law for the distance between successive earthquakes 1 discovery of a new law for the three dimensional spatial distance between the foci of successive earthquakes is reported analyzing the seismic data taken between 1984 and 2001 in southern californian it is found that the cumulative distribution of the distances follows the modified zipf mandelbrot law showing complexity of geometry of the events

topographical changes revealed by high resolution airborne lidar data the 1999 tsaoling landslide induced by the chi chi earthquake abstract the 1999 chi chi earthquake triggered the catastrophic tsaoling landslide in central taiwan we mapped the landslide area and estimated the landslide volume using a high resolution digital elevation model from airborne lidar light detection and ranging aerial photographs and topographic maps the comparison between scar and deposit volumes about 0 126 km3 and 0 150 km3 respectively suggests a coseismic volume increase of 19 due to decompaction during landsliding in july 2003 the scar and deposit volumes were about 0 125 km3 and 0 110 km3 respectively these estimates suggest that 4 years after the event the volume of landslide debris removed by river erosion was nearly 0 040 km3 these determinations are confirmed by direct comparison between the most accurate topographic models of the post landslide period indicating a very high erosion rate at the local scale 0 01 km3 year for the deposit area of the landslide such a large value highlights the importance of landslide processes for erosion and long term denudation in the taiwan mountain belt

fragmentation and boosting of rock falls and rock avalanches fragmentation has been proposed as an important dynamical process in the propagation of rock avalanches the occurrence of an intense block fragmentation inside a rock avalanche traveling on smooth inclined terrain followed by a flat region a geometry common to many landslides is first studied numerically by means of a discrete element 2 d code in which blocks are subjected to mutual collisions and impact with the terrain this numerical model confirms that the locations where fragmentation is more likely to occur are those in correspondence of abrupt slope changes we thus analyze this geometry of impact in two cases low and high impact energy in the first case where recent experimental data are available a kinematic analysis shows that the energy released at impact causes high velocities of the smallest fragments a highly probable scenario in rock avalanche dynamics when the impact is so energetic to disintegrate the landslide we find that explosive fragmentation at the slope break provides an extra horizontal boost to a rock avalanche via a peculiar mechanism coupling the geometry of the slope path to the dynamics of the rock avalanche as a consequence a net momentum gain boost results along the horizontal direction due to the terrain asymmetry however under normal field conditions only when the slope angle is greater than 70 and fragmentation produces clasts of fairly uniform size the momentum and runout distance are significantly enhanced allowing for a spectrum of fragment sizes and velocities we find a relationship between the degree of fragmentation and the magnitude of the extra boost

evidence of non extensive statistical physics of the lithospheric instability approaching the 2004 sumatran andaman and 2011 honshu mega earthquakes abstract in the present study we demonstrate in the frame of non extensive statistical physics significant deviations of the global seismic activity from a quasi stationary regime before sumatra andaman and honshu mega earthquakes suggesting the existence of a global scale intermediate term non extensive tectonic premonitory of impending mega earthquake processes in the lithosphere using non extensive statistical mechanics we describe the frequency moment the inter event time and distance distributions interpreting sumatran s 2004 and honshu 2011 earthquakes influence on these at a phenomenological level we find that global seismicity is described by non extensive statistical mechanics nesm and that the seismic moment and the earthquake inter event time distributions reflect a sub extensive system where long range interactions are important using the cross over formulation of nesm leads us to the conclusion that the seismic moment distribution of moderate events yields thermodynamic q values of qm 1 6 which seem to be constant for the duration of the sumatra and honshu earthquake preparation while rm which describes the seismic moment distribution of great events varies from 1 to 1 5 as we approach the mega events the inter event time and inter event distance distributions with q 1 5 and qd 0 3 respectively support the conclusion of non extensive spatio temporal duality suggesting that global shallow moderate seismicity with 5 5

statistical physics seismogenesis and seismic hazard the scaling properties of earthquake populations show remarkable similarities to those observed at or near the critical point of other composite systems in statistical physics this has led to the development of a variety of different physical models of seismogenesis as a critical phenomenon involving locally nonlinear dynamics with simplified rheologies exhibiting instability or avalanche type behavior in a material composed of a large number of discrete elements in particular it has been suggested that earthquakes are an example of a self organized critical phenomenon analogous to a sandpile that spontaneously evolves to a critical angle of repose in response to the steady supply of new grains at the summit in this stationary state of marginal stability the distribution of avalanche energies is a power law equivalent to the gutenberg richter frequency magnitude law and the behavior is relatively insensitive to the details of the dynamics here we review the results of some of the composite physical models that have been developed to simulate seismogenesis on different scales during 1 dynamic slip on a preexisting fault 2 fault growth and 3 fault nucleation the individual physical models share some generic features such as a dynamic energy flux applied by tectonic loading at a constant strain rate strong local interactions and fluctuations generated either dynamically or by fixed material heterogeneity but they differ significantly in the details of the assumed dynamics and in the methods of numerical solution however all exhibit critical or near critical behavior with behavior quantitatively consistent with many of the observed fractal or multifractal scaling laws of brittle faulting and earthquakes including the gutenberg richter law some of the results are sensitive to the details of the dynamics and hence are not strict examples of self organized criticality nevertheless the results of these different physical models share some generic statistical properties similar to the universal behavior seen in a wide variety of critical phenomena with significant implications for practical problems in probabilistic seismic hazard evaluation in particular the notion of self organized criticality or near criticality gives a scientific rationale for the a priori assumption of stationarity used as a first step in the prediction of the future level of hazard the gutenberg richter law a power law in energy or seismic moment is found to apply only within a finite scale range both in model and natural seismicity accordingly the frequency magnitude distribution can be generalized to a gamma distribution in energy or seismic moment a power law with an exponential tail this allows extrapolations of the frequency magnitude distribution and the maximum credible magnitude to be constrained by observed seismic or tectonic moment release rates the answers to other questions raised are less clear for example the effect of the a priori assumption of a poisson process in a system with strong local interactions and the impact of zoning a potentially multifractal distribution of epicentres with smooth polygons the results of some models show premonitory patterns of seismicity which could in principle be used as mainshock precursors however there remains no consensus on both theoretical and practical grounds on the possibility or otherwise of reliable intermediate term earthquake prediction

dynamics of an unusual cone building trachyte eruption at pu u wa awa a hualālai volcano hawai i the pu u wa awa a pyroclastic cone and pu u anahulu lava flow are two prominent monogenetic eruptive features assumed to result from a single eruption during the trachyte dominated early post shield stage of hual lai volcano hawai i pu u wa awa a is composed of complex repetitions of crudely cross stratified units rich in dark dense clasts which reversely grade into coarser pumice rich units pyroclasts from the cone are extremely diverse texturally ranging from glassy obsidian to vesicular scoria or pumice in addition to fully crystalline end members the 100 m thick pu u anahulu flow is in contrast entirely holocrystalline using field observations coupled with whole rock analyses this study aimed to test whether the pu u wa awa a tephra and pu u anahulu lava flows originated from the same eruption as had been previously assumed crystal and vesicle textures are characterized along with the volatile contents of interstitial glasses to determine the origin of textural variability within pu u wa awa a trachytes e g magma mixing vs degassing origin we find that 1 the two eruptions likely originated from distinct vents and magma reservoirs despite their proximity and similar age 2 the textural diversity of pyroclasts forming pu u wa awa a can be fully explained by variable magma degassing and outgassing within the conduit 3 the pu u wa awa a cone was constructed during explosions transitional in style between violent strombolian and vulcanian involving the formation of a large cone and with repeated disruption of conduit plugs but without production of large pyroclastic density currents pdcs and 4 the contrasting eruption styles of hawaiian trachytes flow cone and pdc forming are probably related to differences in the outgassing capacity of the magmas prior to reaching the surface and not in intrinsic compositional or temperature properties these results further highlight that trachytes are kinetically faster magmas compared to dacites or rhyolites likely degassing and crystallizing more rapidly

effect of the sumatran mega earthquake on the global magnitude cut off and event rate the great sumatran earthquake of 2004 allows us to assess the statistics and statistical stability of the global earthquake catalogue from the digital era a key question is do such mega earthquakes continue to follow the gutenberg richter g r trend1 or is there an observable cut off2

