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

solar and lunar tidal variabilities in gps tec and geomagnetic field variations seasonal as well as during the sudden stratospheric warming of 2010 the global positioning system gps deduced total electron content tec data at 15 n geomagnetic which is the northern crest region of equatorial ionization anomaly are used to study solar and lunar tidal variabilities during the years 2008 and 2009 and also during the 2009 2010 winter when a major sudden stratospheric warming ssw event has occurred the diurnal and semidiurnal tidal amplitudes show semiannual variation with maximum amplitudes during february march and september november whereas terdiurnal tide is larger during april september they show significant longitudinal variability with larger smaller amplitudes over 250 e 150 e 200 e 250 e lunar semidiurnal tidal amplitudes show sporadic enhancements during northern winter months and negligible amplitudes during northern summer months they also show notable longitudinal variabilities the solar migrating tides dw1 and sw2 show semiannual variation with larger amplitudes during spring equinox months whereas tw3 maximizes during northern summer dw2 shows larger amplitudes during summer months during the ssw except tw3 the migrating tides dw1 and sw2 show considerable enhancements among solar nonmigrating tides sw1 tw2 and ds0 show larger enhancements solar tides in tec and equatorial electrojet strength over tirunelveli vary with the time scale of 60 days during october 2009 march 2010 similar to ozone mass mixing ratio at 10 hpa and this confirms the vital role of ozone in tidal variabilities in ionospheric parameters lunar tidal amplitudes in changes in horizontal component of geomagnetic field h are larger over tirunelveli a station near dip equator solar semidiurnal tides in h have larger amplitudes than lunar tides over polar stations mawson and godhavn

equatorial vertical drift modulation by the lunar and solar semidiurnal tides during the 2013 sudden stratospheric warming during the 2013 stratospheric sudden warming ssw period the jicamarca unattended long term investigations of the ionosphere and atmosphere julia radar at jicarmarca peru observed low latitude vertical drift modulation with lows of 0 12 m s daytime maximum drifts between 6 13 and 22 25 january and enhanced drifts up to 43 m s between 15 snd 19 january the ncar thermosphere ionosphere mesosphere electrodynamics general circulation model reproduces the prevailing vertical drift feature and is used to examine possible causes the simulations indicate that the modulation of the vertical drift is generated by the beating of the semidiurnal solar sw2 and lunar m2 tides during the ssw period the beating is observable since the magnitudes of lunar and solar semidiurnal tidal amplitudes are comparable the theoretical beating frequency between sw2 and m2 is 1 15 13 day which may be modified due to phase changes this study highlights the importance of the lunar tide during ssw periods and indicates that the equatorial vertical drift modulation should be observable at other longitudes as well

glassy dynamics of landscape evolution soil creeps imperceptibly downhill but also fails catastrophically to create landslides despite the importance of these processes as hazards and in sculpting landscapes there is no agreed upon model that captures the full range of behavior here we examine the granular origins of hillslope soil transport by discrete element method simulations and reanalysis of measurements in natural landscapes we find creep for slopes below a critical gradient where average particle velocity sediment flux increases exponentially with friction coefficient gradient at critical gradient there is a continuous transition to a dense granular flow rheology slow earthflows and landslides thus exhibit glassy dynamics characteristic of a wide range of disordered materials they are described by a two phase flux equation that emerges from grain scale friction alone this glassy model reproduces topographic profiles of natural hillslopes showing its promise for predicting hillslope evolution over geologic timescales

variabilities of low latitude migrating and nonmigrating tides in gps tec and timed saber temperature during the sudden stratospheric warming event of 2013 the global positioning system gps deduced total electron content tec data at 15 n geomagnetic which is the crest region of equatorial ionization anomaly are used to study tidal variabilities during the 2013 sudden stratospheric warming ssw event the results from space time spectral analysis reveal that the amplitudes of migrating diurnal dw1 and semi diurnal sw2 tides are larger than those of non migrating tides after the ssw onset the amplitudes of dw1 sw2 sw1 and ds0 increase moreover they show 16 day variations similar to the periodicity of the high latitude stratospheric planetary wave pw suggesting that the non migrating tides sw1 and ds0 are possibly generated due to non linear interaction of migrating tides with pw similar spectral analysis on temperature at 10 n obtained from the sounding of atmosphere by broadband emission radiometry saber shows that the sw2 enhances at stratospheric heights and the sw2 is more dominant at 80 90 km but its amplitude decreases around 100 km the amplitudes of non migrating tides become comparable to those of sw2 around 100 km and their contribution become increasingly important at higher heights this suggests that the non linear interaction between migrating tides and pw occur at low latitude upper mesospheric heights as sw2 exhibits 16 day periodicity in saber temperature at 100 km as observed in tec besides it is observed that the eastward propagating tides are less dominant than westward propagating tides in both tec and saber temperature

