evidence for widespread nonlinear strong ground motion in the mw 6 9 loma prieta earthquake we exploit 55 repeating microearthquake sequences on the san andreas fault just south of the rupture zone of the 1989 m w 6 9 loma prieta earthquake to search for time dependent properties of the earth s crust using moving window waveform cross correlation we identify clear and systematic delays as large as 20 msec for the direct s wave and exceeding 50 msec in the early s wave coda following the loma prieta mainshock others have also identified phase delays velocity reductions associated with damaging earthquakes and they have suggested a myriad of possible causal mechanisms here we present new evidence for a mechanism to produce velocity reductions correlated in time and space with an earthquake a strong correlation between the spatial patterns of s delays and the intensity of strong ground motion in the loma prieta earthquake suggests that physical damage the formation or growth of cracks during strong ground motion to the earth s shallow crust is responsible for the observed velocity reductions the strong spatial variability in s delays over short distances and the strong correlation of the magnitude of delays with surface geology indicate that the phase delays accumulate primarily near the receiver the effect is stronger at stations on young soft rocks than at stations on old hard rock disproportionately larger s coda delays than p coda delays suggest that the cracks formed by the strong shaking are fluid filled in the 10 years after loma prieta the initial increase in travel times reduces logarithmically with respect to time often back to the premainshock levels we attribute this behavior to the same slow dynamic healing observed in laboratory studies of the recovery of materials from transient nonlinear strain manuscript received 14 january 2004

temporal changes of shallow seismic velocity around the karadere duzce branch of the north anatolian fault and strong ground motion we analyze temporal variations of seismic velocity along the karadere duzce branch of the north anatolian fault using seismograms generated by repeating earthquake clusters in the aftershock zones of the 1999 mw7 4 izmit and mw7 1 duzce earthquakes the analysis employs 36 sets of highly repeating earthquakes each containing 4 18 events the events in each cluster are relocated by detailed multi step analysis and are likely to rupture approximately the same fault patch at different times the decay rates of the repeating events in individual clusters are compatible with the omori s law for the decay rate of regional aftershocks a sliding window waveform cross correlation technique is used to measure travel time differences and evolving decorrelation in waveforms generated by each set of the repeating events we find clear step like delays in the direct s and early s coda waves sharp seismic velocity reduction immediately after the duzce main shock followed by gradual logarithmic type recoveries a gradual increase of seismic velocities is also observed before the duzce main shock probably reflecting post seismic recovery from the earlier izmit main shock the temporal behavior is similar at each station for clusters at various source locations indicating that the temporal changes of material properties occur in the top most portion of the crust the effects are most prominent at stations situated in the immediate vicinity of the recently ruptured fault zones and generally decrease with normal distance from the fault a strong correlation between the co seismic delays and intensities of the strong ground motion generated by the duzce main shock implies that the radiated seismic waves produced the velocity reductions in the shallow material

onset and timing of deep seated gravitational slope deformations in the eastern alps italy abstract a previously unrecognised complex of deep seated gravitational slope deformations dsgsd extends 20 km along upper venosta valley in the eastern alps italy mt watles exhibits spectacular features indicative of dsgsds including double ridges trenches and counterscarps the slope deformation occurs along a nappe boundary now corresponding to the schlinig normal fault is also conditioned by recent faults marked by shallow earthquakes and shows glacial paraglacial controls on slope evolution the mt watles dsgsd is a complex deep seated compound slide along a basal shear zone involving the schlinig fault gravitational reactivation of ne trending fractures formed gravitational scarps counterscarps and half grabens in the upper slope whereas the lower part of the slope partially collapsed although our work indicates the importance of the schlinig fault and recent fracturing on slope failure the trigger seems to be postglacial debuttressing of the valley walls radiocarbon dating of peat deposits within one of the major counterscarps indicates that slope deformation started during the lateglacial period and continued during the holocene in several slope sectors

practical equivalent continuum characterization of jointed rock masses a simple practical method to characterize the strength and stiffness of jointed rock masses is presented in this paper the empirical relations for the strength and stiffness of rock masses have been arrived based on the statistical analysis of a large amount of experimental data which are used for representing the jointed rock mass as an equivalent continuum the effect of joints in the rock mass is taken into account by a joint factor these obtained relations are incorporated in a non linear fem code to represent the equivalent continuum analysis the equivalent continuum model has been validated against experimental results for jointed rock masses with different joint fabric and joint orientation and also with the results from explicit modeling of joints using fem the developed model has also been applied to calculate the deformation around a large power station cavern in rhyolite rock at 200 m depth

back analysis of a rock landslide to infer rheological parameters abstract on 30 january 2009 a rock slide involving approximately 0 23 mm 3 of highly jointed gneiss from the local ercinic substratum was recorded in southern italy the landslide occurred after exceptional autumnal rainfalls and involved a quarry whose activity has been documented over the past 10 years by aerial images an engineering geology model of the slope involved in the landslide was developed based on the geomechanical classification of the outcropping rock masses the isrm 2007 indexes ib the block size index and jv the volumetric joint count and the observed geological setting of the slope an equivalent continuum approach was adopted to attribute strength and stiffness parameter values to the different classes of jointed rock masses a simplified evolutionary model of the slope was developed starting from 300 ka i e from the erosional phase following the deposition of the 300 m a s l marine terrace deposits overlaying the gneiss substratum to 30 january 2009 the model took into account the main depositional phases as indicated by the pleistocene marine terrace deposits and the documented stages of quarry activity time dependent stress strain numerical modelling was performed by the fdm software flac 6 0 a visco plastic burger model was used to back analyse the landslide event and to define the values of the rheological parameters for the jointed gneiss the results which were strongly constrained by the geomorphological evidences and by the displacement field observed before and after the landslide demonstrated a combination of i time dependent gravitational slope deformation and ii anthropogenic release due to quarry activity which induced a progressive failure process and an increase in the jointing within the gneissic rock mass located behind the cut wall of the quarry failure was ultimately triggered by intense rainfalls that occurred in the 3 months before the landslide the stress strain numerical modelling demonstrated the reliability of visco plastic rheology for simulating the rock mass creep in this case history viscosity values in the range of 10 19 10 23 pa s were derived

tectonic controls on a large landslide complex williams fork mountains near dillon colorado abstract an extensive 25 km2 landslide complex covers a large area on the west side of the williams fork mountains in central colorado the complex is deeply weathered and incised and in most places geomorphic evidence of sliding breakaways hummocky topography transverse ridges and lobate distal zones are no longer visible indicating that the main mass of the slide has long been inactive however localized holocene reactivation of the landslide deposits is common above the timberline at about 3300 m and locally at lower elevations clasts within the complex as long as several tens of meters are entirely of crystalline basement proterozoic gneiss and granitic rocks from the hanging wall of the laramide late cretaceous to early tertiary west directed williams range thrust which forms the western structural boundary of the colorado front range late cretaceous shale and sandstone compose most footwall rocks the crystalline hanging wall rocks are pervasively fractured or shattered and alteration to clay minerals is locally well developed sackung structures trenches or small scale grabens and upslope facing scarps are common near the rounded crest of the range suggesting gravitational spreading of the fractured rocks and oversteepening of the mountain flanks late tertiary and quaternary incision of the blue river valley just west of the williams fork mountains contributed to the oversteepening major landslide movement is suspected during periods of deglaciation when abundant meltwater increased pore water pressure in bedrock fractures a fault flexure model for the development of the widespread fracturing and weakening of the proterozoic basement proposes that the surface of the williams range thrust contains a concave downward flexure the axis of which coincides approximately with the contact in the footwall between proterozoic basement and mostly cretaceous rocks movement of brittle hanging wall rocks through the flexure during laramide deformation pervasively fractured the hanging wall rocks

