thrust fault growth and segment linkage in the active ostler fault zone new zealand abstract thrust faulting is a fundamental mode of crustal deformation yet many of the key geometrical attributes of thrust faults and the controls on fault rupture growth and linkage remain poorly resolved numerous surface rupturing thrust faults cut through upper quaternary glacial outwash terraces within the ostler fault zone an active thrust system in the southern alps new zealand we use these deformed marker surfaces to define the three dimensional deformation field associated with their surface expression and to map displacement and length on 40 fault segments displacement transfer across two fault segment arrays occurs in distinctly different styles in one displacement is transferred between en echelon fault segments to produce a smooth linear displacement gradient in the other large scale folding and a population of small faults transfer displacement between two non overlapping fault segments with a residual displacement minimum within the transfer zone size distribution of fault segment length and maximum displacement follow a power law scaling relationship maximum displacement d max scales linearly with and represents 1 of segment trace length l d max l data from the segments of the ostler fault zone display similar scaling to a global fault dataset this similarity is surprising given that the observed displacements along the ostler fault represent only 20 ky of slip on fault segments that are likely to be many times older

experimental assessment of the infiltration properties of a coarse soil medium in a dielectric infiltration test an accurate determination of the hydrological characteristics of porous media such as the values of the porosity and effective porosity are essential this is important to understand the transport processes of infiltration and the movement of water and contaminants in the porous media in this study a laboratory soil column experiment to estimate the porosity and effective porosity of toyoura standard sand samples using a dielectric method termed the frequency domain reflectometry with vector network analyzer fdr v was performed the fdr v device uses high frequency microwaves ranging from 0 1 to 3 ghz to measure the complex dielectric constants of the sample from the measured complex dielectric constant the two parameters of the soil samples then were derived using a proposed dielectric mixture model and tracer concentration model the effective porosity of the soil sample is measured at 0 311 with the fdr v dielectric method and 0 345 by the soil tracer column test comparing this with the calculated porosities of the soil sample the ratio of effective porosity is approximately 78 for the dielectric method and approximately 86 for the tracer concentration method these different values can be explained to be within the measurement range with regard to the measurement volume for the soil column these results indicate that measurement by the dielectric method using an fdr v device is an efficient and useful tool for estimating the hydrological parameters of porous media because of the dielectric response of earth materials

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

modeling of suction distributions in an unsaturated heterogeneous residual soil slope the formation of residual soil of grade v and grade vi due to tropical weathering process introduces small hydraulic heterogeneities in the soil mantle which greatly alter the suction distribution during rainfall infiltration and hence the stability of the residual soil slopes this paper presents field evidences of suction distributions in a heterogeneous residual soil slope several modeling approaches were attempted to simulate the observation by considering the presence of thin layer of grade vi the variation in the hydraulic conductivity of grade v layer as well as the effect of evaporation the soil hydraulic heterogeneity in grade v layer was modeled by adopting continuum method in which the residual soil was subdivided into three zones of average hydraulic conductivities the analysis results show that the presence of thin layer of grade vi residual soil and the relict discontinuities in grade v soil must be considered in the analysis as these features introduced permeability disparity and thus a natural capillary barrier effect that limited the downward movement of infiltrated rainwater even during the exceptionally wet condition the results also show that the inclusion of evaporation effect provided a better prediction to the suction distributions during wet condition than dry condition

hydrological and geotechnical investigations of mass movements in an equatorial city yaounde cameroon in the present study mass movements landslide and mudslide bound to a gully located at mendong a suburb of yaounde in cameroon were examined using hydrological geotechnical and geomorphological observations the data indicate that water is an important causative factor of mass movements in the area studied in fact the water flow waste water and runoff provokes the saturation of materials at the slope foot these materials lose their mechanical qualities and some deep ruptures generate landslide during the rainy season when the cumulative rainfall is more than 200 mm these landslides are accompanied by mudslides that generate disturbances on the infrastructure situated around the gully and farther downstream the economic and environmental damages resulting from the mendong mass movements are considerable such as degradation of the topography losses in farm land transportation and downstream sedimentation in a pond situated at the slope foot loss of life and damage to the economy all this calls for a multidisciplinary and integrated approach to hazard assessment and risk mitigation which included data collection and interpretation growing public and authority awareness and preventing or reducing runoff and waste water flows by proper management and drainage

comparative analysis of contributing parameters for rainfall triggered landslides in the lesser himalaya of nepal in the himalaya people live in widely spread settlements and suffer more from landslides than from any other type of natural disaster the intense summer monsoons are the main factor in triggering landslides however the relations between landslides and slope hydrology have not been a focal topic in himalayan landslide research this paper deals with the contributing parameters for the rainfall triggered landslides which occurred during an extreme monsoon rainfall event on 23 july 2002 in the south western hills of kathmandu valley in the lesser himalaya nepal parameters such as bedrock geology geomorphology geotechnical properties of soil and clay mineralogy are described in this paper landslide modeling was performed in seep w and slope w to understand the relationship of pore water pressure variations in soil layers and to determine the spatial variation of landslide occurrence soil characteristics low angle of internal friction of fines in soil medium range of soil permeability presence of clay minerals in soil bedrock hydrogeology and human intervention were found to be the main contributing parameters for slope failures in the region

impact of high resolution fwi in the western black sea revealing overburden and reservoir complexity the western black sea wbs is now an area of active petroleum exploration and several seismic surveys have been acquired to support the ongoing activity seismic imaging in the wbs is challenging due to the presence of complex overburden such as canyons shallow gas channels and complex shallow stratigraphy such overburden complexities create amplitude dimming and wipeouts in the images and cause structural distortions of the reservoir units conventional velocity model building and seismic migration methods are not optimal for addressing such challenges full wavefield inversion fwi technology was applied to overcome the complex seismic imaging challenges in the wbs and to support the exploration and development program to date a suite of fwi products has been used to identify shallow hazards derisk prospects optimize well placement perform accurate resource estimation and support development planning unlike traditional seismic migration generated fwi products are not simply depictions of

spatio temporal estimation of shallow landslide hazard triggered by rainfall using a three dimensional model a shallow landslide triggered by rainfall can be forecast in real time by modeling the relationship between rainfall infiltration and decrease of slope stability this paper describes a promising approach that combines an improved three dimensional slope stability model with an approximate method based on the green and ampt model to estimate the time space distribution of shallow landslide hazards once a forecast of rainfall intensity and slope stability related data e g terrain and geology data are acquired this approach is shown to have the ability to estimate the variation of slope stability of a wide natural area during rainfall and to identify the location of potential failure surfaces the effectiveness of the estimation procedures described has been tested by comparison with a one dimensional method and by application to a landslide prone area in japan

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

major earthquake at the pleistocene holocene transition in lake vattern southern sweden lake vattern sweden is within a graben that formed through rifting along the boundary between two precambrian terrains geophysical mapping and geological coring show that substantial tectonic movements along the lake vattern graben occurred at the very onset of the holocene this is evident from deformation structures in the soft sediment accumulated on the lake floor our interpretation of these structures suggests as much as 13 m of vertical tectonic displacements along sections of a 80 km long fault system if these large displacements are from one tectonic event lake vattern must have had an earthquake with seismic moment magnitudes to 7 5 in addition our geophysical mapping shows large landslides along sections of the steep lake shores pollen analysis of sediment infillings of some of the most prominent sediment deformation structures places this major seismic event at the younger dryas preboreal transition ca 11 5 ka we suggest that this event is mainly related to the rapid release of ice sheet load following the deglaciation this paleoseismic event in lake vattern ranks among the larger known intraplate tectonic events in scandinavia and attests to the significance of glacio isostatic unloading

lake sediment evidence of paleoseismicity timing and spatial occurrence of late and postglacial earthquakes in finland abstract sediment profiles in six lake basins located near the late and postglacial fault surface ruptures in northern finland were investigated for turbidites and soft sediment deformation structures that could reveal information on the timing and spatial occurrence of paleoearthquakes in the area we used geophysical sub bottom profiling and lithological logging of sediment cores combined with radiocarbon and paleomagnetic dating in three lakes immeljarvi aakenus and laukkujarvi sediment records provided evidence of postglacial earthquakes or landslides whereas in three others lakes pyhajarvi kallojarvi and syvajarvi no disturbance structures were observed in their sequences that cover roughly the holocene period combined with previous data on paleoseismicity in finland the results enhance the non stationary hypothesis of seismicity throughout the late weichselian and the holocene with three general maxima that cluster around the deglaciation 12 0 10 0 kyr bp the mid holocene 5 0 7 0 kyr bp and the late holocene 1 5 3 0 kyr bp a strong asymmetry of the offset profiles of the finnish postglacial fault complexes indicate that the general rupture propagation was from sw to ne the present data also indicates that the oldest and highest magnitude events mw 7 or higher generally took place in the sw sector of the finnish pgf complexes during or soon after the retreat of the continental ice sheet the ruptures then propagated towards the ne sector of pgf complexes in a cascading fashion and were generally characterized by lower magnitude events mw 6 during the holocene

