space time distribution patterns of destructive earthquakes in the inner belt of central japan part 3 seismic hazard assessment abstract on the basis of the strike and sense of active faults the inner belt of central japan can be divided into the chubu and kinki districts the chubu district can be subdivided into four blocks by lines linking major nw se trending active faults a number of inner belt earthquakes of magnitudes m 6 4 or greater m japan meteorological agency scale have been documented or recorded since 599 a d whereas most epicenters of these earthquakes were located along lines linking active faults a few occurred in intra block areas in the first paper of this series the analysis of space time distribution patterns of destructive earthquakes revealed seismic cycles which consist of an active period of earthquakes and a quiet period with no activity seismic gaps were also detected in which no earthquakes have occurred during the present active period the second paper demonstrated that the average rates of seismic moment release calculated from the average slip rates of active faults which constitute the major tectonic or block boundary lines are nearly equal to those released by the historic earthquakes on the basis of the results of the two former papers two seismic maps a hazard map and an earthquake potential map of the inner belt of central japan are constructed since the seismic activity along tectonic and block boundary lines is much greater than that of the intra block areas the lines and intra block areas are separately evaluated in these seismic maps the hazard map shows the seismic activity by making use of the average rate of seismic moment release while the average rates of the lines range from 0 010to0 030 10 26 dyne cm y those of the intra blocks have values of less than 0 005 10 26 dyne cm y with one exception since regions of higher moment release rate experienced historic earthquakes with larger maximum magnitude the moment release rate is a good indicator for estimating the maximum magnitude of future earthquakes during the present active period future earthquakes will probably occur along seismic gaps these seismic gaps are illustrated in the earthquake potential map the two seismic maps are useful in reducing earthquake disasters by designing earthquake resistant buildings and structures in the earthquake prone regions of central japan

permafrost and climate in europe monitoring and modelling thermal geomorphological and geotechnical responses we present a review of the changing state of european permafrost within a spatial zone that includes the continuous high latitude arctic permafrost of svalbard and the discontinuous high altitude mountain permafrost of iceland fennoscandia and the alps the paper focuses on methodological developments and data collection over the last decade or so including research associated with the continent scale network of instrumented permafrost boreholes established between 1998 and 2001 under the european union pace project data indicate recent warming trends with greatest warming at higher latitudes equally important are the impacts of shorter term extreme climatic events most immediately reflected in changes in active layer thickness a large number of complex variables including altitude topography insolation and snow distribution determine permafrost temperatures the development of regionally calibrated empirical statistical models and physically based process oriented models is described and it is shown that though more complex and data dependent process oriented approaches are better suited to estimating transient effects of climate change in complex mountain topography mapping and characterisation of permafrost depth and distribution requires integrated multiple geophysical approaches and recent advances are discussed we report on recent research into ground ice formation including ice segregation within bedrock and vein ice formation within ice wedge systems the potential impacts of climate change on rock weathering permafrost creep landslides rock falls debris flows and slow mass movements are also discussed recent engineering responses to the potentially damaging effects of climate warming are outlined and risk assessment strategies to minimise geological hazards are described we conclude that forecasting changes in hazard occurrence magnitude and frequency is likely to depend on process based modelling demanding improved understanding of geomorphological process response systems and their impacts on human activity

finite faults and inverse theory with applications to the 1979 imperial valley earthquake abstract using a representation theorem from elastodynamics subsurface slip on a known fault is formulated as the solution to an inverse problem in which recorded surface ground motion is the data two methods of solution are presented the least squares method which minimizes the squared differences between theory and data and the constrained least squares method which simultaneously maintains a set of linear inequalities instabilities in the solution are effectively eliminated in both methods and the sensitivity of the solution to small changes in the data is quantitatively stated the inversion methodology is applied to 77 components of near field ground acceleration recorded during the 15 october 1979 imperial valley earthquake the faulting is constrained to propagate bilaterally away from the epicenter at an average velocity of 90 per cent of the shear wave speed on a vertical fault plane extending from the surface to 10 km depth inequality constraints are used to keep the faulting sequence physically reasonable by maintaining right lateral motion and positive slip velocity the preferred solution is stable and provides a good fit to the data it is also realistic and consistent with observed surface offsets and independent estimates of seismic moment

inversion of complex body waves we have developed a method that inverts seismic body waves to determine the mechanism and rupture pattern of earthquakes the rupture pattern is represented as a sequence of subevents distributed on the fault plane this method is an extension of our earlier method in which the subevent mechanisms were fixed in the new method the subevent mechanisms are determined from the data and are allowed to vary during the sequence when subevent mechanisms are allowed to vary however the inversion often becomes unstable because of the complex trade offs between the mechanism the timing and the location of the subevents many different subevent sequences can explain the same data equally well and it is important to determine the range of allowable solutions some constraints must be imposed on the solution to stabilize the inversion we have developed a procedure to explore the range of allowable solutions and appropriate constraints in this procedure a network of grid points is constructed on the i plane where and i are respectively the onset time and the distance from the epicenter of a subevent the best fit subevent is determined at all grid points then the correlation is computed between the synthetic waveform for each subevent and the observed waveform the correlation as a function of and i and the best fit mechanisms computed at each i grid point depict the character of allowable solutions and facilitate a decision on the appropriate constraints to be imposed on the solution the method is illustrated using the data for the 1976 guatemala earthquake

exploring links between arctic amplification and mid latitude weather 1 this study examines observed changes 1979 2011 in atmospheric planetary wave amplitude over northern mid latitudes which have been proposed as a possible mechanism linking arctic amplification and mid latitude weather extremes we use two distinct but equally valid definitions of planetary wave amplitude termed meridional amplitude a measure of north south meandering and zonal amplitude a measure of the intensity of atmospheric ridges and troughs at 45 n statistically significant changes in either metric are limited to few seasons wavelengths and longitudinal sectors however in summer we identify significant increases in meridional amplitude over europe but significant decreases in zonal amplitude hemispherically and also individually over europe and asia therefore we argue that possible connections between arctic amplification and planetary waves and implications of these are sensitive to how waves are conceptualized the contrasting meridional and zonal amplitude trends have different and complex possible implications for midlatitude weather and we encourage further work to better understand these

on the atmospheric response experiment to a blue arctic ocean we demonstrated atmospheric responses to a reduction in arctic sea ice via simulations in which arctic sea ice decreased stepwise from the present day range to an ice free range in all cases the tropospheric response exhibited a negative arctic oscillation ao like pattern an intensification of the climatological planetary scale wave due to the present day sea ice reduction on the atlantic side of the arctic ocean induced stratospheric polar vortex weakening and the subsequent negative ao conversely strong arctic warming due to ice free conditions across the entire arctic ocean induced a weakening of the tropospheric westerlies corresponding to a negative ao without troposphere stratosphere coupling for which the planetary scale wave response to a surface heat source extending to the pacific side of the arctic ocean was responsible because the resultant negative ao like response was accompanied by secondary circulation in the meridional plane atmospheric heat transport into the arctic increased accelerating the arctic amplification

space time distribution patterns of destructive earthquakes in the inner belt of central japan part 2 moment release rates and earthquake prediction the inner belt of central japan between the itoigawa shizuoka tectonic line istl and tsurugawan isewan tectonic line titl can be divided into four blocks by boundaries linking major nw se trending left lateral active faults historical earthquakes of magnitude 6 4 or greater which caused significant damage mainly occurred along the four block boundaries and have been recorded or documented since 715 a d the average rates of seismic moments released along the block boundaries in the inner belt of central japan have been estimated since no destructive earthquakes were recorded or documented between 888 a d and 1585 a d this period is regarded as a time of seismic quiescence the average rates re of the seismic moments released by destructive earthquakes since 1586 a d the present active period were estimated from the amount of the released moment inferred from the magnitude of the earthquakes average rates rs of seismic moments are also calculated from the average rates of quaternary displacements along the major active faults constituting the block boundaries the average rates re during the active period were found to be0 031 1026dyne cm yr for the istl those for the other three boundaries ranged from 0 087 to0 095 1026dyne cm yr the average release rate re through the quiet and active periods since 888 a d ranged from 0 023 to0 031 1026dyne yr with exception of0 008 1026dyne cm yr for the istl these values were found to be in good agreement with the estimation ofs this suggests that destructive earthquakes are a manifestation of the movement of the block boundary thus it is important to assess the block boundary movements when designing large earthquake resistant structures regions having no incidences of earthquakes seismic gaps during the present active period since 1586 a d have already been detected by us in previous work destructive earthquakes are predicted to occur in these seismic gaps the dates of the future earthquakes are then estimated assuming that the moment accumulated since the last earthquake exceeds the moment inferred from the possible magnitude in the region of the seismic gap future earthquakes are predicted to occur between 2007 and 2076 a d

determination of the location of faulting beneath kobe during the 1995 hyogo ken nanbu japan earthquake from near source particle motion we constrained the location of faulting beneath kobe during the 1995 hyogo ken nanbu kobe japan earthquake by investigating the particle motion of strong motion records from sites close to the causative fault the intersection of the earth s surface and the extension of buried fault plane is consistent with known active fault lines but not with the severely damaged zone the intersection line also agrees with geodetic data

some insight on why bam iran was destroyed by an earthquake of relatively moderate size 1 the bam iran earthquake of 2003 resulted in one of the worst human disaster in recent years yet the magnitude of the event mw 6 6 was relatively moderate we show that the remarkable recording of the ground motion produced in the city itself contains some clues which help explain this disaster we identify three factors whose unfortunate combination led to the strong ground shaking which destroyed the city 1 the rayleigh like speed of the rupture 2 the high slip velocity which exceeded 2m s over a large part of the fault 3 the strong directivity which focused the elastic energy released directly toward the city

