scale dependence of seismic energy to moment ratio for strike slip earthquakes in japan we analyzed four pairs of a large m w 6 and a small m w 3 5 to 4 shallow strike slip earthquakes to investigate the scale dependence of the seismic energy to moment ratio an important macroscopic parameter which reflects the basic physical process of seismic slip these earthquakes occurred in the south western part of japan and high quality close in records epicentral distance 50 km are available for both the small and large earthquakes the paired events have almost the same focal mechanism and hypocenter location we used the spectral ratio of the paired events in order to remove the effects of attenuation along the wave propagation path and the station site response we then estimated the seismic energy from the source spectra estimated from the spectral ratio the energy to moment ratio increases with the earthquake size this scale dependence is very similar to that found earlier for earthquakes in southern california

extracting source characteristics and dynamics of the august 2010 mount meager landslide from broadband seismograms 1 seismic methods can substantially improve the characterization of the dynamics of large and rapid landslides such landslides often generate strong long period seismic waves due to the large scale acceleration of the entire landslide mass which according to theory can be approximated as a single force mechanism at long wavelengths i apply this theory and invert the long period seismic waves generated by the 48 5 mm3 august 2010 mount meager rockslide debris flow in british columbia using data from five broadband seismic stations 70 to 276 km from the source i obtain a time series of forces the landslide exerted on the earth with peak forces of 1 0 1011 n the direction and amplitude of the forces can be used to determine the timing and occurrence of events and subevents using this result in combination with other field and geospatial evidence i calculate an average horizontal acceleration of the rockslide of 0 39 m s2 and an average apparent coefficient of basal friction of 0 38 0 02 which suggests elevated basal fluid pressures the direction and timing of the strongest forces are consistent with the centripetal acceleration of the debris flow around corners in its path i use this correlation to estimate speeds which peak at 92 m s this study demonstrates that the time series recording of forces exerted by a large and rapid landslide derived remotely from seismic records can be used to tie post slide evidence to what actually occurred during the event and can serve to validate numerical models and theoretical methods

numerical modeling of the mount meager landslide constrained by its force history derived from seismic data we focus on the 6 august 2010 mount meager landslide that occurred in southwest british columbia canada this 48 5 mm3 rockslide that rapidly changed into a debris flow was recorded by over 25 broadband seismic stations we showed that the waveform inversion of the seismic signal making it possible to calculate the time history of the force applied by the landslide to the ground is very robust and stable even when using only data from a single station by comparing this force with the force calculated through numerical modeling of the landslide we are able to support the interpretation of seismic data made using a simple block model however our study gives different values of the friction coefficients involved and more details about the volumes and orientation of the subevents and the flow trajectory and velocity our sensitivity analysis shows that the characteristics of the released mass and the friction coefficients all contribute to the amplitude and the phase of the force despite this complexity our study makes it possible to discriminate the best values of all these parameters our results suggest that comparing simulated and inverted forces helps to identify appropriate rheological laws for natural flows we also show that except for the initial collapse peaks in the low frequency force related to bends and runup over topography changes are associated with high frequency generation possibly due to an increased agitation of the granular material involved

automatic approach for increasing the location accuracy of slow moving landslide endogenous seismicity the apoloc method seismological observations offer valuable insights on the stress strain states the physical mechanisms and the possible precursory signs of activation of various earth surface processes i e volcanoes glaciers and landslides comprehensive catalogues of the endogenous landslide seismicity that is corresponding to seismic sources generated by the unstable slope from either mechanical or hydrological origins should include the typology and an estimate of the source parameters location magnitude of the event these advanced catalogues constitute a strong basis to better describe the slope deformation and its time evolution and better understand the controlling factors because the number of seismic events in landslide catalogues is generally large automatic approaches must be considered for defining both the typology and the location of the sources we propose here a new location approach called automatic picking optimization and location method apoloc for locating landslide endogenous seismic sources from seismological arrays located at close distance the approach is based on the automatic picking of the p waves arrivals by optimizing the intertrace correlations the method is tested on calibration shots realized at the super sauze landslide southeast french alps and compared to other location approaches by using a realistic velocity model obtained from a seismic tomography campaign apoloc reduces the epicentre errors to 23 m on average compared to ca 40 m for the other approaches apoloc is then applied for documenting the endogenous seismicity i e slopequakes and rockfalls at the landslide

the relationship between bulk mass momentum and short period seismic radiation in catastrophic landslides the relationship between bulk mass dynamic properties of catastrophic landslides and the generation of short period seismic waves is investigated with a particular focus on the momentum of the landslide mass and the envelope of high frequency seismograms twelve very large landslides that occurred in different geological settings worldwide between 1999 and 2014 are selected for study based on the existence of detailed descriptions of their force histories determined from long period seismic waves frequency lower than 0 1 hz as well as the availability of nearby high quality short period seismic recordings a high average correlation 0 94 is found between the modulus of the landslide momentum and the envelope of the high frequency seismograms band passed filtered between 3 and 10 hz recorded on nearby stations the best correlation is seen during the acceleration phase of each landslide comparatively poor average correlation 0 57 is found between the modulus of the landslide force and the seismogram envelopes a possible scaling between the momentum and the amplitude of short period radiation is investigated the maximum amplitudes of short period seismograms for the nine best recorded landslides are corrected for local attenuation and correlated with the maximum momentum of the landslides the nine data points scatter around a best fitting line that defines a nearly linear relationship between momentum and peak short period radiation it is hypothesized that bulk mass momentum linearly modulates landslide processes that generate short period seismic waves but that the efficiency of short period radiation is highly variable between landslides

characterization of alpine rockslides using statistical analysis of seismic signals 1 seismic data analysis is a powerful tool for remote characterization of rock slope failures here we develop quantitative estimates of fundamental rockslide properties e g volume based solely on data from an existing regional seismic network we assembled a data set of twenty known rockslides in the central alps with volumes between 1 000 and 2 000 000 m3 and analyzed their corresponding seismograms common signal characteristics include emergent onsets slowly decaying tails and a triangular spectrogram shape the main component of seismic energy is contained in frequencies below 3 4 hz while higher frequency signals may be caused by block impacts location estimates were generated using automatic arrival time picks and resulted in a mean location error of 10 9 km a linear relationship for the detection limit of a rockslide as a function of volume was identified for our seismic station network to estimate rockslide volume runout distance drop height potential energy and fahrboschung angle of reach we extracted five simple metrics from each seismogram signal duration peak value of the ground velocity envelope velocity envelope area risetime and average ground velocity using multivariate linear regression the combination of duration peak envelope velocity and envelope area best estimated event parameters with r2 values ranging between 0 8 and 0 88 three new rockslides were then used to validate our method and volume runout drop height and potential energy were estimated within the correct order of magnitude when provided with a suitable data set of rockslide events our method can be easily adapted to other regions and seismic networks

on the link between external forcings and slope instabilities in the piton de la fournaise summit crater reunion island we have analyzed the impact of different forcings such as rain and seismicity on slope instabilites on an active volcano for this we compiled a catalog of the locations and volumes of rockfalls in the piton de la fournaise crater using seismic records we validated it by comparing the locations and volumes to those deduced from photogrammetric data we analyzed 10 477 rockfalls spanning the period 2014 to 2016 this period corresponds to the renewal of volcanic activity after a 41 month rest our analysis reveals that renewed eruptive activity has unsettled the crater edges external forcings such as rain and seismicity are shown to potentially increase the number and the volume of rockfalls with a stronger impact on the volume preeruptive seismicity seems to be the main triggering factor for the largest volumes with a delay of one to several days rain alone does not seem to trigger especially large rockfalls we infer that repetitive vibrations from the many seismic events combined with the action of rain induce crack or slip growth in highly fractured or granular materials leading to the collapse of large volumes regarding their spatial distribution before an eruption the largest rockfalls seem to migrate toward the location of magma extrusion

massive ice avalanches on iapetus mobilized by friction reduction during flash heating the great distance travelled by long runout landslides observed previously on the earth and mars requires a mechanism of friction reduction identification and analysis of long runout landslides on saturn s moon iapetus suggests that the iapetian landslides are enabled by flash heating of the icy sliding surface