the formation and failure of natural dams of the numerous kinds of dams that form by natural processes dams formed from landslides glacial ice and late neoglacial moraines present the greatest threat to people and property landslide dams form in a wide range of physiographic settings the most common types of mass movements that form landslide dams are rock and debris avalanches rock and soil slumps and slides and mud debris and earth flows the most common initiation mechanisms for dam forming landslides are excessive rainfall and snowmelt and earthquakes landslide dams can be classified into six categories based on their relation with the valley floor type i dams 11 of 184 landslide dams from around the world that we were able to classify do not reach from one valley side to the other type ii dams 44 span the entire valley floor in some cases depositing material high on opposite valley sides type iii dams 41 move considerable distances both upstream and downstream from the landslide failure type iv dams 1 are rare and involve the contemporaneous failure of material from both sides of a valley type v dams 1 also are rare and are created when a single landslide sends multiple tongues of debris into a valley and forms two or more landslide dams in the same reach of river type vi dams 3 involve one or more failure surfaces that extend under the stream or valley and emerge on the opposite valley side many landslide dams fail shortly after formation in our sample of 73 documented landslide dam failures 27 of the landslide dams failed less than 1 day after formation and about 50 failed within 10 days over topping is by far the most common cause of failure the timing of failure and the magnitude of the resulting floods are controlled by dam size and geometry material characteristics of the blockage rate of inflow to the impoundment size and depth of the impoundment bedrock control of flow and engineering controls such as artificial spill ways diversions tunnels and planned breaching by blasting or conventional excavation glacial ice dams can produce at least nine kinds of ice dammed lakes the most dangerous are lakes formed in main valleys dammed by tributary glaciers failure can occur by erosion of a drainage tunnel under or through the ice dam or by a channel over the ice dam cold polar ice dams generally drain supraglacially or marginally by downmelting of an outlet channel warmer temperate ice dams tend to fail by sudden englacial or subglacial breaching and drainage late neoglacial moraine dammed lakes are located in steep mountain areas affected by the advances and retreats of valley glaciers in the last several centuries these late neoglacial dams pose hazards because 1 they are sufficiently young that vegetation has not stabilized their slopes 2 many dam faces are steeper than the angle of repose 3 these dams and lakes are immediately downslope from steep crevassed glaciers and near vertical rock slopes and 4 downstream from these dams are steep canyons with easily erodible materials that can be incorporated in the flow and increase flood peaks the most common reported failure mechanism is overtopping and breaching by a wave or series of waves in the lake generated by icefalls rockfalls or snow or rock avalanches melting of ice cores or frozen ground and piping and seepage are other possible failure mechanisms natural dams may cause upstream flooding as the lake rises and downstream flooding as a result of failure of the dam although data are few for the same potential energy at the dam site ownstream flood peaks from the failure of glacier ice dams are smaller than those from landslide moraine and structed earth fill and rock fill dam failures moraine dam failures appear to produce some of the largest downstream flood peaks for potential energy at the dam site greater than 1011 1012 joules differences in flood peaks natural dam failures appear to be controlled by dam characteristics and failure mechanisms

viscosity of hydrous etna basalt implications for plinian style basaltic eruptions water dissolved in a silicate melt can strongly influence its physical properties and thus magma behavior during crystallization degassing foaming and fragmentation etna is a basaltic volcano whose activity is dominated by effusive eruptions which have long represented a threat to the densely populated surrounding area recently recognition of the products of a plinian eruption 122 b c has raised further issues for hazard assessment at etna and other basaltic volcanoes constraining the behavior of etna magma under conditions relevant to both effusive and explosive hazards requires viscosity data under conditions near the glass transition here we have investigated the viscosity of hydrous etna lava in order to better understand eruptive processes which characterize this volcano the experimental methods which have been used include piston cylinder synthesis of the hydrated melts micropenetration viscometry for low temperature viscosity measurements and near infrared spectroscopy for the evaluation of sample homogeneity and measurements of water content additionally scanning calorimetric determinations were performed to check whether incipient crystallization had occurred sample compositions were determined using electron microprobe analysis and 57fe mossbauer spectroscopy results from this study are compared with previous reports of trachytic phonolitic and model calc alkaline rhyolite hpg8 compositions the viscosity of the basaltic melt dry and wet has been parameterized in terms of temperature and water content via the non arrhenian equation log10 4 643 5 812 44 427 04 h2o t k 499 31 28 74 ln h2o where is the viscosity in pa s h2o is the water content in wt and t is the temperature in kelvin we observe that the viscosity of alkali basalt at more than 0 5 wt h2o is similar to that of an alkaline trachyte agnano monte spina eruption phlegrean fields and much higher than that of a peralkaline phonolite teide tenerife at similar silica contents and nbo t for water contents above 1 5 wt the viscosity of the basalt is similar to that of rhyolitic melts with similar water contents at temperatures ranging from 1 050 to 1 150 c and with water contents between 0 5 and 2 3 wt eruptive conditions the viscosities calculated using the equation defined in this study are 1 in reasonable agreement with those calculated using shaw s model and 2 much lower than those experimentally determined in a previous study however outside these temperature and water content ranges the agreement with shaw s model 1972 breaks down

analysis of landslide dams induced by the 2008 wenchuan earthquake abstract landslide dams caused by earthquakes are extremely hazardous disruptions of the flow of water and sediment in mountain rivers capable of delivering large outburst floods that may devastate downstream areas we analyzed a unique inventory of 828 landslide dams triggered by the m w 7 9 2008 wenchuan tectonic earthquake china constituting 1 4 of the 60 000 coseismic slope failures mapped and attributed to this event while 501 landslides blocked the rivers completely the remainder caused only partial damming or channel diversion the spatial distribution of landslide dams follows the same trend of that of the total landslide distribution with landslide dams being most abundant in the steep watersheds of the hanging wall of the yingxiu beichuan thrust fault and in the northeastern part of the strike slip fault near qingchuan besides the co seismic landslide density the river width also played a key role in determining the landslide dam formation narrow rivers are more prone to be dammed than the wide rivers the correlation between river width and landslide dam volume follows a linear relation which can be used to roughly estimate the dam formation possibility however the applicability of this correlation needs to be validated in other regions the decay failure rate of dams defined here as the percentage of the number and area of landslide dams that have failed over time shows that 25 of dams accounting for 30 of total landslide dam area failed one week after the earthquake these percentages increased to 60 within 1 month and to 90 within 1 year the geomorphometric parameters were analyzed revealing power law relations between landslide area and dam width landslide source area and dam area as well as lake area and lake volume the inventory presented in this study will enrich the worldwide earthquake induced landslide dam database and will also contribute to a better understanding of the post earthquake dam decay

physical models of rock avalanche spreading behaviour with dynamic fragmentation the dynamic fragmentation of rock during avalanche motion has been postulated as a mechanism explaining the long runout of large rock avalanches or sturzstrome this paper investigates whether test

redox state microstructure and viscosity of a partially crystallized basalt melt abstract as measured in air above the glass transition range the viscosity of an alkali basalt increases markedly with time by about two orders of magnitude in 12 h this effect is essentially physical and due to the presence of microcrystals although partial crystallization of the melt into spinel and an sio2 poor pyroxene leads to a considerable enrichment in silica of the residual liquid partial crystallization depends strongly on the initial redox state of samples in that the presence of ferrous iron is required for spinel crystals to form and for pyroxene to nucleate and grow around them other measurements show that the viscosity of the crystal free liquid decreases slightly with increasing ratios r fe2 fe because the differences between samples with r 0 16 and 0 83 amount to about 1 5 and 0 3 log units at 950 and 1400 k respectively comparisons of the viscosities of the residual liquid matrix and of the initially crystal free basalt show that physical effects caused by the presence of microcrystals begin to be observed at a low crystal fraction of 5 vol finally a model of viscosity calculation is developed for the melts which reproduces all data obtained in this work to better than 10

structural environment of iron in hydrous aluminosilicate glass and melt evidence from x ray absorption spectroscopy abstract the iron speciation in hydrous haplotonalitic and haplogranitic silicate glasses was studied using xafs spectroscopy and transmission electron microscopy tem spectral features occurring at the main crest of the xanes at the iron k edge of hydrous glasses indicate contributions to the spectra by iron moieties present in a more ordered structural environment than found in the dry glass these differences are also suggested by analysis of the exafs these effects are not completely suppressed even for those samples that were quenched with a higher cooling rate strongest differences to the dry glass are observed for a sample that was quenched slowly through the temperature of glass transformation crystals 60 to 1500 nm in size of magnetite maghemite and another unidentified phase were observed in this sample by tem whereas no crystals were found in samples quenched with regular or high cooling rates in situ xanes measurements up to 700 c and 500 mpa were performed to reveal the origin i e during synthesis or quench of the structural differences for those hydrous glasses that do not display any detectable crystallization the comparison of xanes spectra collected on fe 2 in water saturated haplogranitic melt at 700 c and 500 mpa and on fe 2 in dry melt at 1150 c shows that the local structural environment of fe 2 in both systems is similar this indicates that there is no detectable and direct influence of water on the local structure around iron in this type of melt hence the differences observed between hydrous and dry glasses can only be related to artefacts formed during the quench process

the role of rock fragmentation in the motion of large landslides abstract by considering the implications of the comminution generally associated with very large landslides we arrive at a simple explanation for the remarkably low frictional resistance to motion demonstrated by large intact blockslides e g waikaremoana new zealand volcanic debris avalanches e g socompa chile and large rock avalanches e g falling mountain n z which allows such mass movements to achieve unexpectedly high velocities and long runout distances during rapid grain flow under high direct stress the overall grain motion generates stresses in many force chains that strain individual grains to failure most of the elastic strain energy accumulated in these force chains before failure is returned at failure to the resulting grain fragments resulting in apparent instantaneous pressures of 3q on the surroundings where q is the ambient strength of the previously intact grains gpa these intense pressures support some of the direct force on the shear layer so that the effective intergranular stress in the shear layer is reduced because frictional resistance is proportional to effective stress this reduces the overall frictional resistance to shear the steady state effective stress is that which just allows fragmentation to continue the resistance to motion estimated from this relationship explains to much better than order of magnitude accuracy the reported motions of the large rapid mass movements we also deduce that grain fragmentation can be sustained for sufficiently long to explain the phenomena without reducing the mean grain size by volume in the granular layer to unrealistically small values the presence of pore fluid does not appear to influence the effect of fragmentation dynamics in a major way the proposed mechanism requires further laboratory and simulation studies to reduce its current dependence on limited field data but its success suggests that it is worthwhile investigating further as an explanation for large mass movements in the types of brittle rock in which fragmentation occurs