tutorial on seismic interferometry part 1 basic principles and applications seismic interferometry involves the crosscorrelation of responses at different receivers to obtain the green s function between these receivers for the simple situation of an impulsive plane wave propagating along the x axis the crosscorrelation of the responses at two receivers along the x axis gives the green s function of the direct wave between these receivers when the source function of the plane wave is a transientas in exploration seismology or a noise signalas in passive seismology then the crosscorrelation gives the green s function convolved with the autocorrelation of the source function direct wave interferometry also holds for 2d and 3d situations assuming the receivers are surrounded by a uniform distribution of sources in this case the main contributions to the retrieved direct wave between the receivers come from sources in fresnel zones around stationary points the main application of direct wave interferometry is the retrieval of seismic surface wave responses from ambient noise and the subsequent tomographic determination of the surfacewave velocity distribution of the subsurface seismic interferometry is not restricted to retrieving direct waves between receivers in a classic paper claerbout shows that the autocorrelation of the transmission response of a layered medium gives the plane wave reflection response of that medium this is essentially 1d reflected wave interferometry similarly the crosscorrelation of the transmission responses observed at two receivers of an arbitrary inhomogeneous medium gives the 3d reflection response of that medium one of the main applications of reflected wave interferometry is retrieving the seismic reflection response from ambient noise and imaging of the reflectors in the subsurface a common aspect of direct and reflected wave interferometry is that virtual sources are created at positions where there are only receivers without requiring knowledge of the subsurface medium parameters or of the positions of the actual sources

the acheron dorsum on mars a novel interpretation of its linear depressions and a model for its evolution abstract the acheron dorsum north of olympus mons on mars is a unique 800 km long arcuate ridge apparently unrelated to other adjacent morphologies acheron dorsum is crossed by deep and wide fractures fossae here referred to also as linear depressions or lds commonly interpreted as grabens formed by local lithosphere stress in response to endogenous mantle upwelling we suggest an alternate view that the linear depressions may result from gravitational self adjustment of a loose deposit similar to the deep seated gravitational slope deformations dsgsd or sackung a kind of slow mass movement well documented on earth numerical simulations based on a finite difference numerical model devised for terrestrial dsgsds reproduce the timing and position of lds reasonably well provided that the viscosity of the viscoplastic layer is between 7 10 15 and 10 17 pa s while rock masses typically exhibit much higher values based on comparison with glacial examples we find that these viscosities could be compatible to a rock ice mixture this leads to the hypothesis that the rock underneath acheron dorsum may be highly fragmented and that ice might have been involved in its deformation our hypothesis could shed light on the puzzling stress pattern on acheron dorsum which follows approximately the ridge without requiring the presence of hypothetical small scale endogenous currents

source process of the 2011 tohoku earthquake estimated from the joint inversion of teleseismic body waves and geodetic data including seafloor observation data source model with enhanced reliability by using objectively determined inversion settings the rupture process of the 2011 tohoku earthquake is estimated from the joint inversion of teleseismic body waves and geodetic data using multiple time window analysis to enhance the reliability of the inversion solution two important inversion setting parameters that control the spatiotemporal slip distribution the maximum slip duration of each subfault t sd and the propagation velocity of the first time window v ftw are determined by objective criteria by performing a semblance analysis of small aperture seismic array data of near source strong motion waveforms t sd is determined to be 100 s v ftw is determined to be 2 0 km s from the matching of the teleseismic and geodetic slip models the spatial resolution of geodetic inversion is significantly improved by using seafloor crustal deformation data in the source area in addition to the terrestrial global positioning system network data the estimated seismic moment and the maximum slip are 3 4 1022 n m m w 9 0 and 43 m respectively the total rupture duration is 150 s large slip is seen in the shallow part of the fault surface including the hypocenter and its spatial extent along the trench axis is 300 km this model is consistent with the results of bathymetric surveys and the slip models from tsunami data the relationships among the fault parameters of the characterized source model of the 2011 tohoku earthquake suggest the possibility that saturation of fault width occurs for this huge earthquake online material text s1 denotes the explanation of how the rupture propagation in the dip direction affects the estimated value of maximum slip duration t sd table s1 denotes the detailed information of the teleseismic stations table s2 denotes the detailed information of the terrestrial geodetic stations

temporal changes of subsurface velocities during strong shaking as seen from seismic interferometry 1 we apply a deconvolution method to a strong motion data set recorded at the surface and in boreholes in northeast honshu japan we try to characterize the nonlinear effects of the subsurface soil during strong shaking and show the change of the subsurface velocity structure during the shaking the deconvolved waveforms reflect the subsurface velocity structure and their horizontal and vertical components correspond to s and p wave respectively traveling from the borehole to the ground surface the strong motion records with smaller values of peak acceleration do not include significant nonlinear effects so the deconvolved waveforms of the observed accelerations can be well simulated by the program shake91 for high acceleration motions during the shaking of two separate earthquakes large reductions of near surface velocities are seen in results for the 2008 iwate miyagi nairiku earthquake the large high frequency ground motions over 4g at one near source station caused a nonlinear response of the soil and the reduction of the average shear wave velocity reached 24 this corresponds to a stiffness change of over 75 the soil properties and the stiffness coefficient which changed during the shaking did not fully recover after the shaking leaving a static change

gravitational slope deformation of a resurgent caldera new insights from the mechanical behaviour of mt nuovo tuffs ischia island italy abstract ischia island italy is an impressive example of the rare phenomenon of caldera resurgence the emplacement and replenishment of magmas at shallow depth resulted in a vertical uplift of about 900 m concentrated in the western portion of mt epomeo 789 m a s l as a consequence of this uplift the island has experienced several slope instabilities at different scales since the holocene from shallow mass movements to large rock and debris avalanches these mass wasting events which mobilised large volumes of greenish alkali trachytic tuff the mt epomeo green tuff megt were strictly related to volcano tectonic activity and the interaction between the volcanic slopes and the hydrothermal system beneath the island deep seated gravitational slope deformation dsgsd at mt nuovo located adjacent to densely populated coastal villages is an ongoing process that covers an area of 1 6 km 2 the mt nuovo dsgsd involves a rock mass volume of 190 mm 3 and is accommodated by a main shear zone and a series of sub vertical fault zones associated with high angle joint sets to improve our understanding of this gravity induced process we performed a physical porosity and permeability and mechanical uniaxial and triaxial deformation experiments characterisation of two ignimbrite deposits both from the megt that form a significant component of the nw sector of mt epomeo the main conclusions drawn from our experiments are twofold first the presence of water dramatically reduces the strength of the tuffs suggesting that the movement of fluids within the hydrothermal system could greatly impact slope stability second the transition from brittle dilatant to ductile compactant behaviour in the tuffs of the megt occurs at a very low effective pressure analogous to a depth of a couple of hundred metres and that this transition is likely moved closer to the surface in the presence of water we hypothesise that compactant porosity decreasing behaviour at the base of the layer could therefore facilitate slope instability although our results show that transient exposure to 300 c does not influence the short term strength of the tuff we speculate that the high in situ temperature could increase the efficiency of brittle and compactant creep and therefore increase the rate of slope deformation taken together our experimental data highlight a potentially important role for the hydrothermal system that reaches a minimum depth of 1 km in dictating the dsgsd at mt nuovo an understanding of this deformation process is not only important for the proximal coastal villages at risk of engulfment by a large debris avalanche but also for the towns and cities along the coast of the gulf of naples that are at risk to a secondary consequence of such an avalanche a tsunami wave

velocity change in the zone of a moderate mw 5 0 earthquake revealed by autocorrelations of ambient noise and by event spectra a moderate mw 5 0 earthquake occurred near mogul nevada just west of reno nevada on 26 april 2008 this mainshock was surrounded by notable foreshock and aftershock sequences due to the long foreshock sequence the area was well instrumented at the time of the mainshock we investigated the foreshock and aftershock sequences for evidence of velocity changes in the structure immediate to the hypocenter and above it in the area of observed strong ground motion using autocorrelations of the time periods with nearly continuous foreshocks and aftershocks we detected a nearly 1 negative change in velocity on recordings of station mogl which was approximately over the hypocenter of the mainshock we also observed from these recordings a shift in the spectral peaks to lower frequency following the mainshock again indicative of a velocity decrease due to the different spatial sampling of the two methods the effects could not be attributed to the same subsurface volume however both results are strong evidence for coseismic velocity changes accompanying an earthquake which is very much smaller than those for which previous velocity changes have been reported we hypothesize that these changes can be observed for even smaller earthquakes given a fortuitous placement of observing stations

tectonic significance of the present relief of the betic cordillera abstract tortonian calcarenites of the betic cordillera were deposited in coastal or very shallow marine environments and represent an ideal marker for estimating vertical movements from the late miocene to the present a map showing the heights at which these tortonian marine rocks are situated has a clear correlation with the present relief indicating that today s relief has been formed since the tortonian there is also a good correlation between present relief and the bouguer anomaly distribution in the betic cordillera as well as with crustal thickness likewise the present relief is directly related to the geodynamic setting of a horizontal n s to nnw sse compression and an almost perpendicular extension along with isostatic readjustment existing in the betic cordillera from the tortonian as a result of these regional stresses faults and folds have produced notable vertical movements the highest rates of uplift of the betic cordillera coincide with large antiforms in particular those of the sierra nevada and the sierra filabres several subsiding sectors also exist for example the granada basin or the guadalquivir basin the foreland guadalquivir basin has a complex history because the uplift in its eastern sector and subsidence in the western sector coexisted during the late tortonian today the whole betic cordillera is characterized by differential regional uplift even in the aforementioned subsiding sectors