liquefaction and flowage at archaeological sites in the inner belt of central japan tectonic and hazard implications abstract all archaeological data gathered at 55 archaeological sites excavated in the alluvial plains and basins of the inner belt of central japan revealed the occurrence and age of events of liquefaction and flowage the alluvial plains and basins are bounded on one or both sides by active faults representing tectonic or block boundary lines the excavated sites with liquefaction and flowage events identified are found distributed within a 15 km wide zone along the tectonic or block boundary lines of the alluvial plains and basins this suggests that seismic hazards caused by liquefaction and flowage mainly occur within this 15 km wide zones along the tectonic lines sand filled dikes of various shapes were found and are thought to represent evidence of liquefaction and flowage the sand filled dikes can be classified into two main types a lenticular type arrangeden echelon and a cylindrical type opening upward in a fan shape archaeological age estimates indicate that the liquefaction and flowage were induced by earthquakes which occurred during three periods around 1000 b c between 0 and 500 a d and after 1500 a d suggesting that active seismic periods occurred at an interval of approximately 1000 years

earthquake frequency distribution and the mechanics of faulting the level of intraplate seismicity in japan generally shows a positive correlation with the density of quaternary faulting in southwest japan where intraplate seismicity is concentrated on land rates of seismic moment release m 0 are similar when calculated from either the 400 year historical record of seismicity or geologically determined slip rates of quaternary faults a data set of 18 earthquakes with seismic moments m0 ranging from 0 01 to 3 1027 dyn cm shows a relationship between rupture lengthl and m0 log m0 23 5 1 94 log l when seismic moment on each quaternary fault is assumed to occur in discrete events every t m0 m 0g years where m0 is estimated for a rupture extended over the entire fault length and m 0g is proportional to the slip rate of each quaternary fault the moment frequency distribution of earthquakes log n a b log m0 predicted from the geologic record is virtually identical to that seen with the 400 year record of seismicity in contrast if it is assumed that earthquakes on each fault occur according to the gutenberg richter relation we obtain poor agreement with the observed seismicity thus while regional seismicity satisfies the relation log n a b log m0 or equivalently log n a b log m where m is magnitude it appears that seismicity on individual faults does not this further implies that the primary factor that leads to the magnitude frequency distribution in regional seismicity studies is the relative distribution of the slip rates and lengths of preexisting faults

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

the role of ocean atmosphere coupling in the zonal mean atmospheric response to arctic sea ice loss abstractthe role of ocean atmosphere coupling in the zonal mean climate response to projected late twenty first century arctic sea ice loss is investigated using community climate system model version 4 ccsm4 at 1 spatial resolution parallel experiments with different ocean model configurations full depth slab and no interactive ocean allow the roles of dynamical and thermodynamic ocean feedbacks to be isolated in the absence of ocean coupling the atmospheric response to arctic sea ice loss is confined to north of 30 n consisting of a weakening and equatorward shift of the westerlies accompanied by lower tropospheric warming and enhanced precipitation at high latitudes with ocean feedbacks the response expands to cover the whole globe and exhibits a high degree of equatorial symmetry the entire troposphere warms the global hydrological cycle strengthens and the intertropical convergence zones shift equatorward ocean dynamics are fundamental to producing this equatorially symmetric pattern

surface displacements and source parameters of the 2003 bam iran earthquake from envisat advanced synthetic aperture radar imagery 1 the mw 6 6 26 december 2003 bam iran earthquake was one of the first earthquakes for which envisat advanced synthetic aperture radar asar data were available using interferograms and azimuth offsets from ascending and descending tracks we construct a three dimensional displacement field of the deformation due to the earthquake elastic dislocation modeling shows that the observed deformation pattern cannot be explained by slip on a single planar fault which significantly underestimates eastward and upward motions se of bam we find that the deformation pattern observed can be best explained by slip on two subparallel faults eighty five percent of moment release occurred on a previously unknown strike slip fault running into the center of bam with peak slip of over 2 m occurring at a depth of 5 km the remainder occurred as a combination of strike slip and thrusting motion on a southward extension of the previously mapped bam fault 5 km to the east

3 d velocity structure of the 2003 bam earthquake area se iran existence of a low poisson s ratio layer and its relation to heavy damage abstract to understand the generation mechanism of the bam earthquake mw 6 6 we studied three dimensional v p v s and poisson s ratio structures in the bam area by using the seismic tomography method we inverted accurate arrival times of 19490 p waves and 19015 s waves from 2396 aftershocks recorded by a temporal high sensitivity seismic network the 3 d velocity structure of the seismogenic region was well resolved to a depth of 14 km with significant velocity variations of up to 5 the general pattern of aftershock distribution was relocated by using the 3 d structure to delineate a source fault for a length of approximately 20 km along a line 4 5 km west of the known geological bam fault this source fault dips steeply westward and strikes a nearly north south line the main shallow cluster of aftershocks south of the city of bam is distributed just under the minor surface ruptures in the desert the 3 d velocity structure shows a thick layer of high v s and low minimum 0 20 at a depth range of 2 6 km the deeper layer with a thickness of about 2 km appears to have a low v s and high maximum 0 28 from 6 km depth beneath bam to a depth of 9 km south of the city the inferred increase of poisson s ratio from 2 to 10 km in depth may be associated with a change from rigid and sio 2 rich rock to more mafic rock including the probable existence of fluids the main seismic gap of aftershock distribution at the depth range of 2 to 7 km coincides well with the large slip zone in the shallow thick layer of high v s and low the large slip propagating mainly in the shallow rigid layer may be one of the main reasons why the bam area suffered heavy damage

hydraulic conductivity of active layer soils in the mcmurdo dry valleys antarctica geological legacy controls modern hillslope connectivity abstract spatial variability in the hydraulic and physical properties of active layer soils influences shallow groundwater flow through cold desert hydrological systems this study measures the saturated hydraulic conductivity and grain size distribution of 90 soil samples from the mcmurdo dry valleys mdv antarctica primarily from taylor valley to determine what processes affect the spatial distribution of saturated hydraulic conductivity in a simple mineral soil dominated natural hillslope laboratory we find that the saturated hydraulic conductivity and the grain size distribution of soils are organized longitudinally within taylor valley soils sampled down valley near the coast have a higher percentage of fine sized sediments fine sand silt clay and lower saturated hydraulic conductivities than soils collected up valley near taylor glacier 1 3 10 2 vs 1 2 10 1 cm s soils collected mid valley have intermediate amounts of fines and saturated hydraulic conductivity values consistent with a hydrogeologic gradient spanning the valley from high inland to low near the coast these results suggest the organization of modern soil properties within taylor valley is a relict signature from past glaciations that have deposited soils of decreasing age toward the mouth of the valley modified by fluvial activity acting along temporal and microclimate gradients

coseismic fault related folding during the south golbaf earthquake of november 20 1989 in southeast iran the south golbaf earthquake of november 20 1989 m s 5 7 m b 5 6 i vii in southeast iran was associated with coseismic surface faulting and folding surface faults 11 km west dipping and 8 km east dipping long with oblique reverse mechanisms developed on both sides of a small holocene playa apparently repeated coseismic fault related folding was responsible for the holocene 20 tilting of the playa deposits above the active fault tip at the ground surface this study provided the first evidence of earthquake folding of holocene playa deposits in iran

influence of static stress changes on earthquake locations in southern california earthquakes induce changes in static stress on neighbouring faults that may delay hasten or even trigger subsequent earthquakes1 10 the length of time over which such effects persist has a bearing on the potential contribution of stress analyses to earthquake hazard assessment but is presently unknown here we use an elastic half space model11 to estimate the static stress changes generated by damaging magnitude m 5 earthquakes in southern california over the past 26 years and to investigate the influence of these changes on subsequent earthquake activity we find that in the 1 5 year period following a m 5 earthquake any subsequent nearby m 5 earthquake almost always ruptures a fault that is loaded towards failure by the first earthquake after this period damaging earthquakes are equally likely to rupture loaded and relaxed faults our results suggest that there is a short period of time following a damaging earthquake in southern california in which simple coulomb failure stress models could be used to identify regions of increased seismic hazard

fault mechanics and post seismic deformation at bam se iran the extent to which aseismic deformation relaxes co seismic stress changes on a fault zone is fundamental to assessing the future seismic hazard following any earthquake and in understanding the mechanical behaviour of faults here we use models of stress driven afterslip and viscoelastic relaxation in conjunction with post seismic insar measurements to show that there has been minimal release of co seismic stress changes through post seismic deformation following the 2003 mw 6 6 bam earthquake our analysis indicates the faults at bam remain predominantly locked suggesting that the co plus interseismically accumulated elastic strain stored downdip of the 2003 rupture patch may be released in a future mw 6 earthquake our observations and models also provide an opportunity to probe the growth of topography at bam we find that for our modelled afterslip distribution to be consistent with forming the sharp step in the local topography over repeated earthquake cycles and also to be consistent with the geodetic observations requires either 1 far field tectonic loading equivalent to a 2 10 mpa deviatoric stress acting across the fault system which suggests it supports stresses 60 100 times less than classical views of static fault strength or 2 that the fault surface has some form of mechanical anisotropy potentially related to corrugations on the fault plane that controls the sense of slip

evidence for self similar triangular slip distributions on earthquakes implications for earthquake and fault mechanics we characterize average slip distributions on earthquakes beyond their individual heterogeneity for that we analyze a large number of seismic slip distributions both measured at the surface after earthquakes 44 profiles and derived from slip inversion models 76 models investigating the overall shape of these slip profiles we find that they are roughly triangular both along strike and dip and most of them 70 80 are asymmetric long linear slopes and high slip gradients therefore are the key ingredients to describe earthquake slip profiles the scaling relations between maximum displacement and length or width suggest furthermore that the triangular slip profiles are self similar such slip patterns make earthquakes dominated by one major zone of maximum slip hence one major asperity analyzing the position of hypocenters with respect to these asperities we find that earthquakes nucleate at a distance from them that averages 20 30 of their total length compiling observations on 56 earthquakes we show that this distance i e the asperity size is structurally defined we then compare the earthquake slip profiles to cumulative slip profiles measured on long term faults of various ages and sizes and find that all profiles have a similar shape triangular and asymmetric hence combining data for a large number of earthquakes leads to point out average generic characteristics of the coseismic slip that are similar to those that emerge from the accumulation of events with time on a single fault this suggests that these characteristics result from robust physical properties

