in association with an earthquake swarm that occurred beneath hachijo island japan results from the source mechanism analysis and waveform simulation based on a fluid filled crack model consistently point to the resonance of a dike filled with a basaltic magma as the source of the vlp signals thus vlp signals can be used to probe the state of the fluid and dynamic processes within a volcanic system

real time monitoring and massive inversion of source parameters of very long period seismic signals an application to stromboli volcano italy 1 we present a comprehensive processing tool for the real time analysis of the source mechanism of very long period vlp seismic data based on waveform inversions performed in the frequency domain for a point source a search for the source providing the best fitting solution is conducted over a three dimensional grid of assumed source locations in which the green s functions associated with each point source are calculated by finite differences using the reciprocal relation between source and receiver tests performed on 62 nodes of a linux cluster indicate that the waveform inversion and search for the best fitting signal over 100 000 point sources require roughly 30 s of processing time for a 2 min long record the procedure is applied to post processing of a data archive and to continuous automatic inversion of real time data at stromboli providing insights into different modes of degassing at this volcano

calibrating the amplitude source location asl method by using active seismic sources an example from te maari volcano tongariro national park new zealand a frequently applied amplitude source location asl method is here calibrated and optimized by using active seismic sources located at the surface of a dry stream channel the asl produced location discrepancies larger than 1 0 km laterally and 500 m in depth by using independently determined velocity model attenuation and site amplification factors afs sensitivity tests for asl input parameters show that attenuation and velocity have moderate influence on the location but are easy to independently constrain afs are shown to strongly influence the location and their application may introduce substantial location uncertainties model uncertainties are accommodated with either lateral or depth changes depending on the input parameters station corrections and the source station geometry

identifying elements of the plumbing system beneath kilauea volcano hawaii from the source locations of very long period signals summary we analyzed 16 seismic events recorded by the hawaiian broad band seismic network at kilauea volcano during the period september 9 26 1999 two distinct types of event are identified based on their spectral content very long period vlp waveform amplitude decay pattern and particle motion we locate the vlp signals with a method based on analyses of semblance and particle motion different source regions are identified for the two event types one source region is located at depths of 1 km beneath the northeast edge of the halemaumau pit crater a second region is located at depths of 8 km below the northwest quadrant of kilauea caldera our study represents the first time that such deep sources have been identified in vlp data at kilauea this discovery opens the possibility of obtaining a detailed image of the location and geometry of the magma plumbing system beneath this volcano based on source locations and moment tensor inversions of vlp signals recorded by a permanent large aperture broad band network

backprojection of volcanic tremor backprojection has become a powerful tool for imaging the rupture process of global earthquakes we demonstrate the ability of backprojection to illuminate and track volcanic sources as well we apply the method to the seismic network from okmok volcano alaska at the time of an escalation in tremor during the 2008 eruption although we are able to focus the wavefield close to the location of the active cone the network array response lacks sufficient resolution to reveal kilometer scale changes in tremor location by deconvolving the response in successive backprojection images we enhance resolution and find that the tremor source moved toward an intracaldera lake prior to its escalation the increased tremor therefore resulted from magma water interaction in agreement with the overall phreatomagmatic character of the eruption imaging of eruption tremor shows that time reversal methods such as backprojection can provide new insights into the temporal evolution of volcanic sources

a double correlation tremor location method a double correlation method is introduced to locate tremor sources based on stacks of complex doubly correlated tremor records of multiple triplets of seismographs back projected to hypothetical s

the source of explosive eruptions of sakurajima volcano japan to understand the nature of explosive eruptions in particular the role played by exsolution of magmatic gases we studied the seismic waveforms produced by two such eruptions of sakurajima volcano on october 30 and november 14 1986 an explosion begins when a mixture of magmatic gases and fragmented magma flows upward through a narrow vertical channel to the surface the source region is a reservoir of gas rich magma where the pressure drops as gases flow out the form of low frequency seismic waves can be explained by a source that consists of two components one component is a single force directed downward that represents the reaction to ejection of gas and magma the other more important component is a moment tensor that represents expansion or contraction of rock around a source the first motion of seismic waves produced by an explosion is directed away from the volcano tilt and strain measurements show that the initial motion directed outward is soon followed by subsidence around the volcano the eigenvectors of the seismic moment tensor are either nearly horizontal or vertical the ratio of horizontal to vertical eigenvalues was 1 8 1 for the october 30 explosion this suggests the geometry of the explosive source can be approximated as a buried vertical cylinder the volume of contraction 2 l03 m3 can be produced by a pressure change of 0 3 mpa over a cylinder with a radius of 160 m and a height of 300 m we propose that an explosive eruption occurs after a small shallow source of high pressure forms within a vertical conduit possibly exsolution of magmatic gases eventually the small source bursts and pushes open a pathway to the surface providing an upward escape for trapped gases it is this burst that causes the initial outwardly directed motion at the surface a deeper reservoir of gas rich magma is then subjected to a lower confining pressure and also bursts causing the explosion