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

sediment transport by dry ravel 1 dry ravel is a general term that describes the rolling bouncing and sliding of individual particles down a slope and is a dominant hillslope sediment transport process in steep arid and semiarid landscapes during fires particles can be mobilized by the collapse of sediment wedges that have accumulated behind vegetation on a daily basis particles may be mobilized by bioturbation and by small landslides experiments on a dry ravel flume indicate that a basic expression of the momentum equation predicts the distance traveled by particles propelled down a rough surface this equation is further elaborated to produce a nonlinear slope dependent transport equation for dry ravel that represents the rate at which sediment crosses a contour width of slope sediment traps installed on two hillslope transects near santa barbara california measured the flux from dry ravel initiated by bioturbation and the data support the form of the equation additionally a physical model based on the infinite slope stability analysis is proposed for the initiation of dry ravel by landsliding the analytical result from this model is supported by experiments and field data reported by others

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

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

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

rate weakening friction characterizes both slow sliding and catastrophic failure of landslides abstract catastrophic landslides cause billions of dollars in damages and claim thousands of lives annually whereas slow moving landslides with negligible inertia dominate sediment transport on many weathered hillslopes surprisingly both failure modes are displayed by nearby landslides and individual landslides in different years subjected to almost identical environmental conditions such observations have motivated the search for mechanisms that can cause slow moving landslides to transition via runaway acceleration to catastrophic failure a similarly diverse range of sliding behavior including earthquakes and slow slip events occurs along tectonic faults our understanding of these phenomena has benefitted from mechanical treatments that rely upon key ingredients that are notably absent from previous landslide descriptions here we describe landslide motion using a rate and state dependent frictional model that incorporates a nonlocal stress balance to account for the elastic response to gradients in slip our idealized one dimensional model reproduces both the displacement patterns observed in slow moving landslides and the acceleration toward failure exhibited by catastrophic events catastrophic failure occurs only when the slip surface is characterized by rate weakening friction and its lateral dimensions exceed a critical nucleation length h h that is shorter for higher effective stresses however landslides that are extensive enough to fall within this regime can nevertheless slide slowly for months or years before catastrophic failure our results suggest that the diversity of slip behavior observed during landslides can be described with a single model adapted from standard fault mechanics treatments

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

impact of sudden stratospheric warming of 2009 on the equatorial and low latitude ionosphere of the indian longitudes a case study using the equatorial electrojet eej induced surface magnetic field and total electron content tec measurements we investigated the impact of the sudden stratospheric warming ssw of january 2009 on the equatorial electrodynamics and low latitude ionosphere over the indian longitudes results indicate that the intensity of eej and the tec over low latitudes extending up to 30 n exhibit significant perturbations during and after the ssw peak one of the interesting features is the deviation of eej and tec from the normal quiet time behaviour well before the onset of the ssw this is found to be coincided with the beginning of enhanced planetary wave pw activity over high latitudes the substantial amplification of the semidiurnal perturbation after the ssw peak is seen to be coinciding with the onset of new and full moon the response of tec to ssw is found to be latitude dependent as the near equatorial ne stations show the semidiurnal perturbation only after the ssw peak another notable feature is the presence of reduced ionization in the night sector over the ne and low latitude regions appearing as an ionization hole well after the ssw peak the investigation revealed the existence of a quasi 16 day wave in the tec over low latitudes similar to the one present in the eej strength these results have been discussed in the light of changes in the dynamical background because of enhanced pw activity during ssw which creates favourable conditions for the amplification of lunar tides and their subsequent interaction with the lower thermospheric tidal fields