passive monitoring of anisotropy change associated with the parkfield 2004 earthquake 1 we investigate temporal variations in the polarization of surface waves determined using ambient seismic noise cross correlations between station pairs at the time of the mw 6 0 parkfield earthquake of september 28 2004 we use data recorded by the high resolution seismic network s 3 component seismometers located along the san andreas fault our results show strong variations in azimuthal surface wave polarizations for the paths containing station varb one of the closest stations to the san andreas fault synchronous with the parkfield earthquake concerning the other station pair only smooth temporal variations of are observed two principal contributions to these changes in are identified and separated they are 1 slow and weak variations due to seasonal changes in the incident direction of seismic noise and 2 strong and rapid rotations synchronous with the parkfield earthquake for paths containing station varb strong shifts in are interpreted in terms of changes in crack induced anisotropy due to the co seismic rotation of the stress field because these changes are only observed on paths containing station varb the anisotropic layer responsible for the changes is most likely localized around varb in the shallow crust these results suggest that the polarization of surface waves may be very sensitive to changes in the orientations of distributed cracks and that implementation of our technique on a routine basis may prove useful for monitoring stress changes deep within seismogenic zones

postseismic fault healing on the rupture zone of the 1999 m 7 1 hector mine california earthquake we probed the rupture zone of the october 1999 m 7 1 hector mine earthquake using repeated near surface explosions in october 2000 and november 2001 three dense linear seismic arrays were deployed across the north and south lavic lake faults llfs that broke to the surface in the mainshock and across the bullion fault bf that experienced minor slip in that event two explosions each year were detonated in the rupture zone one on the middle and one on the south llf we found that p and s velocities of fault zone rocks increased by 0 7 1 4 and 0 5 1 0 between 2000 and 2001 respectively in contrast the velocities for p and s waves in surrounding rocks increased much less this trend indicates that the hector mine rupture zone has been healing by strengthening after the main shock most likely due to the closure of cracks that opened during the 1999 earth quake the observed fault zone strength recovery is consistent with an apparent crack density decrease of 1 5 within the rupture zone the ratio of travel time decrease for p to s waves was 0 72 consistent with partially fluid filled cracks near the fault zone this restrengthening is similar to that observed after the 1992 m 7 4 landers earthquake which occurred 25 km to the west li and vidale 2001 we also find that the velocity increase with time varies from one fault segment to another at the hector mine rupture zone we see greater changes on the llfs than on the bf and the greatest change is on the middle llf at shallow depth we tentatively conclude that greater damage was inflicted and thus greater healing is observed in regions with larger slip in the mainshock

s coda and rayleigh waves from a decade of repeating earthquakes reveal discordant temporal velocity changes since the 2004 sumatra earthquake temporal changes in the subsurface seismic velocity structure reflect the physical processes that modulate the properties of the media through which seismic waves propagate these processes such a

time dependent modelling of a mountain front retreat due to a fold to fault controlled lateral spreading abstract the eastern betic cordillera spain exemplifies at the sierra de aitana an impressive case of lateral spreading which involves a mountain anticline ridge dislodged by a post orogenic extensional tectonic the deep trenches testify the ongoing gravitational slope deformation featured by a rock mass lateral spreading the sierra de aitana anticline ridge was dislodged along a normal fault zone which generated a scarp with a kilometric lateral continuity the lateral spreading originated because eocene limestone overlays eocene marls inducing a continuous evolution over time due to visco plastic deformations and isolating huge prismatic blocks to quantify the creep driven stress strain effects at sierra de aitana ridge the mechanical and rheological parameter values of the involved rocks were quantified through field and laboratory tests which allowed to constrain an engineering geological model based on equivalent continuum approach a stress strain numerical modelling aimed at back analysing the sequential morpho structural evolution of the sierra de aitana anticline ridge was performed by reproducing the retreat of the ridge front and the time succession of faults re activations a time dependent solution was approached by assuming a time dependent creep configuration of the modelling and a parametric solution adopted to calibrate rock mass rheology also taking into account tectonic displacement due to the aitana normal fault system by simulating these element as interface in the discretized domain influence of pre existing joint sets by assuming a main anisotropy in the elasto plastic failure solution admissible variations of the regional stress field related to compressive and extensional phases and a generalised visco plastic behaviour representing the ductile marls the numerical modelling outputs that the lateral spreading mainly evolved as a creep driven process while stress release induced by tectonic activity is not sufficient to justify the observed landforms the obtained results highlight a not negligible role of inherited structural elements for regulating the time evolution of the ongoing gravitational process at the sierra the aitana anticline

horizontal dispersion of ocean tracers in internal wave shear 1 the horizontal dispersion of ocean tracers due to the interaction of vertical diffusion and the vertical shear from internal waves is examined using a lagrangian particle tracking model for idealized sinusoidal horizontal velocity profiles of unbounded vertical extent the irreversible horizontal dispersion of particle clouds is maximal when the timescale of particle diffusion across the velocity variations and the period of shear oscillation are comparable for measured velocity profiles from the thermocline in the gulf of aqaba red sea the total dispersion and irreversible dispersion of particle clouds both tend to increase with vertical diffusion cloud height and cloud age the total and irreversible horizontal cloud variances typically grow with time t like t0 to t3 and t1 to t3 respectively estimates of the irreversible horizontal dispersivity from an existing analytical model based on vertically constant oscillating shear agree remarkably well with estimates from the particle tracking model with differences dependent on the vertical variability in vertical diffusion and shear that are not incorporated in the analytical model

a deep seated compound rotational rock slide and rock spread in se spain structural control and dinsar monitoring abstract the northern slope of the sierra de aitana eastern betic cordillera is characterized by a long mountain front with a prominent eocene limestone scarp overlying ductile eocene marlstones this stratigraphic feature and the highly stepped topography produced by several normal faults favor gravitational processes such as rock avalanches rock slides and rock falls this paper reports a compound landslide comprising a rotational rock slide and slab type lateral spreading affecting these materials with blocks of volumes up to 106 m3 this lateral spread process produced singular and spectacular morphological features the simas de partagat which are trenches 20 m wide and up to 40 m deep formed by the widening of discontinuities the use of a differential sar interferometry technique for monitoring this landslide over a time span of 11 yr has revealed that velocity of movement is insignificant with rates comprised between 0 and 2 mm yr 1 and cumulative negligible displacements individual rock blocks initially located at the free face of the scarp were affected by slides at the base of the scarp descending from a few to several dozen meters along the slope blocks broke up as displacement progresses with several in different stages of evolution being recognizable along the slope differential sar interferometry shows a greater activity in the area north of compound landslide although velocity is extremely low below 16 mm yr 1 this extremely slow movement revealed by interferometry is in agreement with other geological and geomorphological evidence such as the existence of speleothems and cemented breccias against the head walls of the trenches both deposits are indicative of a long period of discontinuity widening also undisturbed debris deposits covering ancient rock slides are indicative of very slow gravitational processes characterized by long dormant periods in addition a historical picture from 1898 shows nearly negligible change in the simas de partagat over this 112 yr period

