the december 2002 july 2003 effusive event at stromboli volcano italy insights into the shallow plumbing system by petrochemical studies abstract on 28 december 2002 the persistent strombolian activity at stromboli was interrupted by the sudden onset of lava emission onto the sciara del fuoco slope a horseshoe shaped depression on the nw flank of the volcano the effusive episode went on until 22 july 2003 and produced a cumulative volume of lavas of 11 106 m3 ranking the event as the largest occurred in the past 30 years the eruptive vents were mainly located in the ne sector of the sciara del fuoco depression at an elevation of 550 600 m a s l on 30 december the eastern portion of the sciara del fuoco collapsed producing a tsunamigenic landslide on 5 april 2003 a paroxysmal eruption occurred at the summit craters during which crystal poor pumiceous products were emitted the paroxysm did not interrupt the lava emission the strombolian activity at the summit craters gradually resumed starting from march 2003 and fully recovered by the end of july periodic sampling of the lava at the active vents was carried out during the entire effusive event all the analysed samples are shoshonitic basalts sio2 48 5 50 4 wt k2o 2 1 2 4 wt in the range of composition observed in the products erupted during the past 20 years they bear about 50 vol zoned crystals of plagioclase an90 60 diopside augite and olivine fo70 73 in a compositionally homogeneous shoshonitic groundmass bulk rock major and trace element contents measured with different methodologies at different laboratories show only minor variations sr and nd isotope ratios are close to those of the crystal rich scoriae erupted in the previous years despite of small compositional variations related to the emptying of the zoned topmost portion of the conduit the data show that the switch from strombolian explosive to effusive activity is not associated with changes of the textures and composition of the erupted products slight but somehow systematic variation of trace elements and isotope ratios between products erupted before and after the 5 april eruption are likely accounted by limited mixing between the fresh volatile rich crystal poor magma erupted as pumice during the paroxysm and the volatile poor crystal rich magma feeding the lava flow the uniform composition of the erupted lava indicates the presence of a large volume of well mixed crystal rich homogeneous magma residing in the shallow plumbing system of the volcano two possible trigger mechanism of the effusive event are here proposed i a discrete input of fresh magma into the lower part of the shallow magmatic system occurred some months before the eruption and was followed by crystallisation degassing and mixing with the crystal rich shallow magma which re homogenised the system these processes eventually led to the rise of the magma at a higher level and failure of the conduit walls ii the onset of the effusion may represent the consequence of a gradual rise of the magma level in the conduits occurred in the past two decades the process of progressive refilling initiated after the 1985 effusive eruption ultimately culminated on 28 december 2002 with the failure of the conduit wall and the opening of vents 100 150 m below the summit craters

numerical modelling of strata movement at footwall induced by underground mining abstract during metal mining the deformation and failure of rock mass are very important factors that dominate rock movement and zoning numerical modelling provides a feasible way to study the deformation and failure of rock mass in this study a numerical method of udec was adopted to study strata movement mechanism influenced by nww trending joints at the footwall at chengchao iron mine and the mohr coulomb model and the coulomb slip model with residual strength were adopted as the constitutive models of rock masses and joints respectively the whole strata movement process was simulated and the strata movement mechanism at footwall and zoning phenomenon was clarified in the chimney caving development stage gravity is the driving force and surface deformations are mainly subsidence deformation of the surface above the ore body in the post chimney deformation stage horizontal tectonic stress is the driving force and surface deformation and subsidence are dominated by horizontal deformation of the hanging wall and footwall in the mining area after the level 395 0 m is mined out the deformation characteristics of deep surrounding rock were revealed by means of numerical modelling the maximum failure depth of the cantilever beam and the spatial distribution of deep surrounding rock zones can be determined at last the influencing boundary of surface deformation expands rapidly in a linear way with the excavation step and the expanding velocity of the horizontal deformation is greater than that of the subsidence in the post chimney deformation stage

simulating the failure process of the xinmo landslide using discontinuous deformation analysis abstract the xinmo landslide slope in sichuan china was stable during the intensive wenchuan earthquake in 2008 but failed on june 24 2017 landslide debris buried xinmo village and blocked the songpinggou river at the slope toe this study aims to clarify the post failure behavior of the landslide using two dimensional discontinuous deformation analysis 2d dda the simulation results provide comprehensive information on the initiation and the evolution of the landslide the failure process determined by the dda correlates well with the seismic signal analysis results in addition the location of the calculated rock deposit is similar to that shown by the topographic map after the landslide the maximum rock velocity in the landslide is 65 4 m s therefore the impacts of the high velocity blocks and the buildings in xinmo village must be considered to simulate the burial of xinmo village by rocks and the transport of additional rocks across the songpinggou river this xinmo landslide study demonstrates that the dda accurately simulates the post failure behavior and determines the impact area of a landslide with complicated failure processes and topography

stressing of locked patches along a creeping fault an analysis is presented of the stressing of locked patches along a fault zone which is creeping elsewhere the model consists of strike slip faulted elastic lithospheric plates loaded in a manner equivalent to imposition of a remotely uniform tectonic shear stress the fault zone has an inhomogeneous strength distribution both depth wise and along strike it is modeled as being composed of locked patches and freely slipping parts treated as cracks the solution is given with the use of the line spring model which analyzes the problem by thickness averaged plane stress theory for lithospheric plates which slip along a discontinuity cut at the plate boundary as a boundary condition thickness averaged stress and slip at each local section along the cut was related to one another by the result of an antiplane strain analysis of slip for the crack or crack pair which describes the slipping and locked depth ranges at that section the analysis indicates that the slip distribution along creeping parts of the fault as well as the stress distribution along locked patches depends strongly on the geometry of these zones the model is used to examine stress concentrations associated with a slip deficient seismic gap along strike and to study the effect of local irregularities in the margin of a locked region it is also used to simulate slip and stressing processes associated with the creeping portion of the san andreas fault in central california between the presently locked zones of the great 1906 and 1857 ruptures and to constrain the nature of an apparently locked zone at the southeastern end which ruptures in characteristic parkfield earthquakes near fault creep and broadscale displacement data along the fault since the 1966 parkfield earthquake and inferences from seismicity distributions are used limitations of the modeling procedure at short spatial wavelengths prohibit an accurate description of the parkfield locked patch but results suggest that it may be localized and occupy a small fraction of area of the normal seismogenic zone an effective remote stressing rate of order 0 3 10 6 shear modulus yr is inferred together with a less well constrained 30 to 40 km lithospheric thickness for consistency with the displacement data results enable estimates of stress accumulation along the locked 1857 rupture zone and the build up of fracture energy release capability of order 107 j m2 in 150 yr at its lower margin

seismic insight into explosive paroxysms at stromboli volcano italy abstract at stromboli volcano italy continuous seismic monitoring and periodic visual observations of volcanic activity for surveillance purposes began in the mid 1980s since 1985 two eruptions have occurred one lasting from december 1985 until april 1986 and one in may 1993 there have also been two small overflows in 1990 and 1994 since these episodes of lava effusion the persistent strombolian activity of the volcano has had several fluctuations during the past 15 years some episodes climaxed in powerful explosions according to seismic records these paroxysms consisted of a variable number of explosion quakes in rapid succession i e from tens of seconds to a few minutes associated with a notable increment in the amplitude of volcanic tremor throughout these episodes which are called explosive sequences lapilli fragments of old rock and bombs of varying dimensions were ejected affecting an area greater than the crater terrace where the active craters are located in this article we describe the explosive sequences recorded at stromboli between 1985 and 1999 we provide a characterization in terms of reduced displacement and duration for nine episodes occurring in 1998 and 1999 their reduced displacements range from 15 to 124 cm 2 their durations are between 6 and 18 min we find no change in the frequency content of the seismic signal several minutes before and during the sequences considering medium to long term behavior the spectral amplitude of the seismic signal decreases or has low values over several months preceding the occurrence of the paroxysms this feature is common to 20 of the 22 explosive sequences and is indicative of internal conditions that periodically characterize the feeder we surmise that the paroxysms are the result of the partial obstruction of the volcanic conduit when the magma column is low or dropping the onset of the explosive sequence causing the sudden removal of the material which forms the obstruction would trigger a sudden depressurization of the conduit and the rapid rise of magma from depth

evidence for mechanically coupled lithosphere in central asia and resulting implications the recent dramatic increase in seismic anisotropy and surface global positioning system gps data for central asia permits a comprehensive examination of the mantle s role in mountain building a joint analysis of 178 shear wave splitting and 2000 gps observations using a new technique reveals that the crust and lithospheric mantle deform coherently arguing for crust mantle mechanical coupling during deformation the observed spatial variations in anisotropy refl ect the large scale pattern of lithospheric deformation as well as a change in deformational style from simple shear on the tibetan plateau transitioning to pure shear in surrounding regions

simulating the process of reservoir impoundment induced landslide using the extended dda method abstract in this work three extensions to the traditional discontinuous deformation analysis dda method are tested to simulate the entire process describing the behavior of landslides induced by reservoir impoundment these extensions include the discretization of the area of interest block gluing and the hm hydro mechanical coupling approach several hydraulic boundary conditions are introduced based on the water level during the dry and rainfall seasons as verification the entire processes for two practical landslides the qianjiangping and the majiagou landslides which occurred in the three gorges reservoir tgr of china are simulated the simulation results agree well with the observed failure modes indicating that the proposed methodology can intuitively reproduce the entire reservoir impoundment induced landslide process