evidence for chaotic fault interactions in the seismicity of the san andreas fault and nankai trough interactions between fault segments are one of the main sources of complexity in the seismicity of active tectonic regions such interactions are likely to influence the spatial and temporal patterns of earthquakes here we examine the dynamical behaviour introduced by fault interactions using a simple spring loaded slider block model with velocity weakening friction the model consists of two slider blocks coupled to each other and to a constant velocity driver by elastic springs for an asymmetric system in which the frictional forces on the two blocks are not equal the solutions exhibit chaotic behaviour the system s behaviour over a range of parameter values seems to be generally analogous to that of weakly coupled segments of an active fault we see similarities between our model simulations and observed patterns of seismicity on the south central san andreas fault in california and in the nankai trough along the coast of southwestern japan

integration of geological and seismological data for the analysis of seismic hazard a case study of japan seismic hazard analyses are associated with large uncertainties when historical data are insufficient to define secular rates of seismicity such uncertainties may be decreased with geological data in areas where seismicity is shallow and produced by quaternary faulting to illustrate we examine intraplate japan large intraplate earthquakes in japan characteristically produce surface ruptures along mappable quaternary faults and show a systematic relation between seismic moment m 0 and rupture length i log m 0 23 5 1 94 log i it is observed that within the bounds placed by geologically assessed slip rates the mean regional moment release rate m 0 resulting from slip on mapped quaternary faults is in accord with estimates of m 0 determined with the 400 yr record of seismicity recent work also shows that when the repeat time t of earthquakes on quaternary faults in southwest japan is assumed to equal m 0 m 0 g where m 0 is estimated for rupture extended over the entire fault length and m 0 g is the geologically assessed moment release rate of each fault the moment frequency distribution of earthquakes predicted from the geologic record is virtually identical to that seen with the 400 yr record of seismicity these observations indicate that the geologic record of quaternary fault offsets contains sufficient information to predict both the spatial and size distribution of intraplate earthquakes in japan a contour map of the average recurrence time of ground shaking of jma intensity v is thus computed using an empirical relation between seismic moment and the areal distribution of seismic intensity and assuming that the repeat time t of earthquakes on each quaternary fault equals m 0 m 0 g the map demonstrates how quaternary fault data may be used to assess long term seismic hazard in areas of active faulting where historical records of seismicity are relatively short or absent another shortcoming of conventional seismic hazard analysis is that hazard is not considered a function of the time since each fault in a region last ruptured a simple procedure is used to demonstrate how the time dependent nature of the earthquake cycle affects the evaluation of seismic hazard the distribution of seismic shaking characteristic of large interplate earthquakes offshore of japan is estimated from published isoseismal maps the observed average repeat times of ruptures along specific segments of the plate boundaries then provide the basis to make probabilistic estimates of the next expected time of seismic shaking due to plate boundary earthquakes when data are too few to document the average repeat times of rupture the estimates of probability are calculated with data relating to the relative coseismic slip during past earthquakes and the rate of interseismic strain accumulation interpreted within the framework of the time predictable model of earthquake occurrence results are displayed as maps of instantaneous seismic hazard the probability that seismic shaking will occur conditional to knowledge of where in time each fault in a region presently resides with respect to the earthquake cycle

earthquakes as self organized critical phenomena a cellular automation model with threshold elements previously proposed by bak et al 1988 which generates 1 f noise and self organizes into a critical state is studied as a model for earthquake occurrence the model explains some of fractal features of earthquakes such as the power law distribution of the size of the earthquake the model is modified so that every earthquake may trigger aftershocks the modified trigger model explains other fractal features of earthquakes such as the power law decay of aftershock frequency and the power law decay of aftershock frequency and the power law correlation of the hypocenter distribution

erosion and mobility in granular collapse over sloping beds 1 we describe laboratory experiments of granular material flowing over an inclined plane covered by an erodible bed designed to mimic erosion processes of natural flows travelling over deposits built up by earlier events two controlling parameters are the inclination of the plane and the thickness of the erodible layer we show that erosion processes can increase the flow mobility i e runout over slopes with inclination close to the repose angle of the grains r by up to 40 even for very thin erodible beds erosion efficiency is shown to strongly depend on the slope of the topography entrainment begins to affect the flow at inclination angles exceeding a critical angle c r 2 runout distance increases almost linearly as a function of the thickness of the erodible bed suggesting that erosion is mainly supply dependent two regimes are observed during granular collapse a first spreading phase with high velocity followed by a slow thin flow provided either the slope or the thickness of the erodible bed is high enough surprisingly erosion affects the flow mostly during the deceleration phase and the slow regime the avalanche excavates the erodible layer immediately at the flow front waves are observed behind the front that help to remove grains from the erodible bed steep frontal surges are seen at high inclination angles over both rigid or erodible bed finally simple scaling laws are proposed making it possible to obtain a first estimate of the deposit and emplacement time of a granular collapse over a rigid or erodible inclined bed