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

stress strain time numerical modelling of a deep seated gravitational slope deformation preliminary results abstract an analysis of the effects of creep on the development of a deep seated gravitational slope deformation dsgsd carried out by numerical modelling is described the slope rock mass evolution has been simulated applying different creep rheological models the studied dsgsd is located in the central italian alps val s giacomo it is characterised by three main scarps different sets of tensile trenches and counterscarps mapped during a detailed geomorphological survey the mechanical behaviour of the rock masses in terms of elasto plastic parameters has been defined on the base of laboratory and in situ tests in order to simulate this instability process a stress strain time numerical modelling has been performed by a finite difference numerical code fast lagrangian analysis of continua flac the effects of different constitutive model laws have been considered the visco elastic maxwell model the visco elastic burger model and the elasto visco plastic burger model the modelling has been performed simulating the melting of the ancient glacier starting from its maximum load because of the difficulty to determine rock mass creep parameters for each of the rheological models a sensitivity analysis has been performed varying the physical mechanical properties the visco elasto plastic model allows to underline the formation of shear surface showing a depth and a shape in good agreement with the morphologic features of the slope the only action of unloading due to glacier melting seems to be insufficient to generate deep critical surfaces which can be related with the formation of the dsgsd

quaternary catastrophic rock avalanches in the central apennines italy relationships with inherited tectonic features gravity driven deformations and the geodynamic frame abstract five cases of quaternary rock avalanches detached from carbonate mountain ridges in the central apennines are presented due to the large amount of rock masses involved the width of accumulation and detachment areas and the damming in the host environment the analysed rock avalanches can be considered as catastrophic rock slope failures sporadic events in a mountain region characterized by low elevation but where mountain ridges can have a relative elevation of up to 1 km above the lowermost valley floors the geological setting of tectonic structures that originated during the apennine orogenesis influenced rock avalanche characteristics determining the location and shape of detachment areas the kind of rock mass involved and the failure mechanisms two main types have been identified i forelimb rock slide avalanches frsa such as the lettopalena and mt arezzo rock avalanche which involved cenozoic heterogeneous sequences of carbonate ramp deposits detached from box shaped source areas according to a rock sliding mechanism and ii backlimb slide wedge rock avalanches bswra such as the campo di giove scanno and celano rock avalanches that detached from sub circular source areas carved on fault bounded ridges and involving meso cenozoic carbonate rocks with a combined sliding and rock wedge failure mechanism the campo di giove lettopalena and scanno rock avalanches originated from mountain ridges bounded by inactive fault zones and undergoing deep seated gravitational slope deformations dsgsds at the mountain scale these three rock slope failures are considered as isolated events of long lasting deformative processes featuring creep deformation gravity driven deformations firstly generated as a response to stacking processes and synchronous normal faulting during the neogene early pleistocene apennine tectonics in particular the caramanico fault system cfs and the genzana fault gf bordering the carbonate ridges from which the campo di giove and scanno rock avalanches originated respectively are here considered as backlimb collapse structures accommodating the passive uplift and deformation of positive tectonic structures gravity driven deformations persisted during the post early pleistocene dome like uplift of the whole apennine region the regional uplift created the first order 200 km topographic wave length of the belt i e a periodic loading which has been balanced by the deflection of the apennine crust and lithosphere on the contrary shorter topographic wave lengths inherited from former thrusting and synchronous normal faulting determined local isostatic imbalances bearing a large potential for the mature development of dsgsds on mountain ridges favoured also by lateral unloading due to linear erosion and increase of topographic stress thus a cause effect relationship is hypothesized between the geodynamic evolution of the belt and mountain sized gravity driven deformations including large rock slope failures

time lapse changes of seismic velocity in the shallow ground caused by strong ground motion shock of the 2000 western tottori earthquake japan as revealed from coda deconvolution analysis abstract a large earthquake shock often drops the seismic velocity of the shallow ground however it is not clear whether the dropped velocity recovers shortly after the earthquake shock or not the purpose of this article is to report the time lapse changes of seismic velocity in the shallow ground after the 2000 western tottori earthquake japan we deconvolve the coda record of small earthquakes registered on the ground surface by that registered at the 100 m depth in a borehole at a station that experienced a strong shock from the mainshock because coda waves are mostly composed of randomly scattered s waves deconvolution of the two coda records enables us to obtain a robust image of the ground structure assuming that the shear modulus was reduced at the depth of 0 11 m we estimate the shear modulus change in each time period after the mainshock by fitting synthetic coda deconvolution to the observed one from 1 to 16 hz as a result the shear modulus dropped to 52 of the value obtained before the mainshock a few minutes after the strong earthquake shock this caused a decrease in the s wave velocity of 30 and an increase in s wave travel time of 17 msec the shear modulus continued to recover for over 1 yr following the logarithm of the lapse time it recovered to 69 83 87 and 97 of the value obtained before the mainshock in the periods of 0 to 1 week 1 week to 1 month 1 month to 1 yr and 1 to 4 yr after the mainshock respectively

toward source region tomography with intersource interferometry shear wave velocity from 2018 west bohemia swarm earthquakes the concept of seismic interferometry embraces the construction of waves traveling between receivers or sources with cross correlation techniques in the present study cross correlations of coda waves are used to measure traveltimes of shear waves between earthquake locations for five event clusters of the 2018 west bohemia earthquake swarm with the help of a high quality earthquake catalog i was able to determine the shear wave velocity in the region of the five clusters separately the shear wave velocities range between 3 5 and 4 2 km s the resolution of this novel method is given by the extent of the clusters and better than for a comparable classical tomography it is suggested to use the method in a tomographic inversion and map the shear wave velocity in the source region with unprecedented resolution furthermore the influence of focal mechanisms and the attenuation properties on the polarity and location of the maxima in the cross correlation functions is discussed the intracluster ratio of p wave to s wave velocity is approximately fixed at 1 68

cross correlation analysis of long term ambient seismic noise recordings in the caribbean netherlands to monitor the volcanoes on saba and st eustatius

deformation at depth associated with the 12 may 2008 mw 7 9 wenchuan earthquake from seismic ambient noise monitoring 1 we track the temporal evolution of seismic wave speed to detect changes in material properties at depth driven by deformation associated with the 2008 mw 7 9 wenchuan earthquake we analyze ambient noise correlation functions to monitor seismic wave speed variations the data were continuously recorded during 2 years by 114 broadband stations in a region that covers the southern two thirds of the ruptured fault we perform the analysis in the 12 to 20 s period band by comparison with measurements in the band 1 to 3 s we show that the seismic velocity changes cannot be explained by a shallow perturbation but are related to deformation at depth in the crust the spatial and temporal characteristics of these variations can thus be viewed as reflecting the middle crust behavior in particular the results suggest that the deformation in the middle crust is different beneath tibet and the sichuan basin

trampoline effect in extreme ground motion in earthquake hazard assessment studies the focus is usually on horizontal ground motion however records from the 14 june 2008 iwate miyagi earthquake in japan a crustal event with a moment magnitude of 6 9 revealed an unprecedented vertical surface acceleration of nearly four times gravity more than twice its horizontal counterpart the vertical acceleration was distinctly asymmetric the waveform envelope was about 1 6 times as large in the upward direction as in the downward direction which is not explained by existing models of the soil response we present a simple model of a mass bouncing on a trampoline to account for this asymmetry and the large vertical amplitude the finding of a hitherto unknown mode of strong ground motion may prompt major progress in near source shaking assessments

structural constraints on deep seated slope deformation kinematics abstract a significant sackung type deep seated slope gravitational deformation dsgsd was recognised for the first time by the authors in the middle part of valfurva east of bormio rhaetian alps italy the reconstruction of its kinematics age and state of activity is presented through a detailed description of its morphological geomechanical and structural features an integrated multi disciplinary approach was performed to achieve a clear comprehension of the phenomenon field surveys and aero photo interpretation were carried out in order to clarify the structural geological and geomorphological setting in which the dsgsd developed a kinematic conceptual model of the slope deformation was developed through the analysis of morpho structures of their significance and relationships with lithological markers and quaternary deposits after a geomechanical characterisation of the rock mass involved in the slope deformation numerical modelling was performed to verify the hypotheses made on kinematics and driving factors of the phenomenon the sackung affects pre permian metapelites metabasites and marbles belonging to the upper austroalpine basement of the campo nappe as well as late pleistocene and holocene glacial and rock glacier deposits the deformation started after the late wurmian age 15 000 11 000 years b p and continued until few centuries ago not excluding a present day low rate activity deformation consists in a large oblique sagging along a deep confined sliding surface associated with gravitational reactivation of pre existing late alpine and recent tectonic brittle structures leading to the formation of n s and wnw ese trending gravitational morpho structures the evolution of the wnw ese trending system resulting in asymmetric trenches led to progressive failure of the lower part of the slope during the last 10 000 years as testified by large paleo landslide accumulations and it is still in progress numerical modelling indicates post glacial unloading as the main triggering factor of the slope deformation the importance of this deep seated slope deformation is enhanced by the occurrence of the 30 mm 3 active ruinon landslide in the lower part of the slope such landslide is subjected to rapid evolution and threatens the valley floor establishing an important risk factor connected to human lives and socio economic activities