recent and future warm extreme events and high mountain slope stability the number of large slope failures in some high mountain regions such as the european alps has increased during the past two to three decades there is concern that recent climate change is driving this increase in slope failures thus possibly further exacerbating the hazard in the future although the effects of a gradual temperature rise on glaciers and permafrost have been extensively studied the impacts of short term unusually warm temperature increases on slope stability in high mountains remain largely unexplored we describe several large slope failures in rock and ice in recent years in alaska new zealand and the european alps and analyse weather patterns in the days and weeks before the failures although we did not find one general temperature pattern all the failures were preceded by unusually warm periods some happened immediately after temperatures suddenly dropped to freezing we assessed the frequency of warm extremes in the future by analysing eight regional climate models from the recently completed european union programme ensembles for the central swiss alps the models show an increase in the higher frequency of high temperature events for the period 2001 2050 compared with a 1951 2000 reference period warm events lasting 5 10 and 30 days are projected to increase by about 1 5 4 times by 2050 and in some models by up to 10 times warm extremes can trigger large landslides in temperature sensitive high mountains by enhancing the production of water by melt of snow and ice and by rapid thaw although these processes reduce slope strength they must be considered within the local geological glaciological and topographic context of a slope

a spatial random field model to characterize complexity in earthquake slip 1 finite fault source inversions reveal the spatial complexity of earthquake slip over the fault plane we develop a stochastic characterization of earthquake slip complexity based on published finite source rupture models in which we model the distribution of slip as a spatial random field the model most consistent with the data follows a von karman autocorrelation function acf for which the correlation lengths a increase with source dimension for earthquakes with large fault aspect ratios we observe substantial differences of the correlation length in the along strike a x and downdip a z directions increasing correlation length with increasing magnitude can be understood using concepts of dynamic rupture propagation the power spectrum of the slip distribution can also be well described with a power law decay i e a fractal distribution in which the fractal dimension d remains scale invariant with a median value d 2 29 0 23 while the comer wave number k c which is inversely proportional to source size decreases with earthquake magnitude accounting for larger slip patches for large magnitude events our stochastic slip model can be used to generate realizations of scenario earthquakes for near source ground motion simulations

arctic sea ice loss in different regions leads to contrasting northern hemisphere impacts to explore the mechanisms linking arctic sea ice loss to changes in midlatitude surface temperatures we conduct idealized modeling experiments using an intermediate general circulation model and with sea ice loss confined to the atlantic or pacific sectors of the arctic barents kara or chukchi bering seas extending previous findings there are opposite effects on the winter stratospheric polar vortex for both large magnitude late 21st century and moderate magnitude sea ice loss accordingly there are opposite tropospheric arctic oscillation ao responses for moderate magnitude sea ice loss however there are similar strength negative ao responses for large magnitude sea ice loss suggesting that tropospheric mechanisms become relatively more important than stratospheric mechanisms as the sea ice loss magnitude increases the midlatitude surface temperature response for each loss region and magnitude can be understood as the combination of an indirect part induced by the large scale circulation ao response and a residual direct part that is local to the loss region

strong motion and teleseismic waveform inversions for the source process of the 2003 bam iran earthquake the bam earthquake m w 6 5 occurred on 26 december 2003 in southeastern iran causing a major disaster in the city of bam a remarkable vertical peak ground acceleration value of 988 cm s2 and two horizontal pulses were recorded inside the damaged city previous analyses showed that the earthquake was caused by a subsurface rupture on an unknown strike slip fault in this study we attempt to determine the precise fault location and source process of the 2003 bam earthquake by performing a multiple time window linear waveform inversion of teleseismic and strong motion data both individually and jointly we examined the general features of the fault location and the source process by analyzing the teleseismic displacement waveforms and determined the precise features and fault geometry by inverting the three components of strong motion velocity records the final estimate of the source process of the 2003 bam earthquake was determined by joint inversion of the datasets our results show that a single fault model characterized by the appropriate location of the hypocenter rake angle variations and the rayleigh like speed of the rupture front can satisfactorily explain the three components of the strong motion records at bam station

late twentieth century simulation of arctic sea ice and ocean properties in the ccsm4 abstractto establish how well the new community climate system model version 4 ccsm4 simulates the properties of the arctic sea ice and ocean results from six ccsm4 twentieth century ensemble simulations are compared here with the available data it is found that the ccsm4 simulations capture most of the important climatological features of the arctic sea ice and ocean state well among them the sea ice thickness distribution fraction of multiyear sea ice and sea ice edge the strongest bias exists in the simulated spring to fall sea ice motion field the location of the beaufort gyre and the temperature of the deep arctic ocean below 250 m which are caused by deficiencies in the simulation of the arctic sea level pressure field and the lack of deep water formation on the arctic shelves the observed decrease in the sea ice extent and the multiyear ice cover is well captured by the ccsm4 it is important to note however that the temporal evolution of the simulated arctic sea ice cover over the

the 2003 december 26 bam earthquake iran mw 6 6 aftershock sequence summary from 2003 december 29 to 2004 january 30 a dense seismological network of 23 stations was installed in the epicentral area of the 2003 december 26 bam earthquake to study the aftershock seismicity we select the 331 earthquakes recorded at a minimum of 10 stations with rms less than 0 1 s and uncertainties less than 1 km to infer the precise geometry of the seismicity in the fault region we also process the data with the double difference technique to confirm the results the aftershock cluster is 25 km long trends north south and is located 5 km west of the bam baravat escarpment exactly beneath the observed surface breaks at depth aftershocks are concentrated between 6 and 20 km beneath the upper layer of relatively low velocity that experienced the maximum slip and they dip slightly westward the southernmost part of the aftershock cluster is narrow and defines the rupture zone that is likely the bam baravat fault at depth however it is unlikely that it is connected at surface to the bam baravat escarpment but more likely to the co seismic ruptures south of bam on the contrary the distribution of the northernmost aftershocks spread into a more complex pattern which is consistent with a northward propagation of the rupture along the fault plane the focal mechanisms are consistent with right lateral strike slip faulting on n s trending faults parallel to the bam baravat escarpment

deep learning of aftershock patterns following large earthquakes aftershocks are a response to changes in stress generated by large earthquakes and represent the most common observations of the triggering of earthquakes the maximum magnitude of aftershocks and their temporal decay are well described by empirical laws such as bath s law1 and omori s law2 but explaining and forecasting the spatial distribution of aftershocks is more difficult coulomb failure stress change3 is perhaps the most widely used criterion to explain the spatial distributions of aftershocks4 8 but its applicability has been disputed9 11 here we use a deep learning approach to identify a static stress based criterion that forecasts aftershock locations without prior assumptions about fault orientation we show that a neural network trained on more than 131 000 mainshock aftershock pairs can predict the locations of aftershocks in an independent test dataset of more than 30 000 mainshock aftershock pairs more accurately area under curve of 0 849 than can classic coulomb failure stress change area under curve of 0 583 we find that the learned aftershock pattern is physically interpretable the maximum change in shear stress the von mises yield criterion a scaled version of the second invariant of the deviatoric stress change tensor and the sum of the absolute values of the independent components of the stress change tensor each explain more than 98 per cent of the variance in the neural network prediction this machine learning driven insight provides improved forecasts of aftershock locations and identifies physical quantities that may control earthquake triggering during the most active part of the seismic cycle neural networks trained on data from about 130 000 aftershocks from around 100 large earthquakes improve predictions of the spatial distribution of aftershocks and suggest physical quantities that may control earthquake triggering

the occurrence of alpine permafrost in the front range of colorado abstract permafrost distribution or ground that remains frozen for at least 2 years has been modeled using a combination of geographic information system gis techniques digital elevation model dem variables and land cover in alpine regions of the world in the front range however no such empirical models have been developed and field data are restricted in spatial extent but rock glaciers are in abundance here i present a probabilistic logistic regression model that is based on topoclimatic information elevation and aspect for rock glaciers derived from u s geological survey usgs 10 m dems classes of land cover obtained from an enhanced thematic mapper plus etm image classification were assigned weights and were then multiplied by the regression results to refine estimates the effectiveness of the model was evaluated by comparing mean probability scores with rock glacier activity categories mean annual air temperature maat from climatic stations on niwot ridge and bottom temperature of winter snow bts measurements while a monte carlo simulation was used to detect uncertainty associated with the original dem permafrost scores 50 covered about 8 9 242 km 2 of the study area 2722 km 2 with the highest scores clustered around longs and rowe peaks permafrost locations showed a strong correlation with rock glacier activity classes the 1 0 c maat isotherm and bts measurements less than 3 0 c the uncertainty analysis revealed that slight global differences exist between the original and error prone dem however local variations in aspect caused the most uncertainty these results indicate that the model accurately represents regional distribution of permafrost therefore topoclimatic information from rock glaciers and land cover when combined with an uncertainty analysis can effectively be used to map the occurrence of front range permafrost providing an imperative tool for cartographers planners and geocryologists

inferred seismic fault associated with the 1998 m 6 2 zhangbei shanyi earthquake hebei province china abstract the shallow ms 6 2 1998 zhangbei shanyi earthquake that affected the northwest region of beijing china occurred at the intersection of two active fault zones located on the north and east edges of the ordos tableland a detailed map of the intensity distribution of damaged building shows that the most damaged area was centered 8 to 10 km away from the epicenter including an ellipsoidal region with a strike of nne where more than 70 to 90 of buildings were destroyed many chimneys and gate pillars were broken and fell toward the sse ssw direction in the western side of the most damaged area and to the nne nnw direction in the eastern side aftershocks were also concentrated in the most damaged area it is inferred that the boundary of the downfallen direction change is the surface trace of the seismic fault based on the seismic data the distribution of damaged buildings and the downfallen directions of 70 chimneys and gate pillars it is identified that the seismic fault is a thrust fault striking nne and dipping 40 to 50 northwest with a large right lateral displacement component