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

tectonics of the western margin of the shan plateau central myanmar implication for the india indochina oblique convergence since the oligocene abstract we present new data and interpretations on the neogene tectonics of the shan scarp area central myanmar and its relationship with the india indochina oblique convergence we describe ductile and brittle fabrics associated with the major features in this area the mogok metamorphic belt mmb the shan scarp and the sagaing fault from these data we identify a succession of two tectonic regimes first a dominant nnw sse trending extension marked by ductile stretching that characterizes the mmb and associated n70e brittle normal faults later from middle or upper miocene to the present these structures were cross cut by brittle right lateral faults among which the most important are the n20w transpressive shan scarp fault zone and the n s sagaing fault to explain this transition from a dominant transtensive to a transpressive stress regime that occurred during miocene we place our data within a larger geodynamic context we suggest that like the intraplate deformation in the indian ocean the end of spreading in the south china sea the opening of the andaman basin or the end of subduction within the indo burma range the change in the tectonic regime in central myanmar could be in response to a major miocene regional plate kinematic reorganization

first global positioning system results in northern myanmar constant and localized slip rate along the sagaing fault we present the first recorded global positioning system gps data from myanmar measured at the northern tip of the sagaing fault this area is in a very complex geodynamic context where rigid and semirigid plates interact the 12 gps sites measured in 2005 and 2008 in northern myanmar show that the slip rate is 18 mm yr and is localized along a single active narrow fault trace 20 km wide the same rate was previously demonstrated and remeasured 500 km southward in central myanmar despite the geodynamic regional complexity induced by interaction between the sunda and india plates the burma microplate and the highly deformable eastern himalayan syntaxis the slip rate remains surprisingly constant along this fault however the modeled locking depth varies from 20 km in central myanmar to 5 km in the north

verifying discontinuous deformation analysis simulations of the jointed rock mass behavior of shallow twin mountain tunnels abstract this study extends discontinuous deformation analysis dda to simulate the interactions of twin tunnels in a jointed rock mass the ground subsidence and the rock stress distribution around the tunnels from the dda simulation are compared to those from the trap door model both the experimental and computational results show that the changing tunnel interactions in the jointed rock mass between the two tunnels are coincidently associated with the tunnel distance in addition the dip angle of the rock strata significantly affects the surface subsidence patterns and the stress distribution around the excavation zone therefore the dda method is a useful tool for describing the mechanical behavior of a jointed rock mass when a twin tunnel is constructed in mountain terrain

simulating a mining triggered rock avalanche using dda a case study in nattai north australia abstract this study numerically simulated the failure process of a mining induced landslide at nattai north australia results obtained using discontinuous deformation analysis dda matched the conceptual failure process suggested by local geologists and the observed maximum run out distance the maximum velocity of the sliding rocks exceeded 40 m s computational results showed that the slope with inward sub horizontal bedding planes and sub vertical discontinuities remained stable if the mining induced high principle stresses did not fracture the rocks near the slope toe failure of the rocks near the toe of the slope was a key causal factor in the subsequent landslide this paper presents the first numerical simulation of the post failure behavior of the mining induced landslide at the nattai north site it also represents the first dda simulation to clarify the chain reaction of a mining induced landslide and demonstrate its applicability in such investigations

high precision photogrammetry for monitoring the evolution of the nw flank of stromboli volcano during and after the 2002 2003 eruption high precision aerial photogrammetry has been used in addition to other geophysical techniques such as bathymetric surveys geodetic measurements microseismicity recording etc for monitoring slope deformations and the volcanic activity of stromboli island aeolian arc italy during the last effusive eruption which started on december 28 2002 and soon after the major landslide tsunami event of december 30 qualitative and quantitative description of topographic and morphological changes of the sciara del fuoco were possible thanks to a recent pre eruption photogrammetric survey performed in 2001 the comparisons of 12 multi temporal digital terrain models carried out during the period january june 2003 were used to evaluate the displaced mass by the landslide the lava accumulation and the erosion processes of the sciara del fuoco after the end of the eruption four additional photogrammetric surveys were performed between july 2003 and october 2005 to monitor the evolution of the slope and detect potential instability phenomena the slope appeared significantly modified and continued to evolve showing marked erosion both on the lower part and toward the craters terrace over the same period the new lava flows showed progressive contraction of the thicker part of the lava pile caused by its cooling and compaction and the possible sliding along the shear surface of the december 2002 deep seated movement the present morphology seems to be far from equilibrium and the deformation processes are still ongoing justifying a continuous monitoring activity to understand the evolution of these instability phenomena

global positioning system gps measurements of crustal deformation across the frontal eastern himalayan syntaxis and seismic hazard assessment abstract tectonics and earthquake occurrence processes of the two himalayan syntaxes are complex their limited accessibility has restricted seismological investigations in these regions resulting in poor knowledge about the geodynamic processes here we provide global positioning system gps measurements of crustal deformation across the frontal eastern himalayan syntaxis ehs in this region the indian plate obliquely underthrusts the eurasian plate and the eastward extruding tibetan plateau moves around the ehs due to india eurasia convergence our gps measurements in the region suggest that the frontal ehs accommodates at least 20 mm yr of oblique convergence between the indian and eurasian plates under the frontal ehs on which this convergence is accommodated through a stick and slip process the 65 km wide main thrust zone of the plate boundary interface currently is locked these measurements and the limited information about the great 1950 assam earthquake m w 8 6 suggest that this great earthquake probably occurred in the ehs

importance of structural history in the summit area of stromboli during the 2002 2003 eruptive crisis inferred from temperature soil co2 self potential and electrical resistivity tomography the 2002 2003 eruptive crisis of stromboli volcano in the aeolian islands raised the question of how to assess the stability of the flanks of this volcanic edifice during such a crisis to provide a response to this question we analyzed a detailed fluid flow mapping plus the reiteration of a profile located in the vicinity of the active vents using the self potential method temperature data soil gas co2 measurements and electric resistivity tomography coupling the interpretation of these methods that are sensitive to the flow of gas and water in the ground indicates the position of areas of mechanical weakness in addition they can be used to monitor the change in the discharge of fluids associated with these features before and during the 2002 2003 eruptive crisis our results emphasize the importance of old structural boundaries such as the large fossa crater in the development of the new set of fractures observed during the 2002 2003 eruptive crisis between october 2002 and january 2003 the use of co2 soil gas technique evidenced an increase in the discharge of co2 outside the large fossa crater boundaries along the failure boundary of the southern sciara del fuoco area self potential and temperature measurements made before the 2002 2003 eruptive crisis reveal significant changes along the main structural boundaries of the fossa area the development of these anomalies is interpreted as an increase of the permeability of the structure from may 2000 to may 2002 between january 2003 and march 2003 the reiteration of self potential temperature and co2 measurements shows an increase of fluid discharge along weakness planes located inside the large fossa crater boundary they evidence no change outside this structural boundary the importance of the large fossa crater boundary in controlling the deformation and fluid flow from january to march 2003 has been attested by the development of the fractures inside the large fossa crater boundary and also with a network of electrooptical distance measurement stations located inside and outside this ancient crater this multidisciplinary approach to fluid flow assessment before and during an eruptive crisis is complementary to geodetic measurements of the deformation of the edifice it demonstrates for the first time the powerful potential of combining electrical resistivity tomography self potential temperature and soil co2 measurements in assessing the position of the planes of mechanical weakness in a volcanic edifice

crystal recycling in the steady state system of the active stromboli volcano a 2 5 ka story inferred from in situ sr isotope and trace element data in situ sr isotope data by microdrilling coupled with major and trace element analyses have been performed on plagioclase and clinopyroxene from seven samples collected during the 2002 2003 eruptive crisis at stromboli volcano aeolian islands italy on 28 december 2002 the persistent moderate explosive activity was broken by an effusive event lasting about 7 months a more violent explosion paroxysm occurred on 5 april 2003 two magma types were erupted namely a volatile poor and highly porphyritic magma hp magma poured out as scoria or lava and a volatile rich phenocryst poor magma lp magma found as pumice lp magma differs from the hp magma also for its slightly less evolved chemistry the groundmass composition and the lower sr isotope ratios micro sr isotope data show the presence of zoned minerals in strong isotope disequilibrium as previously found in products erupted in 1984 1985 and 1996 ad with 87sr 86sr values generally decreasing from cores to rims of minerals only some outer rims testify for equilibrium with the host groundmass the internal mineral zones with high sr isotope ratios 0 70665 0 70618 are interpreted as antecrysts crystallised during the previous activity and recycled in the present day system since the opening shoshonitic activity of the recent period which occurred at about 2 5 ka ago this result has implications for the dynamics of the present day plumbing system of stromboli at intermediate pressure about 2 3 km depth and allows us to propose a model whereby an hp magma reservoir is directly interconnected at the bottom with a cumulate crystal much reservoir efficient mixing between residing hp and input lp magmas can occur in this reservoir due to more similar rheological characteristics of the two magmas than in the conduit where crystallisation is enhanced by degassing antecrysts and possibly melts re enter in the hp magma reservoir both from the bottom recycled by ascending lp magmas crossing the crystal mush and from the top recycled by descending degassed and dense hp magma residual of the periodic strombolian explosions at the surface the isotope variation measured in the groundmasses allows calculating the proportion of the lp magma entering the shallow hp magma reservoir at 20 from this proportion we estimate that the total volume of lp magma input during 2002 2003 closely matches the magma volume erupted in the effusive event suggesting a steady state system at broadly constant volume the comparison with estimates of the lp magma volume ejected by the paroxysm indicates that the lp magma amount directly reaching the surface during the 5 april paroxysm is minimal with respect to that entering the system

three dimensional velocity field of present day crustal motion of the tibetan plateau derived from gps measurements 1 using the measurements of 750 gps stations around the tibetan plateau for over 10 years since 1999 we derived a high resolution 3 d velocity field for the present day crustal movement of the plateau the horizontal velocity field relative to stable eurasia displays in details the crustal movement and tectonic deformation features of the india eurasia continental collision zone with thrust compression lateral extrusion and clockwise rotation the vertical velocity field reveals that the tibetan plateau is continuing to rise as a whole relative to its stable north neighbor however in some subregions uplift is insignificant or even negative the main features of the vertical crustal deformation of the plateau are the following a the himalayan range is still rising at a rate of 2 mm yr the uplift rate is 6 mm yr with respect to the south foot of the himalayan range b the middle eastern plateau has a typical uplift rate between 1 and 2 mm yr and some high mountain ranges in this area like the longmen shan and gongga shan have surprising uplift rates as large as 2 3mm yr c in the middle southern plateau there is a basin and endorheic subregion with a series of ns striking normal faults showing obvious sinking with the rates between 0 and 3 mm yr d the present day rising and sinking subregions generally correspond well to the cenozoic orogenic belts and basins respectively e at the southeastern corner of the plateau there is an apparent trend that the uplift rate is gradually decreasing from between 0 8 and 2 3 mm yr in the inner plateau to between 0 5 and 1 6 mm yr outside the plateau with the decrease of terrain height