the 2011 tohoku tsunami observed by an array of ocean bottom electromagnetometers a tsunami induces secondary electromagnetic em fields of significant intensity as a result of faraday s law and these em fields can be recorded by instruments on the seafloor such observations will provide parameters that are useful in understanding tsunami generation and propagation processes as such em sensors can be used as a type of tsunami sensor in the present study we report the observation of tsunami induced em signals by a small array of ocean bottom electromagnetometers consisting of four stations in the northwestern pacific ocean then several data analysis methods are used to estimate tsunami parameters referring to the theoretical relation the wave height is estimated from the observed magnetic and electric fields also the propagation direction of the 2011 tohoku tsunami is estimated by applying analysis methods for an array and a single station

wavefield properties of a shallow long period event and tremor at kilauea volcano hawaii the wavefields of tremor and a long period lp event associated with the ongoing eruptive activity at kilauea volcano hawaii are investigated using a combination of dense small aperture 300 m and sparse large aperture 5 km arrays deployed in the vicinity of the summit caldera measurements of azimuth and slowness for tremor recorded on the small aperture array indicate a bimodal nature of the observed wavefield at frequencies below 2 hz the wavefield is dominated by body waves impinging the array with steep incidence these arrivals are attributed to the oceanic microseismic noise in the 2 6 hz band the wavefield is dominated by waves propagating from sources located at shallow depths 1 km beneath the eastern edge of the halemaumau pit crater the hypocenter of the lp event determined from frequency slowness analyses combined with phase picks appears to be located close to the source of tremor but at a shallower depth 0 1 km the wavefields of tremor and lp event are characterized by a complex composition of body and surface waves whose propagation and polarization properties are strongly affected by topographic and structural features in the summit caldera region analyses of the directional properties of the wavefield in the 2 6 hz band point to the directions of main scattering sources which are consistent with pronounced velocity contrasts imaged in a high resolution three dimensional velocity model of the caldera region the frequency and q of the dominant peak observed in the spectra of the lp event may be explained as the dominant oscillation mode of a crack with scale length 20 100 m and aperture of a few centimeters filled with bubbly water the mechanism driving the shallow tremor appears to he consistent with a sustained excitation originating in the oscillations of a bubble cloud resulting from vesiculation and degassing in the magma

seismic velocity structure and event relocation in kazakhstan from secondary p phases abstract three component seismic data from a set of presumed explosions recorded by stations at bayanaul and karkaralinsk in kazakhstan were analyzed in order to model the crustal structure of the region and to examine the use of the arrival times of secondary p phases primarily pmp in regional event location polarization analysis aided in the identification of the secondary phases low pass filtered data 4 hz corner from the first 5 to 10 sec of 13 presumed explosions were modeled with the reflectivity method the two chemical explosions in 1987 provided a check on accuracy as their locations and origin times are accurately known a good fit to the arrival times and amplitudes in the first 5 sec of the p wave pn pg and pmp was obtained in the epicentral distance range of 100 to 300 km beyond 300 km the simple layered model was not adequate to model the pmp arrival the crustal p wave velocity model we derived has an upper crustal velocity increasing fairly rapidly from 4 5 km sec near the surface to 6 5 km sec at 15 km depth then increasing more slowly to 7 05 km sec at 50 km depth the observed difference in the arrival times of the phases pg pmp and pn in the range between 100 and 250 km distance required a relatively sharp transition at the crust mantle boundary the model is generally similar to previous estimates of p velocity structure in the region though with a gentler gradient in the upper crust and a steeper gradient in the lower crust we used the derived crustal model and the primary and secondary p wave arrival times to relocate events in the kazakhstan region inclusion of the phase pmp substantially decreases the focal depth uncertainty for many of the events all but one of the events analyzed are concluded to be surface explosions the identity of the remaining event is uncertain