the 2003 bam se iran earthquake precise source parameters from satellite radar interferometry summary differential radar interferometry provided high quality near field deformation data for the 2003 bam earthquake and therefore strong constraints on its source parameters the ruptured fault segments could be clearly detected by using a sobel edge filter on the phase unwrapped deformation field the estimated total rupture length is about 24 km more than 80 per cent of the seismic moment was released from its southern segment of about 13 km where the slip reached a maximum of up to 270 cm resulting in a stress drop of at least 6 mpa in addition optical remote sensing data show that the bam fault is not a single fault but consists of a 4 5 km wide fault system with the known main branch running between the city of bam and baravat the fault ruptured by the bam earthquake appears to continue the nw branch of this fault system from bam city southwards based on these results we suggest that the bam earthquake ruptured a hidden or new fault and that in this process an unusually strong asperity was involved

earthquake recurrence and risk assessment in circum pacific seismic gaps the development of the concept of seismic gaps regions of low earthquake activity where large events are expected has been one of the notable achievements of seismology and plate tectonics its application to long term earthquake hazard assessment continues to be an active field of seismological research here i have surveyed well documented case histories of repeated rupture of the same segment of circum pacific plate boundary and characterized their general features i find that variability in fault slip and spatial extent of great earthquakes rupturing the same plate boundary segment is typical rather than exceptional but sequences of major events fill identified seismic gaps with remarkable order earthquakes are concentrated late in the seismic cycle and occur with increasing size and magnitude furthermore earthquake rup ture starts near zones of concentrated moment release suggesting that high slip regions control the timing of recurrent events the absence of major earthquakes early in the seismic cycle indicates a more complex behaviour for lower slip regions which may explain the observed cycle to cycle diversity of gap filling sequences

models of recurrent strike slip earthquake cycles and the state of crustal stress numerical models of the strike slip earthquake cycle assuming a viscoelastic asthenosphere coupling model are examined the time dependent simulations incorporate a stress driven fault which leads to tectonic stress fields and earthquake recurrence histories that are mutually consistent single fault simulations with constant far field plate motion lead to a nearly periodic earthquake cycle and a distinctive spatial distribution of crustal shear stress the predicted stress distribution includes a local minimum in stress at depths less than typical seismogenic depths the width of this stress trough depends on the magnitude of crustal stress relative to asthenospheric drag stresses the models further predict a local near fault stress maximum at greater depths sustained by the cyclic transfer of strain from the elastic crust to the ductile asthenosphere models incorporating both low stress and high stress fault strength assumptions are examined under newtonian and non newtonian rheology assumptions model results suggest a preference for low stress a shear stress level of about 10 mpa fault models in agreement with previous estimates based on heat flow measurements and other stress indicators

influence of low arctic sea ice minima on anomalously cold eurasian winters 1 influence of low arctic sea ice minima in early autumn on the wintertime climate over eurasia is investigated observational evidence shows that significant cold anomalies over the far east in early winter and zonally elongated cold anomalies from europe to far east in late winter are associated with the decrease of the arctic sea ice cover in the preceding summer to autumn seasons results from numerical experiments using an atmospheric general circulation model support these notions the remote response in early winter is regarded as a stationary rossby wave generated thermally through an anomalous turbulent heat fluxes as a result of anomalous ice cover over the barents kara seas in late autumn which tends to induce an amplification of the siberian high causing colder conditions over the far east the late winter cold anomalies over eurasia are also reproduced in our experiment which is associated with the negative phase of the north atlantic oscillation

geomorphological and geochemistry changes in permafrost after the 2002 tundra wildfire in kougarok seward peninsula alaska geomorphological and thermo hydrological changes to tundra caused by a wildfire in 2002 on the central seward peninsula of alaska were investigated as a case study for understanding the response from ice rich permafrost terrain to surface disturbance frozen and unfrozen soil samples were collected at burned and unburned areas and then water isotope geochemistry and cryostratigraphy of the active layer and near surface permafrost were analyzed to investigate past hydrological and freeze thaw conditions and how this information could be recorded within the permafrost the development of thermokarst subsidence due to ice wedge melting after the fire was clear from analyses of historical sub meter resolution remote sensing imagery long term monitoring of thermo hydrological conditions within the active layer in situ surveys of micro relief and geochemical signals recorded in the near surface permafrost the resulting polygonal relief coincided with depression lines along an underground ice wedge network and cumulative subsidence to 2013 was estimated as at least 10 1 to 12 1 cm 0 9 1 1 cm year eleven year average profiles of water geochemistry in the ground indicated mixing or replenishment of older permafrost water with newer meteoric water as a consequence of the increase in active layer thickness due to wildfire or past thaw event our geocryological analysis of cores suggests that permafrost could be used to reconstruct the permafrost degradation history for the study site distinct hydrogen and oxygen isotopic compositions above the global meteoric water line were found for water from these sites where permafrost degradation with geomorphological change and prolonged surface inundation were suggested

space time distribution patterns of destructive earthquakes in the inner belt of central japan activity intervals and locations of earthquakes abstract based on a block structure model of the inner belt of central japan an examination was conducted of the space time distribution patterns of destructiv magnitudes m 6 4 or greater m japan meteorological agency scale the distribution patterns revealed a periodicity in earthquake activit seismic gaps major nw se trending left lateral active faults divide the inner belt of central japan into four blocks 20 80 km wide the occurrenc a d with m 6 4 which have caused significant damage were documented in the inner belt of central japan the epicenters of these earthquakes close to the block boundaries using the relationship between the magnitude of earthquakes which occurred in the japanese islands and the active length of faults that generated them movement is calculated for each historical earthquake space time distributions of earthquakes were obtained from the calculated lengths the latitud of generation when an active period begins a portion or segment of the block boundary creates an earthquake which in turn appears on the ground surf active period ends when the block boundary generates earthquakes over the entire length of the block boundary without overlapping five seismic gaps with fault lengths of 20 km or longer can be found in the inner belt of central japan it is predicted that the gaps will generate ea magnitudes of 7 0 these data are of significance for estimating a regional earthquake risk over central japan in the design of large earthquake resist the time sequences of earthquakes on the block boundaries reveal a similar tendency with alternating active periods with seismic activity and quiet pe activity the inner belt of central japan is now in the last stage of an active period the next active period is predicted to occur around 2500 a d

does ocean coupling matter for the northern extratropical response to projected arctic sea ice loss the question of whether ocean coupling matters for the extratropical northern hemisphere atmospheric response to projected late 21st century arctic sea ice loss is addressed using a series of experiments with community climate system model version 4 at 1 spatial resolution under different configurations of the ocean model component no interactive ocean thermodynamic slab ocean and full depth dynamic plus thermodynamic ocean ocean atmosphere coupling magnifies the response to arctic sea ice loss but does not change its overall structure however a slab ocean is inadequate for inferring the role of oceanic feedbacks the westerly winds along the poleward flank of the eddy driven jet weaken in response to arctic sea ice loss accompanied by a smaller magnitude strengthening on the equatorward side with largest amplitudes in winter dynamical and thermodynamic oceanic feedbacks amplify this response by approximately 50 air temperature precipitation and sea level pressure responses also show sensitivity to the degree of ocean coupling

natural variability of the arctic ocean sea ice during the present interglacial the impact of the ongoing anthropogenic warming on the arctic ocean sea ice is ascertained and closely monitored however its long term fate remains an open question as its natural variability on centennial to millennial timescales is not well documented here we use marine sedimentary records to reconstruct arctic sea ice fluctuations cores collected along the lomonosov ridge that extends across the arctic ocean from northern greenland to the laptev sea were radiocarbon dated and analyzed for their micropaleontological and palynological contents both bearing information on the past sea ice cover results demonstrate that multiyear pack ice remained a robust feature of the western and central lomonosov ridge and that perennial sea ice remained present throughout the present interglacial even during the climate optimum of the middle holocene that globally peaked 6 500 y ago in contradistinction the southeastern lomonosov ridge area experienced seasonally sea ice free conditions at least sporadically until about 4 000 y ago they were marked by relatively high phytoplanktonic productivity and organic carbon fluxes at the seafloor resulting in low biogenic carbonate preservation these results point to contrasted west east surface ocean conditions in the arctic ocean not unlike those of the arctic dipole linked to the recent loss of arctic sea ice hence our data suggest that seasonally ice free conditions in the southeastern arctic ocean with a dominant arctic dipolar pattern may be a recurrent feature under warm world climate

simulation of selected strong motion records of the 2003 mw 6 6 bam earthquake se iran the modal summation ray tracing methods in the wkbj approximation

evidence for and implications of self healing pulses of slip in earthquake rupture dislocation time histories of models derived from waveforms of seven earthquakes are discussed in each model dislocation rise times the duration of slip for a given point on the fault are found to be short compared to the overall duration of the earthquake 10 however in many crack like numerical models of dynamic rupture the slip duration at a given point is comparable to the overall duration of the rupture i e slip at a given point continues until information is received that the rupture has stopped propagating alternative explanations for the discrepancy between the short slip durations used to model waveforms and the long slip durations inferred from dynamic crack models are 1 the dislocation models are unable to resolve the relatively slow parts of earthquake slip and have seriously underestimated the dislocations for these earthquakes 2 earthquakes are composed of a sequence of small dimension short duration events that are separated by locked regions barriers 3 rupture occurs in a narrow self healing pulse of slip that travels along the fault surface evidence is discussed that suggests that slip durations are indeed short and that the self healing slip pulse model is the most appropriate explanation a qualitative model is presented that produces self healing slip pulses the key feature of the model is the assumption that friction on the fault surface is inversely related to the local slip velocity the model has the following features high static strength of materials kilobar range low static stress drops in the range of tens of bars and relatively low frictional stress during slip less than several hundreds of bars it is suggested that the reason that the average dislocation scales with fault length is because large amplitude slip pulses are difficult to stop and hence tend to propagate large distances this model may explain why seismicity and ambient stress are low along fault segments that have experienced large earthquakes it also qualitatively explains why the recurrence time for large earthquakes may be irregular