ionospheric variability over indian low latitude linked with the 2009 sudden stratospheric warming in this paper we analyze radar observations of e b drift and plasma irregularities ionosonde observations of e and f layer parameters including spread f and magnetic field observations made from indian low latitudes linked with the 2009 sudden stratospheric warming ssw event e b drift variations presented here are the first of their kind from the indian sector as far as the effect of ssw is concerned difference of magnetic fields observed from the equator and low latitude h and e b drift show linear relation and both show remarkably large positive values in the morning and negative values in the afternoon exhibiting semidiurnal behavior remarkable changing patterns in the critical frequency of f2 layer fof2 and f3 layer fof3 were observed after the occurrence of ssw large variations with quasi 16 day periodicity were observed in h fof2 and fof3 both semidiurnal and quasi 16 day wave modulation observed after the 2009 ssw event are consistent with those reported earlier we also noted quasi 6 day variations in h and fof2 soon after the ssw commencement not much reported before during the counterelectrojet events linked with the ssw event while equatorial es esq disappeared as expected there were no blanketing es esb a finding not reported and discussed earlier esb was also not formed at the off equatorial location indicating the absence of required vertical wind shear but e region plasma irregularities were observed by the ionosonde and radar with a close relationship between the two weak f region irregularities were observed in the postmidnight hours and case studies suggest the possible role of ssw related background electric field in the manifestation of postmidnight f region irregularities

aura microwave limb sounder observations of dynamics and transport during the record breaking 2009 arctic stratospheric major warming a major stratospheric sudden warming ssw in january 2009 was the strongest and most prolonged on record aura microwave limb sounder mls observations are used to provide an overview of dynamics and transport during the 2009 ssw and to compare with the intense long lasting ssw in january 2006 the arctic polar vortex split during the 2009 ssw whereas the 2006 ssw was a vortex displacement event winds reversed to easterly more rapidly and reverted to westerly more slowly in 2009 than in 2006 more mixing of trace gases out of the vortex during the decay of the vortex fragments and less before the fulfillment of major ssw criteria was seen in 2009 than in 2006 persistent well defined fragments of vortex and anticyclone air were more prevalent in 2009 the 2009 ssw had a more profound impact on the lower stratosphere than any previously observed ssw with no significant recovery of the vortex in that region the stratopause breakdown and subsequent reformation at very high altitude accompanied by enhanced descent into a rapidly strengthening upper stratospheric vortex were similar in 2009 and 2006 many differences between 2006 and 2009 appear to be related to the different character of the ssws in the two years

lunar and solar tidal variabilities in mesospheric winds and eej strength over tirunelveli 8 7 n 77 8 e during the 2009 major stratospheric warming 1 mesospheric wind observations by the medium frequency radar and geomagnetic field observations at tirunelveli 8 7 n 77 8 e 1 75 n dip angle are used to study the relative importance of solar and lunar influences in the variabilities of mesospheric tides and equatorial electrojet eej strength during the unprecedented major stratospheric sudden warming ssw of 2009 it is observed that the afternoon reversal in the eej popularly known as counter electrojet occurs consecutively for several days during the ssw event when there is an enhancement of solar semidiurnal tide in both zonal wind at 90 km and eej strength over tirunelveli although the amplitude of lunar tides also shows enhancement it is much less than that of solar the diurnal tidal amplitude in zonal wind and eej strength also shows large enhancement just before the onset of ssw however solar semidiurnal tide dominates diurnal tide during the ssw the diurnal tidal phase in zonal wind shifts to a few hours earlier during the ssw the lunar semidiurnal tidal phase shifts to later hours in both zonal wind and eej strength the main observation of the present study is that the large semidiurnal tide observed during the ssw 2009 is mostly solar driven and only partly lunar driven although tidal planetary wave interaction also may play a vital role although a similar behavior is noticed during the ssw 2006 also the large lunar semidiurnal tide observed in the eej strength without having large lunar semidiurnal tide in the underlying mesospheric winds needs further investigation