evolution of a bank failure along the river danube at dunaszekcső hungary the banks of the river danube are one of the most susceptible areas to mass wasting in hungary in 2007 a large slump began to develop along the danube at dunaszekcs and jeopardized properties on land and navigation in the river several factors such as geological hydrogeological and morphological conditions recurrent flooding and erosion by the danube led to a gradual development of the large rotational slide slope failure has been monitored using gps precise levelling techniques and tiltmeters since october 2007 the expected location of the maximum lateral displacement and extrusion was indicated by gps measurements from the middle of november 2007 the main phase of the slope failure evolution i e the rapid movement on 12 february 2008 was indicated by accelerated tilting of the southern moving block prior to slumping small rise of the relatively stable part of the slope was measured after the rapid movements which may be explained either by the elastic rebound along the slip surface or by the intrusion of some plastic material into the lower section of the slope comparison of geodetic datasets and field observations with the timing of rainfall and water level changes of the danube suggested that hydrological properties subsurface flow processes soil physical properties infiltration and perched water table were primarily responsible for initiation of the studied slump a model of slope failure evolution is proposed here based on the monitoring and field observations

evidence of multiple strain fields beneath the eastern flank of mt etna volcano sicily italy deduced from seismic and geodetic data during 2003 2004 we carried out a study of the seismicity and ground deformation occurring on mt etna volcano after the end of the 2002 2003 eruption and before the onset of the 2004 2005 eruption data were recorded by the permanent local seismic network run by istituto nazionale di geofisica e vulcanologia sezione di catania and by geodetic surveys carried out in july 2003 and july 2004 on the gps network most earthquakes were grouped in two main clusters located in the northeastern and southeastern sectors of the volcano the areal distribution of seismic energy associated with the recorded earthquakes allowed us to highlight the main seismogenic areas of mt etna in order to better understand the kinematic processes of the volcano 3d seismic locations were used to compute fault plane solutions and a selected dataset was inverted to determine stress and strain tensors the focal mechanisms in the northeastern sector show clear left lateral kinematics along an e w fault plane consistent with events occurring along the pernicana fault system the fault plane solutions in the southeastern sector show mainly right lateral kinematics along a nne and ene fault plane and left lateral kinematics along nw fault planes that together suggest roughly e w oriented compression surface ground deformation affecting mt etna measured by gps surveys highlighted a marked inflation during the same period and exceptionally strong seawards motion of its eastern flank the 2d geodetic strain tensor distribution was calculated and the results show mainly ene wsw extension coupled with wnw ese contraction indicating right lateral shear along a nw se oriented fault plane the different deformation of the eastern sector of the volcano as measured by seismicity and ground deformation must be interpreted by considering the different depths of the two signals seismic activity in the southeastern sector of volcano is located between 3 and 8 km b s l and can be associated with a very strong additional e w compression induced by a pressurizing source just westwards and at the same depth located by inverting gps data ground deformation in contrast is mainly affected by the shallower dynamics of the fast moving eastern flank which produces a shallower opposing e w extension the entire dataset shows that two different processes affect the eastern flank at the same time but at different depths the boundary is clearly located at a depth of 3 km b s l and could represent the decollement surface for the mobile flank

clockwise rotation of the brahmaputra valley relative to india tectonic convergence in the eastern himalaya naga hills and shillong plateau gps data reveal that the brahmaputra valley has broken from the indian plate and rotates clockwise relative to india about a point a few hundred kilometers west of the shillong plateau the gps velocity vectors define two distinct blocks separated by the kopili fault upon which 2 3 mm yr of dextral slip is observed the shillong block between longitudes 89 and 93 e rotating clockwise at 1 15 myr and the assam block from 93 5 e to 97 e rotating at 1 13 myr these two blocks are more than 120 km wide in a north south sense but they extend locally a similar distance beneath the himalaya and tibet a result of these rotations is that convergence across the himalaya east of sikkim decreases in velocity eastward from 18 to 12 mm yr and convergence between the shillong plateau and bangladesh across the dauki fault increases from 3 mm yr in the west to 8 mm yr in the east this fast convergence rate is inconsistent with inferred geological uplift rates on the plateau if a 45 n dip is assumed for the dauki fault unless clockwise rotation of the shillong block has increased substantially in the past 4 8 myr such acceleration is consistent with the reported recent slowing in the convergence rate across the bhutan himalaya the current slip potential near bhutan based on present day convergence rates and assuming no great earthquake since 1713 a d is now 5 4 m similar to the slip reported from alluvial terraces that offsets across the main himalayan thrust and sufficient to sustain a mw 8 0 earthquake in this area

postseismic rebound in fault step overs caused by pore fluid flow near field strain induced by large crustal earthquakes results in changes in pore fluid pressure that dissipate with time and produce surface deformation synthetic aperture radar sar interferometry revealed several centimeters of postseismic uplift in pull apart structures and subsidence in a compressive jog along the landers california 1992 earthquake surface rupture with a relaxation time of 270 45 days such a postseismic rebound may be explained by the transition of the poisson s ratio of the deformed volumes of rock from undrained to drained conditions as pore fluid flow allows pore pressure to return to hydrostatic equilibrium

computer simulations of tsunamis due to sector collapse at stromboli italy abstract stromboli is an island volcano of the aeolian volcanic arc characterised by persistent activity the cone rises about 2500 3000 m from its submarine base with very steep slopes its summit at 924 m above the sea level the subaerial growth of stromboli occurred in the last 100 ka has been marked by repeated episodes of large gravitational collapses especially affecting the nw flank of the island in the last 13 ka the last one occurred less than 5000 years ago forming the deep depression on the nw seaward flank named sciara del fuoco sdf and it produced very likely large water waves this paper envisages a scenario where a huge mass of volcanic material collapses into the sea in the same sector in which the sdf collapse took place in holocenic times and it computes possible tsunami evolutions assuming the present day bathymetry numerical simulations are performed by means of two distinct models one for the mass collapse and one for the tsunami slope failure dynamics are calculated with the aid of a lagrangian model the landslide is subdivided into blocks and the motion of each constituent block is calculated by applying the basic principle of mechanical momentum conservation with block block and block ambient interactions being taken into account water waves are computed by solving a system of shallow water equations including a forcing term dependent on the sliding mass motion the finite element fe technique is employed since it permits the use of non uniform grids which are adequate to account for marine basins with irregular coastlines in addition to the sensitivity analysis concerning the main parameters governing the slide motion two main cases are explored differing in the slide path followed by the mass the resulting tsunami is very large with giant waves as high as several meters tens of meters in the worst cases impinging the coast due to the strong wave refraction induced by bathymetry waves travel around the island affecting even the island coast opposite the source

an enhanced equivalent continuum model for layered rock mass incorporating bedding structure and stress dependence abstract layered rock masses exhibit significant anisotropy in both the deformability and strength properties of this rock mass are largely affected by its bedding structure and also by the stress state change for the purpose of characterizing these salient features using the equivalent continuum concept an enhanced model is proposed in this paper based on the ubiquitous joint model in the enhanced model the intact bedded rock is assumed to behave as a transversely isotropic elastic body a modified anisotropic strength criterion is adopted to describe the direction dependence of the strength of intact bedded rock in addition stress sensitive parameters are utilized for both the intact rock and bedding plane among which the dilation angle and strength parameters of intact rock are influenced by confining pressure and loading history whereas the stiffnesses of bedding planes are closely related to the current normal stress the effect of layer thickness on the mechanical behavior of rock mass is reflected by continuously updating the global stiffness matrix after failure of bedding plane and by conditions for conducting bedding plane related calculations determined by the relative scales between element size and layer thickness preliminary validation of this model is conducted by comparing with the closed form solutions and with laboratory tests generally good agreements can be achieved between numerical simulations and theoretical experimental results which indicate that applicability of the enhanced model on underground engineering issues related to layered rock mass is promising

active tectonics and earthquake potential of the myanmar region this paper describes geomorphologic evidence for the principal neotectonic features of myanmar and its immediate surroundings we combine this evidence with published structural geodetic and seismic data to present an overview of the active tectonic architecture of the region and its seismic potential three tectonic systems accommodate oblique collision of the indian plate with southeast asia and extrusion of asian territory around the eastern syntaxis of the himalayan mountain range subduction and collision associated with the sunda megathrust beneath and within the indoburman range and naga hills accommodate most of the shortening across the transpressional plate boundary the sagaing fault system is the predominant locus of dextral motion associated with the northward translation of india left lateral faults of the northern shan plateau northern laos thailand and southern china facilitate extrusion of rocks around the eastern syntaxis of the himalaya all of these systems have produced major earthquakes within recorded history and continue to present major seismic hazards in the region

chronology of the 2007 eruption of stromboli and the activity of the scientific synthesis group abstract on 27 february 2007 at 12 49 gmt a new eruption of stromboli took place with the effusion of a lava flow from a fracture cutting the flank of the ne cone which rapidly reached the sea the eruption had been heralded by an increase in the amplitude of tremor and flank movement since at least the 14th of february short term precursors were an increase in the rate of occurrence of small landslides within the sciara del fuoco scar on the north western flank of the volcano a new effusive vent opened at 18 30 gmt on the sciara del fuoco at an height of 400 m asl the new lava emission caused the sudden termination of the summit flow and initiated a period of non stationary lava outpouring which ended on 2 april 2007 the eruption has been characterized by a rapid decrease in the eruption rate after the first days and subsequently by episodic pulse increases on the 15th of march the increase in lava outpouring monitored by a thermal camera heralded by 9 min the occurrence of a violent paroxysmal explosion with the formation of an impulsive eruption column and the emission of small pumices mingled with black scoriae the pumice had a bulk composition similar to that of the lava and of the black scoriae but with a distinct lower content of phenocrysts a similar feature has been repeatedly observed during the major explosive paroxysms of stromboli short term precursors of the paroxysm were recorded by strainmeter and tiltmeter stations the volcano monitoring activity has been made by a joint team of researchers from the ingv sections of catania napoli palermo and rome along with researchers from the universities of florence pisa roma tre and palermo the scientific activity was coordinated by a synthesis group made up by scientists responsible for the different monitoring techniques of ingv and universities and by the volcanic experts of commissione nazionale grandi rischi of the prime minister office civil protection department the group made a daily evaluation of the state of the volcano and transmitted its recommendations to the civil protection department dpc several prevention measures were adopted by dpc the main of which were the evacuation of the coast zone when strong acceleration of the sciara del fuoco slope motion occurred twice could led to a dangerous tsunami by flank collapse as last occurred on 30 december 2002 and four days before the 15 march paroxysm when access was prohibited to the part of the volcano above 290 m asl