s wave anisotropy in the aftershock region of the 2003 bam iran earthquake mw 6 5 abstract the 2003 bam earthquake mw 6 5 occurred in the southeastern iran on december 26 2003 we studied s wave anisotropy using the aftershock data observed at 5 stations in and around the aftershock region the fast polarization direction of shear wave splitting at the stations near the aftershock region is almost ne sw which corresponds to the maximum compressive stress trend the p axis of the main shock it is suggested that the inferred anisotropy might be caused by a systematic alignment of cracks resulting from the present day stress field the fast direction at the station just above the fault zone shows ew direction normal to the fault strike the fault normal alignment of cracks introduces a significant reduction of shear stress of the fault which suggests a high stress drop and large slip asperity another possible explanation for different result at the station from that of other stations is the effect of inhomogeneous velocity structure in and around the fault damaged zone the delay time of the split s waves ranges between 20 and 100 ms large delay time area is found in the shallower part of the fault zone with high aftershock activity assuming a uniform distribution of anisotropy inside and outside the aftershock region we estimated that the crack densities are 0 013 inside and 0 004 outside the aftershock region it may show more intense cracks within the high active region of aftershocks

active layer and permafrost thickness in rock glaciers derived from geophysical methods in the semiarid andes of argentina abstract the argentinean central andes region 31 s to 35 s exhibits one of the largest densities of rock glaciers on earth however few studies have focused on the knowledge of the internal structure of these landforms in the present paper a characterization of the internal structure of two rock glaciers has been achieved by using seismic refraction tomography and vertical electrical sounding in one of the rock glaciers the thickness of the active layer is quite homogeneous while in the other said thickness diminishes towards the front in both rock glaciers near the top of the active layer the p wave velocity values vary between 350 and 600 m s while in the bottom of the layer the p values range from 800 to 1700 m s as regards the permafrost layer it shows an irregular thickness with values varying between 4 and 27 m approximately in addition p wave values ranging from 1600 to 3300 m s and a few k m values of electrical resistivity have been recorded the increase of geophysical surveys in rock glaciers in the andes region is expected to give a better understanding of the characteristics distribution and origin of the ice present in these landforms it should also allow researchers to estimate with certainty their ice content as solid state reserves

source fault structure of the 2003 bam earthquake southeastern iran inferred from the aftershock distribution and its relation to the heavily damaged area existence of the arg e bam fault proposed 1 we investigate the hypocenter distribution of aftershocks of the december 26 2003 bam earthquake mw 6 5 by using a temporal seismic network the hypocenters distribute linearly over about 20 km in parallel with a line 3 5 km west of the geological bam fault and extend from the south of bam city to the heavily damaged area in the eastern part of the city including the historical mud brick citadel arg e bam based on the hypocenter distribution we propose a schematic 3 d structural model of a new fault that we have named the arg e bam fault we suggest that the bam earthquake occurred not in the bam fault but in the arg e bam fault bam city is located just above northern part of the arg e bam fault and also on the rupture propagation direction from the asperity this may be one of the main reasons why eastern part of bam city suffered the heaviest damage

recent hydrologic change in a colorado alpine basin an indicator of permafrost thaw hydrologic and hydrochemical studies have been conducted in green lakes valley colorado front range usa above 3550 m since 1982 they show a classic seasonal hydrograph dominated by snowmelt and an earlier date for the start of spring flow and for peak flow over the period of record this is consistent with patterns found at lower elevations in colorado and throughout western north america they also show an increasing trend in flows in september and october of 2 6 0 7 mm a 1 which is not found elsewhere and cannot be accounted for by increased autumn precipitation and the melting of surface ice because this late season increase is not found at the highest elevations or in basins in which there is no evidence of permafrost it seems best explained by the thawing of alpine permafrost at intermediate elevations this is corroborated by an increase in the concentration of base cations and silica and particularly in ca 2 and so4 in the stream discharge starting in 2000 as with the physical hydrology the geochemical signals have not been detected at the higher elevations in the basin though they have previously been associated with streamflow from a small rock glacier in the valley the combined evidence suggests the degradation of ice rich permafrost on the north facing slopes of the valley below 3700 m where it has been detected at 3 m depth by geophysical surveys

fault geometry at the rupture termination of the 1995 hyogo ken nanbu earthquake the source geometry and slip distribution at rupture termination of the 1995 hyogo ken nanbu earthquake were investigated using waveform inversion on the assumption of fault branching in the northeastern part of the rupture model possible branching of the okamoto fault is suggested both by the static displacement distribution and damage extension east of kobe nishinomiya area to exclude data contaminated by the basin edge diffracted wave in the waveform inversion process we examined the spatio temporal variation of its influence and from a comparison with a flat model we determined windows appropriate for the data three subevents were identified as was reported in previous works the largest was in the shallow part on the awaji side whereas the smaller two occurred at great depths 7km on the kobe side we found a smaller subevent in the deep part of the branch total variance reduction was larger and the abic value was smaller when we assumed the branch than when we did not which shows the superiority of the branching fault model resolution checks showed that the slips on proposed branched portions are physical and not caused by random data noise or systematic errors in green s func tions that arise from misestimation of velocity structures calculation of the relative static displacement between two leveling observation stations near the branching fault also showed the greater utility of the branching fault model the effect of slip on the branched fault has been shown in near source ground motion simulation using the 3d finite difference method iwata et al 1999 the characteristic distribution of ground motion in the near source region indicated by the damage distribution is well reproduced by the modeling of both the source process and wave propagation in the realistic 3d velocity structure slip on the branched fault affected the ground motion in eastern kobe nada and higashi nada wards ashiya and nishinomiya cities but its contribution is not dominant even in those regions about 30 to 50 maximum velocity in the frequency range of 0 1 to 1 0 hz we conclude that branching rupture of the okamoto fault during the hyogo ken nanbu earthquake is the preferable interpretation on the source process of this earth quake this supports the idea of a geometrical barrier suggested by geological ob servations

active tectonics and late cenozoic strain distribution in central and eastern iran 1 right lateral shear between central iran and afghanistan is accommodated on n s right lateral strike slip faults surrounding the aseismic dasht e lut north of 34 n the right lateral shear is accommodated on left lateral faults that rotate clockwise about vertical axes little is known of the late tertiary and younger offsets and slip rates on the active fault systems results that are important for understanding the regional tectonics we use observations from satellite imagery to identify displaced geological and geomorphological markers which we use in conjunction with the overall morphology and orientation of the active fault systems to estimate the total cumulative right lateral shear estimates of cumulative fault movements from offset features and inferred vertical axis rotation of fault bounded blocks suggest that the late cenozoic strain is concentrated toward the eastern margin of iran along the sistan shear zone where bedrock offsets of at least 70 km are observed across the active faults the geomorphology of the deh shir anar and great kavir strike slip faults in central iran suggest that although little shortening is accommodated across this region they might still be active and hence capable of producing earthquakes present day activity on these faults in central iran would not be expected from distributions of instrumental and historical earthquakes although speculative the late tertiary strain distribution described in this paper is consistent with what we know of the present day rates of shear in eastern iran and provides a framework to which later more detailed work can be added

isolating the atmospheric circulation response to arctic sea ice loss in the coupled climate system abstractin this study coupled ocean atmosphere land sea ice earth system model esm simulations driven separately by sea ice albedo reduction and by projected greenhouse dominated radiative forcing are combined to cleanly isolate the sea ice loss response of the atmospheric circulation a pattern scaling approach is proposed in which the local multidecadal mean atmospheric response is assumed to be separately proportional to the total sea ice loss and to the total low latitude ocean surface warming the proposed approach estimates the response to arctic sea ice loss with low latitude ocean temperatures fixed and vice versa the sea ice response includes a high northern latitude easterly zonal wind response an equatorward shift of the eddy driven jet a weakening of the stratospheric polar vortex an anticyclonic sea level pressure anomaly over coastal eurasia a cyclonic sea level pressure anomaly over the north pacific and increased wintertime precipitation over the west coast of north america many

field and teleseismic observations of the 1981 golbaf sirch earthquakes in se iran summary in 1981 june and july two large earthquakes occurred on the gowk fault system in south east iran both earthquakes were associated with surface faulting showing a combination of reverse and right lateral strike slip motion on parallel adjacent faults striking north south and dipping both east and west such motion can be seen to have occurred in the recent past and is responsible for the formation of elongated alluvium filled depressions in the footwall region common to both the east and west dipping faults the earthquake of june 11 involved motion along about 15 km of the gowk fault system with a moment of about 1 0 1026 dyne cm the earthquake of july 28 was larger and occurred farther north with movement along at least 65km of the gowk fault system and a moment of about 7 1026 dyne cm surface faulting in both earthquakes was complex and spread over several kilometres width on en echelon fault segments as well as on faults dipping both east and west the long period wwssn seismograms of these two mainshocks are unusually complicated and clearly made up of several individual subevents sensible interpretation of these waveforms without guidance from the surface faulting and the long period sro moment tensor inversion of dziewonski woodhouse would be impossible however a combination of these three data sources allows a geologically plausible interpretation of the rupture processes in these earthquakes to be made although the faulting in both mainshocks was on the same large scale feature the gowk fault the rupture zones of the two earthquakes did not apparently overlap and were separated by a gap of 5 km along strike in which both coseismic and recent geological displacements are very small rupture in both mainshocks appears to have nucleated near this gap and to have propagated away from it other such gaps are visible along the irregular displacement of the northern fault break and may have been the nucleation positions for individual subevents of the july 28 earthquake recognition of such nucleation sites is of obvious importance to earthquake prediction efforts