an overview of lava dome evolution dome collapse and cyclicity at soufriere hills volcano montserrat 2005 2007 1 the third episode of lava dome growth at soufriere hills volcano montserrat was characterised by higher average magma discharge rates than either previous dome growth episode at this volcano and yet fewer collapses during sustained dome growth at moderate high average rates 6 m3 s we identified 2 6 week discharge pulses that each supplied c 20 mm3 magma from depth our observations are consistent with some existing models but we explain discrepancies by a combination of higher volatile contents and higher ascent rates cycles of c 11 16 days were evident in rockfall lp rockfall and shallow lp earthquake counts related to dome growth and degassing we speculate that degassing at the conduit margins together with stick slip conduit flow may drive these cycles only one major collapse 10 mm3 occurred during the third episode on may 20 2006 as a new magma pulse entered the dome and coincided with heavy rainfall

dynamics of the bingham canyon mine landslides from seismic signal analysis joint interpretation of long and short period seismic signals generated by landslides sheds light on the dynamics of slope failure providing constraints on landslide initiation and termination and on the main phases of acceleration and deceleration we carry out a combined analysis of the seismic signals generated by two massive landslides that struck the bingham canyon mine pit on 10 april 2013 inversion of the long period waveforms yields time series for the bulk landslide forces and momenta from which we deduce runout trajectories consistent with the deposit morphology comparing these time series with the short period seismic data we are able to infer when and where major changes take place in landslide momentum along the runout path this combined analysis points to a progressive fracturing of the masses during acceleration indicates that deceleration starts the moment they reach the pit floor and suggests that the bulk movement is stopped by a topographic barrier

forensic investigations of the cima salti landslide northern italy using runout simulations abstract over the last decades a movement has begun to reclassify deposits previously misidentified as having origins other than landsliding the reverse problem of incorrectly assigning deposits a mass movement origin however has been addressed less in the landslide community the cima salti landslide in the lake garda region of northern italy is a cautionary tale of assuming source areas and volumes it was traditionally thought to have dammed tenno lake in the middle ages and to have a volume of 20 30 mm3 we show through geological field data and simple runout simulations with the codes dan3d and shaltop which produced comparable results that the volume of the landslide was likely significantly overestimated in the past and that it most likely did not dam tenno lake as has been assumed we propose that a smaller volume landslide 2 5 mm3 was deposited on stagnant ice melting in situ in the lateglacial period a relatively minor event in the complex history of the magnone valley this interpretation emphasizes the importance of careful field investigations and assumption validation at cima salti and in a broader context it also shows the unique capacity of landslide simulation to guide field observation and discriminate mass emplacement processes

submarine pyroclastic deposits formed at the soufriere hills volcano montserrat 1995 2003 what happens when pyroclastic flows enter the ocean the soufriere hills volcano montserrat west indies has undergone a series of dome growth and collapse events since the eruption began in 1995 over 90 of the pyroclastic material produced has been deposited into the ocean sampling of these submarine deposits reveals that the pyroclastic flows mix rapidly and violently with the water as they enter the sea the coarse components pebbles to boulders are deposited proximally from dense basal slurries to form steep sided near linear ridges that intercalate to form a submarine fan the finer ash grade components are mixed into the overlying water column to form turbidity currents that flow over distances 30 km from the source the total volume of pyroclastic material off the east coast of montserrat exceeds 280 106 m3 with 65 deposited in proximal lobes and 35 deposited as distal turbidites

frequency dependent lg q within the continental united states frequency dependent crustal attenuation 1 q is determined for seven distinct physiographic tectonic regions of the continental united states using high quality lg waveforms recorded on broadband stations in the frequency band 0 5 to 16 hz lg attenuation is determined from time domain amplitude measurements in one octave frequency bands centered on the frequencies 0 75 1 0 3 0 6 0 and 12 0 hz modeling errors are determined using a delete j jackknife resampling technique the frequency dependent quality factor is modeled in the form of q q 0 f regions were initially selected based on tectonic provinces but were eventually limited and adjusted to maximize ray path coverage in each area earthquake data was recorded on several different networks and constrained to events occurring within the crust m b 3 5 in size a singular value decomposition inversion technique was applied to the data to simultaneously solve for source and receiver terms along with q for each region at specific frequencies the lowest crustal q was observed in northern and southern california where q is described by the functions q 152 37 f 0 72 0 16 and q 105 26 f 0 67 0 16 respectively the basin and range province pacific northwest and rocky mountain states also display lower q and a strong frequency dependence characterized by the functions q 200 40 f 0 68 0 12 q 152 49 f 0 76 0 18 and q 166 37 f 0 61 0 14 respectively in contrast in the central and northeast united states q functions are q 640 225 f 0 344 0 22 and q 650 143 f 0 36 0 14 respectively show a high crustal q and a weaker frequency dependence these results improve upon previous lg modeling by subdividing the united states into smaller distinct tectonic regions and using significantly more data that provide improved constraints on frequency dependent attenuation and errors a detailed attenuation map of the continental united states can provide significant input into hazard map mitigation both scattering and intrinsic attenuation mechanisms are likely to play a comparable role in the frequency range considered in the study

seismicity of rockfalls and avalanches at three cascade range volcanoes implications for seismic detection of hazardous mass movements abstract this study reviews seismograms from 14 rockfalls and avalanches of moderate to large volume 10 4 to 10 7 m 3 at mount st helens mount adams and mount rainier in the cascade range of washington to investigate how variations in source volume source materials track materials and failure modes affect avalanche seismicity the largest signals were generated by rockfalls at mount st helens and debris avalanches at mount rainier that initiated as block failures at mount st helens several rockfalls that originated as block failures near the crater rim descended slopes with similar profiles and appear to show a linear or nearly linear relation between source volume and seismogram amplitude those that fell over an extended period of time were poorly recorded at the reference seismic station and did not show this correlation multiple seismograms from three of the four instrumentally recorded debris avalanches at mount rainier indicate a tendency of unstable slopes there to fail progressively a pattern that has important implications for the mass movement hazard at mount rainier seismic evidence shows that the little tahoma rock fall avalanches in december 1963 occurred on 6 december over a week earlier than previously reported mass movements that have been seismically detected span the spectrum of rapid flowage events from water surges and debris flows to dry rock debris ice and snow avalanches the success in identifying and in some cases locating these events in near real time demonstrates that local and regional seismic networks can play a valuable role in reducing hazards from large rapid mass movements

complex force history of a calving generated glacial earthquake derived from broadband seismic inversion the force applied to the earth by the calving of two icebergs at jakobshavn isbrae greenland has been quantified the source force history was recovered by inversion of regional broadband seismograms without any a priori constraint on the source time function in contrast with previous studies for periods 10 100 s the three component force can be obtained from distant stations alone and is proportional to the closest station seismograms this inversion makes it possible to quantify changes of the source force direction and amplitude as a function of time and frequency a detailed comparison with a video of the event was used to identify four forces associated with collision then bottom out and top out rotation of the first and second icebergs and ice melange motion only the two iceberg rotations were identified in previous studies all four processes are found here to contribute to the force amplitude and variability such a complete time frequency force history provides unique dynamical constraints for mechanical calving models

numerical simulation of the december 1997 debris avalanche in montserrat lesser antilles emplacement of a debris avalanche in the white river valley of southern montserrat lesser antilles on 26 december 1997 was caused by sector failure of the south flank of the active soufriere hills volcano pre and post emplacement surveys of the region indicate a debris avalanche deposit volume of about 40 50 106 m this avalanche is modeled as the gravitational flow of a homogeneous continuum governed by a basal friction law mass and momentum equations are depth averaged over the slide thickness numerical results show that the observed distribution of debris and duration of emplacement is simulated well for a coulomb type friction law with a dynamic friction coefficient dependent upon the thickness and the velocity of the flowing mass

analysis of rock fall and rock fall avalanche seismograms in the french alps this study reviews seismograms from 10 rock fall events recorded between 1992 and 2001 by the permanent seismological network sismalp in the french alps a new seismic magnitude scale was defined which allowed us to compare and classify g round motion vibrations generated by these alpine rock falls each rock fall has also been cha racterized by its ground motion duration t30 at an epicentral distance of 30 km no relation was found between rock fall parameters fall height runout distance volume potential energy and rock fall s eismic magnitudes derived from seismogram amplitudes on the other hand the signal duration t30 shows a rough correlation with the potential energy and the runout distance highlighting the co ntrol of the propagation phase on the signal length the signal analysis suggests the existence of at le ast two distinct seismic sources one corresponding to the initial rupture associated with an elastic r ebound during the detachment and the other one generated by the rock impact on the slope although the fall phenomenon includes other complex processes fragmentation of the block interaction with topography plastic deformation during and after impact 2d finite element simulations of thes e two seismic sources are able to retrieve the main seismogram characteristics