the evolution of the sciara del fuoco subaerial slope during the 2007 stromboli eruption relation between deformation processes and effusive activity abstract focusing on the island of stromboli this research investigates whether airborne remote sensing systems such as those based on digital photogrammetry and laser scanner sensors can be adopted to monitor slope deformation and lava emplacement processes in active volcanic areas thanks to the capability of extracting accurate topographic data and working on flexible time schedules these methods can be used to constrain the regular and more frequent measurements derived from satellite observations this work is dedicated to the monitoring of stromboli s volcanic edifice which is beneficial when obtaining quantitative data on the geometry of deformation features and the displaced failures and landslides and emplaced lava flows volumes in particular we focus on the capability of extracting average effusion rates from volume measurements that can be used to validate or integrate satellite derived estimates since 2001 a number of airborne remote sensing surveys namely digital photogrammetry dp and airborne laser scanning als have been carried out on stromboli s volcano to obtain high resolution digital elevation models dem and orthophotos with sub meter spatial resolution and a time schedule suitable for monitoring the morphological evolution of the surface during the quiescent phases during the last two effusive eruptions 2002 2003 and 2007 the surface modifications created on the sciara del fuoco slope and on the crater area as a consequence of effusive activity were quantified and monitored using the same methodologies this work which is based on the results obtained from the multi temporal quantitative analysis of the data collected from 2001 to 2007 mainly focuses on the 2007 eruption but also accounts for analogies and differences regarding the 2002 2003 event the 2007 eruption on the sciara del fuoco slope from 27 february until 2 april produced a compound lava field including a lava delta on the shoreline discharging most of the lava into the sea the comparison of the 2007 dems with a pre eruption surface 2006 lidar survey allowed for the evaluation of the total lava volume that accumulated on the subaerial slope while two syn eruption dems were used to calculate the average effusion rates during the eruption since the evolution of a lava field produced during an eruption can be seen as a proxy for the magma intrusion mechanism hypotheses are formulated on the connection between the lava discharge and the instabilities suffered by the slope

a warning system for stromboli volcano based on statistical analysis in this paper we describe a warning system based on statistical analysis for the purpose of monitoring ground deformation at the sciara del fuoco stromboli volcano sicily after a statistical analysis of ground deformation time series measured at stromboli by the monitoring system known as theodoros theodolite and distancemeter robot observatory of stromboli the paper describes the solution adopted for implementing the warning system a robust statistical index has been defined in order to evaluate the movements of the area a fuzzy approach has been proposed to evaluate an ai alarm intensity index which indicates the level of hazard of the sciara del fuoco sliding

stress evolution on active faults in the southwestern yunnan region southeastern tibetan plateau and implications for seismic hazard abstract southwestern yunnan is expressed as a seismically active region bordering the southeastern tibetan plateau however the recent seismicity in this region has been relatively quiet considering some highly populated cities nearby and the historical record in this region understanding the stress changes on the main active faults is crucial for seismic hazard analysis in this study we calculated the co and post seismic coulomb failure stress change cfs on these faults caused by historical earthquakes in and around the region then by integrating the inter seismic tectonic loading estimated using a geodynamic model and gps data we analyzed the total stress change on all of these faults the results reveal that the cfs patterns caused by events on different segments of the sagaing fault vary the combined cfs increased on the middle segment of the longling lancang fault the heihe fault and the nantinghe fault among which the maximum change reached 3 5 kpa the great 1950 assam earthquake in the eastern himalayan syntax increased the cfs on almost all faults and the maximum change reached 20 kpa more importantly the cfs caused by earthquakes in the southwestern yunnan region was significantly larger than that caused by earthquakes in the surrounding region because of the geographical proximity the inter seismic tectonic stress loading rate reached 2 kpa yr 1 a significant total stress build up occurred on five segments distributed among four faults namely the nantinghe fault the longling lancang fault the heihe fault and the menglian fault making them possible candidates for the next major earthquake in this region

extension and application of discontinuous deformation analysis with a damped contact spring model abstract discontinuous deformation analysis dda is widely used in geological and geotechnical engineering to provide an alternative approach to considering damping effect in dynamic analysis a damped contact spring model is implemented the model assumes that the damping component linear dashpot takes place in joints of dda models the normal and shear damping forces are determined according to the relative velocities of the two contacted points a semi analytical solution is also proposed to calculate damping coefficient from a given damping ratio the viscous damping effect produced by the damped contact spring model is independent to step size the proposed model is incorporated into dda program and then several classic damping dynamic examples are constructed to validate the contact model showing good agreement with analytical solutions after that a seismic spectrum of a recorded ground motion is analyzed to show the contact model is suitable for response spectrum generation finally the donghekou landslide case is studied under different parameters suggesting that the proper consideration of damping is essential to natural hazard analysis

degassing crystallization and eruption dynamics at stromboli trace element and lithium isotopic evidence from 2003 ashes during its 1800 year long persistent activity the stromboli volcano has erupted a highly porphyritic hp volatile poor scoriaceous magma and a low porphyritic lp volatile rich pumiceous magma the hp magma is erupted during normal strombolian explosions and lava effusions while the lp one is related to more energetic paroxysms during the march april 2003 explosive activity stromboli ejected two typologies of juvenile glassy ashes namely highly vesicular lp shards and volatile poor hp shards their textural and in situ chemical characteristics are used to unravel mutual relationships between hp and lp magmas as well as magma dynamics within the shallow plumbing system the mantle normalized trace element patterns of both ash types show the typical arc lava pattern however hp glasses possess incompatible element concentrations higher than lp glasses along with sr and eu negative anomalies hp shards are generally characterized by higher li contents to 20 ppm and lower 7li values 1 2 to 3 8 with respect to lp shards li contents of 7 14 ppm and 7li ranging between 4 6 and 0 9 fractional crystallization models based on major and trace element compositions combined with a degassing model based on open system rayleigh distillation and on the assumption that melt fluiddli 1 show that abundant 30 plagioclase precipitation and variable degrees of degassing can lead the more primitive lp magma to evolve toward a differentiated isotopically lighter hp magma ponding in the upper conduit and undergoing slow continuous degassing induced crystallization this study also evidences that in march 2003 stromboli volcano poured out a small early volume of lp magma that traveled slower within the conduit with respect to later and larger volumes of fast ascending lp magma erupted during the april 5 paroxysm the different ascent rates and cooling rates of the two lp magma batches i e pre and post paroxysm resulted in small but detectable differences in their chemical signatures finally this study highlights the high potential of in situ investigations of juvenile glassy ashes in petrologic and geochemical monitoring the volcanic activity and of li isotopes as tracers of degassing processes within the shallow plumbing system

new integrated geodetic monitoring system at stromboli volcano italy stromboli is a composite volcano forming the northernmost island of the aeolian archipelago volcanic arc tyrrhenian sea on december 28th 2002 lava flows outpoured from the northern wall of the ne crater and descended into the sciara del fuoco sdf a deep depression marking the nw flank of the volcano edifice on december 30th 2002 two landslides occurred on the northern part of the sdf they moved a mass in the order of tens of millions of cubic meters both above and below sea level the landslide produced a tsunami causing significant damage to the eastern coast of the island reaching the other aeolian islands and the sicilian and southern italian coasts this event led to the upgrading of the ground deformation monitoring system already existing on the island the new requirement was the real time detection of the deformations related to potential slope failures of the sdf to this end a remotely controlled monitoring system based both on gps and geodetic techniques was planned and set up in a few months the new monitoring system allowed to continuously measure the ground deformations occurring on the sdf by integrating both terrestrial and satellite geodetic techniques although this system was severely damaged during the 7 month long eruption it allowed to monitor important eruptive phases for the first time an accurate data set on the actual mass movements of the sdf and the crater area was available it provided data that significantly supported the civil protection authorities in making decisions and constrains theories related to landslide movements and volcanic activity after the end of the eruption the system was overhauled in order to optimize the instruments and set up a monitoring system aimed at measuring deformations forecasting other flank collapses

simulation of the mechanical behavior of inclined jointed rock masses during tunnel construction using discontinuous deformation analysis dda in this paper the mechanical behavior of inclined jointed rock masses during tunneling is considered such rock masses can be considered as an assembly of discrete blocks with the discontinuities having a significant influence on the mechanical behavior to simulate this situation a discrete numerical analysis method discontinuous deformation analysis dda is applied the dda results show the existence of stress arching in the rock masses during tunneling this stress arching is the primary influence on the stress distribution and surface subsidence in addition the stress arching is affected by the dip angle of the jointed rock masses moreover the dda results are in good agreement with experiments explaining the reason for the asymmetrical vertical stress and surface subsidence obtained in laboratory tests these results suggest that dda can be applied to model the tunneling behavior of complicated discontinuous rock masses

investigation of the hsien du shan rock avalanche caused by typhoon morakot in 2009 at kaohsiung county taiwan abstract the hsien du shan rock avalanche at kaohsiung county taiwan was triggered by heavy rainfall brought by typhoon morakot in 2009 heavy rainfall began on the day of august 6 and continued to the morning of august 9 when the slope failure and landslide occurred in this post event investigation physical mechanical and hydraulic properties of the rocks soils at this large landslide site are evaluated the in situ hydraulic conductivity of the soils at the source area was found to be too low k 1 48 10 6 m s for rainfall to vertically infiltrate to the deep sliding surface which was found to have a maximum depth of 85 6 m the post failure simulations using discontinuous deformation analysis dda suggest that the geometry of the sliding surface governs the failure behavior and two continuous progressing failures likely occurred at the beginning of the hsien du shan rock avalanche slope deformation was observed by the local residents before the hsien du shan rock avalanche occurred as a geomorphologic precursor in addition water accumulation along the sliding surface governs the behavior of the sliding surface therefore in the future an early warning system of a rock avalanche can be developed by simultaneously applying high resolution airborne lidar to detect slope deformation and using geo electric measurements to image the infiltration of surface water to the sliding surface

stromboli 2007 eruption deflation modeling to infer shallow intermediate plumbing system 1 during the effusive phase of the stromboli 2007 eruption the gps and tilt stations recorded small but significant changes which for the first time at this volcano clearly indicated a deflation we modeled the deflation inferring a depressurizing vertically elongated source with centre under the volcano edifice about 2 8 km below sea level the model whose position is above the magma source region inferred by petrological studies and the associated rapid deflation suggest a near free pathway for magma ascent from this source to the upper shallow conduit