changes in frequency size relationship from small to large earthquakes the constant b value observed in frequency magnitude distributions of earthquakes has been taken as an indication of self similarity at all magnitudes hence earthquake properties should scale uniformly in the same way from small to large earthquakes it has often been observed however that the seismic moment released in small earthquakes scales differently with rupture length than it does for large events1 2 where the crossover between small and large events is defined at a rupture dimension equal to the down dip width of the seismogenic zone a possible explanation for this contradiction is that frequency size distributions are biased by small earthquakes small events dominate most global earthquake catalogues because of the short time period covered another source of bias in size distributions is the saturation of earthquake magnitudes for large events here we correct biases in calculations of b values and present evidence for a change in b value in frequency size distributions we find that a break in self similarity from small to large earthquakes occurs at a point where the dimension of the event equals the down dip width of the seismogenic layer

spatial and temporal distribution of slip for the 1992 landers california earthquake we have determined a source rupture model for the 1992 landers earthquake m w 7 2 compatible with multiple data sets spanning a frequency range from zero to 0 5 hz geodetic survey displacements near field and regional strong motions broadband teleseismic waveforms and surface offset measurements have been used explicitly to constrain both the spatial and temporal slip variations along the model fault surface our fault parameterization involves a variable slip multiple segment finite fault model which treats the diverse data sets in a self consistent manner allowing them to be inverted both independently and in unison the high quality data available for the landers earthquake provide an unprecedented opportunity for direct comparison of rupture models determined from independent data sets that sample both a wide frequency range and a diverse spatial station orientation with respect to the earthquake slip and radiation pattern in all models consistent features include the following 1 similar overall dislocation patterns and amplitudes with seismic moments of 7 to 8 10 26 dyne cm seismic potency of 2 3 to 2 7 km 3 2 very heterogeneous unilateral strike slip distributed over a fault length of 65 km and over a width of at least 15 km though slip is limited to shallower regions in some areas 3 a total rupture duration of 24 sec and an average rupture velocity of 2 7 km sec and 4 substantial variations of slip with depth relative to measured surface offsets the extended rupture length and duration of the landers earthquake also allowed imaging of the propagating rupture front with better resolution than for those of prior shorter duration strike slip events our imaging allows visualization of the rupture evolution including local differences in slip durations and variations in rupture velocity rupture velocity decreases markedly at shallow depths as well as near regions of slip transfer from one fault segment to the next as rupture propagates northwestward along the multiply segmented fault length the rupture front slows as it reaches the northern limit of the johnson valley landers faults where slip is transferred to the southern homestead valley fault an abrupt acceleration is apparent following the transfer this process is repeated and is more pronounced as slip is again passed from the northern homestead valley fault to the emerson fault although the largest surface offsets were observed at the northern end of the rupture our modeling indicates that substantial rupture was also relatively shallow less than 10 km in this region

deformation of an island arc rates of moment release and crustal shortening in intraplate japan determined from seismicity and quaternary fault data the historical record of large m 6 9 earthquakes and geologically determined rates of slip on quaternary faults in intraplate japan honshu and shikoku are used to estimate the average rate of seismic moment release m for the last 400 years and during the late quaternary respectively values of m estimated from the two data sets are similar in regions where seismic activity is concentrated on land we interpret this observation to suggest that m in intraplate japan has been constant during the late quaternary and is relatively free from secular variation when averaged over periods of several hundreds of years m in shikoku may be attributed almost solely to right lateral slip of the median tectonic line mtl the easterly strike of the mtl is consistent with a compressive stress field that trends northwest crustal shortening of the izu peninsula taken up on a set of strike slip faults that show north by northwest compression is 1 mm yr northeast honshu is characterized by a set of reverse type faults that trend northerly conversion of m in northeast japan to strain rates suggests that about 5 of the relative plate motion between japan and the pacific plate 9 7 cm yr is accommodated as a permanent east west shortening 5 mm yr of northeast honshu the predominant deformation in central and western honshu takes place as slip on a conjugate system of strike slip faults that strike northeast and southeast and show right lateral and left lateral motion respectively crustal shortening resulting from slip on faults in central and western honshu is 5 and 0 5 mm yr respectively in an easterly direction central and western honshu are in closest proximity to the nankai trough and hence the stress field in these regions cannot simply be attributed to the accommodation of the relative northwesterly convergence of the philippine sea plate the northward impingement of the izu peninsula into honshu may influence stresses in central and western japan but a conclusive explanation of the stress field in central and western honshu remains an enigma

modelling of ground motion in the higashinada kobe area for an aftershock of the 1995 january 17 hyogo ken nanbu japan earthquake summary we model the ground motion from an aftershock of the 1995 january 17 hyogo ken nanbu kobe earthquake to investigate basin edge effects on wave propagation in higashinada ward downtown kobe point source finite difference seismograms calculated using a double couple solution and a 2 d basin structure are compared with the ground motion velocity seismograms recorded in a small station array deployed at sites within and outside the heavily damage zone in higashinada ward the comparison suggests that in the frequency range 0 1 2 hz that was analysed the observed spatial amplitude variation of the aftershock ground motion is attributable mainly to the basin edge effects we found that the basin edge effect caused by the superposition of the direct s wave and the basin edge diffracted waves amplified the ground motion in a narrow zone that is offset by about 0 7 km from the basin edge

microplate versus continuum descriptions of active tectonic deformation whether deformation of continents is more accurately described by the motions of a few small rigid plates or by quasi continuous flow has important implications for lithospheric dynamics fault mechanics and earthquake hazard assessment actively deforming regions of the western united states central asia japan and new zealand show features that argue for both styles of movement but new observations are necessary to determine which is most appropriate and at what scale the description applies geologic geodetic seismic and paleomagnetic measurements tend to sample complementary aspects of the deformation field so an integrated observation program can utilize the strengths of each method and overcome their separate spatial or temporal biases provided the total relative motion across each region is known and the distribution of active faults is well mapped determination of fault slip rates can provide potentially decisive constraints reconnaissance geological studies supply useful slip rate estimates but precise values depend upon detailed intensive investigation of individual sites geodetic survey measurements can determine the spatial pattern of contemporary movements and extract slip rate information but the sometimes elusive effects of cyclic elastic strain buildup and relief must be accounted for in relating current movements to the long term deformation pattern earthquake catalogs can be applied to determine seismic strain rates and relative velocities but must be averaged over large regions and are usually limited by the inadequate duration of historical or instrumental seismicity catalogs paleomagnetic determinations of vertical axis rotations provide estimates of block rotation rates but are often locally variable and averaged over many millions of years which of the two descriptions of continental tectonics is more nearly correct depends on the local rheological stratification of the lithosphere especially the strength and thickness of the elastic crust relative to the ductile lithosphere and dynamical models can provide contrasting forecasts of observable features with testable consequences

seismotectonic rupture process and earthquake hazard aspects of the 2003 december 26 bam iran earthquake summary the catastrophic 2003 m w 6 6 bam earthquake in southern iran attracted much attention and has been studied with an abundance of observations from synthetic aperture radar teleseismic seismology aftershock studies strong ground motion geomorphology remote sensing and surface field work many reports have focused on the details of one or other data type producing interpretations that either conflict with other data or leave questions unanswered this paper is an attempt to look at all the available data types together to produce a coherent picture of the coseismic faulting in 2003 and to examine its consequences for active tectonics and continuing seismic hazard in the region we conclude that more than 80 per cent of the moment release in the main shock occurred on a near vertical right lateral strike slip fault extending from the city of bam southwards for about 15 km with slip of up t o2mb utmostly restricted to the depth range 2 7 km analysis of the strong ground motion record at bam is consistent with this view and indicates that the extreme damage in the city can be attributed at least in part to the enhancement of ground motion in bam because of its position at the end of the northward propagating rupture little of the slip in the main shock reached the earth s surface and more importantly aftershocks reveal that 12 km vertical extent of a deeper part of the fault system remained unruptured beneath the coseismic rupture plane at depths of 8 20 km this may represent a substantial remaining seismic hazard to the reconstructed city of bam we believe that some oblique reverse slip up to 2 m and less than 20 per cent of the released seismic moment occurred at a restricted depth of 5 7 km on a blind west dipping fault that projects to the surface at the bam baravat escarpment an asymmetric anticline ridge that is the most prominent geomorphological feature in the area this fault did not rupture significantly at shallow levels in 2003 and it may also represent a continuing seismic hazard widespread distributed surface ruptures north of the city are apparently unrelated to substantial slip at depth and may be the result of enhanced ground motion related to northward propagation of the rupture the faulting at bam may be in the early stages of a spatial separation partitioning between the reverse and strike slip components of an oblique convergence across the zone such a separation is common on the continents though in this case the slip vectors between the two faults differ only by 20 as a substantial strike slip component remains on the obliquereverse fault the bam earthquake is one in a series of large earthquakes involving faulting along the western edge of the lut desert in addition to the unruptured parts of the faults near bam itself continuing and substantial hazard is represented by unruptured neighbouring faults particularly blind thrusts along the jebel barez mountains to the south and strike slip faulting at sarvestan to the west

fault behavior and characteristic earthquakes examples from the wasatch and san andreas fault zones paleoseismological data for the wasatch and san andreas fault zones have led to the formulation of the characteristic earthquake model which postulates that individual faults and fault segments tend to generate essentially same size or characteristic earthquakes having a relatively narrow range of magnitudes near the maximum analysis of scarp derived colluvium in trench exposures across the wasatch fault provides estimates of the timing and displacement associated with individual surface faulting earthquakes at all of the sites studied the displacement per event has been consistently large measured values range from 1 6 to 2 6 m and the average is about 2 m on the basis of variability in the timing of individual events as well as changes in scarp morphology and fault geometry six major segments are recognized along the wasatch fault on the basis of the most likely number of surface faulting events 18 that have occurred on segments of the wasatch fault zone during the past 8000 years an average recurrence interval of 400 666 years with a preferred average of 444 years is calculated for the entire zone geologic data on the distribution of slip associated with prehistoric earthquakes and slip rates along the south central segment of the san andreas fault suggest that the m 8 1857 earthquake is a characteristic earthquake for this segment comparisons of earthquake recurrence relationships on both the wasatch and san andreas faults based on historical seismicity data and geologic data show that a linear constant b value extrapolation of the cumulative recurrence curve from the smaller magnitudes leads to gross underestimates of the frequency of occurrence of the large or characteristic earthquakes only by assuming a low b value in the moderate magnitude range can the seismicity data on small earthquakes be reconciled with geologic data on large earthquakes the characteristic earthquake appears to be a fundamental aspect of the behavior of the wasatch and san andreas faults and may apply to many other faults as well