measuring the degree of nanotilization of volcanic glasses understanding syn eruptive processes recorded in melt inclusions iron and water content substantially affect the physical properties of natural silicate melts and may therefore influence magmatic and volcanic processes such as crystallization degassing flow behaviour and eruptive style here we present raman spectroscopic data for a set of synthetic and natural multicomponent glasses with varying iron oxidation state and water content we systematically study the effect of different raman excitation sources on the spectral response of both crystal free and magnetite nanolite bearing glasses spanning basaltic to calc and per alkaline rhyolitic compositions based on these data we document changes in raman spectra resulting from the formation of nano scale crystals we show that the peak located at similar to 970 cm 1 is directly related to the presence of fe2o3 dissolved in the quenched melt structure and that this feature is present regardless of the chemical composition of the sample and the raman excitation source we further show that a peak between 670 and 690 cm 1 which is not related to any other spectral feature of the glass structure reveals the presence of nanolites based on systematic spectral investigations of this feature we present a new index that allows to identify if iron is present in the nanocrystalline state and or bound in the glass structure since the melt structural and physical effects of the formation of nanolites can heavily affect the flow behaviour of melts and the eruptive style of volcanoes the results presented in this study significantly broaden the application of raman spectroscopy for investigations of nano heterogeneity in synthetic and natural glasses we apply this method to study both the degree of nanolitization as well as the h2o content and iron oxidation state of groundmass glasses as well as melt inclusions and glass embayments in explosive products from pantelleria island italy we observe that the process of nanotilization is not purely restricted to magnetite nanolites but that raman spectroscopy may also identify the incipient crystalization of pyroxene and feldspar at sub micron scale the data document that nanolite formation correlates well with the observed intensity of the respective eruptions suggesting that structural changes in the melt caused by incipient crystallization play an important role in defining the eruptive style of relatively low viscosity magmas

granular flow experiments on the interaction with stationary runout path materials and comparison to rock avalanche events the central focus of this work is to study the processes acting well below the surface of a moving rock or debris avalanche during travel over stationary substrate material small scale physical models at a linear scale of 1 104 used coal as avalanche analogue material and different granular material simulating sedimentary substrates varying in frictional resistance thickness and relative basal boundary roughness as well as inerodible non deformable runout path conditions substrate materials with the least frictional resistance showed the greatest response to granular flow overriding becoming entirely mobilized beneath and ahead of the moving mass and producing the longest runout observed with a unique deposit profile shape with a smooth substrate basal contact failure occurred along this plane and avalanche and substrate became coupled during runout with a rough base however temporary force chains of grain contacts in the substrate prevailed longer imparted their resistance to motion shear into the granular flow and the flow rear section consequently halted earlier than when moving over substrates with a weak base reducing substrate thickness diminished the effect of basal contact roughness on granular flow runout and deposit length inerodible non deformable substrate conditions caused changes in granular flow behaviour from essentially en masse sliding on low friction surfaces to increasing granular agitation over rougher paths copyright 2012 john wiley sons ltd

experimental study on the river blockage and landslide dam formation induced by rock slides abstract rock slides triggered by strong earthquake or heavy rainfall may cause different degrees of blockage in flow channels resulting in a significant impact on the continuity of mountainous rivers based on the extent of blocking the blockage type is divided into three categories in this paper no blockage submerged dam partial blockage and complete blockage the accumulation process of sliding materials in the course of rock slides is an important issue for understanding the formation of landslide dams in this study rock slide and river valley models are developed to investigate the typical kinematic process and emplacement of rock slides and the factors that dictate the formation of landslide dams are critically analyzed the experimental study suggests that there is a positive correlation between the deposit height and the rock slide volume despite differences of rock fragmentation and flow condition in addition the less fragmented rocks result in larger maximum deposit height maxi dh and smaller minimum deposit height mini dh while the better fragmented rocks result in smaller maxi dh and larger mini dh furthermore the water depth has a significant impact on the river blockage type a new blockage index bi that combines the landslide volume and the wet cross sectional area is proposed to assess the damming capacity of rock slides then a method for predicting the river blockage type of rock slides is developed based on the relationship between blockage index and the ratio of maxi dh or mini dh and water depth the model proposed in this work can be used to assist estimating the formation of landslide dam for similar rock slides in the future

increased long range intermediate magnitude earthquake activity prior to strong earthquakes in california we study the space time relationships between strong earthquakes in california and the intermediate magnitude earthquakes that both precede and follow them all 11 earthquakes in california with nominal magnitudes greater than or equal to 6 8 from 1941 to 1993 were preceded by an increase in the rate of occurrence of earthquakes having magnitudes greater than 5 1 ten of the 11 earthquakes occurred when or shortly after the intermediate magnitude activity was greater than its 75th percentile three of these strong earthquakes are in a conventional space time foreshock aftershock relationship with others of the 11 strong events the precursory activity is concentrated in regions having linear dimensions of the order of a few hundred kilometers these dimensions are significantly larger than the estimated fracture lengths of the ensuing strong earthquakes the correlations are ill defined for smaller earthquakes and are almost unidentifiable for earthquakes with magnitudes less than about 4 6 the precursors to the strong earthquakes appear over a time interval of the order of 5 to 10 years before the strong earthquake although the onset was about 25 years before the san francisco earthquake in the case of the loma prieta and san francisco earthquakes the onset of increased activity appears to be relatively abrupt the increased activity is either switched off abruptly to distances of the order of hundreds of kilometers shortly after the occurrence of a strong earthquake or the strong events are themselves part of a precursory pattern of continuing high activity before a second strong earthquake that takes place soon thereafter with subsequent extinction of activity after it thus the intermediate magnitude precursors do not directly influence the time and location of the subsequent strong event but the strong event has a strong influence on the stress field in the vicinity of intermediate magnitude earthquakes to distances of the order of many times the scale size of the strong earthquake

a non extensive statistical physics view in the spatiotemporal properties of the 2003 mw6 2 lefkada ionian island greece aftershock sequence investigation of the spatiotemporal properties of the 2003 lefkada seismic sequence is performed through non extensive statistical physics information on highly accurate aftershock source parameters became feasible from the recordings of a portable digital seismological network that was installed and operated in the study area during the evolution of the seismic sequence thus the spatiotemporal distribution of aftershocks onto the main and neighboring fault segments was investigated in detail enabling the recognition of four distinctive seismicity clusters separated by less active patches the aftershock spatiotemporal properties are studied here using the ideas of non extensive statistical physics nesp the cumulative distribution functions of the inter event times and the inter event distances are presented using the data set in each seismicity cluster and the analysis results in values for the statistical thermodynamic qt and qd parameters for each cluster where qt varies from 1 16 to 1 47 and qd from 0 42 to 0 77 for the inter event times and distances distributions respectively these values confirm the complexity and non additivity of the spatiotemporal evolution of seismicity and the applicability of the nesp approach in investigating aftershocks sequence the temporal pattern is discussed using the closely connected to nesp approach of superstatistics which is based on a superposition of ordinary local equilibrium statistical mechanics the result indicates that the temporal evolution of the lefkada aftershock sequence in clusters a b and c is governed by very low number of degrees of freedom while d is a less organized seismicity structure with a much higher number of degrees of freedom

temporal changes in the cumulative piecewise gradient of a variant of the gutenberg richter relationship and the imminence of extreme events abstract it is generally found that the relative frequencies of occurrence of earthquakes of different magnitudes in seismogenic zones have a power law distribution for a long term dataset the overall slope of this logarithmically transformed distribution is usually indicated by a best fit straight line and expressed as a b value this slope is stable and normally lies between 0 8 and 1 2 the actual value depending on the region examined and the threshold selected for data completeness the linearity of the distribution can be used to make statistical inferences about the potential for larger events over the long run and with appropriate reservations may even be extrapolated to magnitudes that are beyond recent experience we suggest the same information can also be viewed over shorter intervals in terms of an empirical piecewise distribution with relative frequencies of occurrence at adjacent magnitude steps controlling the local slope of the distribution an emergence through time of an excess number of lower magnitude earthquakes causes temporal changes to appear in the low end piecewise gradients of this distribution a marked excursion away from an overall uniform trend for the particular zone may be indicative of an imminent larger event on two separate occasions in 1982 and 1997 such temporal variations were seen in the magnitude distributions of sequences of events near tobago west indies and used to anticipate subsequent damaging mainshocks the recognition of temporal departures from overall linearity of the magnitude frequency relation in a suitable dataset may thus provide an evidential element that can contribute to earthquake forecasting this phenomenological approach was used in the analysis of the neic global dataset of earthquakes of magnitude 6 1 and bigger for the period 1973 2003 to explore its wider applicability trends in the piecewise gradients of the global data were interpreted as pointing to an imminent great earthquake perhaps exceeding magnitude 8 5 such an event did occur shortly afterwards in the form of the great sumatran earthquake of 2004 12 26 following that event global magnitude production continued to exhibit sharp imbalances in the lower magnitude bins indicating that another similar event was likely the second sumatran earthquake on 2005 03 28 satisfied that projection since that time a magnitude production imbalance persists in the global dataset suggesting the system could be poised to output an earthquake or earthquakes in the magnitude range 8 6 9 0 or even greater this contribution describes the piecewise gradient approach and examines its application to global earthquake data