how long is a hillslope hillslope length is a fundamental attribute of landscapes intrinsically linked to drainage density landslide hazard biogeochemical cycling and hillslope sediment transport existing methods to estimate catchment average hillslope lengths include inversion of drainage density or identification of a break in slope area scaling where the hillslope domain transitions into the fluvial domain here we implement a technique which models flow from point sources on hilltops across pixels in a digital elevation model dem based on flow directions calculated using pixel aspect until reaching the channel network defined using recently developed channel extraction algorithms through comparisons between these measurement techniques we show that estimating hillslope length from plots of topographic slope versus drainage area or by inverting measures of drainage density systematically underestimates hillslope length in addition hillslope lengths estimated by slope area scaling breaks show large variations between catchments of similar morphology and area we then use hillslope length relief structure of landscapes to explore nature of sediment flux operating on a landscape distinct topographic forms are predicted for end member sediment flux laws which constrain sediment transport on hillslopes as being linearly or nonlinearly dependent on hillslope gradient because our method extracts hillslope profiles originating from every ridgetop pixel in a dem we show that the resulting population of hillslope length relief measurements can be used to differentiate between linear and nonlinear sediment transport laws in soil mantled landscapes we find that across a broad range of sites across the continental united states topography is consistent with a sediment flux law in which transport is nonlinearly proportional to topographic gradient

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

a granular physics based view of fault friction experiments rate and state dependent friction rsf equations are commonly used to describe the time dependent frictional response of fault gouge to perturbations in sliding velocity among the better known v

evidence for stratosphere sudden warming ionosphere coupling due to vertically propagating tides 1 observations of the global positioning system gps total electron content tec are used to study the coupling between the 2009 sudden stratospheric warming ssw and ionospheric perturbations the observations reveal both migrating and nonmigrating perturbations to the semidiurnal tide in the equatorial ionization anomaly crest region that are associated with changes in electric fields induced by the tidal dynamo in particular a significant enhancement is observed in the nonmigrating semidiurnal westward propagating tide with zonal wavenumber 1 sw1 in gps tec during the ssw the sw1 perturbations in the low latitude ionosphere are found to oscillate with a similar period as planetary wave 1 activity in the northern hemisphere stratosphere this connection is attributed to the nonlinear interaction between tides and planetary waves and strongly supports the theory that planetary wave tide interaction is the primary mechanism coupling ssws to ionospheric variability enhancements are also observed in the nonmigrating semidiurnal tide with zonal wavenumber 0 s0 during this time period and may be related to the nonlinear interaction between the migrating semidiurnal tide and planetary wave 2 the connection between planetary wave 2 and s0 is however less clear which may be attributed to differences in the zonal mean zonal winds in the mesosphere and lower thermosphere during the times of peak planetary wave 1 and planetary wave 2 activity we conclude that the changing zonal winds during ssws play an important role in the coupling between ionospheric variability and the forcing from planetary waves of lower atmospheric origin during ssws

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

residual strength of clays in landslides folded strata and the laboratory the post peak drop in drained shear strength of an overconsolidated clay may be considered as taking place in two stages first at relatively small displacements the strength decreases to the fully softened or critical state value owing to an increase in water content dilatancy second after much larger displacements the strength falls to the residual value owing to reorientation of platy clay minerals parallel to the direction of shearing if the clay fraction is less than about 25 the second stage scarcely comes into operation the clay behaves much like a sand or silt with angles of residual shearing resistance typically greater than 20 degrees conversely when the clay fraction is about 50 residual strength is controlled almost entirely by sliding friction of the clay minerals and further increase in clay fraction has little effect the angles of residual shearing resistance of the three most commonly occurring clay minerals are approximately 15 degrees for kaolinite 10 degrees for illite or clay mica and 5 degrees for montmorillonite when the clay fraction lies between 25 and 50 there is a transitional type of behaviour residual strength being dependent on the percentage of clay particles as well as on their nature the post peak drop in strength of a normally consolidated clay is due only to particle reorientation measurements of strength on natural shear surfaces agree within practical limits of variation with values derived from back analysis of reactivated landslides this field residual strength can be recovered by multiple reversal shear box tests on cut plane samples but in high clay fraction materials it is typically somewhat higher than the strength measured in ring shear tests residual strength is little affected by variation in the slow rates of displacement encountered in reactivated landslides and in the usual laboratory tests but at rates faster than about 100 mm min qualitative changes take place in the pattern of behaviour a substantial gain in strength is followed with increasing displacement by a fall to a minimum value in clays and low clay fraction silts this minimum is not less than the slow or static residual but in clayey silts with clay fractions around 15 25 according to tests currently in progress the minimum can be as low as one half of the static value author trrl