mechanisms of shallow landslides on soil mantled hillslopes with permeable and impermeable bedrocks in the boso peninsula japan abstract rainfall induced shallow landslides play a vital role in hillslope denudation processes in humid temperate regions this study demonstrates the contrasting mechanisms of landslides in adjoining hills with permeable sandstone and impermeable mudstone bedrock in the boso peninsula japan the characteristics of slope hydrology were inferred from pressure head monitoring and rainfall runoff observations an analysis of slope stability provided critical conditions for several previously occurring landslides the results are as follows 1 in slopes with the permeable sandstone infiltrated rainwater percolates through the bedrock as an unsaturated gravitational flow the wetting front migration results in a decrease of soil cohesion and causes landsliding at the steep lower part of the hillslopes 2 in contrast the impermeable mudstone beneath a thin soil layer causes a transient positive pressure head that generates a saturated subsurface storm flow the reduction in effective normal stress triggers shallow soil slipping at the uppermost part of a hollow

distribution and morphology of landslides in northern finland an analysis of postglacial seismic activity abstract the ages and sizes of landslides occurring in seismically active areas can be used to reconstruct the seismic history of the area and estimate the maximum moment magnitudes of past earthquakes here we present a data set of 121 landslides discovered in northern finland that were analyzed for their morphometric characteristics we show that 89 debris slide type landslides in the data set are clustered close to known postglacial faults pgfs and thus provide information on the characteristics of postglacial paleoseismic events by using empirical correlations between the landslide volume area data and earthquake moment magnitude we estimate maximum moment magnitudes m w 6 9 7 7 for postglacial earthquakes in the suasselka isovaara riikonkumpu venejarvi and vaalajarvi areas where earlier estimates based on fault length and displacement have yielded magnitudes varying between m w 6 5 and 7 5 we also show that the landslides in northern finland are located within a radius of 35 km from the closest known pgf and that sizes of the landslides decrease as a function of distance from pgfs hence providing strong empirical evidence for their seismic origin as far as we are aware this is the first use of landside data in quantifying postglacial seismicity within the fennoscandian shield area

an assessment of source parameters of earthquakes in the cordillera of the western united states abstract source parameters for 50 earthquakes occurring between 1915 and 1988 have been used to examine the faulting characteristics of magnitude 5 5 to 7 8 earthquakes within the western u s cordillera an area extending from the eastern sierra nevada to the great plains and from northwestern montana to trans pecos texas source parameters used in this study include seismic information from first motion analyses body and surface waveform modeling geodetic studies and geological studies of surface faulting the principal results of this analysis include 1 all earthquakes occurred on faults dipping 38 or more and no evidence for listric of low angle planar faulting was found 2 all m 7 0 earthquakes occurred at depths 12 km and were composed of multiple subevents 3 most earthquakes 70 per cent had unilateral ruptures and 4 no individual subevent had a rupture length 21 km

source complexity of the 1988 armenian earthquake evidence for a slow after slip event we analyzed teleseismic p and s waves using a multiple event deconvolution method to investigate the source process of the spitak armenia earthquake of december 7 1988 teleseismic long period body waves exhibit complex waveforms significantly more complex than those normally seen for an event of this size we identified two groups of subevents one is a group of strike slip events during the first 20 s the other is a dip slip event initiating at about 30 s after the initial rupture the tensor sum of all the subevents is essentially strike slip strike 302 dip 59 rake 143 with a scalar moment of 1 47 10 19 n m the seismic moment of the dip slip event strike 89 dip 60 rake 88 is 5 6 10 18 n m nearly 40 of the total and the moment release rate is slower than the other subevents with a strike slip mechanism we call this event a slow after slip event the mechanism of the after sup event is consistent with the present day deformation pattern in the caucasus where north south compression is predominant due to the continental collision between the arabian plate and the russian platform this result suggests that in a region where both strike slip motion and crustal shortening are taking place like southern california a large strike slip event may accompany large thrust events and vice versa in order to determine the total coseismic deformation pattern it is essential to resolve these multiple events in time space and mechanism

broadband study of the 1989 loma prieta earthquake we determined the source characteristics of the oct 18 1989 loma prieta california earthquake using teleseismic data the solution from body waves gives a mechanism with dip 70 rake 138 and strike 128 and a seismic moment of 3 10 26 dyne cm m w 6 9 this solution is similar to those obtained from long period rayleigh and love waves p nl waves and first motion data the body wave form suggests a depth of about 15 km the effective duration of the source is 6 sec which suggests a fault length of 30 km and 15 km for bilateral and unilateral faulting respectively considering the extent of the aftershock area we used 35 km as an estimate of the total rupture length the strike slip and the thrust components of the coseismic slip are 177 and 159 cm respectively the large thrust component raises an important question regarding the recurrence pattern if the loma prieta earthquake is a characteristic earthquake with a recurrence interval of about 100 years the 159 cm displacement implies a long term uplift rate of about 1 cm year which appears too large for this region three hypotheses for reconciling this apparent conflict are 1 the geometry of plate motion along the santa cruz mountain segment changes over a time scale of several thousand years so that the coseismic displacement has not accumulated enough to produce high topographic relief 2 the coseismic shp direction varies from event to event 3 the slip plane of the 1989 loma prieta earthquake is different from the major boundary between the pacific and the north american plates if this is the case the loma prieta earthquake is a rather rare non characteristic event the surface slip of about l m for the 1906 san francisco earthquake is one of the key data in long term forecasting no surface slip was observed for the 1989 loma prieta earthquake even if the horizontal slip at depth is as large as 1 8 m this points to a risk of relying too heavily on surface observations for long term seismic risk analysis

microearthquakes illuminate the deep structure of the endglacial parvie fault northern sweden at 155 km the parvie fault is the world s longest known endglacial fault egf it is located in northernmost sweden in a region where several kilometre scale egfs have been identified based on s

rupture of a seismic gap in southeastern alaska the 1972 sitka earthquake ms 7 6 abstract the sitka alaska earthquake of july 30 1972 m s 7 6 is one of the largest strike slip events since 1963 this earthquake is thought to have ruptured the pacific north america plate boundary segment between the large strike slip events in 1949 and 1958 and the sitka earthquake was heralded as one of the first successful forecasts of an earthquake based on the seismic gap hypothesis another motivation to study this event is the availability of a strong ground motion recording 50 km from the epicenter which is near the middle of the 180 km long plate boundary segment the teleseismically located aftershocks occur only in the southern half of this segment we have analyzed rayleigh waves and p waves recorded by wwssn long period vertical instruments a total of 25 very long period rayleigh phases r2 r5 define a symmetric four lobed radiation pattern from which we can infer a nearly pure right lateral strike slip fault striking 340 n20 w and a bilateral rupture comparison of synthetic and observed rayleigh waves yields a seismic moment of 3 10 27 dyn cm m w 7 6 the p waves are characterized by a dominant complex pulse in the first 40 s and a succession of smaller pulses after that the source time functions are deconvolved from 32 p waves with good azimuthal distribution to obtain the moment depth extent and rupture history the mean moment of the source time functions is 5 0 2 4 10 27 dyn cm and the depth extent is 0 10 km tomographic inversion of the source time functions produces an image of the earthquake rupture process this procedure maps the moment release of the complex pulse into two high displacement regions i e asperities 1 the epicentral area to 40 km north and 2 between 60 and 90 km south of the epicenter the main asperity just north of the epicenter coincides with a quiescent zone of microaftershocks while the overall average seismic displacement is 6 m the displacement at the main asperity is 7 m the same value as the tectonic displacement accumulated since the previous earthquake in 1848 the fault averaged stress drop is 100 bars while the asperity stress drop is 130 bars tomographic imaging of the source time functions thus resolves several features of the rupture process notably the bilateral propagation and rupture initiation at the largest asperity this is in contrast to the large 1976 guatemala strike slip earthquake where the largest displacements occurred away from rupture initiation

experimental investigation of rainfall criteria for shallow slope failures a theory of the internal response based rainfall criterion for predicting slope failure is proposed based on artificial rainfall tests for a sandy slope key elements in a generic model describing shallow slope failure are identified from the tests with extensive soil moisture and piezometric measurements the observed retrogressive slope failure was triggered by a toe failure followed by an abrupt increase in debris discharge the onset of the failure was preceded by a clear transition point on the soil moisture vs time curve at the soil bedrock interface both external and internal responses of slopes to rainfall can be expressed using widely adopted i d rainfall intensity duration plots experimental results from the tests indicate close relationships between the internal based and external based i d envelopes for critical slope states the theory of the internal based i d criterion proposed here will be useful for more accurate slope failure predictions