seismicity associated with dome growth and collapse at the soufriere hills volcano montserrat varied seismicity has accompanied growth and collapse of the lava dome of the soufriere hills volcano montserrat earthquakes have been classified as either volcano tectonic long period or hybrid and daily variations in the numbers of events have mapped changes in the style of eruption repetitive hybrid earthquakes were common during the first months of dome growth in july 1996 the style of seismicity changed and regular short lived hybrid earthquake swarms became common this change was probably caused by an increase in the magma flux earthquake swarms have preceded almost all major dome collapses and have accompanied cyclical deformation thought to be due to a build up of pressure in the upper conduit which is later released by magma moving into the dome

estimates of shear wave q and κ0 for unconsolidated and semiconsolidated sediments in eastern north america measured and calculated values of the effective quality factor qef and the site attenuation parameter 0 for unconsolidated and semiconsolidated sediments in eastern north america ena indicate that the latter is strongly dependent on sediment thickness estimates of 0 for national earthquake hazard reduction program nehrp bc site profiles sediment plus hard rock in the mississippi embayment and the atlantic coastal plain were found to increase from about 9 to 31 msec for sedi ment thicknesses ranging from 116 to 600 m stochastic simulations using the 175 m thick hypothetical nehrp bc site profile used to estimate ena ground motions in the nationalseismichazardmapsbytheu s geologicalsurvey usgs indicatethat 0 20 msec provides a smaller estimate of amplification that agrees more closely with the low strain short period site coefficients in the nehrp recommended provisions for seismic regulations for new buildings and other structures nehrpprovisions than the10msecvalueusedbytheusgs alinearregressionofthe 0 estimatescompiledin this study indicates that 0 20 msec corresponds to a relatively thick bc sediment thickness of 460 116 m these same stochastic simulations indicate that the rela tivelyshallowusgssiteprofileprovidesestimatesofamplificationthataresmallerthan thelow strainlong periodsitecoefficientsinthenehrpprovisions thedependenceof bothsiteattenuationandsiteamplificationonsedimentthicknesssuggeststhattheuseof a single reference site condition for hazard mapping might not be appropriate instead theseresultsimplythateitheraregionalsetofreferencesiteprofilesshouldbedeveloped or that a more uniform site condition such as hard rock should be used to define a more stable reference site condition in ena

analysis of long period seismic waves excited by the may 18 1980 eruption of mount st helens a terrestrial monopole long period 100 to 260 s love and rayleigh waves excited by the eruption of mount st helens on may 18 1980 and recorded by ida sro and asro stations were analyzed to determine the mechanism of the eruption the amplitude radiation patterns of both rayleigh and love waves are two lobed with a nodal direction in e5 s for rayleigh waves and in n5 e for love waves these radiation patterns preclude any double couple mechanism the radiation pattern the initial phase the relatively large amplitude ratio of love to rayleigh waves and the existence of clear nodes in the radiation patterns of fundamental mode and higher mode rayleigh waves suggest that the source is represented by an almost horizontal less than 15 from the horizontal single force pointed toward s5 w the surface wave spectra fall off very rapidly at periods shorter than 75 s suggesting a very slow source process although the details of the source time history could not be determined a smooth bell shaped time function f o s t 1 2 f o l cos t for 0 t 2 and f o s t 0 for t 2 with 75 s is considered appropriate on the basis of comparison between synthetic and observed seismograms and of the shape of the source spectrum the peak value of the force f 0 is about 10 18 dynes the tailing end of the source time function could not be resolved and some overshoot may be added the magnitude and the time history of the force can be explained by a northward landslide followed by a lateral blast observed at the time of the eruption two distinct events about 110 s apart can be identified on body wave and short period surface wave records the first event may correspond to the earthquake which triggered the landslide and the lateral blast the second event appears to correspond to a second large earthquake and explosion which took place about 2 minutes after the first earthquake

friction weakening in granular flows deduced from seismic records at the soufriere hills volcano montserrat accurate modeling of rockfalls and pyroclastic flows is still an open issue partly due to a lack of measurements related to their dynamics using seismic data from the soufriere hills volcano montserrat and granular flow modeling we show that the power laws relating the seismic energy e s to the seismic duration t s and relating the loss of potential energy e p to the flow duration t f are very similar like the power laws observed at piton de la fournaise reunion island observations showing that t f t s suggest a constant ratio e s e p 10 5 this similarity in these two power laws can be obtained only when the granular flow model uses a friction coefficient that decreases with the volume transported furthermore with this volume dependent friction coefficient the simulated force applied by the flow to the ground correlates well with the seismic energy highlighting the signature of this friction weakening effect in seismic data

automated identification location and volume estimation of rockfalls at piton de la fournaise volcano since the collapse of the dolomieu crater floor at piton de la fournaise volcano la reunion in 2007 hundreds of seismic signals generated by rockfalls have been recorded daily at the observatoire volcanologique du piton de la fournaise ovpf to study rockfall activity over a long period of time automated methods are required to process the available continuous seismic records we present a set of automated methods designed to identify locate and estimate the volume of rockfalls from their seismic signals the method used to automatically discriminate seismic signals generated by rockfalls from other common events recorded at ovpf is based on fuzzy sets and has a success rate of 92 a kurtosis based automated picking method makes it possible to precisely pick the onset time and the final time of the rockfall generated seismic signals we present methods to determine rockfall locations based on these accurate pickings and a surface wave propagation model computed for each station using a fast marching method these methods have successfully located directly observed rockfalls with an accuracy of about 100 m they also make it possible to compute the seismic energy generated by rockfalls which is then used to retrieve their volume the methods developed were applied to a data set of 12 422 rockfalls that occurred over a period extending from the collapse of the dolomieu crater floor in april 2007 to the end of the undervolc project in may 2011 to identify the most hazardous areas of the piton de la fournaise volcano summit

sinuous gullies on mars frequency distribution and implications for flow properties recent gullies on mars are suspected to be the result of liquid water bearing flows a formation from wet flows has been challenged by studies invoking granular dry flows our study focuses on the sinuous shapes observed for some of the recent martian gullies sinuous gullies are found in locations and slopes of 10 15 similar to straight gullies and they are therefore related to the same formation processes numerical simulations of granular flows are performed here by introducing topographic variations such as obstacles roughness or slope changes that could possibly generate flow sinuosity none of these simulations was able to reproduce sinuous shapes on a slope lower than 18 with friction angles typical of dry granular material the only way to simulate sinuous shapes is to create small amplitude periodic variations of the topography of the deposit an origin not supported by current martian imagery given the presence of sinuosity in natural terrestrial debris flows we have concluded that sinuous martian gullies are better reproduced by liquid water bearing debris flows sinuous shapes in leveed flows are used to derive mechanical parameters from several martian gullies using photoclinometry values in yield strength of 100 2200 pa velocities of 1 1 3 3 m s 1 and viscosities from 40 to 1040 pa s are found which are all within the range of values for terrestrial debris flows with various proportions of liquid water 20 40

investigation of surge derived pyroclastic flow formation by numerical modelling of the 25 june 1997 dome collapse at soufriere hills volcano montserrat deposits from ash cloud surges associated with dome collapse can under certain conditions be remobilised to form surge derived pyroclastic flows sdpfs using numerical modelling we reproduce the emplacement of these flows and investigate the conditions that favour their genesis we use the new version of the numerical model volcflow which simulates the two components of a pyroclastic flow the basal avalanche and the overriding ash cloud surge the basal avalanche primary block and ash flows and sdpfs are simulated using three previously published rheological laws plastic frictional and frictional velocity weakening rheologies applied to the 25 june 1997 dome collapse at soufriere hills volcano the models reproduce to different degrees the deposit footprints formed by the block and ash flows the ash cloud surges and the sdpfs in the plastic model sdpfs occur if the ash cloud surge deposit exceeds a threshold thickness that allows it to remobilise and flow in the frictional models sdpfs occur only if ash cloud surge deposition takes place on a slope exceeding the friction angle of the ash results also highlight that sdpfs appeared so clearly in 1997 at montserrat due to a combination of topographic factors i a bend in the mosquito ghaut drainage that allowed the ash cloud surges to detach ii a depositional area on the watershed between the eastern and western drainage channels and iii a network of tributaries that drained all the remobilised mass into dyer s river to form a single large sdpf our model could be a promising tool for the future forecasting of hazards posed by surge derived pyroclastic flows