insights into the catastrophic xinmo rock avalanche in maoxian county china combined effects of historical earthquakes and landslide amplification abstract a large and catastrophic rock avalanche occurred at the xinmo village in the maoxian county of the sichuan province of china on june 24 2017 the avalanche destroyed 64 houses and killed 10 people and 73 people were reported to be missing in this study we focused on the contributions of six historical earthquakes to the collapse of rocks in the source area and the landslide amplification caused by the entrainment of pre existing deposits on the landslide path the historical earthquakes in this area contributed different levels of damage on the source rocks particularly the 1933 diexi earthquake induced a few initial cracks in rocks at the crest of the steep hillslope under the combined time effects of long term weathering and gravity the rock blocks in the source area were detached from the crest along the intersecting cracks and over dip soft layer namely the sliding surface the avalanche was amplified by the entrainment of colluvium on its path the influence of the colluvium on the movement process of the xinmo landslide was modelled by the gpu based parallel discontinuous deformation analysis dda method and the effect of the impact and entrainment in the debris flow was rigorously analysed the results indicate that the impact and entrainment can continuously increase the volume of debris flow and the thickness of the colluvium was established to be in the range of 25 9 33 9 m based on the analysis of the deposit pattern and movement duration of the avalanche there were numerous unstable rocks induced by historical earthquakes at the crests of steep hill slopes in the earthquake stricken area with long term damage caused by environmental factors and gravity the failure of unstable rocks with high potential energy is likely to cause severe disasters the excess pore water pressure likely to be present in the colluvium or deposits during impact and entrainment can considerably reduce the effective stress and degrade friction resistance along the runout path as a result the landslide can be intensively amplified owing to the effect of impact and entrainment under a lower friction resistance

combined effects of eurasia sunda oblique convergence and east tibetan crustal flow on the active tectonics of burma it is widely accepted that deformation of the india sunda plate is the result of partitioned hyper oblique convergence presently sub meridian dextral strike slip faulting accommodates this india sunda motion in a buffer zone the burma platelet this wide dextral strike slip shear zone is complicated by the side effect of the tibet plateau collapse that can be described in term of crustal flow and gravity tectonics the loss of potential energy related to this plateau collapse affects most of the burmese platelet particularly in its northernmost part interaction of these two distinct geodynamic processes is recorded in the gps based regional strain field the analysis of seismic focal mechanism but also from direct geologic observations both onshore and offshore myanmar and bangladesh we propose the apparent e w shortening component of this so called partitioned hyper oblique subduction is only the effect of regional gravitational forces related to the tibet plateau collapse whereas the ns strike slip faulting accommodates the india sunda motion

numerical analysis of a large landslide induced by coal mining subsidence mining induced subsidence is one of the challenging problems in geotechnical engineering the surface topography of the ground over mining excavations plays a key role in the mechanism of subsidence when a mining operation is performed beneath mountainous or hilly terrain it may trigger landslides this study therefore aims to analyse the impacts of underground mining on the stability of slopes by using numerical modelling a coal mining induced landslide at nattai north australia is investigated as a typical case study in this area mining operations beneath the sydney basin escarpments initiated the largest contemporary landslide and mass movement known in australia cunningham 1988 discontinuous numerical modelling is employed to analyse the mechanisms of the ground movements leading to this landslide the role of geological and geotechnical factors such as rock mass characteristics bedding and joints are discussed through the numerical modelling the outcomes of the analyses reveal that mining induced stresses lead to the shear and compressive failure of weak strata at the escarpment base particularly around its toe the failure of the base materials as well as the caving of the overlaying bedded rocks into the extracted panel facilitated the detachment of the massive sandstone this rock column ahead of the escarpment was overlaying the weak strata the numerical results also indicate that the aforementioned rock column remained almost unaffected during mining however the failure of the weak strata at the toe of the escarpment initiated the simultaneous forward sliding and toppling of the rock column this mode of failure which is known as ski jump type of failure was previously observed and explained by pells et al 1987

stability analyses of rainfall induced landslides the slope stability issues concerning rainfall induced slope failures are investigated and presented specifically the effect of both negative and positive pore water pressures on the stability of initially unsaturated slopes are carefully explained and coupled with infinite slope analysis methods in order to present a predictive formulation of slope failures that occur as a result of rainfall events the formulation serves as a baseline analysis method for evaluating potentially unstable soil slopes that are subject to surface infiltration and explains the various triggering mechanisms that may occur based on individual combinations of the slope geometry soil strength and infiltration parameters a procedural method is outlined for utilizing the analytical formulation to predict the change in the factor of safety for a slope subject to infiltration and a detailed analysis of a case study is presented to verify the method quantitative statements are made concerning the time and depth of failure in relationship to the soil slope and rainfall parameters

assessing subsidence susceptibility to coal mining using frequency ratio statistical index and mamdani fuzzy models evidence from raniganj coalfield india raniganj an important coalfield in india is susceptible to mining subsidence ejection of toxicants in the environment and huge subsurface destruction mining with opencast method poses a great risk to the surrounding areas of this coalfield anthropogenic and natural activities have caused ground movement leading to subsidence in raniganj coalfield existing knowledge on subsidence susceptibility to coal mining in raniganj coalfield is scant the study makes an attempt to analyze mining subsidence susceptibility in raniganj coalfield using site specific parameters we first prepared subsidence inventory map to identify old subsidence locations and to construct the model it was later utilized for validating the models fifteen site specific parameters related to subsidence were chosen to analyze coal mining subsidence frequency ratio fr statistical index si and mamdani fuzzy mf models were utilized to assess their effectiveness in preparing susceptibility map findings of the study revealed very high susceptibility in the central part high susceptibility in north western part and moderate susceptibility in the eastern part of raniganj coalfield low and very low susceptibility was found in those parts having largest area under vegetation and water bodies the models were validated through roc curve seed cell area index scai and spatially agreed area approach mamdani fuzzy model with highest success rate 87 and prediction accuracy 85 was found the best fit model for analyzing mining subsidence susceptibility the framework of the methodology will be instructive for analyzing susceptibility at different geographical locations

earthquake occurrence processes in the indo burmese wedge and sagaing fault region abstract earthquakes in the indo burmese wedge and sagaing fault regions occur in response to the partitioning of the india sunda motion along these two distinct boundaries under the accretionary wedge of the indo burmese arc majority of the earthquakes occur in the depth range of 30 60 km and define an eastward gently dipping seismicity trend surface that coincides with the indian slab the dip of the slab steepens in the east direction and earthquakes occur down to a depth of 150 km though the slab can be traced up to the 660 km discontinuity although these features are similar to a subduction zone the nature of the earthquakes and our analysis of their focal mechanisms suggest that these earthquakes are of intra slab type which occur on steep plane within the indian plate and the sense of motion implies a northward relative motion with respect to the sunda plate thus these earthquakes and the stress state do not support active subduction across the indo burmese arc which is also consistent with the relative motion of india sunda plates the absence of inter plate earthquakes lack of evidence of the occurrence of great earthquakes in the historical records and non seismogenic nature of the plate interface under the accretionary wedge suggest that seismic hazard due to earthquakes along the plate boundary may be relatively low however major intra slab earthquakes at shallow and intermediate depths may still cause damage in the sediment filled valley regions of manipur and cachar in india and chittagong and sylhet regions of bangladesh in the sagaing fault region earthquakes occur through dextral strike slip motion along the north south oriented plane and the stress state is consistent with the plate motion across the sagaing fault

effects of entrainment phenomenon on the rapid and long runout movement of landslides in wenjia gully sichuan china as a common phenomenon in landslides entrainment of loose bed material along the sliding path can enhance both the volume and mobility of the sliding mass posing a great threat to the life and property safety of people in the affected area for the purpose of revealing the mechanism of entrainment phenomenon of sliding material in the runout process a dynamic slice based model was firstly proposed in the present study in this model the motion of landslide body is assumed to follow the rheological law proposed by voellmy additionally through voellmy model the increase in kinetic energy mass and volume of landslide body and entrainment depth caused by the entrainment phenomenon were taken into consideration subsequently on the basis of the dynamic slice based model back analyses were performed on the wenjia gully landslide the effect of entrainment phenomenon on the post failure motion was analyzed the calculated results shows that the travel distance obtained from proposed model is closer to field data than that resulted from scheidegger s empirical method moreover the peak value of the maximum velocity calculated by this model is in good agreement with that get from the dynamic analysis model dan3d when considering the entrainment phenomenon the volume of sliding mass increases greatly in post failure motion this paper provides a new method for analyzing the entrainment phenomenon in landslide motion

a modified inverse velocity method for predicting the failure time of landslides abstract prediction of the failure time of landslides is always an important issue based on fukuzono s theory which suggests that the logarithm of the surface displacement velocity is proportional to the logarithm of the surface displacement acceleration in the final stage of the slope movement just before failure a modified inverse velocity method was proposed by introducing a controllable variable one landslide was detected in the certain open pit coal mine and four landslides were detected in the certain open pit iron mine by using ground based radar in the four landslides in the certain open pit iron mine the acceleration obviously decreased a few hours before failure which is inconsistent with the existing creep theory the traditional inverse velocity method and the modified inverse velocity method were employed to analyze the five landslides the analysis results show that the modified inverse velocity method can improve the effectiveness of prediction by reducing the prediction error caused by the acceleration decrease before failure the modified inverse velocity method proposed in this paper not only improves the prediction accuracy but also provides a study direction to improve the inverse velocity method that is it introduces controllable variables to improve the prediction accuracy

dynamic rockfall risk analysis abstract rockfall is a dangerous hazard on steep and susceptible slope however it is not easy to identify potential rockfalls on cliff mountains traditionally rockfall risk analysis ignores the temporal evolution of risk due to the changes of the elements at risk or changes in the annual probability this may lead to an underestimation of risk in time in this paper we present an innovative approach for a dynamic risk analysis and we demonstrate this approach for the shenxianjju scenic area case study where rockfall represent a threat for thousands of tourists each year moreover we studied the role of rock mass quality in controlling the rockfall potential and rockfall volume since this may lead to significant changes of rockfall risk in space we describe the use of unmanned aerial vehicle terrestrial lidar and detailed field surveys to identify 34 potential rockfalls on slopes where historical rockfalls have occurred within ignimbrite and rhyolite rock masses rockfall blocks range in size between large and very large andesite derived rockfalls are characterized by medium size to large block size faulted and fractured ignimbrite and rhyolite rock masses within the fault damage zone exhibit small very small rockfall block sizes based on the identified potential rockfalls in the study area we quantified the dynamic risk by considering the temporal spatial changes of tourist activity to demonstrate the methodology two potential rockfalls on two heavily used tourist routes were selected for these scenarios we quantified the annual probability of occurrence the reach probability the dynamic temporal spatial probability and the vulnerability of tourists the dynamic temporal probability was also calculated considering different visiting periods e g working days weekends holidays showing significant changes in the risk level among the different visiting periods and with time some of the investigated scenarios were within the alarp zone in the first years i e pll on workday in 2017 2019 and subsequently became unacceptable i e pll on workday in 2020 as a conclusion the research demonstrates that the traditional static risk analysis would lead to a significant rockfall risk underestimation