insights into explosive activity at closely spaced eruptive vents using infrasound signals example of mt etna 2008 eruption abstract on 13 may 2008 an eruptive fissure opened on mount etna s eastern flank feeding both explosive activity and lava effusion from multiple vents for about 14 months during the investigated may september 2008 eruptive period infrasound recordings from a 4 station sparse network allowed tracking of the explosive activity in terms of location and dynamics in order to focus on activity from the eruptive fissure the infrasonic events generated by the summit craters were selected by using both spectral features and time delays between pairs of stations and excluded from our analysis then to accurately locate events from the fissure we used a composite method based on the semblance and brightness functions this enabled the study of the co existence of more than one infrasound source and or its migration along the eruptive fissure hence results permitted us to discriminate the number of active vents and their location along the fissure even when due to poor weather conditions it was not possible to access the vents or carry out direct observations the eruptive activity was characterised by variations in the number of active vents according to the overall intensity of the eruptive event variability of the infrasound waveforms highlighted either that distinct vents produced signals with different waveforms or that single vents generated different events during distinct periods of time or finally both the previous phenomena we applied the strombolian bubble vibration model to model waveform differences and attributed the signal variations to bubble radius changes

monitoring seismo volcanic and infrasonic signals at volcanoes mt etna case study volcanoes generate a broad range of seismo volcanic and infrasonic signals whose features and variations are often closely related to volcanic activity the study of these signals is hence very useful in the monitoring and investigation of volcano dynamics the analysis of seismo volcanic and infrasonic signals requires specifically developed techniques due to their unique characteristics which are generally quite distinct compared with tectonic and volcano tectonic earthquakes in this work we describe analysis methods used to detect and locate seismo volcanic and infrasonic signals at mt etna volcanic tremor sources are located using a method based on spatial seismic amplitude distribution assuming propagation in a homogeneous medium the tremor source is found by calculating the goodness of the linear regression fit r 2 of the log linearized equation of the seismic amplitude decay with distance the location method for long period events is based on the joint computation of semblance and r 2 values and the location method of very long period events is based on the application of radial semblance infrasonic events and tremor are located by semblance brightness and semblance based methods respectively the techniques described here can also be applied to other volcanoes and do not require particular network geometries such as arrays but rather simple sparse networks using the source locations of all the considered signals we were able to reconstruct the shallow plumbing system above sea level during 2011

signs of magma ascent in lp and vlp seismic events and link to degassing an example from the 2010 explosive eruption at merapi volcano indonesia the link between seismicity and degassing is investigated during the vei 4 eruptions of merapi volcano indonesia in october and in early november 2010 seismicity comprised a large number and variety of earthquakes including volcano tectonic events a sustained period of long period seismicity lps i e long period events lp very long period events vlp and tremor lps seismicity is ascribed to the excitation of fluid filled cavity resonance and inertial displacement of fluids and magma we investigate here lps that occurred between 17 october and 4 november 2010 to obtain insights into the volcano eruption processes which preceded the paroxysmal phase of the eruption on 4 5 november we proceed to the moment tensor inversion of a well recorded large vlp event during the intrusion phase on 17 october 2010 i e before the first explosion on 26 october by using two simplified models crack and pipe we find a shallow source for this vlp event at about 1 km to the south of the summit and less than 1 km below the surface we analyze more than 90 lp events that occurred during the multi phase eruption 29 october 4 november we show that most of them have a dominant frequency in the range 0 2 4 hz we could locate 48 of those lp events at least 3 clusters of lp events occurred successively we interpret these observations as generated by different fluid filled containers in the summit area that were excited while magma rose we also observe significant variations of the complex frequency during the course of the eruption we discuss these changes in terms of a variable ratio of fluid to solid densities and or by possible conduit geometry change and or permeability of the conduit or the edifice and or by resonance of different fluid containers during the release of more than 0 4 tg of so2 and large but unknown masses of other volcanic gases finally we also discuss how the major explosions of the eruption were possibly triggered by passing waves resulting from regional tectonic earthquakes on 3 and 4 november

a method for climatic reconstruction of the mediterranean pliocene using pollen data pollen data from numerous sites around the mediterranean sea indicate that several important vegetation and climatic changes occurred during the pliocene these data are in good agreement with pollen records from northwest europe and with 18o curves from mediterranean and atlantic deep sea cores quantitative palaeoclimatic reconstructions from pliocene pollen data of the mediterranean region cannot be based on conventional modern analogue techniques as individual pliocene pollen spectra contain taxa representing temperate warm temperate and subtropical plants that do not grow together today instead we propose a new method that uses a climatic amplitude method modified to take partially into account the relative abundances of the taxa we applied this method to the pliocene garraf 1 palynological sequence from catalonia which provides a long continuous record of climatic change from 5 3 ma to the early pleistocene we estimate that annual temperatures were 1 to 5 c higher than today and the annual precipitation 400 to 1000 mm higher than today prior to the beginning of the late cenozoic glacial interglacial cycles in contrast temperature and precipitation both fell sharply during the glacial phases of the earliest glacial interglacial cycles