submarine deposition of volcaniclastic material from the 1995 2005 eruptions of soufriere hills volcano montserrat abstract soufriere hills volcano montserrat has been erupting since 1995 during the current eruption a large part of the material produced by the volcano has been transported into the sea modifying the morphology of the submarine flanks of the volcano we present a unique set of swath bathymetric data collected offshore from montserrat in 1999 2002 and 2005 from 1999 to 2002 pyroclastic flows associated with numerous dome collapses entered the sea to produce 100 mm 3 deposit from 2002 to 2005 the 290 mm 3 submarine deposit is mainly from the 12 13 july 2003 collapse these data allow us to estimate that by may 2005 at least 482 mm 3 of material had been deposited on the sea floor since 1995 we compare on land characteristics and volumes of dome collapse events with the submarine deposits and propose a new analysis of their emplacement on the submarine flanks of the volcano the deposition mechanism shows a slope dependence with the maximum thickness of deposit before the break in the slope probably because of the type of the dense granular flow involved we conclude that from 1995 to 2005 more than 75 of the erupted volume entered the sea

automatic classification and a posteriori analysis of seismic event identification at soufriere hills volcano montserrat abstract seismic energy radiation at soufriere hills volcano montserrat is made up by various types of transient signals which are distinguished by the montserrat volcano observatory mvo in different classes with respect to their characteristics and or origin there are five fundamental classes i e volcano tectonic events regional events long period events hybrid events and rockfalls identification and classification of these transients which have been hitherto carried out manually by various staff members yield important information for the assessment of the state of the volcano system in the frame of the multimo project we proposed the application of artificial neural networks ann for the classification of these kind of data in order to handle large data sets and to achieve reproducible results emulating the expert s analysis using the manual routine classification as a priori information we obtained a fair performance of such an automatic processing with 70 of the automatic classifications being consistent with the original ones from an analysis of the misclassified events however we found that for most of them the original a priori classification was incorrect in this study we first revised manually the original a priori classification based on a data set of 6000 events we carried out a reanalysis of the seismic traces recorded at different seismic stations then using this new information we trained and tested the ann obtaining a successful classification in ca 80 of records particularly the automatic classification was excellent in the identification of rockfalls and volcano tectonic events among the misfits we observe the erroneous attribution of long period and hybrid events to rockfalls this may be partly explained by the fact that signals addressed to as rockfalls contain frequently contributions of various sources overall the failure in the classification between some types of transients highlights the problem of the concurrent activation and or unclear separation of distinctive sources from which the signals stem we conclude that the automatic classification with ann is a powerful tool for handling large data masses as well as for the a posterior analysis of the consistency of the classification problem

numerical modeling of the mount steller landslide flow history and of the generated long period seismic waves the rock ice avalanche that occurred in 2005 on mount steller alaska and the resulting long period seismic waves have been simulated for different avalanche scenarios i e flow histories with and without erosion processes taken into account this 40 60 mm3 avalanche traveled about 10 km down the slope mainly on top of a glacier eroding a significant amount of ice it was recorded by 7 broadband seismic stations the simulations were compared with the recorded long period seismic signal and with the inverted flow history the results show that when erosion processes are taken into account the simulations reproduce the observed signal at all the stations over a wide range of azimuths and source station distances 37 623 km this comparison makes it possible to constrain the rheological parameters involved which should help constrain the volume of eroded material because landslides are continuously recorded by seismic networks this method could significantly broaden quantitative insights into natural flow dynamics

erosion and mobility in granular collapse over sloping beds 1 we describe laboratory experiments of granular material flowing over an inclined plane covered by an erodible bed designed to mimic erosion processes of natural flows travelling over deposits built up by earlier events two controlling parameters are the inclination of the plane and the thickness of the erodible layer we show that erosion processes can increase the flow mobility i e runout over slopes with inclination close to the repose angle of the grains r by up to 40 even for very thin erodible beds erosion efficiency is shown to strongly depend on the slope of the topography entrainment begins to affect the flow at inclination angles exceeding a critical angle c r 2 runout distance increases almost linearly as a function of the thickness of the erodible bed suggesting that erosion is mainly supply dependent two regimes are observed during granular collapse a first spreading phase with high velocity followed by a slow thin flow provided either the slope or the thickness of the erodible bed is high enough surprisingly erosion affects the flow mostly during the deceleration phase and the slow regime the avalanche excavates the erodible layer immediately at the flow front waves are observed behind the front that help to remove grains from the erodible bed steep frontal surges are seen at high inclination angles over both rigid or erodible bed finally simple scaling laws are proposed making it possible to obtain a first estimate of the deposit and emplacement time of a granular collapse over a rigid or erodible inclined bed

mobility and topographic effects for large valles marineris landslides on mars 1 recent experiments on dry granular flows over horizontal plane bare some similarities with large martian landslides observed in valles marineris vm however martian normalized runout are twice as large as those that observed in dry granular flow experiments numerical simulations on theoretical 2d and real 3d topographies reconstructed from remote sensing data show that slope effects significantly reduce the shift between experimental results and martian observation however topography effects are not strong enough to explain the high mobility of martian landslides as a result other physical and or geological processes should play a key role into the dynamics of martian landslides a new mobility is defined that makes it possible to characterize the dynamics of the flow regardless of the geometry of the released mass and of the underlying topography

teleseismic slowness azimuth station corrections for the international monitoring system seismic network abstract the prototype international data center pidc in arlington virginia has been developing and testing software and procedures for use in the verification of the comprehensive test ban treaty after three years of operation with a global network of array and three component stations it has been possible to characterize various systematic biases of those stations that are designated in the treaty as part of the international monitoring system ims these biases include deviations of azimuth and slowness measurements from predicted values caused largely by lateral heterogeneity for events recorded by few stations azimuth and slowness are used in addition to arrival time data for location by the pidc corrections to teleseismic azimuth and slowness observations have been empirically determined for most ims stations providing data to the pidc application of these corrections is shown to improve signal association and event location at some stations an overall systematic bias can be ascribed to local crustal structure or to unreported instrumental problems the corrections have been applied in routine operation of the pidc since february 1998

dynamics of the bingham canyon rock avalanches utah usa resolved from topographic seismic and infrasound data the 2013 bingham canyon mine rock avalanches represent one of the largest cumulative landslide events in recorded u s history and provide a unique opportunity to test remote analysis techniques for landslide characterization here we combine aerial photogrammetry surveying topographic reconstruction numerical runout modeling and analysis of broadband seismic and infrasound data to extract salient details of the dynamics and evolution of the multi phase landslide event our results reveal a cumulative intact rock source volume of 52 mm3 which mobilized in two main rock avalanche phases separated by 1 5 h we estimate the first rock avalanche had 1 5 2 times greater volume than the second each failure initiated by sliding along a gently dipping 21 highly persistent basal fault before transitioning to a rock avalanche and spilling into the inner pit the trajectory and duration of the two rock avalanches were reconstructed using runout modeling and independent force history inversion of intermediate period 10 50 s seismic data intermediate and shorter period 1 50 s seismic data were sensitive to intervals of mass redirection and constrained finer details of the individual slide dynamics back projecting short period 0 2 1 s seismic energy we located the two rock avalanches within 2 and 4 km of the mine further analysis of infrasound and seismic data revealed that the cumulative event included an additional 11 smaller landslides volumes 104 105 m3 and that a trailing signal following the second rock avalanche may result from an air coupled rayleigh wave our results demonstrate new and refined techniques for detailed remote characterization of the dynamics and evolution of large landslides