lunar tide in the equatorial electrojet in relation to stratospheric warmings 1 the relationship between sudden stratospheric warmings ssws and large amplitude lunar tides in the equatorial electrojet eej is studied analysis of ground magnetometer data shows that the lunar tide in the eej is maximum during the northern winter season except in the pacific ocean region since ssws are also a northern winter phenomenon it is suggested that the relation between the large lunar tide in the eej and the ssw may possibly be coincidental the lunar tide in the geomagnetic variations at huancayo is anomalously large compared with other eej stations an examination of geomagnetic variations at eej stations during ssw events shows that afternoon counter electrojets are frequently present at new moon and full moon though the relationship is sometimes broken the observation of large lunar eejs when no ssw is present and of various different delay times suggests that other atmospheric processes are likely to be in play

quiet variability of equatorial e b drifts during a sudden stratospheric warming event 1 we present strong evidence that during the january 2008 minor sudden stratospheric warming ssw event the equatorial vertical e b drifts exhibit a unique and distinctive daytime pattern we do not think one event causes the other however both events might be related through the global effects of planetary waves the drifts were measured by the jicamarca incoherent scatter radar located under the magnetic equator we have observed an anomalous temporal variation of the vertical e b drifts during the minor ssw event showing a semidiurnal variation with very large amplitudes lasting for several days large differences in the e b drifts were observed during a period of large increase of temperature and a large decrease of mean zonal wind in the high latitude stratosphere 60 90 n this high correlation is an unexpected finding which might shed new light on sources and mechanisms of quiet time ionospheric variability

ionosphere variability during the 2009 ssw influence of the lunar semidiurnal tide and mechanisms producing electron density variability to investigate ionosphere variability during the 2009 sudden stratosphere warming ssw we present simulation results that combine the whole atmosphere community climate model extended version and the thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm the simulations reveal notable enhancements in both the migrating semidiurnal solar sw2 and lunar m2 tides during the ssw the sw2 and m2 amplitudes reach 50 m s 1 and 40 m s 1 respectively in zonal wind at e region altitudes the dramatic increase in the m2 at these altitudes influences the dynamo generation of electric fields and the importance of the m2 on the ionosphere variability during the 2009 ssw is demonstrated by comparing simulations with and without the m2 time gcm simulations that incorporate the m2 are found to be in good agreement with jicamarca incoherent scatter radar vertical plasma drifts and constellation observing system for meteorology ionosphere and climate cosmic observations of the maximum f region electron density the agreement with observations is worse if the m2 is not included in the simulation demonstrating that the lunar tide is an important contributor to the ionosphere variability during the 2009 ssw we additionally investigate sources of the f region electron density variability during the ssw the primary driver of the electron density variability is changes in electric fields changes in meridional neutral winds and thermosphere composition are found to also contribute to the electron density variability during the 2009 ssw the electron density variability for the 2009 ssw is therefore not solely due to variability in electric fields as previously thought

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

order and diversity in the modes of circum pacific earthquake recurrence recurrence characteristics of great circum pacific earthquakes and determinations of spatial distribution of seismic moment release are surveyed in order to delineate their general features and relate earthquake slip distribution to models of recurrent rupture as noted by others the pattern of moment release is typically very irregular with strong concentrations in a few isolated regions of a much larger aftershock zone despite this complexity rupture nucleation is notably systematic with mainshock epicenter showing a strong tendency to locate in or immediately adjacent to identified regions of high moment release this generalization suggests that earthquake recurrence is more likely to be controlled by maximum rather than average fault slip well documented case histories from twelve plate boundary regions demonstrate that seismic strain release tends to be temporally well ordered while source dimensions slip and cumulative moment release vary considerably from cycle to cycle on none of the segments studied do earthquakes consistently recur in nearly identical events instead individual great earthquakes differ significantly from cycle to cycle or rerupture takes place in a sequence of two or more smaller events despite these differences the duration of the seismic cycle is approximately uniform furthermore when strain release occurs in a sequence of large earthquakes these events take place towards the end of the cycle and occur with increasing rupture length and magnitude these ordered and irregular features of earthquake recurrence argue for the existence of corresponding elements on plate boundary faults the ordered characteristics are identified with zones of concentrated moment release that slip comparable amounts in each cycle and have high shear strength the irregular features are associated with intervening weaker regions that move in response to the stress concentration of dynamic rupture and slip by differing amounts in each event although these mechanistic associations are indirect and tentative the features of recurrent behavior documented here have implications for long term earthquake hazard assessment that are not dependent on the models proposed to explain them chief among these are the cycle to cycle differences among gap filling events and the absence of shocks that fill major slip deficient regions early in the seismic cycle