an improved numerical manifold method for simulation of sequential excavation in fractured rocks we improve the original numerical manifold method nmm capability to correctly model the stability of underground openings embedded in discontinuous rock masses under high in situ stress conditions by implementing an algorithm which models the excavation sequence during nmm simulations starting with a domain with no opening at all and progressively adding openings according to the planned construction phases the significance of this improvement is demonstrated using the case of zedekiah cave underneath the old city of jerusalem excavated 2000 years ago at a shallow depth in a highly discontinuous rock mass and still stands unsupported the results clearly show that modeling underground openings in discontinuous rocks without consideration of the excavation sequence is overly conservative we proceed with developing a new procedure to impose high initial stresses in nmm for accurate deformation modeling of deep underground excavations and verify our suggested approach using the analytical kirsch solution finally we apply our enhanced nmm code to the jinping hydroelectric project tunnels in sichuan province china using very accurate sliding micrometer data obtained during the excavation of a research tunnel within the jinping tunnel complex we constrain the in situ stress field at depth by inversion of the measured displacement data using the modified nmm code the results provide a quantitative assessment of the in situ stress field in jinping tunnels at a depth of 2525 m below ground surface where the execution of in situ stress measurements by conventional procedures proves an extremely challenging task

viscous boundary of dda for modeling stress wave propagation in jointed rock note roches reference lmr article 2007 010view record in web of science record created on 2007 09 24 modified on 2016 10 14

stability of shallow karstic caverns in blocky rock masses abstract the limiting relationship is explored between underground opening span and required cover height for stability in blocky rock masses characterized by a network of horizontal bedding planes and vertical joints understanding this relationship is crucial for the design of mining excavations in karstic terrain as typically encountered in carbonate rock masses we perform numerical analysis of multiple roof spans vs cover height geometries using the dda method to obtain the boundary curve between stable and unstable opening geometries our results indicate that for cavern spans of up to 18 m a low cover height vs opening span ratio of h b 0 33 is sufficient for stability for spans greater than 18 m the demand for cover height rapidly increases and it appears to stabilize at h b 1 0 for b 26 m and above to validate our numerical analysis results a unique case study is analyzed wherein a 40 m span karstic cavern the ayalon cave has been preserved below an active open pit mine in central israel with cover height of only 30 m thus rendering the cave marginally stable according to our model prediction indeed there is ample evidence of partial collapse of the roof in the cave the predictive capability of our model is further confirmed using two additional case studies in blocky rock masses each of which possesses very different mechanical parameters such as intact rock strength density and deformability suggesting that our model predictions remain valid as long the rock mass maintains a blocky structural configuration

microplate model for the present day deformation of tibet 1 site velocities from 349 global positioning system gps stations are used to construct an 11 element quasi rigid block model of the tibetan plateau and its surroundings rigid rotations of five major blocks are well determined and average translation velocities of six smaller blocks can be constrained where data are well distributed the velocity field can be explained well by rigid block motion and fault slip across block boundaries residual misfits average 1 6 mm yr compared to typical one standard deviation velocity uncertainties of 1 3 mm yr any residual internal straining of the blocks is small and heterogeneous however residual substructure might well represent currently unresolved motions of smaller blocks although any smaller blocks must move at nearly the same rate as the larger blocks within which they lie undetected relative motions between them could be significant particularly where there are gaps in gps coverage predicted relative motions between major blocks agree with the observed sense of slip and along strike partitioning of motion across major faults however predicted slip rates across tibet s major strike slip faults are low only 5 12 mm yr a factor of 2 3 smaller than most rates estimated from fault offset features dated by radiometric methods as 2000 to 100 000 year old previous work has suggested that both gps data and low fault slip rates are incompatible with rigid block motions of tibet the results reported here overcome these objections

aseismic plate boundary in the indo burmese wedge northwest sunda arc plate motion crustal deformation and earthquake occurrence processes in the northwest sunda arc which includes the indo burmese wedge ibw in the forearc and the sagaing fault in the backarc are very poorly constrained plate reconstruction models and geological structures in the region suggest that subduction in the ibw occurred in the geological past but whether it is still active and how the plate motion between the india and sunda plates is partitioned between motion in the ibw and sagaing fault is largely unknown recent gps measurements of crustal deformation and available long term rates of motion across the sagaing fault suggest that 20 3 mm yr of the relative plate motion of 36 mm yr between the india and sunda plates is accommodated at the sagaing fault through dextral strike slip motion we report results from a dense gps network in the ibw that has operated since 2004 our analysis of these measurements and the seismicity of the ibw suggest that the steeply dipping churachandpur mao fault in the ibw accommodates the remaining motion of 18 2 mm yr between the india and sunda plates through dextral strike slip motion and this motion occurs predominantly through velocity strengthening frictional behavior i e aseismic slip the aseismic motion on this plate boundary fault significantly lowers the seismic hazard due to major and great interplate earthquakes along this plate boundary

crustal deformation spatial distribution of earthquakes and along strike segmentation of the sagaing fault myanmar abstract the 1200 km long north south oriented sagaing fault plate boundary fault between the burma and sunda plates entirely located in myanmar passes through some major cities and has witnessed several major earthquakes since prehistoric time including the recent mw 6 8 thabeikkyin earthquake in 2012 the sagaing fault accommodates 50 55 of dextral motion of the india sunda plate motion combined geodetic observations and rheological considerations using topography as a proxy we propose along strike segmentation of the sagaing fault from centrally locked segment to creeping segment further north along the koma fault such segmentation facilitates stress transfer or loading from creeping segment to locked segment and influences earthquake nucleation process and along strike spatial extent of great earthquake ruptures topographic margins and their relative strength predicted from the newtonian channel flow model also support the along strike segmentation behaviour

eastward glacier like flow of the tibetan crust constrained from power law rheology abstract we propose that topography can be used as a proxy for the eastward lateral glacier like flow of the tibetan crust in the himalayan tibetan orogenic system geodetic observations across the tibetan plateau indicate 22 mm yr of crustal motion with respect to stable eurasia by considering newtonian channel flow model further correlation between regional strain rate e and topographic elevation h is found to be statistically robust with stress exponent n of 3 03 0 1 therefore we suggest that the tibetan crust follows well defined power law relation that is consistent with the nonlinear deformation associated with dislocation creep moreover the predicted viscosity range of the tibetan crust is consistent with the channel flow model proposed by previous investigators using different approaches in different time scales

aftershocks and pore fluid diffusion following the 1992 landers earthquake 1 we model the evolution of regional stress following the 1992 landers earthquake in order to test the importance of pore fluid flow in producing aftershocks rising fluid pressure due to pore fluid flow and the resulting coulomb stress changes were found to be strongly correlated with the time and location of aftershock events regional aftershock frequencies computed by integrating pore pressure decay rates also agreed quite well with aftershock data calculations show that regions of rising postseismic poroelastic coulomb stress overlap considerably with regions of positive coseismic coulomb stress thus pore fluid flow which affects pore pressure within faults and causes regional poroelastic stress evolution following earthquakes gradually evolves the initial coseismic stress changes together these changes provide a reasonable physical mechanism for aftershock triggering which agrees with data for the 1992 landers earthquake

evidence of a dyke sheet intrusion at stromboli volcano inferred through continuous tilt a tiltmeter installed in the northern sector of the island of stromboli aeolian archipelago tyrrhenian sea recorded a co seismic offset at the time of the main shock ml 3 7 of the 7 november 1994 swarm located 5 km north of the island during the three months following this event a transient tilt anomaly which was interpreted as due to a lateral intrusion and modelled through a dyke sheet dislocation was recorded the tilt data were used in an analytical inversion based on a propagating tensile source with length and width increasing in time the final result is consistent with the tectonic and structural framework of the volcano area

deformation and stability of a discontinuity controlled rock slope at dagangshan hydropower station using three dimensional discontinuous deformation analysis abstract the right bank slope of the dagangshan hydropower station has undergone large deformation during excavation which may continue to increase and cause slope instability and failure threatening dam construction and safe operation this study analysed the deformation and instability of this discontinuity controlled rock slope by three dimensional discontinuous deformation analysis 3d dda a microseismic monitoring technique was adopted to capture the spatial and temporal distributions of microseismic events the unknown geological discontinuities and the potential slip surface inside the slope were determined by combining monitoring data with the geological information the 3d dda model was established to analyse the 3d deformation characteristics of the slope in addition the slope deformation and failure under various conditions such as over excavations as well as various joint penetrations joint dip directions and friction angles were further investigated it was found that the simulation of the critical sliding state of blocks by 3d dda is effective after improvement of the critical sliding model of joint contact between blocks and the computational results showed good agreement with monitoring results slope deformation is caused by the accumulation of micro crack damage in deep rock masses and it is closely related to its internal and external conditions furthermore the failure modes and mechanisms of the slope with 3d topography are presented which may be helpful for the design of a slope reinforcement scheme

the ground based insar monitoring system at stromboli volcano linking changes in displacement rate and intensity of persistent volcanic activity stromboli volcano aeolian archipelago southern italy experienced an increase in its volcanic activity from late december 2012 to march 2013 when it produced several lava overflows major strombolian explosions crater wall collapses pyroclastic density currents and intense spatter activity an analysis of the displacement of the ne portion of the summit crater terrace and the unstable nw flank of the volcano sciara del fuoco depression has been performed with a ground based interferometric synthetic aperture radar gbinsar by dividing the monitored part of the volcano into five sectors three in the summit vents region and two in the sciara del fuoco changes in the displacement rate were observed in sectors 2 and 3 field and thermal surveys revealed the presence of an alignment of fumaroles confirming the existence of an area of structural discontinuity between sectors 2 and 3 high displacement rates in sector 2 are interpreted to indicate the increase in the magmastatic pressure within the shallow plumbing systems related to the rise of the magma level within the conduits while increased displacement rates in sector 3 are connected to the lateral expansion of the shallow plumbing system the increases and decreases in the displacement rate registered by the gbinsar system in the upper part of the volcano have been used as a proxy for changes in the pressure conditions in the shallow plumbing system of stromboli volcano and hence to forecast the occurrence of phases of higher intensity volcanic activity