interdiffusion of h2o and co2 in metamorphic fluids at 490 to 690 c and 1 gpa interdiffusion coefficients have been determined for h 2o co2 mixtures by quantifying the flux of co2 between two fluid filled chambers in a specially designed piston cylinder cell the two chambers which are maintained at 1 0 gpa and at temperatures differing by 100 c each contain the xco2 buffering assemblage calcite quartz wollastonite in h2o the positive dependence of xco2 on temperature results in a down temperature steady state flux of co 2 through a capillary tube that connects the two chambers this flux drives the wollastonite calcite quartz equilibrium to the right in the cooler chamber producing a measurable amount of calcite that is directly related to co2 h2o interdiffusion rates diffusivities calculated from seven experiments range from 1 0 10 8 to 6 1 10 8 m 2 s for mean capillary temperatures between 490 and 690 c the data set can be approximated by an arrhenius type relation d 4 7 10 6 exp 4560 t m 2 s t in k which yields values within a factor of 2 of but slightly lower than diffusivities estimated by application of the stokes einstein relation because rates of h2o and co2 interdiffusion approach within 1 to 2 orders of magnitude rates of heat conduction in rocks rapid co2 h2o interdiffusion should be expected in deep seated fluids wherever gradients in xco2 are imposed by contrasting mineral assemblages considering the small scale heterogeneity of the crust strong gradients in xco2 are probably quite common particularly where different carbonate bearing assemblages are juxtaposed or where they are interlayered with carbonate absent rocks cross layer diffusive mass transfer of co2 and h2o may play an important role in driving dehydration and decarbonation reactions even in the absence of fluid flow copyright 2004 elsevier ltd

constraining landslide characteristics with bayesian inversion of field and seismic data using a fully nonlinear bayesian approach based on forward modelling of granular flow we invert for landslide parameters volume release geometry and rheology from different kinds of observations synthetic tests show that the runout distance and the deposit area by themselves do not constrain landslide parameters better constraints on landslide parameters are obtained from the thickness distribution of the landslide deposits as well as from the force history applied by the landslide to the ground which contains information on the landslide dynamics therefore inverting force histories calculated from seismic broad band records is an important alternative to inverting thickness distributions of landslide deposits which are usually difficult to obtain we test the method on the 1997 boxing day debris avalanche on montserrat island which involved 40 50 mm3 the bayesian inversion and granular flow model provide good estimates for volume release geometry and effective friction coefficient this study thus underlines the value of broad band seismic records as observations to monitor landslides and validation for their numerical flow models

influence of the scar geometry on landslide dynamics and deposits application to martian landslides received 24 january 2011 revised 23 june 2011 accepted 30 june 2011 published 4 october 2011 1 landslides dynamics prediction remains difficult in spite of a considerable number of studies the runout distance is widely used in analysis of landslide dynamics and in the calibration of the rheological parameters involved in numerical modeling however the unknown impact of the significant uncertainty in the shape of the initial released mass on the runoutdistanceandontheoverallshapeofthedepositraisesquestionsabouttherelevanceof these approaches the impact of the initial scar geometry on flow and distribution of the deposits is studied here using satellite data and numerical modeling of theoretical landslides and martian landslides informed by geomorphological analysis by varying the initial scar geometry from spoon shaped to steep wall geometry our results show that the runout distance is a very robust parameter that is only slightly affected by the change in the geometry of the initial scar on the contrary the lateral extent of the deposit is shown to be controlled by the scar geometry providing unique insights into the initial landsliding conditionsonmarsandmakesitpossibletoaccuratelyrecoverthevolumeinitiallyinvolved an essential ingredient for volume balance calculation a feedback analysis of valles marineris landslides can be drawn showing good agreement between numerical results and geomorphological analysis the geometry of the initial scar inferred from numerical modeling is strongly correlated with the regional tectonic history in valles marineris area

development of the 10 11 july 2015 two stage sequence of multiple emplacements of pyroclastic density currents at volcan de colima mexico insight from associated seismic signals abstract the 10 11 july 2015 partial collapses of the lava dome in the crater of volcan de colima mexico were accompanied by a sequence of two stage multiple pdcs separated by a 15 h interval with a total bulk volume of 14 2 10 6 m 3 of fragmentary material and runout distances reaching 9 1 and 10 3 km respectively reyes davila et al 2016 broad band seismic signals associated with the pdcs and recorded at seismic station ez5 installed at a distance of 4 km from the crater were used for analysis of the 20 h eruption process this process included two stages of the multiple pdcs emplacements two one hour periods of preliminary events to each of the stages and the inter stage period analysis of seismic signals allowed us to identify the types of volcanic events composing this eruption episode and estimate their quantitative characteristics and spectral parameters of generated seismic signals it was shown that the seismic signals produced by pdcs emplacements recorded during the two stages were characterized by different characteristics the second stage pdcs had radiated greater seismic energy than the pdcs emplaced during the first stage spectral analysis of the seismic signals produced by pdcs indicates a clearly separation in frequency content at 1 95 hz between the higher frequency events of the first stage and the lower frequency events of the second stage of the pdcs emplacements the obtained difference in the spectral contents of the seismic signals produced by the movement of two multiple pdcs may be supposed as a consequence of the proposed relative difference in the volumes of the pdcs of two multiple sequences due to a difference in the level of radiated seismic energy and a change in bottom conditions of the ravines during their passing along the ravines results of seismic study were used in discussion of the nature of the two stage eruptive process

slope instabilities in dolomieu crater reunion island from seismic signals to rockfall characteristics 1 the seismic signals of hundreds of rockfalls within dolomieu crater piton de la fournaise volcano reunion island have been analyzed to investigate a possible link between physical rockfall generating processes and associated seismic signal features moreover indirect observation of rockfalls via the seismic signals they generate can provide useful data for studying volcanoes and the temporal variations of their structure an increase in the number of rockfall events and their volumes might be an indicator of structural weakness and deformation of the volcano associated with potential eruptive activity the study focuses on a 10 month period following the 6 april 2007 crater floor collapse within dolomieu crater from may 2007 to february 2008 for granular flows a scaling law is revealed between seismic energy and signal duration a semiempirical approach based on both analytical analysis and numerical simulation of these flows shows that a similar scaling law exists between the difference of potential energy computed for an event and its propagation times and also emphasizes the effect of local topography on this scaling law simulated and observed data were compared to evaluate the proportion of potential energy dissipated in the form of seismic waves and confirm a direct link between the seismic energy and potential energy of a given granular flow the mean ratio of seismic to potential energy is of the order of 10 4 comparable to the range of values observed in previous studies a simple method based on these ratios is proposed to estimate the volumes of rockfalls from their seismic signal observed seismic energy and the frequency of rockfalls decreased at the beginning of the studied period and reached a stable level in july thus suggesting a postcollapse relaxation time of dolomieu crater structure of about 2 months from seismic signal analysis which is confirmed by deformation data the total rockfall volume over the study period is estimated to be 1 85 mm3

seismic monitoring of sechilienne rockslide french alps analysis of seismic signals and their correlation with rainfalls 1 in the french alps sechilienne rockslide is one of the natural phenomena that presents one of the highest levels of risk in terms of socioeconomical outcomes this rockslide has been active for a few decades and has been instrumented since 1985 the current very active volume of this rockslide is estimated to be up to 5 million m3 located on the border of a slowly moving mass reaching 50 100 million m3 the velocity of the most active zone reached 1 4 m yr in 2008 about twice the value of 2000 a seismic network was installed on this rockslide in may 2007 to supplement the monitoring system it has now recorded several thousand events mostly rockfalls but also hundreds of local and regional earthquakes which can be distinguished and classified from their signal characteristics rockfalls and microseismicity which occur in bursts of activity are found to be weakly but significantly correlated with rainfall rockfall occurrence increases linearly with precipitation with however strong fluctuations of the numbers of rockfalls per day for the same rainfall intensity no threshold was found for rainfall triggering with even 1 mm of rain being enough to trigger rockfalls rockfall activity starts almost immediately during a rainfall episode and lasts for several days after the rainfall rain also induces strong accelerations of the rockslide movement which also start quasi instantaneously and last for about a month