electron probe microanalysis of fe2 σfe ratios in calcic and sodic calcic amphibole and biotite using the flank method abstract we present an analytical approach to determine the fe2 fe ratio in amphiboles and biotites using electron probe microanalysis epma the flank method applied in this study is based on the fact that fel line spectra show different peak position and intensity for fe2 and fe3 which is associated with a resonant process involving both x ray absorption and emission the flank positions for l and l which correspond to sites with minimal fe3 l3 absorption and maximal fe2 l2 absorption respectively are determined based on the l line spectra difference of two fe rich ferric and ferrous garnet endmembers i e andradite and almandine spectra intensities measured at the l and l flank positions for selected amphibole and biotite references can be quantitatively correlated with their fe2 weight contents by a linear relation l l a b fe2 in which a and b are constants calibrated upon reference materials it is emphasized that the constants a and b may vary significantly for different mineral groups and analytical conditions thus a calibration is necessary for each analytical session our tests show that the potential beam damage during epma that may induce oxidation of the measured material can be minimized by using a large beam size e g 20 m the fe2 fe ratios determined using the epma flank method in collected natural calcic and sodic calcic amphiboles feot 2 4 12 7 wt fe2 fe 0 45 75 and biotites feot 4 3 28 2 wt fe2 fe 0 67 0 87 are consistent within an error of 0 1 with the data obtained from the colorimetric wet chemistry method the epma flank method has the potential to be widely applied for accurate in situ determination of fe oxidation states in a wide range of minerals provided that references are available

accelerating seismicity and stress accumulation before large earthquakes the stress field that existed before a large earth quake can be calculated based on the known source parame ters of the event this stress field can be used to define a region that shows greater seismic moment rate changes prior to the event than arbitrarily shaped regions allowing us to link two previously unrelated subjects coulomb stress interactions and accelerating seismicity before large earthquakes as an example we have examined all m 6 5 earthquakes in california since 1950 while we illustrate the model using seismicity in california the technique i s general and can be applied to any tectonically active re gion we show that where sufficient knowledge of the re gional tectonics exists this method can be used to aug ment current techniques for seismic hazard estimation

the formation and breach of a short lived landslide dam at hsiaolin village taiwan part i post event reconstruction of dam geometry abstract in this paper technologies from multiple disciplines are used to reconstruct the shape of the hsiaolin landslide dam a short lived landslide dam sld that was triggered by typhoon morakot here the formation failure mode and breaching process of this sld are investigated the results indicate that the overtopping time and the debris budget constrained the dam geometry the inferred volume of the hsiaolin landslide dam 15 4 million m3 is much smaller than the actual landslide volume 25 2 million m3 even considering the rock mass dilation and debris entrainment meanwhile a 46 error could be induced if an over simplified equation a function of the dam height length and width is used to calculate the dam volume the saddle of the dam crest which is where overtopping occurred could be used as a reference to measure the dam height and length accordingly the determined dam dimensions of height 44 m length 370 m and width 1500 m are suggested to be the representative geometrical indices that influenced the stability of the hsiaolin landslide dam the flow rate of the dammed river another variable relevant to dam stability was determined from a run off simulation it is suggested that instead of the peak flow before the dam formation the flow rate during the blockage period 2974 m3 s should be used as the training data for building a statistical model for stability predictions finally the low hydraulic gradient at the toe of the dam s surface and the high safety factor of the dam slope indicate that the piping and slope instability were irrelevant to the failure of the hsiaolin short lived landslide dam it is postulated that overtopping about one hour after the blockage dominated the failure process of this heavy rainfall induced landslide dam

empirical prediction of coseismic landslide dam formation in this study we develop an empirical method to estimate the volume threshold for predicting coseismic landslide dam formation using landscape parameters obtained from digital elevation models dems we hypothesize that the potential runout and volume of landslides together with river features determine the likelihood of the formation of a landslide dam to develop this method a database was created by randomly selecting 140 damming and 200 non damming landslides from 501 landslide dams and 60 000 landslides induced by the mw 7 9 2008 wenchuan earthquake in china we used this database to parameterize empirical runout models by stepwise multivariate regression we find that factors controlling landslide runout are landslide initiation volume landslide type internal relief h and the h l ratio between h and landslide horizontal distance to river l in order to obtain a first volume threshold for a landslide to reach a river the runout regression equations were converted into inverse volume equations by taking the runout to be the distance to river a second volume threshold above which a landslide is predicted to block a river was determined by the correlation between river width and landslide volume of the known damming landslides the larger of these two thresholds was taken as the final damming threshold this method was applied to several landslide types over a fine geographic grid of assumed initiation points in a selected catchment the overall prediction accuracy was 97 4 and 86 0 for non damming and damming landslides respectively the model was further tested by predicting the damming landslides over the whole region with promising results we conclude that our method is robust and reliable for the wenchuan event in combination with pre event landslide susceptibility and frequency size assessments it can be used to predict likely damming locations of future coseismic landslides thereby helping to plan emergency response copyright 2014 john wiley sons ltd

influence of composition and thermal history of volcanic glasses on water content as determined by micro raman spectrometry development of raman spectrometry for quantification of water content in natural glasses requires the assessment of the dependence of the technique on glass composition and thermal history in the low frequency domain raman spectra topology varies due to glass depolymerization and substitution in the framework of si4 iv by alkali balanced al3 iv and fe3 iv in calcalkaline rhyolite to basaltic andesite and alkaline trachyte phonolite to alkali basalt glasses these processes result in strong dependence of previous analytical procedure internal calibration on glass composition here we show that an analytical procedure based on calibration to an external standard is only faintly composition dependent for si rich alkaline glasses trachytes phonolites for a given glass composition thermal history also plays a fundamental role in the choice of raman procedure for water analysis repeated cycles of thermal annealing induce microcrystallization of hydrous trachyte glasses and modify cation distribution in the glass structure application of these concepts to analysis of banded obsidians suggests that small scale heterogeneities in glasses are not simply related to magma degassing but could depend on thermal history and consequent relaxation paths in the melt

a nonextensive statistical physics analysis of the 1995 kobe japan earthquake this paper presents an analysis of the distribution of earthquake magnitudes for the period 1990 1998 in a broad area surrounding the epicenter of the 1995 kobe earthquake the frequency magnitude distribution analysis is performed in a nonextensive statistical physics context the nonextensive parameter q m which is related to the frequency magnitude distribution reflects the existence of long range correlations and is used as an index of the physical state of the studied area examination of the possible variations of q m values is performed during the period 1990 1998 a significant increase of q m occurs some months before the strong earthquake on april 9 1994 indicating the start of a preparation phase prior to the kobe earthquake it should be noted that this increase coincides with the occurrence of six seismic events each of these events had a magnitude m 4 1 the evolution of seismicity along with the increase of q m indicate the system s transition away from equilibrium and its preparation for energy release it seems that the variations of q m values reflect rather well the physical evolution towards the 1995 kobe earthquake

the effect of water and fo2 on the ferric ferrous ratio of silicic melts new experiments on the effect of dissolved water on the ferric ferrous ratio of silicic melts have been performed at 200 mpa between 800 c and 1000 c and for fo2 between nno 1 35 and nno 6 6 water saturated conditions were investigated compositions studied include six metaluminous synthetic melts with feotot progressively increasing from 0 47 to 4 25 wt two natural obsidian glasses one peraluminous and the other peralkaline and a synthetic rhyolitic glass having the composition of the matrix glass of the june 15 1991 pinatubo dacite ferrous iron was analyzed by titration and feotot by electron microprobe variation of quench rate was found to have no detectable effect on the ferric ferrous ratio of the hydrous silicic melts investigated at nno no dependence of the ferric ferrous ratio with temperature is observed at fo2 nno 1 the experimental ferric ferrous ratios are equal or lower than calculated the peralkaline samples show the same type of behaviour a non linear relationship between xfe2o3 xfeo and fo2 implies that a term for dissolved water must be added to the kc equation if it is to be applied to the calculation of ferric ferrous ratios of hydrous silicic melts above nno 1 the ferric ferrous ratio is essentially controlled by the anhydrous melt composition and fo2 however differences exist between measured and calculated ferric ferrous ratios of silicic melts that are not all attributable to the effect of dissolved water additional work is needed to describe more precisely the dependence of the ferric ferrous ratio on anhydrous melt composition the oxidizing effect of water is restricted to relatively reduced magmatic liquids in oxidized calk alkaline magma series the presence of dissolved water will not largely influence melt ferric ferrous ratios

seismic moment distribution revisited ii moment conservation principle summary we compare the tectonic rate with earthquake data using several theoretical distributions to approximate the seismic moment frequency relation we derive formulae to estimate parameters of the seismic moment distributions by comparing the earthquake occurrence rate with tectonic strain we analyse the tectonic moment rate and the earthquake moment distribution for several types of tectonic environments including subduction zones plate bounding transform faults and deforming continental regions in this analysis we use finer subdivisions of tectonic regions to infer whether earthquake size distribution properties established previously for large provinces flinn engdahl seismic regions could be applied to smaller zones extending over a few hundred kilometres although the shortness of the available earthquake catalogues makes our results less reliable several conclusions can be drawn from the analysis the universality of the parameter the slope of the moment frequency relation is reasonably well confirmed for all of these tectonic regions and their subdivisions in each region we estimate the strain rate or relative plate motion from a plate tectonic model active fault data or geodetic data according to the moment frequency relation the ratio of the tectonic moment rate to the earthquake rate depends on the value the corner magnitude mc and the effective seismogenic thickness we find that this ratio does not vary systematically with the relative plate velocity the ratio of parallel to perpendicular plate motion time since the last major earthquake and the length of fault zone segments established by previous earthquake history we obtain similar results for the western united states and southeast asia the corner magnitude is approximately equal to that for the circum pacific rim and there is no systematic dependence of the mc parameter on a geographic region or strain rate assuming the commonly accepted values for seismogenic thickness elastic modulus and 100 per cent seismic coupling the corner magnitude values for plate boundary zones and continental areas are 8 3 8 8 i e similar to those values obtained by statistical analysis