seismic evidence of nonlinear crustal deformation during a large slow slip event in mexico repeated cross correlations of ambient seismic noise indicate a long term seismic velocity change associated with the 2006 m7 5 slow slip event sse in the guerrero region mexico because the sse does not radiate seismic waves the measured velocity change cannot be associated with the response of superficial soil layers to strong shaking as observed for regular earthquakes the perturbation observed maximized at periods between 7 s and 17 s which correspond to surface waves with sensitivity to the upper and middle crust the amplitude of the relative velocity change 10 3 was much larger than the volumetric deformation 10 6 at the depths probed 5 20 km moreover the time dependence of the velocity perturbation indicated that it was related to the strain rate rather than the strain itself this suggests that during strong slow slip events the deformation of the overlying crust shows significant nonlinear elastic behavior

rupture process of the 2008 iwate miyagi nairiku japan earthquake derived from near source strong motion records abstract we derive the rupture process of the 2008 iwate miyagi nairiku japan earthquake m jma 7 2 during which the largest ground acceleration to date namely 4022 cm sec 2 was recorded at a hanging wall station iwth25 station of kik net just above the hypocenter velocity waveform data 0 1 1 hz at 14 strong motion stations of k net and kik net including the borehole records of iwth25 are inverted using the multi time window linear waveform inversion method we assume a horizontally layered velocity structure model having low velocity subsurface layers for each station in order to calculate the green s functions the waveform inversion indicates that there are two major slip patches one patch extends from the hypocenter to the southern shallower part of the fault a particularly large slip area in this patch is centered approximately 8 km to the south of the hypocenter with a maximum slip of 6 2 m the area ruptured between 4 and 9 sec after the initial break the other patch with smaller slip is located in the northern part which broke after the rupture of the southern slip patch the initial 0 4 sec rupture occurred beneath iwth25 contributing to the synthesis of a distinctive upward velocity pulse at this station examination of the slip contribution to the synthetic velocity waveforms and comparison of the isochrones with the slip distribution suggest that a peak acceleration greater than 4000 cm sec 2 observed at iwth25 was generated from the area that is closest to the hypocenter in the southern particularly large slip area

coda wave interferometry for estimating nonlinear behavior in seismic velocity in coda wave interferometry one records multiply scattered waves at a limited number of receivers to infer changes in the medium over time with this technique we have determined the nonlinear dependence of the seismic velocity in granite on temperature and the associated acoustic emissions this technique can be used in warning mode to detect the presence of temporal changes in the medium or in diagnostic mode where the temporal change in the medium is quantified

imaging preeruptive and coeruptive structural and mechanical changes of a volcano with ambient seismic noise 1 forecasting the location of an eruption is of primary importance for risk management in volcanic regions locating the underground structural changes associated with a potential eruption is also a key issue to better understand the dynamics at work in a volcano using recent results in wave physics we develop an imaging procedure that is based on the sensitivity of multiply scattered waves to weak changes in heterogeneous media this procedure allows to locate changes in both mechanical and scattering properties of the studied medium we study ambient seismic noise from 19 broadband stations at the active volcano piton de la fournaise on reunion island recorded from june to december 2010 during this period two volcanic eruptions occurred at two different locations we calculate the noise cross correlations and study two types of changes in the coda apparent velocity variations related to changes in the elastic properties of the medium and waveform decoherence associated with variations in the scattering and thus the geological structures we observe that the temporal variations of both of these parameters provide potential precursors of volcanic eruptions at piton de la fournaise the locations determined from the preeruptive and coeruptive changes in both parameters are in good agreement with the actual eruptive activities these data demonstrate that the coda of ambient noise correlations contains deterministic information on the locations of the eruptive processes in an active volcano our analysis offers an original and significant constraint for the localization of forthcoming volcanic eruptions

coseismic and postseismic velocity changes measured by repeating earthquakes 1 repeating earthquakes that rupture approximately the same fault patch and have nearly identical waveforms are a useful tool for measuring temporal changes in wave propagation in the earth s crust since source and path effects are common to all earthquakes in a repeating earthquake sequence multiplet differences in their waveforms can be attributed to changes in the characteristics of the medium we have identified over 20 multiplets containing between 5 and 40 repeating events in the aftershock zones of the 1989 loma prieta and 1984 morgan hill california earthquakes postmain shock events reveal delays of phases in the early s wave coda of as much as 0 2 s relative to premain shock events the delay amounts to a path averaged coseismic velocity decrease of about 1 5 for p waves and 3 5 for s waves since most of the multiplets are aftershocks and follow omori s law we have excellent temporal sampling in the immediate postmain shock period we find that the amplitude of the velocity decrease decays logarithmically in time following the main shock in some cases it returns to the premain shock values while in others it does not similar results are obtained for the morgan hill main shock because the fractional change in s wave velocity is greater than the fractional change in p wave velocity it suggests that the opening or connection of fluid filled fractures is the underlying cause the magnitude of the velocity change implies that low effective pressures are present in the source region of the velocity change our results suggest that the changes are predominantly near the stations and shallow but we cannot exclude the possibility that changes occur at greater depth as well if the variations are shallow we may be detecting the lingering effects of nonlinearity during main shock strong ground motion if the variations are deep it suggests that pore pressures at seismogenic depths are high which would likely play a key role in the earthquake process

time lapse monitoring of seismic velocity associated with 2011 shinmoe dake eruption using seismic interferometry an extended kalman filter approach seismic interferometry is a powerful tool to monitor the seismic velocity change associated with volcanic eruptions for the monitoring changes in seismic velocity with environmental origins such

distribution of seismic wave speed changes associated with the 12 may 2008 mw 7 9 wenchuan earthquake 1 we used continuous recordings in sichuan china to track the temporal change of the seismic wave speed at a regional scale for 2 years including the wenchuan mw 7 9 earthquake the data are recorded by a temporary network of 156 broad band seismographs in a region that covers the southern 2 3 of the fault activated during the earthquake a doublet analysis applied on the codas of seismic noise cross correlation functions is used to detect temporal velocity changes we found clear evidence that the seismic velocity drops by up to 0 08 in the fault region just after the earthquake with fluctuations within 0 02 before the earthquake we compared the measurements in different sub arrays to get a spatial distribution of the velocity changes this distribution is consistent with the volumetric strain change during the wenchuan earthquake and shows that the co seismic velocity change is not controlled by the response of sediments

seismic evidence for rock damage and healing on the san andreas fault associated with the 2004 m 6 0 parkfield earthquake we deployed a dense linear array of 45 seismometers across and along the san andreas fault near parkfield a week after the m 6 0 parkfield earthquake on 28 september 2004 to record fault zone seismic waves generated by aftershocks and explosions seismic stations and explosions were co sited with our previous exper iment conducted in 2002 the data from repeated shots detonated in the fall of 2002 and 3 months after the 2004 m 6 0 mainshock show 1 0 1 5 decreases in seismic wave velocity within an 200 m wide zone along the fault strike and smaller changes 0 2 0 5 beyond this zone most likely due to the coseismic damage of rocks during dynamic rupture in the 2004 m 6 0 earthquake the width of the damage zone characterized by larger velocity changes is consistent with the low velocity waveguide model on the san andreas fault near parkfield that we derived from fault zone trapped waves li et al 2004 the damage zone is not symmetric but extends farther on the southwest side of the main fault trace waveform cross correlations for repeated aftershocks in 21 clusters with a total of 130 events located at different depths and distances from the array site show 0 7 1 1 increases in s wave velocity within the fault zone in 3 months starting a week after the earthquake the velocity recovery indicates that the damaged rock has been healing and regaining the strength through rigidity recovery with time most likely due to the closure of cracks opened during the mainshock we estimate that the net decrease in seismic velocities within the fault zone was at least 2 5 caused by the 2004 m 6 0 parkfield earthquake the healing rate was largest in the earlier stage of the postmainshock healing process the magnitude of fault healing varies along the rupture zone being slightly larger for the healing beneath middle mountain correlating well with an area of large mapped slip the fault healing is most promi nent at depths above 7 km

seismic velocity reductions caused by the 2003 tokachi oki earthquake 1 we use four repeating earthquake sequences located near hokkaido to identify velocity changes caused by the mw 8 0 2003 tokachi oki earthquake using a moving window cross correlation technique we identify delays in the arrival time of seismic waves that accumulate linearly with time into the seismogram this behavior is indicative of multiple scattering within a medium where the seismic velocity has been reduced for all of our earthquake receiver geometries we find evidence of significant velocity reductions close to the receiver the correlation of the size of the velocity reductions with both strong shaking and site characteristics suggests that these velocity reductions are caused by damage to near surface materials created by nonlinear strong ground motion for earthquake receiver geometries where the seismic waves cross the tokachi oki rupture zone we identify particularly large reductions in velocity as a result of the earthquake for these geometries we believe that the rupture zone of the tokachi oki earthquake or the shallow crust above it represents a second region where seismic velocities are reduced as a result of the main shock