slip accumulation and lateral propagation of active normal faults in afar we investigate fault growth in afar where normal fault systems are known to be currently growing fast and most are propagating to the northwest using digital elevation models we have examined the cumulative slip distribution along 255 faults with lengths ranging from 0 3 to 60 km faults exhibiting the elliptical or bell shaped slip profiles predicted by simple linear elastic fracture mechanics or elastic plastic theories are rare most slip profiles are roughly linear for more than half of their length with overall slopes always 0 035 for the dominant population of nw striking faults and fault systems longer than 2 km the slip profiles are asymmetric with slip being maximum near the eastern ends of the profiles where it drops abruptly to zero whereas slip decreases roughly linearly and tapers in the direction of overall aden rift propagation at a more detailed level most faults appear to be composed of distinct shorter subfaults or segments whose slip profiles while different from one to the next combine to produce the roughly linear overall slip decrease along the entire fault on a larger scale faults cluster into kinematically coupled systems along which the slip on any scale individual fault or fault system complements that of its neighbors so that the total slip of the whole system is roughly linearly related to its length with an average slope again 0 035 we discuss the origin of these quasilinear asymmetric profiles in terms of initiation points where slip starts and barriers where fault propagation is arrested in the absence of a barrier slip apparently extends with a roughly linear profile tapered in the direction of fault propagation

source mechanisms of three moderate california earthquakes of july 1986 abstract we studied the source processes of three moderate size earthquakes in california the m s 6 0 event of july 8 1986 near palm springs the m s 5 8 shock of july 13 1986 offshore of oceanside and the m s 6 2 event of july 21 1986 in the chalfant valley on the east side of the sierra nevada the centroidal source parameters are estimated by inversion of long period p and sh waves recorded at teleseismic distances by seismographs of worldwide networks a more detailed description of the source is then obtained by analyzing broadband seismograms the north palm springs earthquake had a simple rupture process most of the seismic moment was released in the first 3 sec in a single step the strike of the source fault plane follows the average trend of the banning fault and its dip agrees with the dip of the fault plane delineated by the aftershocks the faulting mechanism of the main shock is right lateral strike slip with a sizable reverse component that is consistent with uplift north of the banning fault the earthquake offshore of oceanside had a slightly more complex rupture process the far field source time function consists of two pulses that represent the release of most of the moment in the first 3 sec the source mechanism indicates reverse faulting with the compressional axis trending northeast almost perpendicular to the trend of mapped faults offshore the event does not appear to be associated with major mapped faults in the area but the strike of one of the nodal planes agrees with the trend of the major mapped faults offshore and its mechanism is consistent with the missing component of plate convergence not taken up by the onshore strike slip fault systems and the idea of a weak san andreas fault system the rupture process of the chalfant valley earthquake was yet more complicated the source time function indicates that in a 4 sec time window three asperities were broken the source mechanism indicates right lateral strike slip faulting with a small normal faulting component on a fault that dips approximately 50 southwest earthquake activity suggests that presently the deformation in the northern part of the owens valley which includes the chalfant valley is dominated by conjugate strike slip faults which strike obliquely to the main range bounding normal faults the waveforms indicate the presence of a low velocity zone at a depth of about 20 km in the crust in the chalfant valley a synthesis of information from waveform modeling first motion fault plane solutions and aftershock distributions indicates that the nucleation and or termination of rupture for the north palm springs and the chalfant valley events were controlled by preexisting fault geometry

centroid moment tensor solutions for 35 earthquakes in western north america 1977 1983 abstract seismic records from the gdsn sro asro dwwssn rstn and ida networks were used to obtain long period t 45 sec focal mechanisms for 35 earthquakes in western north america longitude 140 to 110 latitude 30 to 60 employing the centroid moment tensor method of dziewonski et al 1981 and dziewonski and woodhouse 1983 the same algorithm was applied to all events the smallest m 0 6 4 10 23 dyne cm being an aftershock to the 1979 imperial valley california earthquake and the largest m 0 8 5 10 26 dyne cm the 1980 eureka california earthquake all events were analyzed with and without the constraint m r m r 0 on the moment tensor an ad hoc criterion on the relative variance reduction was employed to determine a favored solution our solutions show general agreement with other published results as well as with tectonic structures agreement with results obtained using the abundant local and regional data confirms the adequacy of the method in determining long period source parameters and verifies its applicability in regions where local and regional data are scarce or nonexistent in some cases disagreement between our solution and results from first motion studies appears to be related to source complexities our moment tensor represents the total stress release of the composite event a consistent westward movement of the centroid locations reflects lateral heterogeneities in the crust and mantle

correlation of unsaturated soil and dielectric property for monitoring of subsurface characteristics development of unsaturated dielectric mixing models and its application the behavior due to rainfall infiltrating the ground plays a role in landslides groundwater recharge and various other ground responses most of these geotechnical behaviors have a correlation between soil pore space and soil volumetric water content in the unsaturated and saturated soil porous media therefore the soil porosity associated with soil pores and the distribution of volumetric water content are significantly important hydrological characteristics in the case of shallow slope failure such as landslide the infiltration activity due to the connectivity of soil pore spaces in a porous media is induced slope failure may be attributed to the effect of a wetting front with the slope due to liquid infiltration which changes the volumetric water content soil matric suction and shear strength of the slope this study was performed with an unsaturated injection test using a frequency domain reflectometry fdr dielectric device which measures the dielectric constant of unsaturated soil and the study then proposed the unsaturated dielectric mixing models to calculate soil porosity and effective porosity of unsaturated soils from the experimental results the ratio of effective porosity to porosity of soils are measured in a range of 70 85 these experimental results show a decrease of about 5 10 for unsaturated soil compared to the ratio of effective porosity to porosity of saturated soil the infiltration passages of tracer material are restricted within the pore connectivity in the unsaturated soil which is caused by dead pores in the soil using the fdr device and the unsaturated dielectric mixing models we can consider the acquisition of physical properties to detect the infiltration activity the response of the dielectric constant along with the injected tracer and hydrological parameters for the unsaturated soil porous media

postglacial rebound and fault instability in fennoscandia summary the best available rebound model is used to investigate the role that postglacial rebound plays in triggering seismicity in fennoscandia the salient features of the model include tectonic stress due to spreading at the north atlantic ridge overburden pressure gravitationally self consistent ocean loading and the realistic deglaciation history and compressible earth model which best fits the sea level and ice data in fennoscandia the model predicts the spatio temporal evolution of the state of stress the magnitude of fault instability the timing of the onset of this instability and the mode of failure of lateglacial and postglacial seismicity the consistency of the predictions with the observations suggests that postglacial rebound is probably the cause of the large postglacial thrust faults observed in fennoscandia the model also predicts a uniform stress field and instability in central fennoscandia for the present with thrust faulting as the predicted mode of failure however the lack of spatial correlation of the present seismicity with the region of uplift and the existence of strike slip and normal modes of current seismicity are inconsistent with this model further unmodelled factors such as the presence of high angle faults in the central region of uplift along the baltic coast would be required in order to explain the pattern of seismicity today in terms of postglacial rebound stress the sensitivity of the model predictions to the evects of compressibility tectonic stress viscosity and ice model is also investigated for sites outside the ice margin it is found that the mode of failure is sensitive to the presence of tectonic stress and that the onset timing is also dependent on compressibility for sites within the ice margin the evect of earth rheology is shown to be small however ice load history is shown to have larger evects on the onset time of earthquakes and the magnitude of fault instability

comparison of soil thickness in a zero order basin in the oregon coast range using a soil probe and electrical resistivity tomography abstractaccurate estimation of the soil thickness distribution in steepland drainage basins is essential for understanding ecosystem and subsurface response to infiltration one important aspect of this characterization is assessing the heavy and antecedent rainfall conditions that lead to shallow landsliding in this paper we investigate the direct current dc resistivity method as a tool for quickly estimating soil thickness over a steep 33 40 zero order basin in the oregon coast range a landslide prone region point measurements throughout the basin showed bedrock depths between 0 55 and 3 2 m resistivity of soil and bedrock samples collected from the site was measured for degrees of saturation between 40 and 92 resistivity of the soil was typically higher than that of the bedrock for degrees of saturation lower than 70 results from the laboratory measurements and point depth measurements were used in a numerical model to evaluate the resistivity contrast at the soil bedrock interface a dec

instability of partially saturated soil slopes due to alteration of rainfall pattern abstract the influence of climate change on rainfall patterns has the potential to alter stability of partially saturated soil slopes changes in rainfall patterns have a strong influence on stability of partially saturated soil slopes which recently have resulted in shallow landslides in this paper slope stability is assessed using a monolithically coupled finite element model for a deformable partially saturated soil subjected to surface infiltration of water numerical analysis solves for the matric suction distribution over a two dimensional cross section of a soil slope while varying permeability and considering a surface layer of soil with different permeability the formulation of hydraulic conductivity for a coupled analysis includes dependence on porosity and degree of saturation to illustrate the effects of water infiltration and deformation behavior in partially saturated soils numerical examples demonstrate that change in rainfall patterns may trigger slope instability earlier in the rainfall event than for rainfall events of the past assessment of these simulations can provide an indication of the potential influence of climate change on shallow landslides in many mountainous areas in south korea