characteristics and source modeling of broadband seismic signals associated with the hydrothermal system at satsuma iwojima volcano japan abstract the broadband seismic data observed at satsuma iwojima volcanic island in southwestern japan show a wide variety of interesting features one of them is the periodic and frequency dependent amplitude modulation of volcanic tremors another interesting feature is the occurrence of very long period vlp seismic pulses synchronized with the tremor amplitude modulation both the tremor amplitude modulation and the vlp pulses have fairly regular intervals of 46 50 min suggesting a spatially fixed non destructive repetitive source we performed waveform inversions to reveal the source mechanism of the vlp pulses assuming a point source embedded in a medium that realistically represented the topography of the island numerical tests showed that the green s functions used in the inversion were significantly affected by the topography the observed vlp pulses were well explained by the rapid expansion of an inclined crack 100 m beneath the floor of the summit crater which had a seismic moment of 3 10 10 nm both the characteristic amplitude modulation and the vlp pulses are explained systematically by a model consisting of a water filled crack and a network of gas paths the water filled crack was heated above the boiling temperature of the water in it a sudden break of the unstable superheated state caused sudden vaporization and a pressure increase which was observed as the vlp pulse the network of gas paths consisted of swollen portions and constricted portions which worked as tremor generators when vapor from the water filled crack passed through

the ages and soils of two levels of rana surfaces in central spain abstract the geomorphology of two ranas and a specimen soil profile on each have been studied in the province of guadalajara central spain the ranas were first delineated on an aerial photograph then examined in the field for further identification and for the preparation of topographic profiles two soil profiles were described and sampled by horizons analyses were made of the samples for particle size distribution ph cation exchange relations and organic matter plus some observations on mineralogy of clay and fine sand fractions results of the study support earlier suggestions that the younger ran asurface s 1 is of donau age middle villafranchian but indicate that the second s 2 should be assigned to the middle upper pliocene lower villafranchian the soil profiles were found to be an alfisol on the younger and an ultisol on the older rana which is consistent with a greater age for the latter

mapping complex vent eruptive activity at santiaguito guatemala using network infrasound semblance pyroclastic laden explosive eruptions from santiaguito volcano guatemala are vented from the 200 m diameter caliente dome summit and result in a superposition of spatially extensive and temporally sustained tens of seconds to minutes acoustic sources a network of infrasonic microphones distributed on various sides of the volcano record distinct waveforms which are poorly correlated across the network and suggestive of acoustic interference from multiple sources presuming the infrasound wavefield is a linear superposition of spatially and temporally distinct sub events we introduce a semblance mapping technique to recover the time history of the spatially evolving sources during successive time windows coincident high resolution video footage corroborates that both rapid dome uplift and individual explosive pulses are likely sources of high semblance infrasound that are identifiable during short 2 s time windows this study suggests that complex and network variable infrasound waveforms are produced whenever a volcanic vent source dimension is large compared to the wavelength of the sound being produced non compact infrasound radiators are probably commonplace at silicic volcanic systems where venting often occurs across a dome surface

three dimensional volcano acoustic source localization at karymsky volcano kamchatka russia abstract we test two methods of 3 d acoustic source localization on volcanic explosions and small scale jetting events at karymsky volcano kamchatka russia recent infrasound studies have provided evidence that volcanic jets produce low frequency aerodynamic sound jet noise similar to that from man made jet engines for man made jet noise noise sources localize along the turbulent jet flow downstream of the nozzle discrimination of jet noise sources along the axis of a volcanic jet requires high resolution in the vertical dimension which is very difficult to achieve with typical volcano acoustic network geometries at karymsky volcano an eroded edifice dvor caldera adjacent to the active cone provided a platform for the deployment of five infrasound sensors in july 2012 with intra network relief of 600 m the network was designed to target large scale jetting but unfortunately only small scale jetting and explosions were recorded during the 12 day experiment a novel 3 d inverse localization method srcloc is tested and compared against a more common grid search semblance technique simulations using synthetic signals show that srcloc is capable of determining vertical solutions to within 150 m or better for signal to noise ratios 1 for this network configuration however srcloc locations for explosions and small scale jetting at karymsky volcano show a persistent overestimation of source elevation and underestimation of sound speed the semblance method provides more realistic source locations likely because it uses a fixed realistic sound speed of 340 m s explosion waveforms exhibit amplitude relationships and waveform distortion strikingly similar to those theorized by modeling studies of wave diffraction around the crater rim we suggest that the delay of acoustic signals and apparent elevated source locations are due to raypaths altered by topography and or crater diffraction effects implying that topography in the vent region must be accounted for when attempting 3 d volcano acoustic source localization though the data presented here are insufficient to resolve small scale jet noise sources similar techniques may be successfully applied to large volcanic jets in the future