coseismic velocity change in and around the focal region of the 2008 iwate miyagi nairiku earthquake 1 the 2008 m7 2 iwate miyagi nairiku earthquake occurred in ne japan where dense seismic networks exist using the data from these networks we determined the coseismic seismic velocity change associated with this earthquake by two different methods ambient noise interferometry and vertical array interferometry of coda wave the purpose of this article is to reveal the spatial distribution and the cause of the velocity change by integrating these two approaches ambient noise interferometry revealed a coseismic velocity decrease of rayleigh wave by 0 1 0 5 at 0 25 0 5 hz we also estimated the spatial distribution of the velocity change by a tomographic inversion the velocity decrease was distributed in and around the focal area in the second method we applied cross correlation analysis to coda waves observed by the kik net vertical array we detected a shear velocity decrease of approximately 5 in shallow layers up to a few hundred meters depth quantitative comparison of the two results reveals that the 5 shear velocity decrease in shallow layers can explain the 0 1 0 5 decrease of rayleigh wave velocity the distribution of the velocity decrease is similar to that of the strong ground motion and the static stress change however a significant velocity increase is not observed in the compression area where a velocity increase is expected based on the observations we consider that the primary factor affecting the velocity change is damage in shallow layers due to strong motion the effect of the static stress change might be masked by the larger effect of the strong motion

numerical modelling of plio quaternary slope evolution based on geological constraints a case study from the caramanico valley central apennines italy evidence of deep seated gravitational slope deformations dsgsd and of large prehistoric landslides is fairly widespread within the central apennines italy these gravity induced processes accompanied the intense plio quaternary uplift phases that affected the mountain chain in this study a multidisciplinary approach has been adopted in order to better constrain the relationship between the tectonic evolution and the gravitational morphogenesis of a typical apennine morphostructure such as the caramanico valley for this purpose a conceptual model of the morphostructural evolution of the area has been reconstructed on the basis of geo logical constraints derived by the integration of detailed geological structural and geomorpholo gical surveys with available literature data based on this evolutionary model a multistage numerical modelling using the finite difference method code flac 6 0 has been performed in order to i evaluate the effect of the uplift related morphological changes of the valley slope system and ii assess the role of the horizontal vertical stress ratio variations due to geodynamic regime shifts the results of the numerical model show a good fit with the actual geomorphical evidence and also confirm the presence during some evolutionary stages of stress strain conditions compatible with those necessary to produce the massive rock slope failures testified by the presence of large palaeo landslide deposits

influence of structural framework on mountain slope deformation in the maiella anticline central apennines italy abstract relationships between tectonic framework and gravity driven phenomena have been investigated in an area of the central apennines italy characterised by high relief the north south half dome shaped maiella anticline lies in the easternmost part of the apennine fold and thrust belt its backlimb is bordered by the caramanico fault a normal fault with a maximum downthrown of about 3 5 km that separates the western slope of the maiella massif from the caramanico valley the southwestern maiella area is affected by deep seated gravitational slope deformation indicated by major double crest lines down hill and up hill facing scarps a pattern of crossing trenches bulging at the base of slopes and the presence of different types of landslide and talus slope deposits the onset and development of deep seated gravitational slope deformations and the location of quaternary massive rockslope failures have been strongly influenced by the structural framework and tectonic pattern of the anticline deep seated gravitational slope deformation at mt macellaro mt amaro ridge has developed along the maiella western reverse slope in correspondence with the anticline axial culmination it is bordered at the rear by a nnw sse oriented dextral strike slip fault zone and has an e w direction of rock mass deformation closer to the southern plunging area of the anticline gravity driven phenomena show instead a n s and nw se direction influenced by bedding attitude 3d topographic models illustrate the relationship between deep seated gravitational slope deformation and massive rockslope failures the campo di giove rock avalanche a huge quaternary failure event was the result of an instantaneous collapse on a mountaine slope affected by a long term gravity driven deformation

analysis of lateral rock spreading process initiation with a numerical modelling approach the first erosional front of the south eastern alps has been affected by several deep seated landslides the movements affected a jurassic limestone sequence underlain by an upper trias unit keuper mainly composed of marl and clays horst and graben like structures newly formed gravitational faults outflow and other field evidence suggest that such movements are consistent with lateral rock spreading processes an example of such processes is the la marbriere slope where field investigations have revealed that three distinct zones corresponding to three evolutionary stages of movement exist the question is what are the structural and mechanical modifications undergone by the slope between those evolution stages to tackle this question numerical models based on a 2d cross section of the la marbriere slope have been performed results show that to fit the structural evidence of the precollapse situation elasto plastic behaviour of the trias keuper unit is needed the transition between the precollapse and fresh post collapse situations requires a modification of the mechanical behaviour of the trias keuper unit to burger type resulting in the formation of antithetic and synthetic gravitational faults producing a graben like structure

lateral spreading processes in mountain ranges insights from an analogue modelling experiment abstract the results of a study on gravitational induced lateral spreading phenomena are here reported the lateral spreading processes are widely represented in the italian apennines due to the widespread overlapping of stiff rock masses on more ductile ones the stress strain evolution of these processes was investigated by combining an analogical and a numerical modelling approach the analogue modelling reproduced the evolution of a carbonate ridge thrust over a clayey flysch with reference to the case study of mt roccatagliata mt sant angelo ridge the rock mass juxtaposition was reproduced in a laboratory experiment by overlapping a brittle concrete on a viscous ductile material these materials were selected with rheological properties physically scaled with respect to the natural rock mass prototypes the spreading phenomenon was modelled by opening horizontal panels in sequential stages and monitoring the resulting stresses within the ductile material during the experiment a stress strain modelling was also performed by an fdm numerical solution this modelling replied the laboratory experiment by testing the use of different rheological constitutive laws the resulting stresses and morphological evolutions are comparable with the analogical laboratory experiment only if a time dependent rheological behaviour is assumed for the ductile material the results show that lateral spreading processes can be properly investigated by combining analogue and numerical modelling techniques which take into account the viscous plastic behaviour of the used materials

empirical synthesis of time asymmetrical green functions from the correlation of coda waves we demonstrate the existence of long range field correlations in the seismic coda of regional records in alaska the cross correlations between the different components of coda records at two points are measured for a set of distant earthquakes remarkably while individual correlations have a random character the correlations averaged over source and time exhibit deterministic arrivals that obey the same symmetry rules as the green tensor between the two points in addition the arrival times of these waves coincide with propagating surface waves between the two stations thus we propose to identify the averaged correlation signals with the surface wave part of the green tensor we observe the causal and anticausal parts of the green function however we find experimentally that amplitudes at positive and negative times are not equal we explain this observation by the long lasting anisotropy of the diffuse field we show that the flux of energy coming from the source can still dominate the late coda and result in nonsymmetric cross correlations when the distribution of earthquakes is not isotropic around the stations the extraction of green functions from coda waves allows new types of measurements with seismic waves along paths between stations that could not be obtained with the waves produced by earthquakes

modelling of thermo mechanical effects in a rock quarry wall induced by near surface temperature fluctuations abstract mechanical response of rock masses to the periodical fluctuation of surface temperatures is a relevant topic to be focused on for the comprehension of short to long term stability of rock slopes continuously stressed by slight yet periodical actions to better understand how preparatory factors can lead rock masses toward failure thermal and strain monitoring activities are ongoing in a selected quarry wall where an experimental test site was implemented on a jointed rock block the role of pervasive joints in perturbing the heating cooling process of the rock mass and their related effects was already output by direct and remote monitoring for these purposes fdm numerical modelling was focused on the comprehension and simulation of induced mechanical effects due to cyclical thermal forcings over a simplified 2d half space therefore the role of rock mass joints on both heat propagation and resulting thermo mechanical effects was analysed basing on monitoring data field experiments and numerical modelling numerical results output the role of periodic daily annual and compound thermal input in inducing irreversible deformation along joints under different rock mass jointing configuration as a function of the intrinsic period of thermal input and joint attitude temperature distribution across joints was also analysed as a possible constraining effect for time and space distribution of yielding a sensitivity analysis of heat propagation conditions was performed in order to infer the role of joint sets on induced thermo mechanical strains at the rock block scale a non negligible influence on surficial as well as deeper portions of the rock mass was observed highlighting how near surface temperature fluctuations can drive the long term evolution of rock block conditions towards failure