an improved approach for evaluating the time dependent stability of colluvial landslides during intense rainfall the paper presents an improved analytical approach for evaluating the time dependent stability of colluvial landslides during intense rainfall infiltration the approach comprises two steps first to simulate rainfall infiltration and then to compute the safety factor in terms of the irregularity of the natural landslide surface in implementation of the method the landslide is divided into several soil slices with approximately straight sides each single slice is regarded as a finite slope so that the infiltration formula and safety factor can be deduced the infiltration formula is derived with combination of the green ampt model and mass conservation law considering seepage perpendicular and parallel to slope surface simultaneously in the modified infiltration model both size effect and angle effect are vividly observed in the process of rainfall infiltration into the finite slope while the former of which is not presented in the original green ampt model the safety factor is computed using the limit equilibrium method with the influence of infiltrating water on the shear strength gravity and seepage force of soil slices considered by case study of the shuping landslide in three gorges decline in the safety factor and the decrease in the tendency are definite specifically under the rainfall intensity of 50 mm h the failure of shuping landslide is most likely to occur at the time of 102 h in addition the results highlight shallow failure along the wetting front under intense rainfall

glacio seismotectonics ice sheets crustal deformation and seismicity abstract the last decade has witnessed a significant growth in our understanding of the past and continuing effects of ice sheets and glaciers on contemporary crustal deformation and seismicity this growth has been driven largely by the emergence of postglacial rebound models pgm constrained by new field observations that incorporate increasingly realistic rheological mechanical and glacial parameters in this paper we highlight some of these recent field based investigations and new pgms and examine their implications for understanding crustal deformation and seismicity during glaciation and following deglaciation the emerging glacial rebound models outlined in the paper support the view that both tectonic stresses and glacial rebound stresses are needed to explain the distribution and style of contemporary earthquake activity in former glaciated shields of eastern canada and fennoscandia however many of these models neglect important parameters such as topography lateral variations in lithospheric strength and tectonic strain built up during glaciation in glaciated mountainous terrains glacial erosion may directly modulate tectonic deformation by resetting the orogenic topography and thereby providing an additional compensatory uplift mechanism such effects are likely to be important both in tectonically active orogens and in the mountainous regions of glaciated shields in general the short term response to ice fluctuations is similar to the earth s response to fluctuations in water reservoirs with the subsequent increase or decrease in seismicity which depends on the pre existing stress state when the ice fluctuations occur on the spatial scale and magnitude of the late pleistocene glaciation and deglaciation however the viscoelastic response of the earth especially the mantle causes significant changes in crustal deformation and earthquake activity that is spatially extensive and temporally complex the regions of greatest ice thickness and the regions marginal to the late pleistocene ice sheets indicate the most dramatic evidence of earthquake faulting the mantle response to these large ice mass fluctuations and the change in mass between the oceans and land caused and continues to cause measureable crustal deformation at hundreds of kilometres from the ice margins for both tectonically active and cratonic regions palaeoseismic investigations of late pleistocene and holocene faults are an important tool in evaluating earthquake hazard the predicted response of the earth over this time however is very dependent on the model assumed for most regions far more carefully designed field observations are needed to constrain the existing rheological and ice models

model for the prediction of shear strength with respect to soil suction experimental studies on unsaturated soils are generally costly time consuming and difficult to conduct shear strength data from the research literature suggests that there is a nonlinear increas

electrical sedimentary anisotropy of landforms adjacent to postglacial faults in lapland abstract postglacial faults pgfs are common sw ne trending features in the northern part of the fennoscandian shield being attributed to former high magnitude mw 7 8 2 earthquakes arvidsson 1996 these are of interest for the long term seismic hazard of deep geological nuclear waste repositories the pgfs are still seismically active and many of the deformation features such as paleolandslides are spatially coextensive within these earthquake zones based on the 14c datings of landslide buried organic materials three postglacial seismic episodes 9 7 11 5 6 and 1 3 1 8 ky ago have been found in western finnish lapland because the model predictions by wu et al 1999 suggested that the onset of fault instability started at 15 ky and that the maximum fault instability was reached at 13 10 ky in fennoscandia we postulate that not only subaerial but also subglacial types of deformations may have been associated with the past seismic events here we present lidar dem observations and sediment electromagnetic anisotropy data on the landforms such as the rim ridged arcuate pulju moraine kujansuu 1967 roundish liquefaction bowls postdepositional liquefaction deformations on streamlined landforms as well as hummocky ridge fields of massflow sediments the sediments in the pulju moraine and massflow ridges displayed clear anisotropy indicating lateral transportation in subglacial wet based environment instead sediments in the bowl shaped morphologies next to pgfs and deformed ice stream flutings tended to be isotropic suggesting postdepositional and vertical liquefaction processes based on the lidar morphology and sedimentary anisotropy data these landforms may be linked to past earthquakes

monitored and simulated variations in matric suction during rainfall in a residual soil slope this research combines field laboratory and numerical investigations to estimate the development of a wetting front within a 1 2 m residual soil mantle on a steep forested slope during rainfall events the field monitored variations in matric suction due to rain water infiltration during various events revealed that the maximum infiltration rate was much higher when the wetting front resided in the upper 20 cm of soil compared to the case when the wetting front advanced to depths 20 cm laboratory investigations on soil hydraulic properties i e soil water characteristic curve and hydraulic conductivity were useful to establish the parameters of a multilayer finite element model for one dimensional vertical infiltration these parameters were subsequently calibrated by matching the predicted and field measured transient pore water pressure responses during actual rainstorms with irregular rainfall patterns the calibrated simulation model was used to assess the migration of the wetting front under uniform rainfall with different intensities based on the numerical results a hyperbolic equation was developed to predict the duration of uniform rainfall required for the propagation of wetting front to a certain depth for a given rainfall intensity the proposed equation was subsequently tested against field monitored advancements of the wetting front during real rainstorms with variable rainfall intensity

on the evaluation of unsaturated flow in a natural slope in rio de janeiro brazil abstract geotechnical engineers and geologists are frequently concerned with the complex phenomenon of rainstorm induced landslides in mountainous tropical regions this paper analyses the hydrological conditions that contributed to a huge deep seated slide of a slope in rio de janeiro brazil the slope failure occurred after a short period of intense rainfall buried cars and caused structural damages to an adjacent building on the following day the failure surface was completely saturated despite the fact that no groundwater was observed within the slope understanding a rain induced landslide is a considerable challenge in the present case there was an extra question to be answered why were no slope movements observed a few months earlier when a more intense rainfall reached the slope geological and geotechnical surveys were carried out aiming at determining complete soil profile characterization piezometric levels and hydraulic parameters field investigations indicated a variable thickness unsaturated residual soil layer overlying a gneissic rock the transition between the saprolitic soil and the sound rock consisted of a highly fractured and weathered rock 3d flow modelling has shown that the amount of rain infiltration was insufficient to produce positive pore water pressures it was likely that development of preferential infiltration paths could explain the hydrological conditions of the slope during landslide water infiltration through the fractured soil rock transition induced a rapid development of positive pore water within the soil mass this favourable scenario might have been created by the lack of maintenance of the crest drainage channel adjacent to the slide area it is a common engineering practice to try to associate rainfall amounts to the risk of slope failure the role that bedrock plays in generating pore pressure is seldom considered the numerical analyses presented in this paper pointed out at the complexity of flow modeling of rain infiltration through unsaturated residual soil slopes it essentially revealed that flow mechanisms other than rain infiltration over the slope surface might play a major role on hydrological pattern of slopes

shear strength characteristics of a residual soil shallow landslides in natural residual soils slopes are common all over the world the slip surfaces associated with these landslides are often situated above the groundwater table therefore it i

fennoscandian earthquakes whole crustal rupturing related to postglacial rebound local and regional earthquake locations provide seismic evidence that large shield earthquakes have occurred in northern fennoscandia these paleoearthquakes with fault lengths of up to 160 kilometers and average displacements of up to 15 meters were triggered by nonisostatic compressive stresses caused by the removal of the ice at the end of the last deglaciation the fennoscandian faults were probably formed by single events that ruptured through most of the crust the largest event moment magnitude mw 8 2 was larger than other known stable continent earthquakes outside failed rifts or extended crust