the 1998 march 14 fandoqa earthquake mw 6 6 in kerman province southeast iran re rupture of the 1981 sirch earthquake fault triggering of slip on adjacent thrusts and the active tectonics of the gowk fault zone summary the 1998 march 14 fandoqa earthquake ms 6 6 was the penultimate in a series of five substantial earthquakes on the gowk fault system of southeast iran since 1981 all of which were associated with co seismic surface ruptures we use observations of surface faulting analysis of p and sh body waves sar interferometry and geomorphology to investigate the ruptures in these earthquakes and how they are related both to each other and to the regional active tectonics the 1998 fandoqa earthquake produced 23 km of surface faulting with up to 3 m right lateral strike slip and 1 m vertical offsets sar interferometry and seismic waveforms show that the main rupture plane dipped west at 50 and had a normal component although the surface ruptures were more complicated being downthrown to both the east and the west on steep faults in near surface sediments in addition sar interferometry shows that a nearby thrust with a similar strike but dipping at 6 w moved about 8 cm in a time interval and in a position that makes it likely that its slip was triggered by the fandoqa earthquake the 1998 surface ruptures in the gowk valley followed part of a much longer 80 km set of co seismic ruptures with smaller offsets that were observed after larger earthquakes in 1981 mw 6 6 and 7 1 the main ruptures in these 1981 earthquakes probably occurred on different deeper parts of the same fault system producing only minor reactivation of the shallower faults at the surface although the 1981 1998 earthquake sequence apparently ruptured parts of the same fault system repeatedly these earthquakes had very different rupture characteristics an important lesson for the interpretation of both palaeoseismological trenching investigations and historical accounts of earthquakes the regional kinematics which involve oblique right lateral and convergent motion are evidently achieved by a complex configuration of faults with normal reverse and strike slip components some of the complexity at the surface may be related to a ramp and flat fault geometry at depth but could also be related to the large topographic contrast of 2000 m across the fault system which separates the high kerman plateau from the low dasht e lut desert details of the fault geometry at depth remain speculative but it must be unstable and evolve with time it may be this requirement that causes the principal features of geological flower structures to develop such as series of subparallel faults which accommodate dip slip components of motion

stream geochemistry as an indicator of increasing permafrost thaw depth in an arctic watershed the presence of permafrost has a strong influence on arctic hydrology ecology and engineering therefore understanding the response of permafrost to arctic warming is critical to predicting the regional effects of global climate change recent research suggests that thaw depth may be increasing in response to warming but physical thaw depth surveys in the alaskan arctic are often not sensitive enough to detect incremental increases and cannot measure increases in the permafrost thaw bulbs beneath lakes and streams here we assess the use of geochemical tracers in stream water to identify changes in thaw depth in an arctic watershed based on marked differences in geochemistry with depth in soils and permafrost on the alaskan north slope we used 87sr 86sr and elemental ratios in an arctic stream as tracers of increases in the maximum depth of soil water flow and therefore the integrated thaw depth in the watershed from 1994 to 2004 stream water 87sr 86sr ca na and ca ba at base flow showed significant trends with time consistent with increasing depth of soil water flowpaths although long time series will be necessary to identify long term trends stream geochemistry may be useful as a qualitative indicator of changes in thaw depth in other areas where permafrost and active layer soil geochemistry differs

the 1995 kobe earthquake and problems of evaluation of active faults in japan abstract the kobe earthquake m 7 2 of january 17 1995 which was the most damaging earthquake in recent japanese history made manifest the need for reconsidering the method of evaluating active faults an earthquake of this magnitude at this time was unexpected according to conventional evaluation in which the potential magnitude of earthquakes at a certain site is estimated by considering the greatest earthquake in the past 400 years and the length of the active fault the following characteristics of this earthquake made it appear unlikely by conventional understanding 1 the kobe earthquake involved several neighboring faults which had been previously been identified as separate fault systems 2 the surface rupture of about 10 km length was much shorter than the 50 km seismic faulting 3 the interval of 400 years between the kobe and penultimate keicho earthquake of 1596 ad m 7 5 which has been revealed by historical documents and some excavations is much shorter than the 2000 years estimated by calculating the average slip rate of displaced landforms these shortcomings imply that active fault evaluation with the traditional characteristic earthquake model which deals with each fault separately is not adequate for an area like japan where active faults swarm new concepts such as the block rotation model kanaori 1990 late mesozoic cenozoic strike slip and block rotation in the inner belt of southwest japan tectonophysics 177 381 399 considering the macroscopic tectonic framework for fault interactions are needed furthermore fault dynamics cannot be ignored physical and temporal parameters associated with faulting such as moment release rate must be considered for realistic and precise evaluation

present day crustal deformation and plate kinematics in the middle east constrained by gps measurements in iran and northern oman summary a network of 27 gps sites was implemented in iran and northern oman to measure displacements in this part of the alpine himalayan mountain belt we present and interpret the results of two surveys performed in 1999 september and 2001 october gps sites in oman show northward motion of the arabian plate relative to eurasia slower than the nuvel 1a estimates e g 22 2m m yr 1 at n8 5 e instead of 30 5 mm yr 1 at n6 e at bahrain longitude we define a gps arabia eurasia euler vector of 27 9 0 5 n 19 5 1 4 e 0 41 0 1 myr 1 the arabia eurasia convergence is accommodated differently in eastern and western iran east of 58 e most of the shortening is accommodated by the makran subduction zone 19 5 2m m yr 1 and less by the kopet dag 6 5 2m m yr 1 west of 58 e the deformation is distributed in separate fold and thrust belts at the longitude of tehran the zagros and the alborz mountain ranges accommodate 6 5 2m m yr 1 and 8 2m m yr 1 respectively the right lateral displacement along the main recent fault in the northern zagros is about 3 2m m yr 1 smaller than what was generally expected by contrast large rightlateral displacement takes place in northwestern iran up to 8 mm yr 1 the central iranian block is characterized by coherent plate motion internal deformation 2m m yr 1 sites east of 61 e show very low displacements relative to eurasia the kinematic contrast between eastern and western iran is accommodated by strike slip motions along the lut block to the south the transition zone between zagros and makran is under transpression with right lateral displacements of 11 2m m yr 1

near fault strong motion complexity of the 2003 bam earthquake iran and low frequency ground motion simulation summary the 2003 december 26 bam earthquake was an intermediate size strike slip event that occurred beneath the bam city causing more than 26000 fatalities the record of the only near fault station bam station shows a clear long period pulse in almost fault normal direction suggesting a near fault forward directivity effect contributing to the heavy damage observed in bam city in this study the long period 0 1 1 5hz strong ground motions were simulated to answer some ambiguities in source parameters for fully description of the observed motion in different components at bam station to this end the hisada s kinematic model accounting for both heterogeneous source characteristics and underground geology is applied to simulate the long period ground motion different source scenarios suggested by previous studies are examined and the optimum scenario that could provide the best fitting between the simulated and observed motions for different components was introduced the slip model and asperities as well as velocity structure parameters are optimized in order to have the best possible fit between the simulated and observed velocity time histories and spectra the good agreements between the simulated and observed low frequency motions indicate a successful identification of source and slip parameters of the bam earthquake and provide a good test for the simulation technique furthermore the uniqueness of the identified source parameters and the slip model is further checked against the observed near and far field recordings of the bam earthquake a good agreement between the simulated and the observed waveforms provides a base for model verification and results confirmation

nitrate content and potential microbial signature of rock glacier outflow colorado front range here we characterize the nutrient content in the outflow of the green lake 5 rock glacier located in the green lakes valley of the colorado front range dissolved organic carbon doc was present in all samples with a mean concentration of 0 85 mg l 1 a one way analysis of variance test shows no statistical difference in doc amounts among surface waters p 0 42 average nitrate concentrations were 69 moles l 1 in the outflow of the rock glacier compared to 7 moles l 1 in snow and 25 moles l 1 in rain nitrate concentrations from the rock glacier generally increased with time with maximum concentrations of 135 moles l 1 in october among the highest nitrate concentrations reported for high elevation surface waters these high nitrate concentrations appear to be characteristic of rock glacier outflow in the rocky mountains as a paired difference t test shows that nitrate concentrations from the outflow of 7 additional rock glaciers were significantly greater compared to their reference streams p 0 003 end member mixing analysis suggest that snow was the dominant source of nitrate in june soil solution was the dominant nitrate source in july and base flow was the dominant source in september fluoresence index values and parafac analyses of dissolved organic matter dom are also consistent with a switch from terrestrial dom in the summer time period to an increasing aquatic like microbial source during the autumn months copyright 2006 john wiley sons ltd

waveform inversion using abic for the rupture process of the 1983 hindu kush earthquake abstract an inversion method was developed to infer earthquake rupture process from far field velocity waveforms we devise a source model that has variable slip and variable rupture velocity the fault plane is divided into many subfaults slip amplitude is assumed to be dependent on the subfaults and slip velocity at a point is assumed to be a triangle function of time rupture time is expressed by an interpolation equation using the rupture times at the corners of the subfaults the slip distribution and the rupture front motion are estimated by constrained least squares inversion we incorporate smoothing constraints on slip distribution and on rupture propagation into the observed data the degree of the constraints is controlled by hyperparameters the optimal values of the hyperparameters are determined by minimizing akaike s bayesian information criterion abic under the assumption of abic we can obtain a unique solution with reasonable resolution we apply this inversion method to the hindu kush earthquake of 30 december 1983 with a depth of 212 km we found that the rupture process of this earthquake was composed of two subevents the first subevent occurs near the initiation point of the rupture the centre of the second subevent region is approximately 20 km to the west of the first subevent the released moment of the second subevent is about seven times larger than that of the first subevent