laboratory experiments on the failure of coarse homogeneous sediment natural dams on a sloping bed we present the results of a systematic series of 168 laboratory experiments that examine the critical conditions for the failure of landslide dams which obstruct the course of mountain rivers the experiments were carried out by using three different sediment materials with a quasiuniform grain size distribution and with a flume bed slope angles that ranged between 0 and 5 71 0 10 three main typologies of dam failure were observed for increasing values of the dam s downstream face angle 1 overtopping 2 headcutting which led to the formation of an erosion channel on the dam s downstream face that progressively migrated up to the dam crest and 3 initial slide of large part of superficial layer of the dam s downstream face which was followed by headcutting the experiments focused on the second type of failure to provide a safety criterion based on the upstream reservoir level the quantities that govern this phenomenon have been identified and a functional relationship is proposed based on

premonitory spreading of seismicity over the faults network in southern california precursor accord 1 we establish a connection between geometry of the faults network in a region and seismicity preceding the strong earthquakes in the intermediate term timescale of years previous studies of observed and computer simulated seismicity demonstrated that strong earthquakes are preceded in that timescale by the rise of seismic activity in a lower magnitude range here we explore a complementary phenomenon spreading of activity over the fault network this phenomenon is depicted by the seismicity pattern accord defined as a simultaneous rise of seismicity in a sufficiently large number of fault zones hence its name pattern accord has been found recently in synthetic seismicity generated by the colliding cascades cc model the present study demonstrates this pattern in observed seismicity of southern california we applied to observations a prediction algorithm based on the pattern accord scaled to the target magnitude 7 5 the pattern accord emerges within a few years before each of the three largest earthquakes in southern california kern county 1952 landers 1992 and hector mine 1999 and at no other time scaled to the target magnitude interval from 6 5 to 7 4 the pattern accord precedes six out of nine earthquakes the duration of alarms in both cases is about 30 of the time considered we repeated prediction with different combinations of adjustable numerical parameters of the algorithm summing up the success and error scores on an error diagram this numerical experiment shows that the prediction results are stable under moderate variations of adjustable parameters the final test would be as always an advance prediction the pattern accord has a simple physical explanation connected with equilibrium of the crustal blocks system under the impact of tectonic driving forces at the same time accord is a manifestation of a broader phenomenon premonitory increase of earthquakes correlation range the latter phenomenon was found for the first time in the cc model although it was hypothesized by one of the authors much earlier

predictability of slip events along a laboratory fault a long sequence of stick slip events generated along a laboratory fault which consists of eight spring connected masses that are elastically driven to slide on a frictional surface has been examined to check whether the large events are predictable the large events are found to recur at intervals of very different durations although the elastic and frictional properties along the fault are quite uniform the recurrence intervals are however approximately proportional to the displacements of the preceding events but not of the following events thus the occurrence time of a large event is approximately predictable whereas its displacement is not the size logarithmic energy release distribution of all the events of different sizes can be fitted by a maximum entropy model which has an upper bound in size corresponding to the complete release of the maximum strain energy stored along the fault

a non extensive statistics of the fault population at the valles marineris extensional province mars a non extensive statistical physics approach is formulated and tested for the fault length distribution in the valles marineris extensional province mars the approach is composed of the following parts 1 the tsallis entropy 5 defined as s q k b 1 sigma w i 1 p i q q 1 2 maximization of the tsallis entropy under appropriate constraints 3 derivation of the cumulative distribution function cdf of the fault length population in testing the model a non extensive q parameter equal to 1 10 for independent non interacting faults and q 1 75 for linked faults are estimated the latter supports the conclusion that the fault system in the valles marineris extensional province mars is a sub extensive one and verifies with statistical physics terms the geological criteria introduced by schultz 2000 to classify the faults in independent and linked respectively c 2011 elsevier b v all rights reserved

landslide dam deformation analysis under aftershocks using large scale shaking table tests measured by videogrammetric technique abstract the ms 8 0 wenchuan earthquake triggered at least 257 landslide dams more than 849 aftershocks with magnitudes higher than ms 4 0 occurred after the wenchuan earthquake by 12 march 2012 shen et al 2013 which might largely influence the structure and soil properties of these dams this paper aims to study the dynamic deformation of landslide dams under aftershocks through larger scale shaking table tests videogrammetric technique was applied to measure the dynamic deformation of the model dams two groups of shaking table tests were conducted with two types of landslide dam materials one with quartz sands containing 10 kaolin dam i and the other with only quartz sands dam ii the dam deformation and its influencing factors were analyzed with the results measured by videogrammetric technique the deformations were generally higher on the surface of the dams either on the crest or on the both upstream and downstream slopes higher peak ground acceleration pga resulted in larger dam deformations due to higher seismic force the deformations under the combination of x and z directional shakings were larger than those under x directional shaking for sufficient vibratory compaction water rising led to the increase of dam deformations because that the water seepage reduced the effective soil stress especially reduced the matric suction the settlements of the dam composed of more fine particles were larger than that composed of large particle size because that the soil pores in the former were filled more sufficiently with fine particles the aftershocks may not directly trigger the failures of landslide dams but accelerate the overtopping failures by lowering the dam crest with settlement and cracking

geomorphometric characteristics of new zealand landslide dams abstract this study presents results from a quantitative analysis of a new inventory of n 232 landslide dam occurrences in new zealand previously published data were expanded by documentation of recent events and evidence from a regional air photo reconnaissance focused on the upland regions of southwestern south island additional geomorphometric data on landslide dams associated lakes and contributing catchment characteristics were extracted from a 25 m digital elevation model dem augmented by limited ground truthing and compiled in a gis based inventory the new zealand case examples fall into the global trend although they contain both two extremely large features in terms of landslide dam volume vd and lake volume vl analysis suggests that landslide dam height hd landslide dam volume vd lake volume vl contributing catchment area ac and local relief hr are key variables for assessing landslide dam stability independently from other catchment parameters such as lithology climate or dam sedimentology they may be provisionally used as representative characteristics of landslide dams irrespective of environmental boundary conditions such as climate geology or site specific valley geomorphometry three newly proposed dimensionless indices i e the backstow index is basin index ia and relief index ir based on landslide dam height hd allow limited yet promising preliminary assessments of landslide dam stability compared with worldwide examples they also demonstrate a much narrower conditional range for the formation of stable landslide dams in new zealand catchment parameters such as maximum elevation emax upstream relief hr contributing catchment area ac and relief ratio rr are significantly different at sites of former and existing landslide dammed lakes and may be used as independent variables in future terrain based classification schemes generally data are incomplete with underreporting of small and ephemeral landslide dams and over representation of earthquake case studies nonparametric correlation highlights the statistical interdependence between geomorphometric variables as an artefact of initial data calculation while varying accuracy poses a significant drawback for complex multivariate statistical techniques such as principal component cluster or discriminant analyses

entrainment of debris in rock avalanches an analysis of a long run out mechanism many rock avalanches entrain and liquefy saturated soil from their paths evidence for this includes mud displaced from the margins of rock avalanche deposits substrate material smeared along the base of deposits extrusion of liquefied soil upward through the deposits and increases of volume a hypothesis first suggested in 1881 and since reinforced by several authors suggests that entrainment of substrate material increases mobility although the process has been discussed in the literature for more than 100 years few detailed and quantitative descriptions exist the main purpose of this paper is to describe two recent cases from british columbia canada where rockslides entrained substrate on a very large scale influencing the character of the events estimated volume balance curves based on detailed field mapping are provided for both cases dynamic analyses are carried out using a numerical model and using the same set of rheological parameters the mechanism of material entrainment and displacement is discussed the data suggest that rapid rock failures entraining very large quantities of saturated substrate material represent a special type of landslide transitional between rock avalanche and debris avalanche many rock avalanches can thus be seen as end members of a continuum of phenomena involving rock failure followed by interaction with saturated substrate

micro raman determination of iron redox state in dry natural glasses application to peralkaline rhyolites and basalts abstract the position scaled intensity and topology of the raman stretching envelope at 1000 cm 1 hf have been established in complex anhydrous glasses having variable fe 3 fe ratios and contrasting compositions of peralkaline rhyolite pantellerite feo t 7 8 wt iron poor and iron rich basalts feo t 7 6 and 10 1 wt sensitivity of glass structure to iron redox decreases with increasing glass basicity raman spectra of pantellerite glasses fe 3 fe 0 04 0 97 evidence the sharp increase of a band at 970 cm 1 with the progressive entry of 4 fold fe 3 in alkali bonded q 3 units the spectral evolution of basalts with increasing iron oxidation fe 3 fe 0 05 0 87 is more subtle and is likely determined by formation of less polymerized units the moderate to low influence of redox state changes on the structure of natural basalt glass compared with the high sensitivity of their synthetic analogues can be attributed to strong competition between network forming cations al fe in the absence of an excess of alkalis we demonstrate that raman calibration against reference glasses allows precise determination of fe 2 fe 3 ratio but is highly composition dependent as a consequence of the variable link existing between fe 2 fe 3 and glass polymerization specific calibration procedures based on deconvolution shift or intensity of hf band are required for compositions with high acid glasses moderate or poor basic glasses sensitivity to iron redox changes respectively