seismic deformation of varved sediments in southern fennoscandia at 7400 cal bp abstract soft sediment deformation structures are preserved in clastic biogenic varves of the lake nurmijarvi sequence from central southern finland deformation structures include centimeter scale folding and faulting structures and larger convolute bedding which are separated from the overlying undisturbed varved section by a turbidite dated at 7400 cal bp the soft sediment deformation provides evidence for postglacial seismic activity ca 3500 years after the deglaciation of the study area by screening the sizes of potential source faults for the event the maximum earthquake moment magnitudes associated with the deformation structures were constrained to mw 5 1 6 9 with realistic 40 rupture scenarios or up to mw 5 1 7 7 if more conservative scenarios are considered the results of the study thus indicate a relatively high magnitude postglacial seismic event in southern finland which adds to the evidence that the postglacial seismic activity was not just restricted to northern fennoscandia but was a more widespread phenomenon the age of the lake nurmijarvi seismic event further demonstrates that high magnitude seismic activity was not restricted to a relatively short period after deglaciation but the period of high magnitude postglacial seismic activity was much longer than previously thought by assessing the orientations of faults that are presently active and using available focal mechanism data our results suggest that strike slip faulting may be a more important mechanism for the generation of both present day and postglacial earthquakes in southern finland than reverse faulting which should further be accounted for in the assessment of long term seismic hazards

the 1971 san fernando earthquake a double event evidence is presented which suggest that the 1971 san fernando earthquake may have been a double event that occurred on two separate subparallel thrust faults it is postulated that the initial event took place at depth on the sierra madre fault zone which runs along the base of the san gabriel mountains rupture is postulated to have occurred from a depth of about 15 km to a depth of about 3 km a second event is thought to have initiated about 4 sec later on another steeply dipping thrust fault which is located about 4 km south of the sierra madre fault zone the surface trace of this fault coincides with the san fernando fault zone which was the principal fault associated with surface rupture it is postulated that rupture propagated from a depth of 8 km to the free surface the moments of the first and second events are approximately 0 7 10 26 dyne cm and 1 0 10 26 dyne cm respectively this model is found to explain the combined data sets of strong ground motions teleseismic p and s waveforms and static offsets better than previous models which consist of either a single fault plane or a plane having a dip angle which shallows with decreasing depth nevertheless many features of the observed motions remain unexplained and considerable uncertainty still exists regarding the faulting history of the san fernando earthquake

evidence of multiple slip events on postglacial faults in northern fennoscandia abstract an analysis of high resolution lidar based digital elevation models dems trenching of quaternary deposits diamond drilling and a structural analysis of the bedrock were conducted in order to characterise the geological structure and to derive full slip profiles of the venejarvi jauhojarvi postglacial fault complex located in northern finland the venejarvi jauhojarvi fault complex consists of 17 surface ruptures striking in a sw ne direction cutting through late weichselian till and traceable for a total distance of 29 9 km based on stratigraphical and structural analysis we show that the naamivitikko fault segment which is part of the venejarvi jauhojarvi complex hosted up to three distinct slip events and it is therefore argued that the prevailing single rupture hypothesis of postglacial faults should be treated with caution based on the measured surface rupture dimensions it is conservatively estimated that the maximum moment magnitude of the paleoseismic event that the complex hosted ranged between mw 5 8 8 4 if uncertainties in the scaling laws equating surface rupture dimensions to moment magnitudes are accounted for a more realistic maximum moment magnitude range between mw 5 8 7 6 is given

depth of faulting during the 1968 meckering australia earthquake sequence determined from waveform analysis of local seismograms waveforms for 11 foreshocks and 48 aftershocks of the ms 6 8 meckering earthquake recorded at the world wide standard seismograph network station mundaring are analyzed to determine the depth distribtion of faulting during this unusual intraplate earthquake sequence clear depth phases including sp and rg are seen in the local seismograms at distances of 60 95 km and are studied using synthetic seismograms computed using generalized ray theory and wave number integration techniques large rg s ratios seen on the vertical component short period data for many events imply source depths less than 2 km the short period p waveform contains the best depth estimator in the form of sp so that depth can be estimated to within an uncertainty of about 1 km for most events the foreshocks cluster at less than 2 km depth and most aftershocks occur within 1 km of the surface a few aftershocks occur as deep as 7 km these results are consistent with a previous teleseismic waveform study in which faulting was inferred to start near the surface at 1 5 km depth with rupture proceeding downward and not exceeding 6 km depth these results coupled with previous stress studies in the australian shield and models of crustal strength show that faulting in a cold shield area is a near surface phenomenon and implies that most of the crust is too strong to be fractured

anisotropic 3d full waveform inversion abstractwe have developed and implemented a robust and practical scheme for anisotropic 3d acoustic full waveform inversion fwi we demonstrate this scheme on a field data set applying it to a 4c ocean bottom survey over the tommeliten alpha field in the north sea this shallow water data set provides good azimuthal coverage to offsets of 7 km with reduced coverage to a maximum offset of about 11 km the reservoir lies at the crest of a high velocity antiformal chalk section overlain by about 3000 m of clastics within which a low velocity gas cloud produces a seismic obscured area we inverted only the hydrophone data and we retained free surface multiples and ghosts within the field data we invert in six narrow frequency bands in the range 3 to 6 5 hz at each iteration we selected only a subset of sources using a different subset at each iteration this strategy is more efficient than inverting all the data every iteration our starting velocity model was obtained using standard psdm model bui

application of an iterative least squares waveform inversion of strong motion and teleseismic records to the 1978 tabas iran earthquake an iterative least squares technique is used to simultaneously invert the strong motion records and teleseismic p waveforms for the 1978 tabas iran earthquake to deduce the rupture history the method solves for both slip amplitudes and rupture times on a finite fault several inversions of the data are done to determine the best fitting hypocenter average rupture velocity and source time function within the range of our parameter search the effects of using different data sets and different parametrizations of the problem linear versus nonlinear are also considered teleseismic body waves are shown to be essential to obtain a reliable solution due to the sparse coverage of the fault plane by strong motion stations a simple triangular source time function is compared with a modified kostrov source time function for a circular rupture and a constant propagating stress drop although the waveforms used in the inversions can not resolve between these two time functions the kostrov source time function gives a moment estimate and maximum fault displacement more consistent with long period surface waves and field observations the results of the iterative inversion for slip amplitudes and rupture times are compared with the results of a linear inversion for slip amplitudes in which the rupture velocity is fixed flexibility in the sequence of faulting for the linear inversion is obtained by allowing multiple rupture intervals a consensus of all the inversion runs indicates a complex multiple source for the tabas earthquake with four main source regions over a fault length of 90 km and an average rupture velocity of 2 5 km sec

the july 1986 oceanside ml 5 3 earthquake sequence in the continental borderland southern california an earthquake of m l 5 3 occurred at 32 58 7 n 117 51 5 w southwest of oceanside in san diego county at 13 47 13 july 1986 ut this main shock was followed by an extensive aftershock sequence with 55 events of m l 3 0 during july 1986 the epicenters of the main shock and aftershocks are located at the northern end of the san diego trough bahia soledad fault zone sdt bs where it changes strike from northwest to a more westerly direction through a left offset or a bend in the fault the northwest striking sdt bs is one of three strike slip fault systems that constitute the offshore agua blanca fault system the spatial distribution of the aftershocks indicates a unilateral 7 to 9 km long rupture to the east southeast away from the epicenter of the main shock the focal mechanism of the main shock also has an east southeast striking and south dipping plane with mostly reverse movement on it focal mechanisms of the m l 3 0 aftershocks show both reverse and strike slip movement the reverse focal mechanisms indicate that this sequence may have occurred on a thrust fault that provides for a left stepping offset or a bend in the san diego trough fault as movement is transferred to the west along the santa cruz catalina island escarpment some of the aftershocks that are located to the southeast of the main shock and have strike slip focal mechanisms suggest activation of the northwest trending san diego trough fault a stress inversion of the focal mechanism data shows that the maximum principal stress determined from the focal mechanisms of the main shock and 22 aftershocks that occurred within 36 hours of the main shock has an azimuth of s30 w plunging 18 the maximum principal stress determined from 30 aftershocks that occurred from 15 july to 2 october 1986 has an azimuth of s20 w plunging 18 the values the measure of the relative sizes of the principal stresses are approximately 0 07 and 0 1 respectively indicating that the intermediate and minimum principal stress are of similar magnitude the results of the stress inversion and the focal mechanisms that showed reverse faulting suggest that the inner continental borderland offshore from oceanside is not currently a pure strike slip tectonic regime but rather a strike slip mixed with reverse faulting regime when the 52 aftershock focal mechanisms are divided into four groups and the stress inversion is repeated the change in stress can be described as a progressive counter clockwise rotation of 14 of the orientation of the maximum principal stress to a more southerly direction with the greatest change in stress orientation observed shortly after the main shock the abundance of aftershocks may be related to the large temporal variation in stress orientation that in turn may have resulted from the small stress drop of the main shock