estimating near surface shear wave velocities in japan by applying seismic interferometry to kik net data 1 we estimate shear wave velocities in the shallow subsurface throughout japan by applying seismic interferometry to the data recorded with kik net a strong motion network in japan each kik net station has two receivers one receiver on the surface and the other in a borehole by using seismic interferometry we extract the shear wave that propagates between these two receivers applying this method to earthquake recorded data at all kik net stations from 2000 to 2010 and measuring the arrival time of these shear waves we analyze monthly and annual averages of the near surface shear wave velocity all over japan shear wave velocities estimated by seismic interferometry agree well with the velocities obtained from logging data the estimated shear wave velocities of each year are stable for the niigata region we observe a velocity reduction caused by major earthquakes for stations on soft rock the measured shear wave velocity varies with the seasons and we show negative correlation between the shear wave velocities and precipitation we also analyze shear wave splitting by rotating the horizontal components of the surface sensors and borehole sensors and measuring the dependence on the shear wave polarization this allows us to estimate the polarization with the fast shear wave velocity throughout japan for the data recorded at the stations built on hard rock sites the fast shear wave polarization directions correlate with the direction of the plate motion

fractional seismic velocity change related to magma intrusions during earthquake swarms in the eastern izu peninsula central japan 1 we investigated temporal changes in seismic velocity associated with active seismic swarms and crustal deformations that occurred in 2006 and 2009 in the eastern izu peninsula of japan to detect changes in seismic velocity during and after these swarm episodes we used a passive image interferometry technique by estimating the phase shift of auto correlation functions of continuous seismic waveforms in a frequency band of 1 3 hz during the 2006 and 2009 swarm episodes a significant velocity decrease 0 3 was detected at the station nearest the swarm area this velocity decrease occurred when the volumetric strain change at the surface due to magma intrusion was larger than 10 6 we could not however find a clear correlation between the velocity decrease and the peak ground acceleration caused by moderate earthquakes m 5 that occurred during the swarms we also found that during the interseismic period the velocity decrease gradually recovered and appears to be proportional to displacement at the surface measured by gps stations these results suggest that the change in the subsurface velocity structure in the eastern izu peninsula strongly reflects strain changes caused by magma intrusion into the crust

mapping pressurized volcanic fluids from induced crustal seismic velocity drops volcanic eruptions are caused by the release of pressure that has accumulated due to hot volcanic fluids at depth here we show that the extent of the regions affected by pressurized fluids can be imaged through the measurement of their response to transient stress perturbations we used records of seismic noise from the japanese hi net seismic network to measure the crustal seismic velocity changes below volcanic regions caused by the 2011 moment magnitude m w 9 0 tohoku oki earthquake we interpret coseismic crustal seismic velocity reductions as related to the mechanical weakening of the pressurized crust by the dynamic stress associated with the seismic waves we suggest therefore that mapping seismic velocity susceptibility to dynamic stress perturbations can be used for the imaging and characterization of volcanic systems

sudden drop of seismic velocity after the 2004 mw 6 6 mid niigata earthquake japan observed with passive image interferometry 1 passive image interferometry pii is a seismological method employing ambient seismic noise to monitor the temporal evolution of mean shear wave velocity within the earth first the elastic green s tensor between two seismometers is computed from the cross correlation of seismic noise recorded during a certain period second the constructed seismograms of different time periods are treated as earthquake multiplets and small time shifts in their coda are used to invert a relative change in mean shear wave velocity when applied to the source region of the 2004 mw 6 6 mid niigata earthquake japan centroid depth 5 km we used noise recorded at six seismometers located at a distance of less than 25 km from the epicenter daily inversions during the 2 months before and after the earthquake show a sudden drop of mean shear wave velocity of some tenths of a percent at the time of the mid niigata earthquake using noise in two frequency bands 0 1 0 5 hz and 2 8 hz we find similar amplitudes for the velocity drop which indicates that changes are not restricted to the shallow subsurface possible interpretations of this velocity decrease are a decrease of crustal stress after the earthquake a nonlinear site response in the shallow subsurface layer due to strong ground motion or structural weakening due to the creation of new fractures in the source area of the earthquake

time lapse changes of p and s wave velocities and shear wave splitting in the first year after the 2011 tohoku earthquake japan shallow subsurface

large sackung along major tectonic features in the central italian alps deep seated gravitational slope deformation sackung is common in alpine mountain belts it is controlled by lithological geomorphological and structural features we describe and discuss five examples of dsgsd along the insubric line periadriatic fault in the central italian alps the five examples are different in morphology size state of activity and distribution and are located along both primary and secondary valleys we demonstrate relations between structural and gravitational features and discuss the possibility that structural has both passive and active roles in sackung development analysis of ps sar data shows that the studied examples are not active today numerical modelling demonstrates the importance of lithological and structural constraints postglacial debuttressing groundwater fluctuations and weathering on sackung triggering and development

temporal change in site response caused by earthquake strong motion as revealed from coda spectral ratio measurement 1 the spectral ratios of coda waves of local earthquakes have been often used as measures of relative amplification factors of different sites applying this method to coda waves registered by seismometers installed on the surface and at the bottom of a borehole we succeeded in stably measuring the temporal change in site response associated with the occurrence of a large earthquake strong motion a remarkable drop of coda spectral ratio and a shift of the peak frequency were observed during strong shake at two sites by the 2000 western tottori earthquake and at a site by the 2003 tokachi oki earthquake in japan the reduction of the peak frequency reached 30 70 at all the sites after that the peak frequency logarithmically recovered to the value before the strong motions for a few years at two sites whereas the other one quickly recovered in a few tens of minutes

an investigation into the development of toppling at the edge of fractured rock plateaux using a numerical modelling approach abstract the mechanisms controlling the onset of minor slope instability at the edges of rocky plateaux exhibiting lateral spreading phenomena are yet to be fully understood hypotheses have recently been introduced to explain the influence of groundwater within these plateaux on geomorphological processes leading to slope instability we present a back analysis of a recent landslide which occurred on 27th february 2014 in the town of san leo italy the role of the softening of basal clay shales and erosion due to seepage is investigated using finite element geomechanical models both processes were observed in the field and are related to groundwater discharging along the contact between the rocky slab and the clay rich substratum fracture propagation paths involving pre existing discontinuities and intact rock bridges failure were simulated using a simplified discrete fracture network dfn model coupled with a voronoi polygonal mesh approach model results allow the failure to be classified as a secondary toppling phenomenon moreover a critical amount of undermining was indicated by the models agreeing with field observations made prior to the failure based on the modelling results an interpretation of the overall mechanism inducing failures at the edges of fractured rock slabs is given in particular the inter relationships between groundwater flow and geomorphic processes acting within the rock masses are presented

monitoring seismic velocity change caused by the 2011 tohoku oki earthquake using ambient noise records 1 we estimated the changes in seismic velocity in the southern tohoku district of japan during the six month period centered on the 11 march 2011 tohoku oki earthquake using scattered waves retrieved by autocorrelation of ambient seismic noise the estimated velocity decrease after the earthquake and after two large aftershocks in the study area was as great as 1 5 in the area nearest to the mainshock the velocity changes displayed gradual healing the spatial distribution of the velocity change showed a correlation with both the changes in static strain derived from gps records and the peak particle velocity experienced during the three earthquakes derived from strong motion records therefore our results show that velocity changes possibly contain information from deep in the crust bearing on coseismic stress release in addition to shallower effects due to strong ground motion