modeling of natural dam failure modes and downstream riverbed morphological changes with different dam materials in a flume test abstract landslide dam failure modes are influenced by dam geometry material characteristics and riverbed conditions the different characteristics of earthquake and rainfall induced natural dams and the effects of riverbed conditions on dam failure have not attracted much attention from researchers in the past this study used flume tests to simulate earthquake and rainfall induced landslide dam failures for various combinations of dam geometry materials and riverbed conditions the 64 flume test combinations thus included two discharge rates two dam shapes triangular and trapezoidal with two heights two types of riverbed conditions and two types of dam material with two different water contents the experimental results show that dam geometry the amount of inflow hydraulic conductivity of the dam material and riverbed conditions have considerable effect on dams lifespan and their corresponding failure mode the hydraulic conductivity of the dam material affected the dam lifespan and its corresponding failure mode the four observed failure modes of dam breaks in rigid and mobile riverbeds constitute progressive erosion overtopping erosion slope slide and complex failure the complex failure mode which involves headward erosion slope slide and overtopping can occur in highly hydraulically conductive dams with high discharge progressive erosion occurs in highly hydraulically conductive dams with low discharge dam material with low hydraulic conductivity tends to fail by pure overtopping regardless of the dam shape and material dams in a mobile riverbed had a longer lifespan than those in a rigid riverbed the composition of the dam material affected the peak outflow discharge after dam break compared with rigid riverbeds dams in mobile riverbeds delay the arrival time of peak sediment discharge failure modes triggering flash floods and sediment transport after a dam break involved a series of sandbars and an armoring layer in the downstream riverbed earthquake induced dry material forming highly hydraulically conductive dams generally fail through complex when failure was subjected to a high discharge dams composed of wet materials tend to fail by overtopping in flume tests dam failure mode and inflow changed downstream mobile riverbed morphology in ways similar to those seen in full scale model tests conducted in the field

non linear dynamics of the lithosphere and intermediate term earthquake prediction abstract the lithosphere of the earth is structured as a hierarchical system of volumes of different sizes from about 10 tectonic plates to about 10 25 grains of rock their relative movement against the forces of friction and cohesion is realized to a large extent through earthquakes the movement is controlled by a wide variety of independent processes concentrated in the thin boundary zones between the volumes the boundary zone has a similar hierarchical structure consisting of volumes separated by boundary zones etc altogether this hierarchy of volumes and multitude of processes compose the lithosphere into a large non linear complex system upon coarse graining the integral mesoscale empirical regularities emerge indicating a wide range of similarity collective behavior and the possibility of earthquake prediction this approach led to new paradigms in the dynamics of the lithosphere and on the practical side created a capacity to predict from 70 to 90 of large earthquakes with alarms occupying 10 20 of the time space considered such predictions may be used to undertake earthquake preparedness measures which would prevent a considerable part of the damage although far from the total damage the methodology linking prediction with preparedness was developed it may help a disaster management authority to choose the preparedness measures allowing for the currently realistic accuracy of predictions a large scale experiment in advance prediction of large earthquakes worldwide has been launched to test the prediction algorithms the test is unprecedented in rigor and coverage the forecasts are communicated with due discretion to several dozen leading scientists and administrators in many countries among already predicted earthquakes are all the last eight great ones with magnitude 8 and more the major drawback is the rate of false alarms the possibility is outlined to develop a new generation of prediction methods with fivefold increase in accuracy and the transition to short term prediction the links with prediction of geotechnical and engineering disasters are established scenarios of transitions to a large earthquake happen to share some features with a broader class of catastrophes this experience now opens as yet untapped possibilities for reduction of technological disasters

accelerated seismic release and related aspects of seismicity patterns on earthquake faults observational studies indicate that large earthquakes are sometimes preceded by phases of accelerated seismic release asr characterized by cumulative benioff strain following a power law timeto failure relation with a term tf t m where tr is the failure time of the large event and observed values of m are close to 0 3 we discuss properties of asr and related aspects of seismicity patterns associated with several theoretical frameworks the subcritical crack growth approach developed to describe deformation on a crack prior to the occurrence of dynamic rupture predicts great variability and low asymptotic values of the exponent m that are not compatible with observed asr phases statistical physics studies assuming that system size failures in a deforming region correspond to critical phase transitions predict establishment of long range correlations of dynamic variables and power law statistics before large events using stress and earthquake histories simulated by the model of ben zion 1996 for a discrete fault with quenched heterogeneities in a 3 d elastic half space we show that large model earthquakes are associated with nonrepeating cyclical establishment and destruction of long range stress correlations accompanied by nonstationary cumulative benioff strain release we then analyze results associated with a regional lithospheric model consisting of a seismogenic upper crust governed by the damage rheology of lyakhovsky et al 39 over a viscoelastic substrate we demonstrate analytically for a simplified 1 d case that the employed damage rheology leads to a singular power law equation for strain proportional to t f t 1 3 and a nonsingular power law relation for cumulative benioff strain proportional to t f t 1 3 a simple approximate generalization of the latter for regional cumulative benioff strain is obtained by adding to the result a linear function of time representing a stationary background release to go beyond the analytical expectations we examine results generated by various realizations of the regional lithospheric model producing seismicity following the characteristic frequency size statistics gutenberg richter power law distribution and mode switching activity we find that phases of asr exist only when the seismicity preceding a given large event has broad frequency size statistics in such cases the simulated asr phases can be fitted well by the singular analytical relation with m 1 3 the nonsingular equation with m 0 2 and the generalized version of the latter including a linear term with m 1 3 the obtained good fits with all three relations highlight the difficulty of deriving reliable information on functional forms and parameter values from such data sets the activation process in the simulated asr phases is found to be accommodated both by increasing rates of moderate events and increasing average event size with the former starting a few years earlier than the latter the lack of asr in portions of the seismicity not having broad frequency size statistics may explain why some large earthquakes are preceded by asr and other are not the results suggest that observations of moderate and large events contain two complementary end member predictive signals on the time of future large earthquakes in portions of seismicity following the characteristic earthquake distribution such information exists directly in the associated quasi periodic temporal distribution of large events in portions of seismicity having broad frequency size statistics withrandom or clustered temporal distribution of large events the asr phases have predictive information the extent to which natural seismicity may be understood in terms of these end member cases remains to be clarified continuing studies of evolving stress and other dynamic variables in model calculations combined with advanced analyses of simulated and observed seismicity patterns may lead to improvements in existing forecasting strategies

experimental study of the impact factors of natural dam failure introduced by a landslide surge a large amount of loose deposit between the sides of a landslide lake may slide into a reservoir at any time because of influences such as earthquakes heavy rainfall or other triggering factors these factors can cause the formation of a huge surge and result in the instantaneous failure of a landslide dam the failure of a landslide dam can threaten people s lives and property downstream this paper analyzes the destruction mechanism of landslide dams because of a surge and the impact of the contact area the landslide height and the distance between the entry point and the dam site for a dam break through physical experiment and compares the experimental results with the calculated values experimental results show that the contact area and the landslide height have a significant impact on the dam break surge a measure based on the previously mentioned factors can be made to reduce the dam failure risk caused by a landslide surge two empirical methods pan s method and miller s method are used to predict the landslide surge wave and compared with the experimental results the simulated results show that the miller s method used for predicting the landslide surge wave is more reasonable

towards a structural model for the viscosity of geological melts abstract the viscosity of silicate melts is the most important physical property governing magma transport and eruption dynamics this macroscopic property is controlled by composition and temperature but ultimately reflects the structural organization of the melt operating at the microscale at present there is no explicit relationship connecting viscosity to silicate melt structure and vice versa here we use a single raman spectroscopic parameter indicative of melt structure to accurately forecast the viscosity of natural multicomponent silicate melts from spectroscopic measurements on glasses preserved on earth and other planets the raman parameter is taken as the ratio of low and high frequency vibrational bands from the silicate glass by employing a green source laser wavelength of 514 5 nm r514 5 our model is based on an empirical linkage between r514 5 and coefficients in the vogel fulcher tammann function for the temperature dependence of melt viscosity the calibration of the raman based model for melt viscosity is based on 413 high temperature measurements of viscosity on 23 melt compositions for which published raman spectra are available the empirical model obviates the need for chemical measurement of glass compositions thereby providing new opportunities for tracking physical and thermochemical properties of melts during igneous processes e g differentiation mixing assimilation furthermore our model serves as a milepost for the future use of raman spectral data for predicting transport and calorimetric properties of natural melts at geological conditions e g volatiles and pressure and production