evaluation of a combined spatial multi criteria evaluation model and deterministic model for landslide susceptibility mapping abstract this study evaluated the application of a combined spatial multi criteria evaluation model and deterministic model for landslide susceptibility mapping in deokjeok ri creek located in the northeastern part of korea this region has frequent shallow landslides often caused by intense rainfall on weathered granite soil slopes this study compared the predictive capability of two different models a spatial multi criteria evaluation smce model which is a semi quantitative model and a shallow landslide stability shalstab model which is a deterministic model used to produce shallow landslide susceptibility maps for the smce model input layers of landslide causative factors i e topographic hydrological soil forest and geological factors were prepared for pairwise comparison to obtain susceptibility weightage for shalstab a digital elevation model was used to calculate slope and wetness indices field inventories were used to validate and combine the two models a comparison of the susceptibility map obtained from the smce method with that obtained with the shalstab method revealed that the total mismatch area between the two maps for all three susceptibility classes was about 53 therefore the two results were combined to improve the reliability of the susceptibility map the performance of the combined map was determined using the receiver operator curve roc the area under curve auc revealed a success accuracy of 79 56 and the predictive accuracy was 83 6 these results demonstrate that the combined model was more accurate than either individual model at delineating landslide prone areas of weathered granite soil slopes

use of an artificial crown pillar in transition from open pit to underground mining abstract in the transition from open pit to underground mining a crown pillar is usually left at the open pit bottom crown pillars are often not recovered and as a result they are deemed as permanent losses to address this problem this paper discusses use of an artificial crown pillar as replacement for the natural crown pillar during a transition from open pit to underground mining the substitution of the natural crown pillar with an artificial one enabled total recovery of sterilized ore in the natural crown pillar a case study is presented on shandong guilai village gold mine open pit transition to underground mining the safe and profitable mining of the natural crown pillar and the simultaneous construction of the artificial crown pillar was achieved by combined use of analytical and empirical methods numerical modelling and instrumentation the analytical and empirical methodologies were used to determine the natural crown pillar thickness numerical modelling was performed to further evaluate the results of the analytical and empirical methods and to predict the performances of the artificial crown pillar the instrumentation monitoring ensured safety of the open pit slopes and underground infrastructure prior to during and after the process of mining and simultaneous construction of the artificial crown pillar it was concluded that the process of simultaneously mining the natural crown pillar and replacing it with an artificial one was successful in protecting the open pit slopes and underground infrastructure a comparison of the cost of mining the natural crown pillar processing the ore and constructing the artificial crown pillar with the market price of the gold obtained showed a profit of 30 while this study is limited to a particular mine the procedure could be used in other mines in similar situations

failure characteristics of rainfall induced shallow landslides in granitic terrains of shikoku island of japan soil slips debris slides and flow occurrences on hill slopes of particular areas are closely related to the mode of rainfall because of geological geomorphological and climatic settings japan is highly prone to rainfall induced landslides in 2004 shikoku the smallest island of japan faced extreme events of typhoon rainfalls and suffered huge losses of life and property because of floods and landslides this paper deals with the synoptic descriptions of failures that occurred in the granitic terrain of northeast shikoku island japan along with rainfall and failure relationships during the typhoon 0423 tokage of 2004 examples of typical failures that occurred in moriyuki and monnyu of northeast shikoku are taken into consideration in this study data from laboratory and field were used to perform sensitivity and stability analyses with respect to varying slope angles strength parameters and thicknesses of saturated residual soil this study attempts to employ a standard method of stability analysis of translational slides which are very common in masa soil weathered granite during extreme rainfall average rainfall intensities and duration during typhoon tokage were also used to interpret landslide triggering thresholds for the study area

influence of rainfall induced wetting on the stability of slopes in weathered soils abstract shallow failures of slopes in weathered soil are caused by infiltration due to prolonged rainfall these failures are mainly triggered by the deepening of the wetting band accompanied by a decrease in matric suction induced by the water infiltration this paper reports trends of rainfall induced wetting band depth in two types of weathered soils that are commonly found in korea both theoretical and numerical analyses for wetting band depth are presented based on the soil water characteristic curve obtained using filter paper as well as tensiometer tests it is found that the magnitude of wetting front suction plays a key role in the stability of slopes in weathered soils theoretical analysis based on modified green and ampt model tends to underestimate the wetting band depth for typical korean weathered soils it was also deduced that for korean weathered soils the factor of safety drops rapidly once the wetting band depth of 1 2 m reached

field study of a highly active fault zone the xianshuihe fault of southwestern china the xianshuihe fault of western sichuan province china is one of the world s most active faults having produced 4 earthquakes during this century of magnitude 7 along a 350 km length of the fault at least 8 such events have occurred since 1725 in the more limited 150 km long segment including luhuo and daofu major earthquakes in 1904 1923 1973 and 1981 m 7 7 7 6 6 9 were associated with overlapping surficial fault ruptures and with individual left lateral displacements as large as 3 6 m field studies indicate that this high degree of activity is typical of the fault s longer term history the holocene left lateral slip rate on the north western segment of the fault has been 15 5 mm yr decreasing to about 5 mm yr on its southeastern segment based on radiometrically dated offset stream channel and terrace deposits and on offset glacial moraines physiographic features of active faulting are fully as diagrammatic as those of california s san andreas fault mainly because of high altitude preservation and the absence of cultural modification on this eastern margin of the tibetan plateau detailed en echelon tensional and pushup features resulting from surface ruptures in 1973 1955 1923 and 1893 can still be recognized today and new data have been collected bearing on the offsets and fault rupture lengths during these and other events the locations and magnitudes of historic earthquakes suggest that the characteristic earthquake model may apply to the xianshuihe fault obvious geometric segmentation of the fault has controlled the initiation and termination of ruptures in some events whereas segmentation control for others remains obscure based on the historic record repeat times estimated from slip rates and current seismic gaps two segments are particularly likely sites for m 7 earthquakes in the near future the 65 km long segment between daofu and qianning and the 135 km long segment bracketing kangding continuing creep has been documented along some segments of the fault and this together with the high degree of activity and other unique attributes makes the xianshuihe fault one of the most promising sites in the world for earthquake prediction and hazard evaluation studies

analysis of physical testing of rainfall induced soil slope failures rainfall is a significant factor that triggers slope failures around the world this paper reports a series of physical tests which were conducted to simulate rain induced slope failures the experiments dealt with two scenarios including 1 rainwater infiltration into the slope and 2 slope failures induced by artificial rainfall with different initial conditions slope deformation and slope failures were observed and possible mechanisms were interpreted based on the experimental results the results confirm the hypothesis that pore water pressure and water content in a loose soil slope change rapidly and that water infiltration into cracks in the slope has a great impact on landslide development the observed slope failures can be divided into three types overall sliding failure partial sliding failure and flow slide the effect of slope gradient rainfall intensity and distribution of initial suction on the slope deformation and failure process are also summarized for possible applications under the similar conditions

pattern recognition of lidar data and sediment anisotropy advocate a polygenetic subglacial mass flow origin for the kemijarvi hummocky moraine field in northern finland abstract object based image analysis and supervised machine learning on a digital elevation model derived from airborne laser scanning data were conducted to assess the aggregate raw material potential over the kemijarvi hummocky moraine field in finnish lapland geomorphometric analysis revealed surface stoniness to be diagnostic of moraine hummocks it was utilized to detect true moraine hummocks from among the potential hummocks delineated using object based image analysis with logistic regression of curvature features derived from the digital elevation model area under the receiver operating characteristics curve auc 0 77 based on the electrical sedimentary anisotropy data the kemijarvi moraine is polygenetic such that the ridges are diagonally and erosionally fluted from sector 280 290 on their surfaces while the ridge cores are deposited from the nw from sector 310 340 the cores are composed of infill gravels and crudely stratified diamict sequences we consider the core of the kemijarvi hummocky moraine field to represent pre existing early weichselian subglacial ridges rather than being generated through monogenetic late weichselian compressional shearing and stacking frozen bed extension or bed ribbing instability mechanisms as presented for ribbed moraines that are transverse to ice flow recently evidence has been presented of multiple slip events earthquakes with moment magnitudes mw 6 7 7 0 up ice from kemijarvi we therefore propose that the genesis of the hummocks may be associated with past early weichselian fault instability within glacio isostatic adjustment s which was able to generate subglacial water bodies possibly lakes and saturated materials that were forced towards the se based on this new geomorphological evidence from mapping using a digital elevation model derived from airborne laser scanning data and azimuthal conductivity surveys combined with the reinterpretation of previously presented geophysics and sedimentological observations we suggest the kemijarvi hummocky moraine field to be reconsidered as the kemijarvi subglacial mass flow field which holds significant potential for construction aggregate materials

development of an initiation criterion for debris flows based on local topographic properties and applicability assessment at a regional scale abstract damages caused by landslides have been increasing because of the greater frequency of localized heavy rain to prevent landslide disasters more efficiently more studies in relation to predicting the initiation areas of debris flows that cause large scale damage are necessary the main purpose of this study is to develop a criterion for detecting debris flow initiation areas by using an empirical method that was chosen from several types of approaches to debris flow initiation detection in this study ten gis based geomorphological datasets were obtained from slide and debris flow initiation areas located in seoul gyeonggi province and gangwon province the geomorphological characteristics of slide and debris flow occurrence areas were analyzed through a comparative analysis to identify relationships between debris flow initiation and each topographic index an initiation criterion for debris flows based on the geomorphological characteristics was suggested using an artificial neural network ann model combined with a modified threshold for the relationship between slope and upslope contributing area to validate the suitability of the initiation criterion for debris flow sequential applications of slope failure analysis and debris flow initiation analysis were conducted on a case study site to simulate the actual debris flow events as a result of the debris flow initiation analysis the prediction capture rate of the debris flow initiation criterion was determined to be 88 9 debris flow initiation areas totaling 143 300 m2 were identified among 1 935 400 m2 of slope failure areas predicted in the slope failure analysis it is efficient to apply the debris flow initiation criterion in the debris flow simulation because slope failure areas are only partly transformed into debris flows