stable isotope record in mollusca and pedogenic carbonate from late pliocene soils of central italy abstract the late pliocene younger than 2 5 ma alluvial fan succession of toppetti quarry near todi umbria central italy includes many palaeosols pedogenic carbonate concretions and mollusc remains were separated from 73 palaeosols collected along 150 m of exposure and analysed for their oxygen and carbon stable isotope content 13c and 18o of the pedogenic carbonate and land snail shells suggest that no dramatic change in local climate took place values of the pedogenic carbonates are similar to other data reported for the mediterranean region 18o data suggest a mean annual temperature and or 18o similar to modern climatic conditions carbon isotope data from both land snails and pedogenic carbonate are consistent with a prevailing type c3 vegetation a mixture of forest and c3 grassland sustained by a mean annual precipitation between 300 and 1000 mm mainly in the cool periods of the year seems to be the most likely scenario the limited variation shown by the isotope composition of the biogenic and inorganically precipitated carbonate indicates that the environmental variations are referable mainly to change of humidity rather than temperature

pressurization and depressurization phases inside the plumbing system of mount etna volcano evidence from a multiparametric approach during 2013 mount etna volcano experienced intense eruptive activity at the summit craters foremost at the new southeast crater and to a minor degree at the voragine and bocca nuova bn which took place in two cycles february april and september december in this work we mainly focus on the period between these cycles applying a multiparametric approach the period from the end of april to 5 september showed a gradual increase in the amplitude of long period lp events and volcanic tremor a slight inflation testified by both tilt and gps data and a co2 flux increase such variations were interpreted as due to a gradual pressurization of the plumbing system from the shallowest part where lp and volcanic tremor are located down to about 3 9 km below sea level pressure source depths obtained by both geodetic and co2 data on 5 september at the same time as a large explosion at bn we observed an instantaneous variation of the aforementioned signals decrease in amplitude of lp events and volcanic tremor slight deflation and co2 flux decrease and the activation of a new infrasonic source located at bn in the light of it the bn explosion probably caused the instantaneous end of the pressurization and the opening of a new vent at bn that has become a new steady source of infrasonic events this apparently slight change in the plumbing system also led to the gradual resumption of activity at the new southeast crater culminating with the second lava fountain cycle of 2013

characterization of very long period seismicity accompanying summit activity at kīlauea volcano hawai i 2007 2013 abstract eruptive activity returned to the summit region of k lauea volcano hawai i with the formation of the overlook crater within the halema uma u crater in march 2008 the new crater continued to grow through episodic collapse of the crater walls and as of late 2013 had grown into an approximately elliptical opening with dimensions of 160 215 m extending to a depth of 200 m occasional weak explosive events and a persistent gas plume continued to occur through 2013 lava was first observed in the new crater in september 2008 and through 2009 the lava level remained deep in the crater and was only occasionally observed since early 2010 a lava lake with fluctuating level within the overlook crater has been nearly continuously present and has reached to within 22 m of the overlook crater rim volcanic activity at k lauea volcano is episodic at all time scales and the characterization of very long period seismicity in the band 2 100 s for the years 2007 2013 illuminates a portion of this broad spectrum of volcanic behavior three types of very long period events have been observed over this time and each is associated with distinct processes type 1 events are associated with vigorous degassing and occurred primarily between 2007 and 2009 type 2 events are associated with rockfalls onto the lava lake and occurred primarily after early 2010 both of these event types are induced by pressure and momentum changes at the top of the magma column that are transmitted downward to a source centroid 1 km below the northeast corner of the halema uma u crater where the energy couples to the solid earth at a geometrical discontinuity in the underlying dike system type 3 events are not related to surficial phenomena but are associated with transients in mass transfer that occur within the dike system very long period tremor has also accompanied the return of eruptive activity with increasing amplitude associated with hours to months long changes in gas emission rates and summit deformation