towards field bounds on rock mass failure criteria abstract various rock mass failure criteria are being validated against field performance as part of a large research program into the geotechnical risk of concrete gravity dams the project has sought rock structures which may contribute to providing either upper or lower bounds to various failure criteria and therefore the emphais has been on finding sites with high quality field and laboratory data the first two sites investigated have been chichester dam foundation and nattai north escarpment failure both in new south wales australia the paper summarises the existing information for both cases each case has been analysed using the distinct element method the results of these analyses allow the field occurrence to be compared with the commonly used hoek brown empirical rock mass failure criterion as expected the bounds on the various failure criteria are very broad and care must be taken when placing any reliance on any particular criterion

review of ten years of volcano deformations recorded by the ground based insar monitoring system at stromboli volcano a tool to mitigate volcano flank dynamics and intense volcanic activity abstract stromboli volcano southern italy is one of the most monitored volcano in the world with a surveillance network that includes a permanently sited ground based sar interferometer gbinsar this work is the review of the gbinsar data gained from the last decade of monitoring activity the analysis of the entire dataset of gbinsar measurements allowed the assessment of the deformation field of the northern part of the summit crater area and the sciara del fuoco depression in detail the main displacements recognized can be related to different factors 1 the inflation deflation respectively immediately before and after each new effusive event 2 the bulging of localized sectors of the volcano involved in the vent opening 3 the gravitational sliding of the sciara del fuoco infill 4 the movement of lava flows accelerations in this sector are related to sheet intrusions while the possibility of vent opening associated with small sliding or catastrophic flank failure are related to highly overpressurized sheets able to produce high displacement rate in the sciara del fuoco in the summit crater area the increases in the displacement rate are related to the pressurization of the shallow conduit system as the consequence of the variation in the magma level magmastatic pressure or to the lateral magma migration lateral conduit expansion or dike intrusion in response to the increase of the overpressure component fluctuations in the displacement rate in the summit crater area can be related to the magma overturning within the conduit with the increases in displacement rate during the upwelling of less dense magma while displacement rate decreases as the degassed magma column is pushed out from the conduit lava flows or overflows instead the decrease in the displacement rate without coeval lava outpouring could be related to the sink of the degassed magma due to density contrast between the gas poor and the gas charged magmas using the displacement rate in the summit crater area as a proxy for the variation in the pressure condition in conduit both magmastatic and overpressure components thresholds for the crises characterized by the occurrence of overflows eventually associated with major explosions and flank effusions eventually associated with paroxysmal explosions are identified small conduit overpressure will produce overflows sometimes associated with crater rim collapses while large magma overpressure will laterally expand the conduit forming ne sw striking sheets feeding eruptive vents at the base of the summit crater area and within the sciara del fuoco generating conditions of instability that can evolve into catastrophic collapse of the instable flank

geodetic evidence and modeling of a slow small scale inflation episode in the thera santorini volcano caldera aegean sea abstract analysis of a radial geodetic monitoring record indicated small scale inflation of the nw part of the thera santorini caldera up to 10 cm baseline length increase between 1994 and 2000 corresponding to up to 2 10 5 strain and subsequent stabilization especially after 2006 as gps data indicate the southern part of the caldera on the contrary remained practically stable this partial caldera inflation was assigned to slow magma intrusion which was not associated with changes in the seismicity using a stochastic approach based on numerical analysis and the theory of graphs and sets the mogi source of this magmatic activity was identified between the nea kammeni and the therasia islets along a major tectonovolcanic lineament at a depth of around 1 km or possibly 5 5 km it remained stable during the whole small scale inflation period and was associated with small scale pressure changes slow deformation events have been observed in other volcanoes as well but they were associated with abrupt seismicity changes

dynamic stability analysis of jointed rock slopes using the dda method king herod s palace masada israel abstract a dynamic two dimensional stability analysis of a highly discontinuous rock slope is demonstrated in this paper the studied rock slope is the upper terrace of king herod s palace in masada situated on the western margins of the seismically active dead sea rift the slope consists of sub horizontally bedded and sub vertically jointed stiff dolomite blocks the dynamic deformation of the slope is calculated using a fully dynamic version of dda in which time dependent acceleration is used as input the analytically determined failure modes of critical keyblocks in the jointed rock slope are clearly predicted by dda at the end of the dynamic calculation it is found however that for realistic displacement estimates some amount of energy dissipation must be introduced into the otherwise fully elastic un damped dda formulation comparison of predicted damage with actual slope performance over a historic time span of 2000 years allows us to conclude that introduction of 2 kinetic damping should suffice for realistic damage predictions this conclusion is in agreement with recent results of tsesarsky et al in y h hatzor ed stability of rock structures proceedings of the fifth international conference of analysis of discontinuous deformation balkema publishers lisse 2002 pp 195 203 who compared displacements of a single block on an inclined plane subjected to dynamic loading obtained by dda and by shaking table experiments using dynamic dda it is shown that introduction of a simple rock bolting pattern completely stabilizes the slope

fracture evolution in artificial bedded rocks containing a structural flaw under uniaxial compression abstract the observation and prediction of crack propagation are important in understanding rock behavior in engineering practice previous studies have focused on homogeneous and isotropic rocks but the influence of bedding planes on rock fracture is sparingly documented in this study we investigate the fracturing response in uniaxial compression of artificial bedded rocks containing variable inclination bedding planes and single structural flaws the recorded stress strain data and captured cracking patterns are examined together nine separate crack types are identified in which bedding plane sliding and splitting are potentially new the presence of bedding planes plays a decisive role in crack propagation with a steepening of the bedding plane tensile cracks initiating from the structural flaw are better able to propagate along bedding planes and the accumulative length of bedding fractures accordingly increases failure transforms from a purely tensile mode to a bedding sliding mode and subsequently to a bedding splitting mode as the bedding inclination increases compared to pro dip flaw tests the fracturing of bedding planes is triggered by both the tensile and shear stress with more far field tensile cracks initiating from bedding planes in the specimens containing anti dip flaws finally the results are applied to predict the failure mode and fracture evolution in bedded rock slopes

intraplate deformation of the indian subcontinent 1 while deformation at the earth s surface primarily occurs along tectonic plate boundaries major earthquakes have shaken regions deep within continental interiors three of the largest m 7 5 historic intraplate earthquakes occurred within the indian subcontinent suggesting the possibility of significant intraplate deformation we consider surface velocities determined from new gps data collected at 29 continuous gps stations and 41 survey mode gps stations in india between 1995 and 2007 to find a north south shortening rate of 0 3 0 05 nanostrain yr 1 which may be accommodated by 2 1 mm yr of more localized convergence across central india southward motions at 4 7 mm yr of sites on the shillong plateau in northeast india reflect rapid shortening and high earthquake hazard associated with active thrust faults bounding the plateau the width and magnitude of the elastic strain accumulation field across the himalaya varies little from 76 90 longitude but the strain is more broadly distributed and convergence rates are higher along the eastern 200 km of the range

instantaneous geodetic positioning at medium distances with the global positioning system we evaluate a new method of global positioning system gps data analysis called instantaneous positioning at spatial scale lengths typical of interstation spacings in a modern crustal motion network this method is more precise and versatile than traditional gps static and kinematic processing of multi epoch batches of data the key to instantaneous positioning is the ability to resolve integer cycle phase ambiguities with only a single epoch of dual frequency phase and pseudorange data rendering receiver cycle slips irrelevant we estimate three dimensional relative coordinates and atmospheric zenith delay parameters independently every 30 s over a 12 week period for baseline distances of 50 m 14 km and 37 km horizontal precision of a single epoch coordinate solution is about 15 mm and vertical precision is about 7 8 times worse removing that component of each time series which repeats with a period of exactly 1 sidereal day and thus manifests signal multipath reduces the scatter by about 50 in all components solution averaging of the high frequency time series can be performed using any number of measurement epochs to further improve coordinate precision we demonstrate that the daily coordinates estimated with instantaneous positioning are more precise by 20 50 per coordinate component than those estimated with 24 hour batch processing spectral analysis of the single epoch solutions indicates that the flicker noise characteristic of gps time series observed in lower frequency bands also affects gps solutions in the frequency band 0 01 mhz to 10 mhz we argue that the flicker noise is induced by tropospheric effects since modern gps receivers are capable of observing at frequencies as high as 10 hz our technique significantly overlaps and complements the frequency band of broadband seismology and benefits other research areas such as earthquake geodesy volcanology and gps meteorology

crustal deformation across and beyond the los angeles basin from geodetic measurements we combine 6 years of global positioning system gps data with 20 years of trilateration data and a century of triangulation taped distance and astronomic azimuth measurements to derive 66 interseismic station velocities in the greater los angeles region we interpolate the velocities to construct a regional strain rate map beyond the los angeles basin our results generally agree with the model proposed by the working group on california earthquake probabilities in 1995 important regional findings of this study are as follows 1 there is a significant n s convergence and e w extension about 0 22 and 0 17 0 05 strain yr respectively for the two components along the southern frontal fault system of the san gabriel mountains 2 the crustal deformation around the big bend of the san andreas fault saf cannot be explained solely by wrench style motion across the saf remaining motion could be part of a nw se extension which is the response to nfsw compression in the central transverse ranges region alternatively it could be caused by left lateral faulting on an oblique blind thrust beneath the san gabriel mountains 3 low strain rates axe found along the elsinore fault and newport inglewood 4 north south compression decreases from the raymond hill fault westward to the santa monica fault there is little east west extension along this fault system