rupture complexity of a moderate sized mb 6 0 earthquake broadband body wave analysis of the north yemen earthquake of 13 december 1982 abstract the occurrence of the north yemen earthquake of 13 december 1982 provides an important opportunity to study source properties of earthquakes in the southern arabian peninsula although moderate in size m b 6 0 this earthquake is the largest to have occurred in the region since the deployment of the global digital seismograph network p waves recorded at teleseismic distances can be obtained from stations of this network and of the graefenberg array that are flat to displacement and velocity in the frequency range from 0 01 to 5 0 hz the broad bandwidth of the data is necessary for deriving a dynamic description of the earthquake as well as the static properties of the source in contrast inversions using only long period data provide much less insight into the complexity of rupture by fitting the displacement pulse shapes with synthetics we find that the yemen earthquake was a complex rupture consisting of two events that occurred about 3 0 sec apart the depth of both hypocenters is estimated to be 7 km the focal mechanisms of the events each have a nodal plane that strikes 340 and dips 60 to the east however the slip directions of the focal mechanisms are in slightly different directions 230 and 300 respectively the total moment of the earthquake is 3 0 10 25 dyne cm with the second event having three times the moment of the initial event by inverting p wave arrival time differences at each station we find the second hypocenter is located 7 5 km from the initial hypocenter in a direction that is nearly colinear with the nnw striking nodal plane of the focal mechanisms of each event the trend of extensional ground cracks in the epicentral region and the predominant strike of composite focal mechanisms of locally recorded aftershocks are also in a nnw direction from the consistency of these observations we infer that the east dipping nnw striking nodal planes are the fault planes the static stress drop of the first and second events are 44 and 31 bars respectively inverting the energy flux in the velocity waveforms we find the energy radiated by the earthquake is 4 8 10 20 dyne cm this implies an average apparent stress of 4 bars at different times during the aftershock sequence seismicity tended to cluster about one or another of two different planes which although having roughly the same strike had conjugate dips one of these planes delineated late in the aftershock sequence coincides with the inferred fault plane for the main shock the complexity of the main shock and of the aftershock sequence suggests that strain accumulated on a system of strongly interdependent faults as the region became critically loaded the effect of a major rupture was to critically stress faults adjacent to the initial nucleation the second event of the main shock represents the rapid release of stress from the fault system while the ensuing aftershock sequence represents the gradual release of stress

slip along the san andreas fault associated with the great 1857 earthquake historical records indicate that several meters of lateral slip along the san andreas fault accompanied the great 1857 earthquake in central and southern california these records together with dendrochronological evidence suggest that the rupture occurred along 360 to 400 km of the fault including several tens of kilometers of the currently creeping reach in central california geomorphic expressions of late holocene right lateral offsets are abundant along the 1857 rupture along 300 kilometers of the 1857 rupture between cholame and wrightwood the youngest discernible offset ranges from 3 to 9 1 2 meters dormancy of the fault since 1857 almost certainly indicates that this latest offset was created in 1857 fault slip apparently associated with the 1857 earthquake varies in a broadly systematic way along the trace of the fault it is relatively uniform along each of several long segments but changes rather abruptly in value between these segments this nonuniform displacement pattern may imply that some segments of the fault rupture more frequently or experience a slower long term slip rate than others the 1857 offsets indicate a seismic moment m o between 5 3 and 8 7 10 27 dyne cm assuming a 10 to 15 km depth of rupture and relatively uniform slip as a function of depth a comparison with the rupture length average slip value and tectonic setting of the california earthquake of 1906 m s 8 1 4 indicates a value of m 8 1 4 for the 1857 event

the pyrenean earthquake of february 29 1980 an example of complex faulting abstract an m b 5 1 earthquake occurred on february 29 1980 in the western pyrenees near arudy france the telemetred network of the i p g p operating in this area since 1978 allowed a good localization of this earthquake 43 4 21 n 0 24 59 w depth 4km during the two years preceding this earthquake the seismic activity exhibited a gradual decrease a foreshock of magnitude 1 6 was recorded three hours before the main shock a temporary network set up in the epicentral area a few days after the main shock permitted a precise study of the aftershock sequence fifty fault plane solutions for earthquakes ranging from magnitude 1 5 4 were obtained a complex pattern of faulting was revealed with both strike slip and normal faulting however a regional tectonic stress tensor can be proposed from a detailed investigation of the aftershock sequence this stress tensor is in agreement with previous results in this area

faulting associated with large earthquakes and the average rate of deformation in central and eastern asia we determine approximate average rates of deformation in portions of eastern and central asia for the last 80 years these rates are based on estimates of source dimensions average displacements seismic moments and orientations of faults of all large earthquakes m 7 5 and as many other major earthquakes m 7 0 as possible in asia since 1900 a major part of this study is the compilation of these data for separate parts of asia we combine seismic moment tensors to estimate the average rotational strain or deformation tensors for these regions for the last 80 years we estimate that shortening across the tien shan has occurred at 11 mm yr between 5 and 19 mm yr left lateral shear on easterly trending planes in mongolia in northwestern tibet gansu and ningxia and on the xianshuihe fault in western sichuan has been very rapid more than 10 mm yr in each region and apparently as rapid as 40 mm yr in northwestern tibet gansu and ningxia slower rates of a few to 10 mm yr appear to characterize east west extension and conjugate north south shortening of tibet the earthquake history of the himalaya is consistent with rates of underthrusting of more than 10 mm yr but is probably less than the convergence rate of india with eurasia of about 50 mm yr the overall strain field is consistent with a large part of india s penetration into eurasia being absorbed by the extrusion of material out of india s way as a result southeast china moved at about 21 mm yr east southeast with respect to eurasia in the last 80 years with an uncertainty of about a factor of 2 in this estimated rate

coupled hydro mechanical analysis of two unstable unsaturated slopes subject to rainfall infiltration abstract this paper presents a case study and numerical investigation of two unstable unsaturated slopes along the taipei maokong gondola system one slope collapsed because of torrential rainfall during typhoon jangmi in september 2008 and another nearby slope developed excessive deformation under consecutive wetting and drying cycles recorded rainfall measured soil parameters site geology and slope geometry were used in coupled hydro mechanical finite element analyses to investigate the failure and deformation mechanisms of these two slopes the stress paths of these two slopes were also examined and are discussed in this paper the numerical results demonstrated that the coupled hydro mechanical analysis satisfactorily predicted the failure and deformation characteristics of the two unstable slopes in the collapse case failure occurred at a shallow depth when the surficial residual soil was saturated the slope failure was attributed to a decrease in soil shear strength when the matric suction gradually decreased as rainfall progressed in the excessive deformation case the numerical results suggested that pore water pressure pwp varied at shallow depths under wetting and drying cycles whereas positive pwp accumulated at the soil rock interface and induced non uniform lateral flows parallel to the interface the accumulated positive pwp at the interface mobilized a considerable plastic deformation in the soil examination of the relationships between the slope factor of safety and the corresponding hydrological data i e rainfall and soil pwp revealed a positive correlation between the slope factor of safety and accumulated rainfall the factor of safety predicted by the infinite slope equation significantly varied with the input of pwp this study demonstrated that the infinite slope equation using the pwp measurements obtained from the lower half of the slope could effectively predict the slope factor of safety

suggestion of a method for landslide early warning using the change in the volumetric water content gradient due to rainfall infiltration an early warning system can be an effective measure to reduce the damage caused by landslides by facilitating the timely evacuation of residents from a landslide prone area early detection of landslide triggering across a broad range of natural terrain types can be accomplished by monitoring rainfall and the physical property changes of soils in real time or near real time this study involved the installation of a real time monitoring system to observe physical property changes in soils in a valley during rainfall events this monitoring included the measurement of volumetric water content which was compared with the results of laboratory flume tests to identify landslide indicators in the soils the response of volumetric water content to rainfall events is more immediate than that of pore water pressure and volumetric water content retains its maximum value for some time before slope failure therefore an alternative method for landslide monitoring can be based on the observation of volumetric water content and its changes over time at shallow soil depths although no landslide occurred the field monitoring results showed a directly proportional relationship between the effective cumulative rainfall and the gradient of volumetric water content per unit time t t max this preliminary study thus related slope failure to the volumetric water content gradient as a function of rainfall laboratory results showed that a high amount of rainfall and a high gradient of volumetric water content could induce slope failure based on these results it is possible to suggest a threshold value of the volumetric water content gradient demarcating the conditions for slope stability and slope failure this threshold can thus serve as the basis of an early warning system for landslides considering both rainfall and soil properties