global seismicity of 2003 centroid moment tensor solutions for 1087 earthquakes abstract centroid moment tensor cmt solutions are presented for 1087 earthquakes that occurred during 2003 the solutions are obtained using the method of dziewonski et al dziewonski a m chou t a woodward j h 1981 determination of earthquake source parameters from waveform data for studies of global and regional seismicity j geophys res 86 2825 2852 and applying corrections for aspherical earth structure as represented by the whole mantle shear velocity model sh8 u4l8 of dziewonski and woodward dziewonski a m woodward r l 1992 acoustic imaging at the planetary scale in emert h harjes h p eds acoustical imaging vol 19 plenum press new york pp 785 797 the model of inelastic attenuation of durek and ekstrom durek j j ekstrom g 1996 a radial model of inelasticity consistent with long period surface wave attenuation bull seism soc am 86 144 158 is used to predict the decay of the waveforms the focal mechanisms of the largest or otherwise significant earthquakes of 2003 are reviewed

statistical physics approach to understanding the multiscale dynamics of earthquake fault systems 1 earthquakes and the faults upon which they occur interact over a wide range of spatial and temporal scales in addition many aspects of regional seismicity appear to be stochastic both in space and time however within this complexity there is considerable self organization we argue that the occurrence of earthquakes is a problem that can be attacked using the fundamentals of statistical physics concepts of statistical physics associated with phase changes and critical points have been successfully applied to a variety of cellular automata models examples include sandpile models forest fire models and particularly slider block models these models exhibit avalanche behavior very similar to observed seismicity a fundamental question is whether variations in seismicity can be used to successfully forecast the occurrence of earthquakes several attempts have been made to utilize precursory seismic activation and quiescence to make earthquake forecasts some of which show promise

experimental studies on fragmentation of rock falls on impact with rock surfaces rock fall is a common natural hazard causing significant damage to infrastructure and loss of life rock fragmentation is frequently observed during rock fall events and several authors have raised issues related to the impact of fragments on the protection structure however this phenomenon is not accounted for when designing the protection barriers the paper presents the results of 20 rockfall tests performed in a quarry in italy to provide new insight into the fragmentation phenomenon especially in the case of foliated materials the results have shown that the impacting angle plays a key role in the fragmentation of foliated rocks whereas the effect of the impacting energy tends to be of second order no threshold in impacting energy could be defined to explain what triggers the fragmentation it has been noticed that the proportion of impacting energy dissipated during fragmentation is relatively constant and depends on the choice of the normal restitution coefficient

from the search of precursors to the research on crustal transients abstract earthquake prediction research of the last decade has produced many observations of precursory phenomena but the reliability of their physical correlation to the subsequent earthquake is often debatable and in any case very little can be inferred concerning the underlying coupling processes as precursors are only a small subset of the large family of crustal transients earthquakes swarms fluid instabilities episodic fault creep and as the latter are generally very poorly understood it is clear that any progress in short term prediction requires to study and model these transients a significant advantage of this approach is that transients are much more common than precursors and are thus easier targets for well focussed experiments i propose to consider a broader conceptual framework of a generalized self organized critical model for the crust where the interacting instabilities leading to distribution power laws are not only earthquakes but also transients such a model implies a significant coupling and cross triggerring between both inertial and slow instabilities our future ability to detect transients and to model the transient to earthquake triggering processes will be the key for assessing the predictability of earthquakes

dam break characteristics of landslide dams with different types of open channel discharge sections the excavation of artificial open channels in landslide dams is one efficient method for reducing the risks of landslide lake formation this method has often been used in emergencies to eliminate landslide lakes in earthquake prone areas of wenchuan china in this study the dam break characteristics of landslide dams with different open channel cross sections and longitudinal sections were evaluated the degree of headward erosion was extremely strong in the natural dam break experiment and moderately strong in the compound section dam break experiment the degree of headward erosion in the open channel with the trapezoidal section was comparatively mild furthermore the natural dam break resulted in large peak discharge and short dam break duration by contrast the artificially opened channel dam breaks resulted in peak discharges that were approximately 7 7 20 1 lower than those of natural dam breaks and the dam break duration i e the time until the dam broke was longer than that of the natural dam breaking the channels with gentle steep slopes or alternating gentle steep slopes resulted in greater discharge rates and a significant amount of erosion occurred due to these open channels the degree of headward erosion in the channel with alternating gentle steep slopes was greater than that in the other channels the peak discharges of the open channels with gentle steep slopes or alternating mild steep slopes were approximately 29 6 65 0 greater than those of the open channel with a linear section a channel with a triangular cross section and a linear longitudinal section should be used to dispose of small landslide lakes however channels with compound cross sections and longitudinal sections with alternating slopes should be used for large or medium landslide lakes

on the nature and dynamics of the seismogenetic systems of north california usa an analysis based on non extensive statistical physics abstract we examine the nature of the seismogenetic system in north california usa by searching for evidence of complexity and non extensivity in the earthquake record we attempt to determine whether earthquakes are generated by a self excited poisson process in which case they obey boltzmann gibbs thermodynamics or by a critical process in which long range interactions in non equilibrium states are expected correlation and the thermodynamics deviate from the boltzmann gibbs formalism emphasis is given to background seismicity since it is generally agreed that aftershock sequences comprise correlated sets we use the complete and homogeneous earthquake catalogue published by the north california earthquake data centre in which aftershocks are either included or have been removed by a stochastic declustering procedure we examine multivariate cumulative frequency distributions of earthquake magnitudes interevent time and interevent distance in the context of non extensive statistical physics which is a generalization of extensive boltzmann gibbs thermodynamics to non equilibrating non extensive systems our results indicate that the seismogenetic systems of north california are generally sub extensive complex and non poissonian the background seismicity exhibits long range interaction as evidenced by the overall increase of correlation observed by declustering the earthquake catalogues as well as by the high correlation observed for earthquakes separated by long interevent distances it is also important to emphasize that two subsystems with rather different properties appear to exist the correlation observed along the sierra nevada range walker lane is quasi stationary and indicates a self organized critical fault system conversely the north segment of the san andreas fault exhibits changes in the level of correlation with reference to the large loma prieta event of 1989 and thus has attributes of critical point behaviour albeit without acceleration of seismic release rates soc appears to be a likely explanation of complexity mechanisms but since there are other ways by which complexity may emerge additional work is required before assertive conclusions can be drawn

global scale analysis of seismic activity prior to 2004 sumatra andaman mega earthquake abstract following our experience in intermediate term monitoring of seismicity before large earthquakes worldwide and in some regions we apply a similar approach to the analysis of seismicity on global scale several decades before the december 26 2004 sumatra andaman mega earthquake the earth lithosphere is being considered as a single whole representing the ultimate level of the complex earth s hierarchy the study brings up the following questions are there any anomalies of the global seismicity behaviour observed in advance of the mega earthquake do these anomalies correspond to the global scale seismic patterns similar to those detected on the regional scale before great major and strong events in other words does the earth lithosphere considered as a single whole show up an approach of the mega earthquake in the way typical for events on the smaller levels of hierarchy the results of our investigation favour the positive answer to the questions specifically we found that during the decade before the sumatra andaman mega earthquake the earth lithosphere reveals at least in intermediate term scale classical symptoms of instability which can be depicted by known precursory seismic patterns these are i transformation of frequency magnitude distribution ii change in the rate of seismic activity and iii depth redistribution of activity moreover changes of dependencies between magnitudes of different types are detected at the same time the observed global scale patterns of collective behaviour of seismicity may indicate the state of criticality of the earth lithosphere before the sumatra andaman mega earthquake

statistical mechanics and scaling of fault populations with increasing strain in the corinth rift scaling properties of fracture fault systems are studied in order to characterize the mechanical properties of rocks and to provide insight into the mechanisms that govern fault growth a comprehensive image of the fault network in the corinth rift greece obtained through numerous field studies and marine geophysical surveys allows for the first time such a study over the entire area of the rift we compile a detailed fault map of the area and analyze the scaling properties of fault trace lengths by using a statistical mechanics model derived in the framework of generalized statistical mechanics and associated maximum entropy principle by using this framework a range of asymptotic power law to exponential like distributions are derived that can well describe the observed scaling patterns of fault trace lengths in the rift systematic variations and in particular a transition from asymptotic power law to exponential like scaling are observed to be a function of increasing strain in distinct strain regimes in the rift providing quantitative evidence for such crustal processes in a single tectonic setting these results indicate the organization of the fault system as a function of brittle strain in the earth s crust and suggest there are different mechanisms for fault growth in the distinct parts of the rift in addition other factors such as fault interactions and the thickness of the brittle layer affect how the fault system evolves in time the results suggest that regional strain fault interactions and the boundary condition of the brittle layer may control fault growth and the fault network evolution in the corinth rift

fragmentation energy in rock avalanches fragmentation is one of the mechanisms involved in rock avalanches quantifying the associated energy dur ing a rock avalanche can help to assess the influence of fragmentation on post failure mass movements in this paper in situ block size distributions of the intact rock mass and the debris deposits are presented and analyzed for nine rock avalanches five in the canadian rocky mountains and four in the european alps degrees of fragmentation are esti mated from these data two methods are examined to assess fragmentation energy one based on the comminution the ory and one on the blasting energy used in the mining industry the results show that for the studied rock avalanches there is a relationship between the reduction in diameter ratio rr d50 d50 where d50 and d50 are the mean diameter of the intact rock mass and the mean diameter of the debris respectively and the potential energy per unit volume normalized with respect to the point load strength of rock hg c where is the unit weight of the material hg is the vertical distance between the centres of gravity of the mass at the start and end positions and c is the point load strength for the cases studied fragmentation energy calculations average 20 of the potential energy an empirical relationship between rr and hg c has been established and is used in the definition of a disintegration index id this index seems to reflect the physics of the disintegration process since it accounts for the fact that the reduction in diameter ratio is a function of the dissipated energy and the strength of the rock these factors have long been known to affect fragmentation but have never been presented in a coherent manner for rock avalanches