investigation on the variability of the geomagnetic daily current during sudden stratospheric warmings the magnetic field records of the magnetometer networks in the american east asian australian and european african sectors were employed in this present work we used them to investigate equatorial electrojet eej counter electrojet cej tidal variability in eej strength and ionospheric current during the 2005 2006 and 2008 2009 sudden stratospheric warming ssw events in addition to the well investigated tidal variability in eej strength over the american and east asian sectors we investigated that of the african sector for the first time interestingly the tidal components in eej strength during both ssw events clearly exhibit marked longitudinal differences with high moderate and low amplitudes in the american east asian and african sectors respectively an exception found around day 71 in the african sector after the 2008 2009 ssw event had higher solar diurnal tidal component as compared to that of the asian sector over the american sector solar and lunar semidiurnal tides were strongly associated with cej current during both ssw events whereas at the african and east asian sectors such variabilities are not evident a solar diurnal tidal component was strongly related to a reduction in the eej strength over the east asian sector in addition a prolonged period of cej occurrence that begins during the ssw precondition and ends when the ssw was evolving characterized the african sector during both ssw events there is a steady shift in phase at later hours when both ssw events are evolving

variability of the equatorial electrojet its relations to the sq current system and semidiurnal tides average diurnal and seasonal variations of the horizontal geomagnetic element delta h are examined the semiannual variation in equatorial electrojet strength is found to disappear in afternoon hours this may be related to changes in the latitude of the sq current system focus during the day this in turn may be caused by a superposed semidiurnal tide and may also explain delta h variations at stations near the focus

lunar tidal winds at adelaide and saskatoon at 80 to 100 km heights 1985 1990 winds data from the two sites were analyzed for lunar tides in 2 year groups the variation with height of the phase and amplitude of the tide showed considerable variability from year to year yet in general seasonal variations at particular heights were similar to those determined previously phases of the tide at the two sites were compared in order to estimate whether the tide was symmetric or antisymmetric for this purpose it was found necessary to use only 1 year data sets the predominance of symmetric tides during solstice months and antisymmetric tides at the equinox came as a surprise yet the result is in broad agreement with phase relations of the lunar geomagnetic tide

integration of geochemical mass balance with sediment transport to calculate rates of soil chemical weathering and transport on hillslopes 1 we developed a process oriented hillslope soil mass balance model that integrates chemical and physical processes within hillslope soils the model explicitly factors that soil chemical weathering at any hillslope position is related to the flux of soil eroded from upslope as well as soil production from underlying bedrock the model was merged with measurements of soil elemental chemistry and cosmogenic radionuclide based saprolite to soil conversion rates along a 50 m transect of a semiarid granodiorite hillslope in the southeastern australian highlands inverse modeling results in the simultaneous quantification of the rates of soil chemical weathering and soil transport as a function of hillslope position soil chemical weathering rates per land surface area systematically varied along the transect from losses of 0 035 kg m 2 yr 1 on the ridge to gains of 0 035 kg m 2 yr 1 at the lowest slope position the mass loss via soil chemical weathering would have been overestimated by 40 if the impact of soil transport on soil chemistry was ignored the chemical mobility of elements combined with biological nutrient demand controlled the spatial redistribution of individual elements p and ca were preferentially retained relative to si al and fe within the hillslope base the calculated soil transport rate is linearly related to the product of soil thickness and slope gradient instead of slope alone soil residence time was determined by calculating the time length for a 3 dimensional box volume 1 m2 surface area soil thickness to be entirely removed by mass flux of soil transport 4 ka on the ridge to 0 9 ka at the hillslope base these soil residence times combined with soil chemical weathering rates indicate that a 1 m2 area of soil loses 1 800 kg via chemical weathering while passing through the upslope portion of the hillslope but that it regains 90 kg probably via clay precipitation and biological retention of cations during its passage through the lower segments of the transect this study provides a previously unrecognized linkage between physical soil transport and soil chemical weathering that have implications for hillslope evolution as well as biogeochemistry