shallow magma pathway geometry at mt etna volcano 1 a fundamental goal of volcano seismology is to understand the dynamics of active magmatic systems in order to assess eruptive behavior and the associated hazard imaging of magma conduits quantification of magma transport and investigation of long period seismic sources together with their temporal variations are crucial for the comprehension of eruption triggering mechanisms at mt etna volcano several intense episodes of tremor activity were recorded during 2007 in association with strombolian activity and or intense fire fountaining episodes occurring from the south east crater sec the locations of the tremor sources and of the long period seismic events are used here to constrain both the area and the depth range of magma degassing highlighting the geometry of the shallow conduits feeding sec the imaged conduits consist of two connected resonating dike like bodies nnw sse and nw se oriented extending from sea level to the surface in addition we show how tremor long period lp and very long period vlp event locations and signatures reflect pressure fluctuations in the plumbing system associated with the ascent discharge of gas rich magma linked to the lava fountains the evidence here reported also corroborated by ground deformation variations can help develop a better prediction and early warning system for those eruptions effusive or explosive that apparently manifest no clear precursors

towards an automatic monitoring system of infrasonic events at mt etna strategies for source location and modeling active volcanoes characterized by open conduit conditions generate sonic and infrasonic signals whose investigation provides useful information for both monitoring purposes and studying the dynamics of explosive processes in this work we discuss the automatic procedures implemented for a real time application to the data acquired by a permanent network of five infrasound stations running at mt etna volcano the infrasound signals at mt etna consist in amplitude transients called infrasound events the adopted procedure uses a multi algorithm approach for event detection counting characterization and location it is designed for an efficient and accurate processing of infrasound records provided by single site and array stations moreover the source mechanism of these events can be investigated off line or in near real time by using three different models 1 strombolian bubble 2 resonating conduit and 3 helmholtz resonator the infrasound waveforms allow us to choose the most suitable model to get quantitative information about the source and to follow the time evolution of the source parameters

mapping the sources of the seismic wave field at kilauea volcano hawaii using data recorded on multiple seismic antennas seismic antennas constitute a powerful tool for the analysis of complex wave fields well designed antennas can identify and separate components of a complex wave field based on their distinct propagation properties the combination of several antennas provides the basis for a more complete understanding of volcanic wave fields including an estimate of the location of each individual wave field component identified simultaneously by at least two antennas we used frequency slowness analyses of data from three antennas to identify and locate the different components contributing to the wave fields recorded at kilauea volcano hawaii in february 1997 the wave field components identified are 1 a sustained background volcanic tremor in the form of body waves generated in a shallow hydrothermal system located below the northeastern edge of the halemaumau pit crater 2 surface waves generated along the path between this hydrothermal source and the antennas 3 back scattered surface wave energy from a shallow reflector located near the southeastern rim of kilauea caldera 4 evidence for diffracted wave components originating at the southeastern edge of halemaumau and 5 body waves reflecting the activation of a deeper tremor source between 02 hr 00 min and 16 hr 00 min hawaii standard time on 11 february

volume flow rate estimation for small explosions at mt etna italy from acoustic waveform inversion this study was supported by nerc grant ne p00105x 1 and by european unions horizon 2020 research and innovation programme under the marie sklodowska curie grant agreement 798480

rare earth element and stable isotope signatures of kaolin from a pliocene lateritic weathering profile at mid latitude region andalusia spain implications for paleoweathering and paleoclimatic reconstructions abstract this study reports the impact of weathering on behavior of rare earth elements ree in a coastal lateritic profile developed on pliocene sediments at mid latitude location 37 n in the guadalquivir basin spain it also explores the stable isotope signature of kaolinite providing constraints on paleotemperature and isotopic composition of the ancient meteoric water the paleoweathering profile 20 m thick comprises a white sandy clayey saprolite overlain by a red mottled clay zone which in turn is capped by a pisolitic ferricrete the kaolinitic regolith was practically reduced to a mixture of kaolinite and quartz by intense chemical weathering under warm and seasonally humid climate the kaolinized material is markedly depleted in total ree mean value of 77 30 mg kg 1 in the white saprolite and 72 70 mg kg 1 in the mottled zone relative to the parent rock 168 96 mg kg 1 development of acidic and oxidizing conditions promoted a suitable soil environment for ree release and leaching with percolating rainwater leading to an apparent loss of ree from the profile up to 87 the parent rock normalized ree patterns display concave upward shapes tracing a remarkable depletion in middle ree mree with no significant anomalies the ree concentrations normalized against the north american shale composite nasc showed consistently similar fractionation patterns the mree depleted signature nasc normalized ratios of la sm up to 3 32 and gd lu as low as 0 45 probably arises from reductive dissolution of iron oxyhydroxide phases due to seasonal water saturation as indicated from redoximorphic features the the lateritic weathering profiles evolved during the mid pliocene warm period in the southwestern iberian margin could be useful for predicting potential future environmental effects of increased atmospheric co2 on the earth s critical zone