seismic and acoustic signatures of surficial mass movements at volcanoes abstract surficial mass movements such as debris avalanches rock falls lahars pyroclastic flows and outburst floods are a dominant hazard at many volcanoes worldwide understanding these processes cataloging their spatio temporal occurrence and detecting tracking and characterizing these events would advance the science of volcano monitoring and help mitigate hazards seismic and acoustic methods show promise for achieving these objectives many surficial mass movements generate observable seismic and acoustic signals and many volcanoes are already monitored significant progress has been made toward understanding modeling and extracting quantitative information from seismic and infrasonic signals generated by surficial mass movements however much work remains in this paper we review the state of the art of the topic covering a range of scales and event types from individual rock falls to sector collapses we consider a full variety of volcanic settings from submarine to subaerial shield volcano to stratovolcano finally we discuss future directions toward operational seismo acoustic monitoring of surficial mass movements at volcanoes

dynamic landslide processes revealed by broadband seismic records 1 we use broadband seismic recordings to trace the dynamic process of the deep seated akatani landslide that occurred on the kii peninsula japan which is one of the best recorded large slope failures combining analyses of the seismic records with precise topographic surveys done before and after the event we can resolve a detailed time history of the mass movement during 50 s of the large landslide we observe a smooth initiation acceleration with changes in basal friction and reversal of the momentum when the mass collides with the opposite valley wall of particular importance is the determination of the dynamic friction during the landslide the coefficient of friction is estimated to be 0 56 at the beginning of the event and drops to 0 38 for most of the sliding the change in the frictional level on the sliding surface may be due to liquefaction or breaking of rough patches and contributes to the extended propagation of the large landslide

locating pyroclastic flows on soufriere hills volcano montserrat west indies using amplitude signals from high dynamic range instruments pyroclastic flows are located using amplitude signals from a seven station high dynamic range seismograph array located 1 9 6 1 km from soufriere hills volcano in montserrat west indies locations are determined by measuring the seismograph signal amplitude for an event recorded at several stations in a moving time window analysis for a given window the measured amplitudes are corrected to a trial source location by removing the effect of the surface wave geometric spreading instrument gain and the attenuation at calculated travel times the trial source location is then compared to other trial locations via an iterative localised grid search where the root mean squared amplitude residual a is minimised the process is repeated for subsequent time steps resulting in a best fit event location and size through time the method has been tested on four small events occurring on april 8 1999 august 12 1999 february 25 2001 and july 4 2001 when visual observations of pyroclastic flows coincided with good seismograph station coverage number of stations 5 azimuthal gap 160 based on the location results the four events propagated 0 5 1 4 1 3 and 1 0 km from the dome and had maximum attenuation corrected reduced displacements drq of 9 0 2 8 6 9 and 2 3 cm2 and maximum pyroclastic flow velocities of 7 30 20 and 8 ms 1 respectively a time lapse video of the event of august 12 1999 shows that amplitude based location through time closely matches the observed run out distance and velocity in contrast amplitude based locations for the events of april 8 1999 and july 4 2001 underestimated the actual flow run out by 1 5 km underestimation of the true run out distance is probably due to both the increased distribution of sources as coherent dome material disaggregates into many blocks and signal contamination from other sources results indicate that pyroclastic flows and rockfalls can be located using amplitude signals from high dynamic range seismograph stations yielding estimates of size and trajectory regardless of visibility conditions on the volcano this new method is being tested as a hazard mitigation and research tool on montserrat

seismic energy release in mexican subduction zone earthquakes we estimated radiated seismic energy es from 18 shallow thrust mexican subduction zone earthquakes 4 1022 m 1 1 1028 dyne cm 11 h 37 km using digital accelerograms from the guerrero accelerograph array and neglecting stations with large site effects es is computed by integrating squared velocity spectra after applying geometrical spreading and q corrections we discarded epicentral recordings for the largest michoacan event we find that log es m 4 152 0 275 which gives a median value of es m and apparent stress a of 7 1 10 5 and 24 bars respectively the median es m value is in accordance with gutenberg and richter s g r 1956 formula for es in which es m 5 10 5 is implicit worldwide es m data where es is computed from local records mostly fall between 5 10 5 and 5 10 4 for events with m 1022 dyne cm on the other hand es m values generally lie between 5 10 6 and 5 10 5 if es is estimated from teleseismic records especially anomalous are the es m data from kikuchi and fukao 1988 for large and great earthquakes which fall near 5 10 6 thus while es from local data suggests that the g r relation seldom overestimates seismic energy release the teleseismic data point to the contrary the cause of this discrepancy may lie in the difficulty of resolving incoherent radiation from the fault and inappropriate choice of t in the analysis of teleseismic data

simple scaling of catastrophic landslide dynamics catastrophic landslides involve the acceleration and deceleration of millions of tons of rock and debris in response to the forces of gravity and dissipation their unpredictability and frequent location in remote areas have made observations of their dynamics rare through real time detection and inverse modeling of teleseismic data we show that landslide dynamics are primarily determined by the length scale of the source mass when combined with geometric constraints from satellite imagery the seismically determined landslide force histories yield estimates of landslide duration momenta potential energy loss mass and runout trajectory measurements of these dynamical properties for 29 teleseismogenic landslides are consistent with a simple acceleration model in which height drop and rupture depth scale with the length of the failing slope

simulation of tsaoling landslide taiwan based on saint venant equations over general topography the 1999 chi chi earthquake triggered the catastrophic tsaoling landslide in taiwan the geomorphological change measured from the data of the 1989 and 2000 aerial photos reveals that the scar and deposit volumes are about 0 126 km3 and 0 15 km3 respectively the debris material ran over a distance of 1 6 km with 500 m descent in elevation in this paper we use the continuum model of hydraulic flow shaltop2d based on the equations of bouchut and westdickenberg to simulate numerically the landslide dynamics when the mass is moving the flow is assumed hydrostatic with a basal coulomb friction the best fit is obtained using the basal friction angle equal to 6 the only parameter of the simulation uniformly applied in the calculation domain the landslide front reaches the chinshui river valley the foothill of the slope within only about 25 s after initiation and the motion settles in about 113 s the maximum speed is estimated 75 m s the spreading of the deposit agrees well with the field measurement

analyzing high frequency seismic signals generated during a landslide using source discrepancies between two landslides abstract high frequency seismic signals are generated during landslides and can be analyzed to obtain detailed information regarding landslide dynamics however a better understanding of the physical process that produces such high frequency signals is required the two massive landslides that occurred on april 11 2013 in the bingham canyon mine pit utah usa generated low and high frequency seismic signals using the low frequency signals we inverted the force time functions of the two events and estimated their dynamics we used the signals generated by the two events and filtered in three frequency bands to obtain the source discrepancies between the two events by analyzing these source discrepancies we found that the low and medium frequency signals were generated due to the bulk movement of sliding material furthermore the medium frequency signals contained information regarding small particle impacts along the sliding path the high frequency 1 3 hz signals are controlled by small scale process of sliding materials and are sum of stochastic phenomena this clarification of the source of the high frequency signals is expected to improve the analyses of seismic signals generated during landslides

geomorphological evolution of montserrat west indies importance of flank collapse and erosional processes analysis of topography and new swath bathymetry as well as geophysical data provides information about aerial and submarine morphological features and mass transfer processes on montserrat the island has a characteristic shallow c 4000 years ago or the boxing day event during the current eruption 26 december 1997 montserrat9s older volcanic centres the centre hills and silver hills illustrate the third stage of evolution extinction and erosion magma production long term erosion and total sedimentation rates on montserrat have been estimated as 0 17 km 3 ka 1 0 0125 km 3 ka 1 and 0 11 km 3 ka 1 i e 1 1 cm ka 1 respectively

insights into rock ice avalanche dynamics by combined analysis of seismic recordings and a numerical avalanche model 1 rock ice avalanches larger than 1 106 m3 are high magnitude low frequency events that may occur in all ice covered high mountain areas around the world and can cause extensive damage if they reach populated regions the temporal and spatial evolution of the seismic signature from two events was analyzed and recordings at selected stations were compared to numerical model results of avalanche propagation the first event is a rock ice avalanche from iliamna volcano in alaska which serves as a natural laboratory with simple geometric conditions the second one originated on aoraki mt cook new zealand southern alps and is characterized by a much more complex topography a dynamic numerical model was used to calculate total avalanche momentum total kinetic energy and total frictional work rate among other parameters these three parameters correlate with characteristics of the seismic signature such as duration and signal envelopes while other parameters such as flow depths flow path and deposition geometry are well in agreement with observations the total frictional work rate shows the best correlation with the absolute seismic amplitude suggesting that it may be used as an independent model evaluation criterion and in certain cases as model calibration parameter the good fit is likely because the total frictional work rate represents the avalanche s energy loss rate part of which is captured by the seismometer deviations between corresponding calculated and measured parameters result from site and path effects which affect the recorded seismic signal or indicate deficiencies of the numerical model the seismic recordings contain additional information about when an avalanche reaches changes in topography along the runout path and enable more accurate velocity calculations the new concept of direct comparison of seismic and avalanche modeling data helps to constrain the numerical model input parameters and to improve the understanding of rock ice avalanche dynamics