predictive modeling of the seismic cycle of the greater san francisco bay region the seismic cycle for the san francisco bay region is synthesized by a model combining the pre and post 1906 seismic histories the long term acceleration of seismic release seismic moment benioff strain release or event count in the seismic cycle and the shorter term accelerations preceding the larger earthquakes within that cycle are modeled using an empirical predictive technique called time to failure analysis in which rate of seismic release is proportional to an inverse power of the remaining time to failure the exponent of time to failure in the accelerating sequences appears to be scale invariant and the length of the full cycle is estimated at 269 50 years the 1989 loma prieta earthquake which is the culmination of the first subcycle in the present long term seismic cycle should have been predictable with an uncertainty of 2 years in time and 0 5 in magnitude although the specific location at loma prieta was not predictable by this technique if our model is correct and if the loma prieta earthquake is the culmination of a subcycle the san francisco bay region should be entering a relatively long 20 50 years period of seismic quiescence above magnitude 6 a great earthquake such as the 1906 san francisco event would appear to be more than a century in the future

evidence for a global seismic moment release sequence temporal clustering of the larger earthquakes foreshock mainshock aftershock followed by relative quiescence stress shadow are characteristic of seismic cycles along plate boundaries a global seismic moment release history based on a little more than 100 years of instrumental earthquake data in an extended version of the catalog of pacheco and sykes 1992 illustrates similar behavior for earth as a whole although the largest earthquakes have occurred in the circum pacific region an analysis of moment release in the hemisphere antipodal to the pacific plate shows a very similar pattern monte carlo simulations confirm that the global temporal clustering of great shallow earthquakes during 1952 1964 at m 9 0 is highly significant 4 random probability as is the clustering of the events of m 8 6 0 2 random probability during 1950 1965 we have extended the pacheco and sykes 1992 catalog from 1989 through 2001 using harvard moment centroid data immediately after the 1950 1965 cluster significant quiescence at and above m 8 4 begins and continues until 2001 0 5 random probability in alternative catalogs derived by correcting for possible random errors in magnitude estimates in the extended pacheco sykes catalog the clustering of m 9 persists at a significant level these observations indicate that for great earthquakes earth behaves as a coherent seismotectonic system a very large scale mechanism for global earthquake triggering and or stress transfer is implied there are several candidates but so far only viscoelastic relaxation has been modeled on a global scale

seismic moment frequency relation for shallow earthquakes regional comparison we determine the parameter values for the seismic moment frequency relation using flinn engdahl s regionalization of global seismicity and the harvard centroid moment tensor data the earthquake size distribution is approximated by the gamma law a version of the gutenberg richter distribution with an exponential taper at the maximum moment there is no statistically significant variation of the fj value the analog of the b value for all seismic regions except for the midocean ridge systems for the latter regions fj 0 93 whereas for all other zones fj 0 63 the maximum moment mxg can be statistically evaluated only for subduction zones treated as a whole mxg 10 21 2 x 10 22 newton m which corresponds to the worldwide mxg value for other regions as well as for single subduction zones mxg is determined by comparing the number of events in each zone with the seismic moment rate calculated on the basis of the nuvel 1 model of plate motion for subduction zones we obtain the estimate of mxg which agrees with the statistical value giving evidence that most tectonic deformation is released by earthquakes we test the hypothesis that no statistically significant variation in mxg occurs in subduction and continent collision zones the hypothesis cannot be rejected with available data for the midocean ridges the mxg estimate cannot be unambiguously determined it is quite possible that the estimate is significantly biased because only a small part of tectonic deformation at the ridges is released by earthquakes these results have importance in evaluating seismic risk and may also lead to developing a physical theory for earthquake generation

dynamics mobility controlling factors and transport mechanisms of rapid long runout rock avalanches in china abstract the dynamics and occurrence conditions of 43 rapid and long run out rock avalanches in china were summarized their dynamics were classified into 5 types the standard dynamic type was designated to be fail squirt and flow where part of the landslide path always has a parabolic airborne course because the slide body has an initial speed and the toe of the surface of rupture projects the landslide into the air the occurrence conditions of rock avalanches of the standard dynamic type are huge kinetic energy elevated toe to the surface of rupture and enough transport space to run out into the occurrence conditions of the other four types were then compared with the standard dynamic type statistical analysis showed that volume topography huge kinetic energy and an elevated toe to the surface of rupture were the principal factors controlling mobility in the rock avalanches four of the rapid long run out rock avalanches each in a different geological setting were then examined in more detail to reveal the transport mechanisms leading to their high speed and long runout the results suggested that besides their huge kinetic energy high pore water pressure produced by undrained shear and elastic energy released by grain fragmentation were the main transport mechanisms contributing to the long travel distances and high speeds of rock avalanches field investigation indicated that air was involved during the transport but whether it influenced the transport or how much the influence was is still much disputed

geomorphic indexing of landslide dams evolution abstract landslide dams are rather common events in hilly and mountainous areas and they occur when a landslide reaches a valley floor closing the riverbed if they form a lake basin unstable landslide dams can have catastrophic consequences when they occur in upstream of populated regions landslide dam behavior is not completely understood yet however several studies suggested implementing geomorphological index in order to assess their formation and evolution these indexes result from the composition of two or more morphological attributes that characterize the landslide e g landslide volume or length and the involved river valley e g valley width the objective of this work is the definition of a procedure based on the joint use of different indexes to assess landslide dams evolution over large areas e g entire river catchment or even a region or a nation and in short times in order to be used for emergency response or for planning activities about 300 landslide dam events collected in italy were analyzed and some state of the art geomorphological indexes were applied to characterize the damming phenomena at the national scale to overcome some limitations of the aforementioned indexes we introduce two new indexes the morphological obstruction index and the hydromorphological dam stability index the former combines the river width and the landslide volume and it can be used to identify the conditions associated to dam formation discriminating between circumstances where a landslide dam is formed and circumstances where it is not the latter uses a simplified stream power formulation combining the upstream catchment area and the local slope gradient to account for the river energy this index allows evaluating the stability of a dam in near real time as soon as it occurs and can be used to discriminate between stable and unstable dams if compared with the reviewed state of the art indexes the newly proposed ones show an improvement in the forecasting effectiveness and have the advantage of being based on morphometric input parameters that can be easily and quickly assessed on a distributed way even over large areas we propose a tool that is based on the joint use of the newly proposed indexes and that can be used to provide fast and effective assessment on landslide dam formation and stability during emergency or planning activities

the heat capacity of hydrous multicomponent natural melts and glasses abstract the thermophysical properties of silicate melts and glasses are of fundamental importance for the characterization of the dynamics and energetics of silicate melts on earth and terrestrial planets the heat capacity of silicate melts is of particular importance because of its implications for the temperature dependencies of melt enthalpy and entropy and for the potential relationship to melt structure and transport properties currently there are reliable models for predicting the heat capacity of simple and multicomponent silicate glasses c p glass as a function of composition and temperature recent differential scanning calorimetry dsc measurements of heat capacity for multicomponent silicate liquid c p liquid however have shown that published models do not accurately reproduce heat capacity measurements on some silicate melts here we have compiled a database of heat capacity values for hydrous and anhydrous multicomponent natural samples the measurements are on pairs of glasses and melts over the compositional range wt of sio 2 44 79 al 2 o 3 5 35 tio 2 0 3 feo tot 0 11 na 2 o k 2 o 0 27 cao mgo 0 39 h 2 o 0 6 3 and minor oxides the compiled data show strong correlations between silica content x sio2 and the configurational heat capacity c p config defined as c p liquid cp glass measured across the glass transition temperature t g this correlation is used to establish an empirical model for predicting c p liquid as a function of melt composition i e sio 2 content and values of c p glass measured at the onset of the glass transition c p liquid 52 6 55 88 x sio 2 c p glass the model reproduces values of c p liquid to within an average relative error of 2 4 published models for the heat capacities of silicate melts e g stebbins 1984 richet and bottinga 1985 lange and navrotsky 1992 applied to the same dataset have average relative errors in excess of 5 5

search for direct empirical spatial correlation signatures of the critical triggering earthquake model summary we propose a new test of the critical earthquake model based on the hypothesis that precursory earthquakes are actors that create fluctuations in the stress field which exhibit an increasing correlation length as the critical large event becomes imminent our approach constitutes an attempt to build a more physically based time dependent indicator cumulative scalar stress function in the spirit of but improving on the cumulative benioff strain used in previous works documenting the phenomenon of accelerating seismicity using a simplified scalar space and time dependent viscoelastic green s function in a two layer model of the earth s lithosphere we compute spatiotemporal pseudo stress fluctuations induced by a series of events before four of the largest recent shocks in southern california through an appropriate spatial wavelet transform we then estimate the contribution of each event in the series to the correlation properties of the simplified pseudo stress field around the location of the mainshock at different scales this allows us to define a cumulative scalar pseudo stress function which reveals neither an acceleration of stress storage at the epicentre of the mainshock nor an increase of the spatial stress stress correlation length similar to those observed previously for the cumulative benioff strain the earthquakes we studied are thus either simple witnesses of a large scale tectonic organization or are simply unrelated and or the green s function describing interactions between earthquakes has a significantly longer range than predicted for standard viscoelastic media used here