development of three dimensional numerical manifold method for jointed rock slope stability analysis abstract this paper presents a three dimensional numerical manifold method nmm for jointed rock slope stability analysis the main barriers for realistic rock slope stability analysis are discussed and the unique features of the nmm which make it stand out in slope analysis are emphasized the framework of the 3 d nmm is established via a regularly patterned tetrahedral mesh based mathematical cover system a contact detection algorithm is then customized to fit the 3 d nmm characteristics the developed code is first calibrated by two simple cases inclined plane sliding and tetrahedral wedge sliding and then applied to a more complex slope scenario the complete failure process involving large displacement and rotation of multiple interaction blocks is exhibited dynamically two typical stabilization protection techniques are also investigated the developed 3 d nmm could be potentially used to find the trigger failure mechanism of jointed rock slopes so as to optimize the slope stabilization or protection design

the stability of a laminated voussoir beam back analysis of a historic roof collapse using dda abstract the stability of a horizontally bedded and vertically jointed roof referred to here as a laminated voussoir beam is studied using careful documentation of a historic roof collapse which occurred in an ancient underground water storage reservoir dated back to ca 1000 b c the roof of the opening failed immediately after the excavation leaving a dome shaped loosened zone with a span of 7 m and height of 2 5 m consisting of horizontal beds and vertical joints with mean spacing of 50 and 25 cm respectively the ancient engineers erected a massive pillar at the center of the dome in order to passively support the failed roof and the opening remained in service for several hundred years following the failure analysis of the roof using iterative voussoir beam procedure beer g and meek j l design curves for roofs and hanging walls in bedded rock based on voussoir beam and plate solutions trans inst min metall 1982 91 a18 22 shows that the roof was more sensitive to failure by shear along the abutments rather than by crushing at hinge zones and that the required friction angle req for stability would have been 36 the available friction angle is estimated between 38 6 and 46 4 and therefore the result of the iterative solution is considered unconservatively wrong results of dda shi g h and goodman r e two dimensional discontinuous deformation analysis int j numer anal methods geomech 1989 13 359 380 shi g h block system modeling by discontinuous deformation analysis computational mechanics publications southampton 1993 pp 209 however indicate that req must have been greater than 60 a shear strength which was not available at the time of construction thus the immediate failure using dda we further demonstrate that req is related to joint spacing or block length in a parabolic function with increasing joint spacing req decreases to a minimum value and than increases with further increase in joint spacing this result is attributed to the interaction of two competing forces one is the stabilizing axial thrust which increases with increasing moment arm in individual blocks a function of joint spacing or block length the other is the destabilizing vertical load which increases with increasing weight of overlying blocks

insight on recent stromboli eruption inferred from terrestrial and satellite ground deformation measurements abstract the multi parametric permanent system tilt and gps networks robotized geodetic station for monitoring ground deformation at stromboli volcano was set up in the 1990s and later greatly improved during the effusive event of 2002 2003 unlike other volcanoes e g mt etna the magnitude of ground deformation signals of stromboli is very small and through the entire period of operation of the monitoring system only two major episodes of deformation in 1994 1995 and 2000 which did not lead to an eruption but rather pure intrusion were measured similarly to the 2002 2003 eruption no important deformations were detected in the months before the 2007 eruption however unlike the 2002 2003 eruption gps and tilt stations recorded a continuous deflation during the entire 2007 eruption which allowed us to infer a vertical elongated prolate ellipsoidal source centered below the summit craters at depth of about 2 8 km b s l due to its geometry and position this source simulates an elongated plumbing system connecting the deeper lp magma storage depth from 5 to 10 km with the hp shallower storage 0 8 3 km both previously identified by petrologic and geochemical studies this result represents the first contribution of geophysics to the definition of the plumbing system of stromboli at intermediate depth finally no deformation due to the plumbing system was measured for a long time after the end of the eruption meanwhile the new terrestrial geodetic monitoring system installed within the sciara del fuoco on the lava fan formed during the eruption indicated that during the first months after the end of the eruption the ground velocity progressively decreased in time suggesting that part of the deformation was due to the thermal contraction of the lava flow

automatic recognition of landslides based on neural network analysis of seismic signals an application to the monitoring of stromboli volcano southern italy in the last 9 years the amount and the quality of geophysical and volcanological observations of stromboli s activity have undergone a marked increase this new information highlighted that the landslides on the sciara del fuoco flank are tightly linked to the volcanic activity actually at the beginning of the december 28 2002 effusive eruption the seismic monitoring network was less dense than now and therefore it is not known if there was an increase in the landslide rate before the eruption despite this it is known that a big landslide occurred 2 days after the beginning of the eruption which caused a tsunami december 30 2002 more recently the effusive eruption in february 2007 was preceded by an increase in landslides on the sciara del fuoco flank which were recorded by the seismological monitoring system that had been improved after the 2002 2003 crisis these episodes led us to believe that monitoring the sciara del fuoco flank instability is an important topic and that landslides might be significant short term precursors of effusive eruptions at the stromboli volcano to automatically detect landslide signals we have developed a specialized neural algorithm this can distinguish between landslides and the other types of seismic signals usually recorded at the stromboli volcano i e explosion quakes and volcanic tremor the discrimination results show an average performance of 98 67 according to the experience of the crisis of 2007 to identify changes that can be considered as precursors of effusive eruptions we set up an automatic decision making method based on the neural network responses this method can operate on a continuous data stream it calculates a landslide percentage index lpi that depends on the number of records that are classified by the net as landslides over a given time interval we tested the method on february 27 2007 including the beginning of the effusive phase the index showed an increase as early as at 09 00 utc on that day and reached its maximum value 100 at 12 00 about 40 min before the onset of the eruption after the beginning of the effusive phase the index remains high due to the blocks that roll down along the slope from the front of the lava flow on the basis of these tests we propose a decision making method that is able to recognize a trend in the lpi similar to that of 2007 eruption allowing the identification of precursors of effusive phases at the stromboli volcano

dda validation of the mobility of earthquake induced landslides abstract this paper studies the run out of earthquake induced landslides there are more than 20 mechanical models to explain long run out of rapid landslides including some earthquake induced landslides however notably few of them considered the effect of seismic loading on the run out of landslides in a previous study we have proposed a model which is called the multiplex acceleration model mam to interpret the long run out mechanism and a shaking table test has been performed to verify the mam because the previous mam is a conceptual model and only a single stone has been examined under sine waves by the shaking table test the mam needs to be extended and further verified in this paper the mam was extended by introducing the movement change that was induced by the so called trampoline effect of earthquake loading and the latest practical numerical simulation program discontinuous deformation analysis dda was used to verify the mobility of earthquake induced landslides after a conceptual landslide model was used to verify the effect of seismic loading on the mobility the donghekou landslide which was a typical long run out landslide that was induced by the 2008 wenchuan earthquake was analyzed the results show that the seismic loading could be one of the factors that could eventually help increase the run out of landslides

mantle fluids in the karakoram fault helium isotope evidence abstract the karakoram fault kkf is the 1000 km long strike slip fault separating the western himalaya from the tibetan plateau from geologic and geodetic data the kkf is argued either to be a lithospheric scale fault with hundreds of km of offset at several cm a or to be almost inactive with cumulative offset of only a few tens of kilometers and to be just the upper crustal localization of distributed deformation at depth here we show 3he 4he ratios in geothermal springs along a 500 km segment of the kkf are 3 100 times the normal ratio in continental crust providing unequivocal evidence that a component of these hydrologic systems is derived from tectonically active mantle mantle enrichment is absent along the indus yarlung suture zone isz just 35 km southwest of the kkf suggesting that the mantle fluids flow only within the kkf within the last few ma the kkf must have accessed tectonically active tibetan mantle northeast of the mantle suture which we therefore locate vertically beneath the kkf very close to the surface trace of the isz hence in southwestern tibet indian crust may not now be underthrusting substantially north of the isz even though miocene underthrusting may have placed indian crust north of the isz in the lower half of the tibetan plateau crust this is in significant contrast to central and eastern tibet where underthrust indian material not only forms the lower half of the tibetan crust but is also currently underthrusting for 200 km north of the isz our new constraint on kkf penetration to the mantle allows an improved description of the continuously evolving karakoram fault as a tectonically significant yet perhaps geologically ephemeral lithospheric structure

tsunami squares modeling of landslide generated impulsive waves and its application to the 1792 unzen mayuyama mega slide in japan abstract the frequent occurrence of landslide tsunami has aroused great social concern hence an efficient approach for modeling the phenomena is required urgently herein we present and supplement a meshless numerical model named tsunami squares ts ts simulates both the landslide and its generated wave using an updated numerical scheme that has enhanced computational efficiency ts also provides an artful way of approximating linear dispersive wave propagation and non linear wave inundation that makes it quite capable of simulating real scale events a well designed test that compares ts output with an analytical formula for a tsunami propagation calculation provides firm validation of the approach we then applied the tsunami squares to simulate the 1792 unzen mayuyama mega slide and generated tsunami this event remains the largest volcanic disaster in the history of japan landslide dynamics simulated by ts coincide with historical reports and the known geometry of landslide deposits the model output of tsunami runup heights well match the observed values recorded by the locations of historical tsunami stones this well documented and data rich case further validates the tsunami squares model and the excellent reproduction of the 1792 event provides new insights for better understanding of landslide tsunami hazards

understanding shallow magma emplacement at volcanoes orthogonal feeder dikes during the 2002 2003 stromboli italy eruption 1 understanding how shallow magma is emplaced within volcanoes is crucial for hazard assessment the 2002 2003 stromboli eruption provides the opportunity to investigate shallow magma emplacement resulting from orthogonal feeder dikes and its possible effects stromboli erupted in 2002 2003 when effusive activity replaced strombolian activity on december 28 a ne sw fissure propagated from the lava filled northernmost summit crater on december 29 a nw se fissure propagated north of the craters feeding nw se aligned vents on december 30 this area collapsed reaching the sea and generating a tsunami in mid february 2003 the nw se fissure became inactive while the ne sw effusive fissure continued until july a model for shallow magma emplacement is proposed the lateral propagation of a ne sw dike from the northernmost crater was triggered below a nw se dike propagating from the magma filled ne tip of the ne sw elongated conduit fed the nw se aligned vents in february the conduit periphery became solidified freezing the nw se dike and the transport of magma was limited to the central part focusing its rise below the craters this fed the ne sw fissure until the supply decreased further july returning to the ordinary level sustaining strombolian activity orthogonal dike emplacement followed the trajectories of the maximum gravitational stress 1 partly controlled by the irregular topography of the uppermost edifice the emplacement of orthogonal dikes in a limited area is feasible at non perfectly conical active volcanoes where the maximum gravitational stress may show variations from a purely radial path