a faulting model for the 1979 imperial valley earthquake by comparing synthetic particle velocities with the near source strong motion data we have constructed by trial and error a faulting model for the 1979 imperial valley earthquake the calculation of the synthetic seismograms takes into account the vertical inhomogeneity of the elastic parameters in the imperial valley and the spatial variation of the slip rate parameters on the fault plane the independent slip rate parameters are 1 the strike slip rate amplitude 2 the dip slip rate amplitude 3 the duration that slip rate is nonzero the rise time of the slip function and 4 the rupture time which determines when the slip rate is initiated our faulting model has the following principal features 1 faulting occurred on the imperial fault and on the brawley fault rupture on the brawley fault being triggered by rupture on the imperial fault 2 the imperial fault is a plane 35 km long and 13 km wide with a strike of 323 measured clockwise from north and a dip of 80 ne the brawley fault is a 10 km long and 8 km wide plane with a strike of 360 and a dip of 90 3 faulting on the imperial fault is primarily right lateral strike slip with a small component of normal dip slip in the sediments at its northern end the larger strike slip rates are generally confined between depths of 5 and 13 km with maximum values of about 1 0 m s the duration varies on the fault with a maximum of 1 9 s which is considerably shorter than the total time for the rupture to take place 4 the rupture velocity on the imperial fault is highly variable locally it exceeds the shear wave velocity and in one instance the compressional wave velocity the average rupture velocity though is less than the shear wave velocity 5 although the slip on the brawley fault contributes only about 4 of the total moment it greatly affects the ground motion at nearby stations 6 the total seismic moment is 6 7 1018 n m where the imperial fault contributes 6 4 1018 n m and the brawley fault contributes 2 7 1017 n m in the process of trying almost 300 faulting models we found that given the elastic parameters of the medium the synthetic seismograms were most sensitive to the specification of the rupture time although the slip rate amplitudes are linearly related to the data the rupture time and the duration are not the parameterization of the nonlinear variables has a strong effect on the generation of synthetic seismograms from a finite fault

inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 imperial valley california earthquake a least squares point by point inversion of strong ground motion and teleseismic body waves is used to infer the fault rupture history of the 1979 imperial valley california earthquake the imperial fault is represented by a plane embedded in a half space where the elastic properties vary with depth the inversion yields both the spatial and temporal variations in dislocation on the fault plane for both right lateral strike slip and normal dip slip components of motion inversions are run for different fault dips and for both constant and variable rupture velocity models effects of different data sets are also investigated inversions are compared which use the strong ground motions alone the teleseismic body waves alone and simultaneously the strong ground motion and teleseismic records the inversions are stabilized by adding both smoothing and positivity constraints the moment is estimated to be 5 0 10 25 dyne cm and the fault dip 90 5 dislocation in the hypocentral region south of the united states mexican border is relatively small and almost dies out near the border dislocation then increases sharply north of the border to a maximum of about 2 m under interstate 8 dipslip motion is minor compared to strike slip motion and is concentrated in the sediments the best fitting constant rupture velocity is 80 per cent of the local shear wave velocity however there is a suggestion that the rupture front accelerated from the hypocenter northward the 1979 imperial valley earthquake can be characterized as a magnitude 5 earthquake at the hypocenter which then grew into or triggered a magnitude 6 earthquake north of the border

three dimensional simulation of the near fault ground motion for the 1995 hyogo ken nanbu kobe japan earthquake abstract the 17 january 1995 hyogo ken nanbu earthquake is a typical example showing that the ground motions along basin edge faults can be very destructive in this study we simulate the near fault ground motion from this earthquake based on a kinematic fault model and a simplified 3d velocity structure of the kobe area the kinematic earthquake rupture and the wave propagation are modeled using a 3d finite difference method fdm our simulation identifies the basin edge effect as an important factor that influenced the ground motion amplification pattern in the kobe area we found that the coupling of the source directivity and basin edge effects causes impulsive ground motions with extremely high amplitude at periods greater than 1 sec and in a narrow zone offset less than 1 km from the basin edge the combination of these effects acted to create a fairly continuous band of amplification that extends about 30 km in an elongated zone parallel to the basin edge boundary in some areas localized site effects might have been as important as the abovementioned effects but they cannot explain the continuity of the extended east west zone of damage

timing and displacement of holocene faulting on the median tectonic line in central shikoku southwest japan abstract the median tectonic line mtl extends about 900 km parallel to the general trend of the southwest japan island arc the central segment of the mtl has been active during the quaternary although the average slip rate along the mtl is up to several mm a 1 there is no historical record of destructive earthquakes along it in order to collect data on the behavior of the mtl during late holocene times especially on the timing of seismic events and the amount of displacement during each event trench studies were conducted on the active segment in central shikoku in 1984 and 1988 the results are summarized as follows 1 the latest two seismic events produced by slip on the mtl in central shikoku occurred during the early 8th century a d and between 3250 and 2820 years b p 2 the amount of displacement during the latest event is inferred to have been about 5 7 m 3 the earthquake magnitude for the latest event is estimated at 7 9 richter scale and a fault segment trace about 70 km long ruptured during that event 4 an average slip rate along the active trace of the mtl in central shikoku during the late quaternary is estimated to be 5 8 mm a 1

the 2003 bam iran earthquake rupture of a blind strike slip fault a magnitude 6 5 earthquake devastated the town of bam in southeast iran on 26 december 2003 surface displacements and decorrelation effects mapped using envisat radar data reveal that over 2 m of slip occurred at depth on a fault that had not previously been identified it is common for earthquakes to occur on blind faults which despite their name usually produce long term surface effects by which their existence may be recognised however in this case there is a complete absence of morphological features associated with the seismogenic fault that destroyed bam

revisiting the basin edge effect at kobe during the 1995 hyogo ken nanbu earthquake the basin edge effect i e the interference of the direct s wave with the surface wave diffracted off the basin edge has been invoked by many authors to explain the damage distribution during the january 17 1995 hyogo ken nanbu kobe earthquake here we present the results of numerical experiments obtained with the spectral element method in 2 d geometry our results confirm that the amplification of horizontal motion close to the basin edge can be twice as large as the one measured in the center of the basin this additional amplification is shown to depend strongly on the edge geometry and on frequency due to physical dispersion of diffracted surface waves in particular we obtain maximal amplification around 3 hz at frequencies critical for buildings

surface ruptures and building damage of the 2003 bam iran earthquake mapped by satellite synthetic aperture radar interferometric correlation 1 we use the interferometric correlation from envisat synthetic aperture radar sar images to map the details of the surface ruptures related to the 26 december 2003 earthquake that devastated bam iran the main strike slip fault rupture south of the city of bam has a series of four segments with left steps shown by a narrow line of low correlation in the coseismic interferogram this also has a clear expression in the field because of the net extension across the fault just south of the city limits the surface strain becomes distributed over a width of about 500 m probably because of a thicker layer of soft sedimentary material another fault north of bam shows offset and low correlation over a wider zone in the interferograms but it has no discrete surface rupture possibly because of a net shortening across this fault taking the difference between the interferometric correlation for an interval including the earthquake and an interval before the earthquake separates the changes due to the earthquake from other effects in the partially vegetated city of bam we map the damage to buildings by measuring the change from high correlation to low correlation where buildings were destroyed by the earthquake

earthquake source characteristics from dynamic rupture with constrained stochastic fault stress one of the challenging tasks in predicting near source ground motion for future earthquakes is to anticipate the spatiotemporal evolution of the rupture process the final size of an event but also its temporal properties propagation velocity slip velocity depend on the distribution of shear stress on the fault plane though these incipient stresses are not known for future earthquakes they might be sufficiently well characterized in a stochastic sense we examine the evolution of dynamic rupture in numerical models of a fault subjected to heterogeneous stress fields with varying statistical properties by exploring the parameter space of the stochastic stress characterization for a large number of random realizations we relate generalized properties of the resulting events to the stochastic stress parameters the nucleation zone of the simulated earthquake ruptures in general has a complex shape but its average size is found to be independent of the stress field parameterization and is determined only by the material parameters and the friction law furthermore we observe a sharp transition in event size from small to system wide events governed mainly by the standard deviation of the stress field a simplified model based on fracture mechanics is able to explain this transition finally we find that the macroscopic rupture parameters e g moment moment rate seismic energy of our catalog of model quakes are generally consistent with observational data

theory of time dependent rupture in the earth at a velocity x which is a well defined function of k this propagation is stable and quasi static and is referred to as subcritical crack growth we shall use the terms stable quasistatic and subcritical to mean propagation at velocities much less than the sonic velocities of the medium this behavior results from stress induced corrosion at the crack tip the principal corrodent for the present application being h20 this behavior has been firmly established in the laboratory for mode i tensile cracks in a wide variety of materials ineluding silicates and silicate glasses see cholz 1968a 1972a martin 1972 wiederhorn and bolz 1970 atkinson 1979 lawn and wilshaw 1975 knott 1973 the form of the relationship between k and x does not vary significantly with the material only the parameters in the law vary as an example we show in figure 1 data on subcritical crack growth in quartz after atkinson 1979 the empirical relationship is found to take the form

new stratospheric dust belt due to the chelyabinsk bolide 1 the ozone mapping profiler suite omps limb profiler lp on the recently launched nasa noaa npp suomi satellite detected aerosol excess in the mid stratosphere 25 45 km altitude between 50 n and 70 n latitudes omps lp observations trace this aerosol plume to the meteor that struck near chelyabinsk russia on 15 february 2013 this new dust layer located above the junge aerosol layer has persisted over at least a 3 month period material collected on the ground following the bolide explosion showed that the meteor was mostly composed of olivine and pyroxenes simulations using lagrangian and eulerian atmospheric models trace the plume back to chelyabinsk and confirm that the plume altitude was at altitudes between 25 and 45 km the models also confirm the plume circumpolar longitudinal spreading observed by omps lp with propagation speeds up to 85 m s