coseismic and postseismic elastic wave velocity variations caused by the 2008 iwate miyagi nairiku earthquake japan 1 we analyze coseismic and postseismic velocity variations caused by the june 13 2008 iwate miyagi nairiku earthquake mw 6 9 using passive image interferometry pii seismic noise is correlated in order to reconstruct the green s function between two sensors shear wave velocity changes are determined by relating the coda parts of the daily green s functions to a long term reference green s function our study extends from january 2008 to august 2010 and includes the correlations for 190 station pairs in three different frequency ranges from 0 125 to 1 0 hz we show that combining the 9 different component cross correlation functions stabilizes the velocity change estimation and increases analysis resolution the observed velocity change curves can be fitted by model time series consisting of a coseismic velocity drop followed by logarithmic postseismic recovery and seasonal velocity variations the coseismic velocity drops are stronger at higher frequencies and are concentrated in the southern part of the fault zone a tomography algorithm was developed to reproject the observed velocity variations of the different sensor pairs onto the single sensors the depth distribution of coseismic changes was modeled for the three stations with the largest velocity drops at two stations the coseismic velocity changes are located in the upper several hundred meters the third station shows indications for deeper changes in the order of kilometers postseismic recovery takes significantly longer than the analyzed two year period seasonal velocity variations with periods of one year are observed at all analyzed frequencies for most station pairs

landslides in eastern honshu induced by the 2011 tohoku earthquake in this article we discuss the character and spatial pattern of coseismic landslides from the eastern honshu region of japan which was strongly shaken in the 2011 tohoku earthquake we developed a detailed geospatial database of 3477 landslides based on postearthquake field surveys and examination of high resolution satellite imagery across a 28 380 km2 landslide study area analysis of the database shows that a substantial majority 80 of landslides occurred in quaternary soil and neogene rock units despite their abundance in the study area relatively few landslides occurred in pre neogene rocks i e older than 23 ma further examination of the data showed that the most common types of landslides were 1 disrupted landslides in neogene sedimentary rocks and 2 lateral spreading in quaternary sediments however we found that coseismic landslide erosion i e debris mobilization was almost fully dominated by lateral spreading within quaternary sediments when comparing the landslide inventory with ground motions recorded by dense regional seismic arrays we found no statistically significant correlation between landslide intensity and ground motion within the study area online material derivation of empirical parameters used in the area to volume transformations for lateral spreads

temporal change in shear velocity and polarization anisotropy related to the 2011 m9 0 tohoku oki earthquake examined using kik net vertical array data 1 the m9 0 tohoku oki earthquake took place off ne japan which is covered by a dense seismic network in particular kik net observed the strong motions of the main shock and numerous aftershocks both on the ground and at the bottom of boreholes at a depth of a few hundred meters we applied cross correlation analysis to the coda part of a seismogram observed by kik net and estimated not only the temporal change in shear velocity but also the change in polarization anisotropy between the bottom of the borehole and the ground the shear velocity was suddenly reduced by 5 to 10 after the tohoku oki earthquake over a wide area of ne japan which is consistent with the results of a previous study although some stations also reveal a change in polarization anisotropy the polarization anisotropy change is smaller than the velocity change which may suggest that the static stress change due to the coseismic slip on the pacific plate is not large enough to change the direction of polarization anisotropy and or deviatoric stress in the land area of ne japan

mountain slope deformations along thrust fronts in jointed limestone an equivalent continuum modelling approach abstract engineering geology studies of natural slope stability have rarely relied on continuum modelling of discontinuous rock mass or the use of conventional constitutive laws in fem or fdm codes the paper proposes the use of numerical modelling based on a practical equivalent continuum approach for analysing the deep seated gravitational slope deformations dsgsd observed in the thrust front area of the lepini mountains italian apennines the dsgsd phenomena affect a carbonate ridge close to the villages of san sebastiano and sgurgola inducing a significant risk this study began with the construction of engineering geology sections by distinguishing lithotechnical units on the basis of both site and geomechanical parameters considering geological and geomorphological field evidence the numerical simulations validated the assumed kinematic model of the slope these simulations aimed at estimating the instability of the affected rock masses by identifying a critical mass beyond which ongoing deformations become morphologically evident on the involved slope a ratio of the weight of a critical mass which is the minimum mass required to produce some geomorphological evidence to the weight of the mass involved in the gravitational slope deformations was calculated in order to quantitatively assess the evolutionary stage of the ongoing deformations the calculated ratio demonstrates a more advanced evolutionary stage for the slope sector near the village of sgurgola due to its particular geological setting than the one near the village of san sebastiano

time dependent evolution of rock slopes by a multi modelling approach abstract this paper presents a multi modelling approach that incorporates contributions from morpho evolutionary modelling detailed engineering geological modelling and time dependent stress strain numerical modelling to analyse the rheological evolution of a river valley slope over approximately 10 2 kyr the slope is located in a transient tectonically active landscape in southwestern tyrrhenian calabria italy where gravitational processes drive failures in rock slopes constraints on the valley profile development were provided by a morpho evolutionary model based on the correlation of marine and river strath terraces rock mass classes were identified through geomechanical parameters that were derived from engineering geological surveys and outputs of a multi sensor slope monitoring system the rock mass classes were associated to lithotechnical units to obtain a high resolution engineering geological model along a cross section of the valley time dependent stress strain numerical modelling reproduced the main morpho evolutionary stages of the valley slopes the findings demonstrate that a complex combination of eustatism uplift and mass rock creep mrc deformations can lead to first time failures of rock slopes when unstable conditions are encountered up to the generation of stress controlled shear zones the multi modelling approach enabled us to determine that such complex combinations may have been sufficient for the first time failure of the s giovanni slope at approximately 140 ka mis 7 even without invoking any trigger conversely further reactivations of the landslide must be related to triggers such as earthquakes rainfall and anthropogenic activities this failure involved a portion of the slope where a plasticity zone resulted from mass rock creep that evolved with a maximum strain rate of 40 per thousand years after the formation of a river strath terrace this study demonstrates that the multi modelling approach presented herein is a useful tool for estimating the progressive development of slope failures because it can highlight time dependent continuous deformations as the major processes that drive rocky slopes to failure this type of approach can be devoted to the best selection of risk mitigation strategies with respect to both human life and anthropic infrastructure

quaternary gravitational morpho genesis of central apennines italy insights from the mt genzana case history abstract this paper focuses on a study aimed at defining the role of geological structural setting and quaternary morpho structural evolution on the onset and development of a deep seated gravitational slope deformation which affects the western slope of mt genzana ridge central apennines italy this case history is particularly significant as it comprises several aspects of such gravitational processes both in general terms and with particular reference to the apennines in fact i the morpho structural setting is representative of widespread conditions in central apennines ii the deforming slope partially evolved in a large rockslide avalanche iii the deformational process provides evidence of an ongoing state of activity iv the rockslide avalanche debris formed a stable natural dam thus implying significant variations in the morphologic hydraulic and hydrogeological setting v the gravitational deformation as well as the rockslide avalanche reveal a strong structural control the main study activities were addressed to define a detailed geological model of the gravity driven process by means of geological structural geomorphological and geomechanical surveys as a result a robust hypothesis about the kinematics of the process was possible with particular reference to the identification of geological structural constraints the process in fact involves a specific section of the slope exactly where a dextral transtensional structure is present thus implying local structural conditions that favor sliding processes the rock mass is intensively jointed by high angle discontinuity sets and the bedding attitude is quite parallel to the slope angle within this frame the gravitational process can be classified as a structurally constrained translational slide locally evolved into a rockslide avalanche the activation of such a deformation can be in its turn related to the quaternary morphological evolution of the area which was affected by a significant topographic stress increase testified by stratigraphic and morphologic evidence

morpho structural evolution of the valley slope systems and related implications on slope scale gravitational processes new results from the mt genzana case history central apennines italy abstract this work is aimed at constraining a slope scale deep seated gravitational slope deformation dsgsd and an associated rockslide avalanche in the frame of the quaternary morpho structural evolution of central apennines italy the study area is the western slope of the mt genzana calcareous ridge for which a conceptual slope evolutionary model had been already proposed the existing model has highlighted the role of inherited geological structural setting combined with quaternary morpho evolution in the onset of rock slope deformational processes until paroxysmal phases i e occurrence of massive rock slope failures in this work the previous conceptual evolutionary model was strengthened and detailed by means of a mid term landscape evolution model based on the study of geomorphic markers hanging at different elevations above the present valley floor the quaternary landscape evolution was also constrained by means of time dependent landscape metrics consequently it was possible to back analyse the observed dsgsd process from its onset up to the occurrence of localized massive rock slope failures through a time dependent stress strain numerical modeling the results of such a multi modeling approach i highlighted the importance of rock mass creep during some stages of the morpho evolution ii pointed out the relevant role of the inherited structural pattern in identifying the preferential strain concentration zones and failure surfaces and iii confirmed the hypothesis that the scanno rockslide avalanche scar is the result of two separate failure events as an initial landslide involving the lower part of the slope that favoured a subsequent failure in the upper part of the slope