intensive kaolinization during a lateritic weathering event in south west spain mineralogical and geochemical inferences from a relict paleosol abstract this study documents the mineralogical and geochemical record of a lateritic weathering event during the pliocene in south west spain the paleoweathering profile derived from arkosic sands and comprises a white sandy clayey saprolite a red mottled clay zone overlain by a thick soft layer and a ferruginous pisolitic hardcap partially dismantled by erosive processes kaolinite quartz and degraded k feldspars are the major minerals forming the saprolite along with al goethite mottled zone as well as gibbsite and boehmite soft layer while the pisolitic duricrust is essentially composed of quartz grains embedded in a matrix of fe oxy hydroxides hematite goethite and or maghemite besides quartz the phases most resistant to alteration were a variety of heavy minerals mostly titanium oxides that are present as minor impurities in the residual kaolin deposit the dominant weathering process of kaolinization is geochemically characterized by striking losses of na k ca mg and large ion lithophile elements rb sr cs ba and u because of the almost entirely breakdown of primary minerals mainly feldspars and 2 1 phyllosilicates the ti normalized distribution patterns of trace elements also reveals remobilization and redistribution processes within the profile involving high field strength elements classically regarded as immobile like zr and hf iron showed a contrasted behaviour with depletion in the saprolite zone and strong accumulation in the pisolitic duricrust various transition trace metals cr v sc th nb and ta remained relatively immobile during the weathering and were residually concentrated in the duricrust linked to the fe oxy hydroxides the geochemical and mineralogical evolution of the paleosol studied is consistent with a laterization process evolved under humid subtropical conditions and driven by morphodynamic and hydrodynamic factors gently sloping coastal area with fluctuating water table and rapid water percolation favourable for the development of a deeply kaolinized paleosurface

long plio pleistocene terrestrial record of climate change and mammal turnover in southern spain abstract cyclostratigraphic analysis of the pliocene zujar section guadix baza basin southeastern spain has enabled the recognition of a number of climatically forced cycles reflecting alternating dry and wet periods peaks of aridity are recorded at ca 3 95 3 55 3 2 2 8 and 1 8 myr b p the first dry period at about 4 0 myr b p corresponds to the early ruscinian mammal age while the second arid interval at about 3 6 myr b p corresponds to the establishment of the mediterranean double seasonality the significant mammal turnover between the late ruscinian and early villanyian stages is placed between chron 2an 2n and the very base of chron 2an 1n coincident with the dry phase recognized at about 3 2 myr b p the fourth aridity maximum at 2 8 myr b p roughly coincides with the equus event in western europe and is probably related to the beginning of the glacial interglacial dynamics in the northern hemisphere finally the last dry peak at about 1 8 myr b p is probably related to the set of mammalian events characterizing the transition from the late pliocene faunas to those of the early pleistocene

ground motion in the near field of a fluid driven crack and its interpretation in the study of shallow volcanic tremor we present a study of the motion of the ground in the near field of a fluid driven tensile crack embedded in a layered half space the source that we consider is the jerky opening of a channel connecting two fluid filled cracks and the cause of this opening is the excess pressure of fluid in one of the cracks we make a complete representation of the three components of ground motion in the space time and frequency domains and analyze the effects of fluid compressibility source depth and medium structure on the ground response the calculations show the presence of a dominant frequency of motion which depends not only on the source geometry and bulk modulus of the fluid but also on medium characteristics receiver position and the component of motion being considered using this source model we view an episode of volcanic tremor as a continuous sequence produced by numerous jerky openings of channels occurring randomly in time along a chain of cracks our results are applied to the october 5 6 1963 east rift eruption of kilauea volcano hawaii and found to be compatible with available seismic data suggesting that magma is transported through an ensemble of cracks with the area of 1 1 km each pair of cracks constituting an individual dike segment which opens in discrete increments at a rate of 1 s we obtain the following parameters for each dike segment opening increase in cavity volume 40 m3 stress drop 0 004 bar seismic moment 1019 dyn cm and force applied by the fluid to open the dike 1014 dyn the total moment integrated over the entire duration of tremor for the eruption is 0 5 1024 dyn cm roughly equivalent to a single magnitude m 5 earthquake the seismic source parameters and other field observations offer constraints on the process of mass transport and are compatible with the excess pressure and viscosity of magma of about 40 bars and 102 p respectively