high velocity frictional properties of gabbro high velocity friction experiments have been performed on a pair of hollow cylindrical specimens of gabbro initially at room temperature at slip rates from 7 5 mm s to 1 8 m s with total circumferential displacements of 125 to 174 m and at normal stresses to 5 mpa using a rotary shear high speed friction testing machine steady state friction increases slightly with increasing slip rate at slip rates to about 100 mm s velocity strengthening and it decreases markedly with increasing slip rate at higher velocities velocity weakening steady state friction in the velocity weakening regime is lower for the non melting case than the frictional melting case due perhaps to severe thermal fracturing a very large peak friction is always recognized upon the initiation of visible frictional melting presumably owing to the welding of fault surfaces upon the solidification of melt patches frictional properties thus change dramatically with increasing displacement at high velocities and such a non linear effect must be incorporated into the analysis of earthquake initiation processes

overview of the eruption of soufriere hills volcano montserrat 18 july 1995 to december 1997 the onset of phreatic volcanic activity at the soufriere hills volcano montserrat on 18 july 1995 followed a three year period of heightened volcano seismic activity beneath the island phreatic explosions gave way to continuous eruption of juvenile andesitic magma in the form of a lava dome on or around 15 november 1995 magma production rate has varied leading to changes in eruptive style an explosive eruption on 17 september 1996 followed a period of enhanced dome growth and large scale gravitational collapses from its eastern flank increasing dome volume led to stressing and overtopping of the confining crater walls to the southwest north and west during early 1997 sustained high magma production rate since june 1997 has led to three periods of major gravitational dome collapses followed by vulcanian explosive eruptions dome growth re started immediately after the cessation of the latest of these explosive phases in october 1997 and continues as of december 1997

location of seismic signals associated with microearthquakes and rockfalls on the sechilienne landslide french alps the sechilienne rockslide in the french alps has recently been instrumented with three seismic arrays this network has recorded numerous rockfalls and local microearthquakes because the media is highly fractured it is difficult to identify and pick first arrivals beam forming methods were therefore used to locate these events the method has been adapted to take into account the heterogeneity of seismic wave velocities the location accuracy has been estimated to be about 50 m for epicenters by applying the method to calibration shots depth is less constrained due to uncertainties on the velocity model and due to the seismic network geometry this method of location has then been applied to rockfalls and microearthquakes most rockfalls initiate in the most active part of the rockslide called les ruines the others are located on a recent eroded area aside from les ruines the network also allows the estimation of the rockfall trajectory and propagation speed finally 55 microearthquakes have been located within two zones microearthquakes are located within the first 250 m below the surface most microearthquakes are located in les ruines the most active part of the rockslide where the velocity has increased from 0 5 m yr in 1996 to 1 4 m yr in 2008 these events are located close to three faults that delimit a mass of about 3 6 million m3 other events are located close to the summital scarp in a zone moving at a few centimeters per year the western part of the rockslide which moves more slowly did not produce any event large enough to be detected simultaneously by all stations this seismic monitoring suggests that only a very small fraction of the deformation is released through seismic events

the anatomy of a pyroclastic density current the 10 july 2015 event at volcan de colima mexico pyroclastic density currents pdcs represent one of the most dangerous phenomena occurring in explosive volcanic eruptions and any advance in the physical understanding of their transport and sedimentation processes can contribute to improving their hazard assessment the 10 11 july 2015 eruption at volcan de colima provided a unique opportunity to better understand the internal behaviour of pdcs based on seismic monitoring data on 10 july 2015 the summit dome collapsed producing concentrated pdcs that filled the main channel of the montegrande ravine a lahar monitoring station installed 6 km from the volcano summit recorded a pdc before being completely destroyed real time data acquisition from a camcorder and a geophone that were part of the station along with field observations and grain size data of the pyroclastic deposits are used here to interpret the internal flow structure and time variant transport dynamics of low volume valley confined concentrated pdcs the pdc that reached the monitoring station moved at a velocity of 7 m s and filled a 12 m deep channel the outcrops show massive block and ash flow deposits with trains of coarse clasts in the middle and towards the top of the depositional units the seismic record gathered with the geophone was analysed for the time window when the flow travelled past the sensor the geophone record was also compared with the recordings of a broadband seismic station located nearby two main frequency ranges were recognised which could be correlated with the basal frictional forces exerted by the flow on the channel bed 10 20 hz and a collisional regime 20 40 hz interpreted to be associated with a clast segregation process i e kinematic squeezing this latter regime promoted the upward migration of large blocks which subsequently deviated towards the margin of the flow where they interacted with the sidewall of the main channel the energy calculated for both seismic components shows that the collisional regime represents 30 of the total energy including an important sidewall stress component these results gathered directly from a moving flow contribute to unravelling the internal behaviour of concentrated pdcs providing information on energy partitioning and particle particle interactions this confirms previous assumptions inferred from field observations and tested by analogue or numerical modelling the nature of the contact between grains is still poorly documented in natural pdcs and there is still much uncertainty and discussion about dominant forces in such currents data reported here may thus be useful to better constrain the physics of low volume valley confined concentrated pdcs and our findings need to be considered in theoretical models in parallel this study shows how geophones can provide a cheap alternative for pdc detection

model space exploration for determining landslide source history from long period seismic data the seismic signals generated by two large volcanic debris avalanches montserrat lesser antilles 1997 and mount st helens usa 1980 and a large rock ice avalanche mount steller usa 2005 have been analyzed for the two debris avalanches given the times and locations of such landslides their signals were recorded by only a few seismic stations moreover these signals cover only a very narrow frequency band and include considerable noise the mount steller on the contrary was precisely recorded for each event the source mechanism i e point force has been determined by waveform inversion using at most two broadband seismic stations the resulting force is very difficult to interpret in terms of landslide characteristics a monte carlo inversion was therefore performed by imposing a simple force model associated with the landslide based on the schematic view of an accelerating decelerating mass traveling down the slope the best parameter set of the force model was then found by minimizing misfits and maximizing correlations between data and synthetic signals this model appears to contain the minimum degree of complexity required to well reproduce the seismic data we detail here the method for the montserrat debris avalanche and then present it s validation on the well studied mount st helens debris avalanche and the well recorded mount steller rock ice avalanche the horizontal and vertical components of the resulting force have different source time functions the best force model compares well with the force obtained by waveform inversion finally this simple force model was interpreted using analytical and empirical relations derived from the sliding block model granular flow model and landslide studies this made it possible to estimate the order of magnitude of the mass flow duration and direction initial topography slope mean velocity and travel distance of the avalanches for these three avalanches the calculated characteristics are consistent with former studies

a single force model for the 1975 kalapana hawaii earthquake a single force mechanism is investigated as the source of long period seismic radiation from the 1975 kalapana hawaii earthquake m s 7 1 the observed love wave radiation pattern determined from the spectra of world wide standard seismograph network and high gain long period records at 100 s is two lobed with azimuth consistent with a near horizontal single force acting opposite strike 330 to the observed displacement direction of the earthquake this pattern is inconsistent with the expected double couple pattern assuming a form of the force time history of a one cycle sinusoid the total duration of the event estimated from rayleigh waves at two international deployment of accelerometers stations is approximately 180 s the peak amplitude f o of the time function is 1 10 15 n from amplitudes of love and rayleigh waves the interpretation is that the bulk of the seismic radiation was produced by large scale slumping of a large area of the south flank of kilauea volcano the single force is a crude representation of the effect on the earth of the motion of a partially decoupled large slide mass using the mass estimated from the tsunami generation area 10 15 10 16 kg the peak acceleration of the slide block 0 1 1 m s 2 inferred from the seismic force is comparable with the acceleration due to gravity on a gently inclined plane the slump model for the kalapana earthquake is also more qualitatively consistent with the large horizontal deformation 8 m on land and tsunami associated with the earthquake which are difficult to explain with the conventional double couple source model the single force source has been used previously to model the long period seismic waves from the landslide accompanying the eruption of mount st helens volcano and may explain other anomalous seismic events as being due to massive slumping of sediments or unconsolidated material and not to elastic dislocation