postglacial reactivation of the suasselka pgf complex in sw finnish lapland the suasselka fault complex is recognized from high resolution digital elevation models lidar dems as a complex of 37 surface ruptures striking sw ne and cutting through weichselian glacial sediments confirming the postglacial nature of the rupturing event the analysis of lidar dems geophysical profiles and trenching of glacial sediments at two sites along the suasselka postglacial fault pgf system has provided evidence of earthquakes that post and predate the late weichselian deglaciation at the suaspalo trenching site at least two different rupture events are observed the first one predates the deposition of the lowermost till unit and potentially dates to the early or even pre weichselian the second rupture event on the other hand deforms overlying tills and is thus a post weichselian event our results indicate that multiple rupturing events can take place within postglacial fault complexes which is the second time such a characteristic has been proven for pgfs in northern fennoscandia furthermore the present results provide the first evidence of either early or even pre weichselian faulting in finland suggesting that the same fault complexes were also active after glacial phases that predated the last glacial maximum of the late weichselian these results warrant re evaluation of the long term seismic risk associated with the faults as the assumption of single rupture events is erroneous considering that the suasselka pgf complex is composed of four pgf systems and 37 isolated 150 7500 m long segments we calculated the potential moment magnitudes based on the rupture length and mean maximum vertical displacement for each individual segment and system taken that they potentially ruptured independently and finally for the entire suasselka pgf complex for the entire complex rupturing in a single event the observed displacement and length of the complex yields a moment magnitude estimate of mw 6 7 8 1 however based on geomorphological and sedimentological evidence we believe that this is a conservative estimate of the moment magnitude of the paleoearthquake if isolated pgf systems are considered to have ruptured individually the moment magnitudes estimated based on surface rupture lengths range from mw 5 5 6 7 and based on mean and maximum cumulative displacement values the estimated values range from mw 6 2 7 3 and mw 6 7 8 0 respectively as we cannot with the available data distinguish the exact number of events the age of events or which segments potentially ruptured at the same time we conclude that the events that took place in the complex ranged in moment magnitude from c mw 5 5 to 8 1 the mw 8 1 estimate representing conservative upper bound for the maximum moment magnitude

rupture patterns and preshocks of large earthquakes in the southern san jacinto fault zone we relocated the large 1937 1942 and 1954 earthquakes in the san jacinto fault zone the epicenters of the main shocks aftershocks and some preshocks were determined using empirical station corrections from recent small events in the study areas the 1937 ml 5 9 earthquake has an epicenter between the surface traces of the san jacinto and buck ridge faults and aftershocks suggest about 7 km of rupture predominantly to the northwest a significant increase in small earthquake activity occurred about formula yr before this event the 1954 m l 6 2 earthquake is located at the southeast end of the mapped trace of the san jacinto fault and aftershocks suggest about 15 km of rupture further southeast into an area of folded young sediments with no surface fault trace this event was preceded by a cluster of small earthquakes which occurred within an 8 hr period 10 weeks before the main event and in the eventual rupture zone the 1942 m l 6 3 earthquake is located southwest of the southeast end of the coyote creek fault large aftershocks of this event are spread over a 15 by 18 km area southwest of the coyote creek fault and are not associated with any one fault the relation of the 1942 event to the san jacinto fault zone is not simple

gis based prediction method of landslide susceptibility using a rainfall infiltration groundwater flow model this paper describes a physical based model to predict rainfall induced landsides special attention was given to the introduction of a gis based model ys slope model yonsei slope model which can evaluate the susceptibility of landslides the model has been improved by incorporating the combined effects of groundwater flow and rainfall infiltration into the raster model the two dimensional darcy s law was used to reflect the effect of groundwater flow in the soil slope and the modified green ampt model which is a one dimensional infiltration model was selected to capture the effect of rainfall infiltration into the soil mass these elements were integrated into the infinite slope stability model for a rainfall induced landslide the proposed model was verified by comparing the results from existing models as well as an actual slope failure case that occurred in korea with further study the ys model could be adopted as a prediction method for rainfall induced landslides

a hybrid feature selection algorithm integrating an extreme learning machine for landslide susceptibility modeling of mt woomyeon south korea abstract an ever increasing trend of extreme rainfall events in south korea owing to climate change is causing shallow landslides and debris flows in mountains that cover 70 of the total land area of the nation these catastrophic gravity driven processes cost the government several billion krw south korean won in losses in addition to fatalities every year the most common type of landslide observed is the shallow landslide which occurs at 1 3 m depth and may mobilize into more catastrophic flow type landslides hence to predict potential landslide areas susceptibility maps are developed in a geographical information system gis environment utilizing available morphological hydrological geotechnical and geological data landslide susceptibility models were developed using 163 landslide points and an equal number of nonlandslide points in mt woomyeon seoul and 23 landslide conditioning factors however because not all of the factors contribute to the determination of the spatial probability for landslide initiation and a simple filter or wrapper based approach is not efficient in identifying all of the relevant features a feedback loop based hybrid algorithm was implemented in conjunction with a learning scheme called an extreme learning machine which is based on a single layer feed forward network validation of the constructed susceptibility model was conducted using a testing set of landslide inventory data through a prediction rate curve the model selected 13 relevant conditioning factors out of the initial 23 and the resulting susceptibility map shows a success rate of 85 and a prediction rate of 89 45 indicating a good performance in contrast to the low success and prediction rate of 69 19 and 56 19 respectively as obtained using a wrapper technique

influence of environmental factors on the wetting front depth a case study in the loess plateau abstract reliable information on the wetting front depth and variation of water contents within the zone of wetting is required for addressing geotechnical problems in loess deposits such as estimation of the collapse deformation and assessment of the slope stability for this reason a field test was conducted at a site in the loess plateau of china to obtain data on soil water contents and temperatures at different depths for a period of one year the variation of water contents was interpreted from the influence of environmental factors and soil temperature and used to determine the maximum wetting front depth in the loess soils in the study region in addition a commercial software vadose w was used to simulate the flow behaviour in unsaturated loess taking account of the influence of environmental factors a reasonable agreement was found between the results of field investigations and numerical simulations the study results are useful as they provide valuable information about the wetting front depth and water content variation in unsaturated loess in response to environmental factors the field investigations and numerical simulations summarized in this paper can serve as a reference for future studies on other soils

displacement and geometrical characteristics of earthquake surface ruptures issues and implications for seismic hazard analysis and the process of earthquake rupture there now exist about three dozen historical earthquakes for which in vestigators have constructed maps of earthquake rupture traces accompanied by de scriptions of the coseismic slip observed along the fault strike the maps and slip distributions are compiled here to place observational bounds on aspects of seismic hazard analysis and fault mechanics analysis leads to an initial statistical basis to predict the end points of rupture and the amount of surface slip expected at sites along the strike during earthquakes on mapped faults the observations also give support to the ideas that there exists a process zone or volume of about 3 4 km in dimension at the fronts of large laterally propagating earthquake ruptures within which stress changes may be sufficient to trigger slip on adjacent faults and that the ultimate length of earthquake ruptures is controlled primarily by the geometrical complexity of fault traces and variations in accumulated stress levels along faults that arise due to the location of past earthquakes to this may be added the observation that the form of earthquake surface slip distributions is better described by asymmetric rather than symmetric curve forms and that earthquake epicenters do not appear to correlate in any systematic manner to regions of maximum surface slip observed along strike online material maps of surface ruptures digitized values and curve fits to surface slip distributions and notes and references for tables 1 and 2

rainfall induced landslides by deficit field matric suction in unsaturated soil slopes landslides are mainly triggered by decrease in the matric suction with deepening the wetting band by rainfall infiltrations this paper reports rainfall induced landslides in partially saturated soil slopes through a field study a comprehensive analysis on umyeonsan mt landslides in 2011 was highlighted the incident involves the collapse of unsaturated soil slopes under extreme rainfall event fundamental studies on the mechanism and the cause of landslides were carried out a number of technical findings are of interest including the failure mechanism of a depth of soil and effect of groundwater flow the downward movement of wetting band and the increase of groundwater level based on this an integrated analysis methodology for a rainfall induced landslide is proposed in this paper that incorporates the field matric suction for obtaining hydraulic parameters of unsaturated soil the field matric suction is shown to govern the rate of change in the water infiltration for the landslide analysis with respect to an antecedent rainfall special attention was given to a one dimensional infiltration model to determine the wetting band depth in the absence of the field matric suction the results indicate that landslide activities were primarily dependent on rainfall infiltration soil properties slope geometries vegetation and groundwater table positions the proposed methodology has clearly demonstrated both shallow and deep seated landslides and shows good agreement with the results of landslide investigations