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

effects of volcano topography on seismic broad band waveforms volcano seismology often deals with rather shallow seismic sources and seismic stations deployed in their near field the complex stratigraphy on volcanoes and near field source effects have a strong impact on the seismic wavefield complicating the interpretation techniques that are usually employed in earthquake seismology in addition as most volcanoes have a pronounced topography the interference of the seismic wavefield with the stress free surface results in severe waveform perturbations that affect seismic interpretation methods in this study we deal predominantly with the surface effects but take into account the impact of a typical volcano stratigraphy as well as near field source effects we derive a correction term for plane seismic waves and a plane free surface such that for smooth topographies the effect of the free surface can be totally removed seismo volcanic sources radiate energy in a broad frequency range with a correspondingly wide range of different fresnel zones a 2 d boundary element method is employed to study how the size of the fresnel zone is dependent on source depth dominant wavelength and topography in order to estimate the limits of the plane wave approximation this approximation remains valid if the dominant wavelength does not exceed twice the source depth further aspects of this study concern particle motion analysis to locate point sources and the influence of the stratigraphy on particle motions furthermore the deployment strategy of seismic instruments on volcanoes as well as the direct interpretation of the broad band waveforms in terms of pressure fluctuations in the volcanic plumbing system are discussed

array measurements and modeling of sources of shallow volcanic tremor at kilauea volcano hawaii we show that resonances in near surface layers path effects or a combination of near surface resonances and source resonances source effects could be responsible for the sharp spectral peaks found in the records of gas piston activity and volcanic tremor recorded near puu oo crater on kilauea volcano hawaii two types of sources are found to be compatible with observations and can not be distinguished using our data in one model impulsive explosion point sources are embedded in the puu oo structure in the other model impulsive point sources of pressure excite the resonances of a fluid filled crack embedded in that structure both models require shallow sources z 100 m and display a strong dependence of the radiated spectrum on source depth over a depth range comparable to the overall thickness of the surficial layers based on these results it may be possible to track changes in source depth through temporal changes in observed spectra a potentially useful tool for monitoring volcanic activity at this site we estimate the depth and spatial extent of volcanic tremor and gas piston activity using two dense arrays with respective apertures of 800 and 120 m located near puu oo measurements of slowness ray parameter and azimuth as a function of time clearly indicate that the sources of volcanic tremor and gas piston activity are located beneath or in close proximity to the puu oo crater at depths shallower than approximately 1 km based on slowness and particle motion analyses we find that the records of volcanic tremor and gas piston events at puu oo consist of a complex combination of body and surface waves

observations of high frequency scattered waves using dense arrays at teide volcano abstract a study of the seismic coda of seven small earthquakes recorded on the teide volcano canary islands spain was carried out using a temporary small aperture 12 station seismic array the purpose was to measure backazimuth apparent velocity and the type of waves that compose the coda in the frequency range 4 to 6 hz we used the zero lag cross correlation zlc method to obtain the components of the wave vector and three component analysis techniques based on the covariance matrix of the signal in the time domain to investigate the polarization properties of the signals the results show that a great part of the coda signals in the analyzed frequency range are almost uncorrelated while a low number of isolated correlated arrivals show an apparent slowness between 2 10 3 and 2 5 10 4 sec m and an almost random distribution of backazimuths the correlated arrivals have been interpreted as generated by strong scatterers probably related to the presence in the study area of surface topography irregularities the volcanic cone and the caldera rim the wave type varies from pure s type waves to mixed surface waves with some rayleigh components

characterization and location of infrasonic sources in active volcanoes mount etna september november 2007 1 the period september november 2007 was characterized at mount etna by explosive activity and intense degassing during this time interval infrasonic signals were recorded by an infrasonic network by a triggering procedure about 1000 infrasonic events were found characterized by very high signal to noise ratio and grouped into nine families successively the spectral analysis allowed subdividing these nine families into three clusters based on the peak frequency and the quality factor of the events finally by the location analysis a cluster cluster 1 was related to the degassing activity of the northeast crater nec while the other two clusters 2 and 3 to the explosive activity of the southeast crater sec the comparison between the stacked infrasonic waveforms interpreted as generated by the vibration of large gas bubbles and the synthetic ones permitted to calculate radius length of the bubble and initial overpressure by a genetic algorithm method the higher overpressure values of cluster 3 compared to the cluster 2 values were in good agreement with the stronger intensity of the explosions accompanying the infrasonic events of cluster 3 the variation of both intensities and waveforms is tentatively attributed to the occasional accumulation of lithic clasts due to moderate landslides on the explosive vent indeed events belonging to cluster 3 were no longer observed once the landslides had ended finally the daily emitted gas volume related to the active degassing was estimated for nec and sec by using the infrasonic data during the studied period