analysis of broadband seismic recordings of landslide using empirical green s function the 2010 mount meager landslide generated strong seismic waves we used seismic signals generated by a smaller landslide that occurred within 2 min of the end of the main landslide as the empirical green s function egf with which to obtain landslide dynamics from high frequency signals we then obtained the apparent force time function of the landslide based on the egf by inverting the higher frequency seismic signals the apparent force time function shows that the source material of the main landslide came from four collapses and that the second collapse involved multiple small collapses we also used the egf to simulate the vertical seismogram recorded at one station and found that the synthesized seismogram fits the response of the bulk mobilization of the sliding materials remarkably well our study demonstrates that the use of the egf can significantly broaden quantitative insights into landslide dynamics plain language summary seismic records reflect the effects of landslide dynamics and the path of seismic waves through the earth because the calculation of the high frequency component of the effect of a wave s path through the earth requires a detailed characterization of the velocity and attenuation structure the effects of landslide dynamics can only be estimated by inverting the long period seismic signals to study the high frequency seismic signals generated from the mount meager landslide we considered the seismic signals generated by a smaller landslide as the effects of the path of seismic waves we used the seismic signals generated by the smaller landslide to simulate the signal generated by the main landslide to overcome the effects of a potential overlap in the frequency domain between signals from the bulk and those from smaller particles our results show that the seismic signals generated by a small landslide can be used to improve our understanding of those generated by the main landslide

numerical modeling of landquakes the thurwieser landslide that occurred in italy in 2004 and the seismic waves it generated have been simulated and compared to the seismic signal recorded a few tens of kilometers from the landslide source i e landquake the main features of the low frequency seismic signal are reproduced by the simulation topography effects on the flowing mass have a major impact on the generated seismic signal whereas they weakly affect low frequency wave propagation simulation of the seismic signal makes it possible to discriminate between possible alternative scenarios for flow dynamics and to provide first estimates of the rheological parameters during the flow as landquakes are continuously recorded by seismic networks our results provide a new way to collect data on the dynamics and rheology of natural flows

late pleistocene tephrochronology of marine sediments adjacent to montserrat lesser antilles volcanic arc the recent history of the soufriere hills volcano montserrat lesser antilles volcanic arc is deduced using data obtained from a submarine core collected in 2002 the core contains concentrations of ash and several tephra layers which are identified by the abundance of glass shards dense and poorly vesiculated particles and scoria the tephra layers have been dated using micropalaeontology and stable isotope stratigraphy tephra layers in a marine sediment core off the coast of montserrat record the volcanic history of south soufriere hills soufriere hills volcano back to 250 ka eight layers are composed of dense juvenile ash related to dome eruptions five of which can be directly correlated to dated domes or related pyroclastic flow sequences on land six layers are composed of pumiceous glassy ash and relate to significant explosive eruptions a marker sequence of basalt tephra layers is dated at 124 147 ka and is correlated with construction of the south soufriere hills basaltic stratocone pelagic sediments between the main tephra layers have low abundances of volcanogenic components c 10 4 years of dormancy or low activity

two stage modeling of strombolian type eruptions and quantification of the model parameters insight from the seismic and acoustic signals abstract the seismic signals of majority strombolian explosions show a two phase structure that may be the result of a two stage explosive eruption we quantify the parameters of two proposed stages of strombolian eruptions at volcanoes arenal aso and yasur using 193 seismic records and 18 acoustic signals and considering that the first stage of eruption represents the seismically active process of the gas slug expansion and ascent gsea in the conduit and the second stage is associated with the gas slug burst at the surface it is shown that the radiated seismic energy of strombolian explosions at volcanoes is strongly dependent on the seismic energy radiated during gsea the seismic energy of explosions is correlated also with the duration of gsea process in the interval of durations between 1 3 and 3 7 s for shorter gsea durations the correlation is absent the acoustic energy of explosions is characterized by inverse dependence on the durations of gsea these results demonstrate the influence of the gsea process on the surface manifestations of strombolian explosions

remote sensing and seismic data integration for the characterization of a rock slide and an artificially triggered rock fall abstract on may 5th 2013 a planar rock slide 450 m3 occurred in the village of la riba ne spain which forced the closure of the road c 240z for 6 months this slide left a hanging block 130 m3 suspended on the slope forcing a controlled blasting followed by rock slope stabilization works the volume of rock displaced during the both events was deduced from lidar and photogrammetry data following two approaches subtracting pre and post event data and reconstructing the volume by fitting planes on the structural surfaces after a structural analysis of the slope information about the natural rock slide was obtained from the records of two permanent broadband seismic stations located 10 km from the site from these seismic records the existence of a rock slide was confirmed and its time of occurrence was determined information that would be otherwise unknown in addition despite the small volume displaced during the event its location was deduced from a single seismic station analysis the blasting process was recorded with two high definition hd video cameras and by two temporary seismic stations deployed close to the site 10 km partially because only a part of the released energy is transmitted into the ground as seismic energy and partially because the recorded seismic signal is highly dependent on the event characteristics and the geotechnical conditions of the ground materials nevertheless seismic data is very well suited to detect and characterize in detail both rockfall events of different nature and size merging and integrating remote sensing techniques such as lidar or photogrammetry with seismic measurements should allow the implementation of rockfall early warning systems

arc parallel extension and localization of volcanic complexes in guadeloupe lesser antilles 1 subduction of atlantic seafloor under the caribbean plate causes shallow earthquakes within the lesser antilles volcanic arc such earthquakes above the subduction interface show strike slip or normal fault plane solutions the latter with e w striking nodal planes to better assess seismic hazard and the coupling between volcanism and tectonics we investigated faulting related to overriding plate deformation in the guadeloupe archipelago using aerial photographs satellite spot images and topographic maps 1 25000 scale we mapped active and middle to late pleistocene fissures and normal fault systems that cut the uplifted coral platforms grande terre and marie galante and the volcanic rocks of basse terre the available marine geophysical data show that the faults extend offshore to bound submarine rifts the e w striking 1500 m deep v shaped marie galante rift separates the two islands of marie galante and grande terre normal faults in the north of grande terre appear to mark the similarly v shaped western termination of the 5000 m deep n 50e to n130 e striking desirade graben three shallow m 5 5 earthquakes 6 may 1851 29 april 1897 3 august 1992 appear to have ruptured segments of the marie galante rift boundary faults the young la grande decouverte volcanic complex of basse terre including the 1440 a d soufriere dome lies within the western termination of the marie galante rift the ancient volcanic shoulders of the rift buttress the active dome to the north and south which may explain why major prehistoric sector collapses and pyroclastic avalanches have been directed southwestward into the caribbean sea or southeastward into the atlantic ocean the marie galante rift is typical of other troughs transverse to the northeastern edge of the caribbean plate we interpret such troughs which are roughly orthogonal to the arc to result from slip partitioning and extension perpendicular to plate convergence that they disappear southward implies that they result from interaction between the caribbean and north american plates

broadband seismic analysis of a massive landslide in southwestern china dynamics and fragmentation implications abstract we analyse broadband seismic records generated by the massive xinmo landslide that occurred in southwestern china at 5 39 on 24 june 2017 beijing time utc 8 characteristics of landslide seismic signals including propagation velocity duration and frequency contents are presented and discussed by comparing them with seismic signals generated by a local earthquake of similar magnitude we perform a long period seismic waveform inversion in the frequency band of 0 01 0 1 hz to acquire the landslide force history using 46 seismic traces from 21 seismic stations with distances from the epicentre extending to 360 km based on the inversion we calculate the dynamic parameters of the landslide and recognize its stages and movement characteristics landslide basal friction coefficients are also acquired using both a constant dip and varying dips along the slope a combined analysis of near field short period seismic records and dynamic inversion results indicates that the high frequency energy of landslide signals is most likely generated by rock fragmentations during collision and scraping