a simplified spring block model of earthquakes the time interval between earthquakes is much larger than the actual time involved during slip in an individual event the authors have used this fact to construct a cellular automaton model of earthquakes this model describes the time evolution of a 2 d system of coupled masses and springs sliding on a frictional surface the model exhibits power law frequency size relations and can exhibit large earthquakes with the same scatter in the recurrence time observed for actual earthquakes

coupling between mesosphere and ionosphere over beijing through semidiurnal tides during the 2009 sudden stratospheric warming 1 sudden stratospheric warming ssw in the winter of 2008 2009 is the strongest recorded ssw event the enhancement in semidiurnal variation of ionospheric tec total electron content with phase shift forward is shown during 22 to 27 january 2009 based on the tec observations in beijing 40 30 n 116 19 e geographic 39 73 n dip latitude we focus on finding the reason for the tec variation winds observed by an all sky meteor radar in the same observatory are used to study mesospheric variation the semidiurnal solar tide in the mesosphere starts to increase before the ssw and maintains oscillation with period 16 20 days during the ssw the semidiurnal lunar tides in tec and wind start to increase on 17 and 15 january respectively although the semidiurnal lunar tide in tec over beijing almost dies out on 1 february that over equatorial ionospheric anomaly crest does not vanish until 15 february when lunar tide in wind tends to be very weak the maximum of lunar tide in wind appears on 2 february at 96 km with amplitudes of 15 m s and 21 m s for zonal and meridional winds the phase comparison shows that lunar tides in tec and zonal wind reach their maxima at almost the same time which is 2 4 h lag behind the meridional wind the coupling between the mesosphere and ionosphere contributes to the semidiurnal variation of tec through both solar and semidiurnal lunar tides the enhancement in semidiurnal lunar tide is responsible for the tec peak shift forward during the ssw

evidence for nonlinear diffusive sediment transport on hillslopes and implications for landscape morphology steep soil mantled hillslopes evolve through the downslope movement of soil driven largely by slope dependent transport processes most landscape evolution models represent hillslope transport by linear diffusion in which rates of sediment transport are proportional to slope such that equilibrium hillslopes should have constant curvature between divides and channels on many soil mantled hillslopes however curvature appears to vary systematically such that slopes are typically convex near the divide and become increasingly planar downslope this suggests that linear diffusion is not an adequate model to describe the entire morphology of soil mantled hillslopes here we show that the interaction between local disturbances such as rainsplash and biogenic activity and frictional and gravitational forces results in a diffusive transport law that depends nonlinearly on hillslope gradient our proposed transport law 1 approximates linear diffusion at low gradients and 2 indicates that sediment flux increases rapidly as gradient approaches a critical value we calibrated and tested this transport law using high resolution topographic data from the oregon coast range these data obtained by airborne laser altimetry allow us to characterize hillslope morphology at 2 m scale at five small basins in our study area hillslope curvature approaches zero with increasing gradient consistent with our proposed nonlinear diffusive transport law hillslope gradients tend to cluster near values for which sediment flux increases rapidly with slope such that large changes in erosion rate will correspond to small changes in gradient therefore average hillslope gradient is unlikely to be a reliable indicator of rates of tectonic forcing or baselevel lowering where hillslope erosion is dominated by nonlinear diffusion rates of tectonic forcing will be more reliably reflected in hillslope curvature near the divide rather than average hillslope gradient

the search for a topographic signature of life landscapes are shaped by the uplift deformation and breakdown of bedrock and the erosion transport and deposition of sediment life is important in all of these processes over short timescales the impact of life is quite apparent rock weathering soil formation and erosion slope stability and river dynamics are directly influenced by biotic processes that mediate chemical reactions dilate soil disrupt the ground surface and add strength with a weave of roots over geologic time biotic effects are less obvious but equally important biota affect climate and climatic conditions dictate the mechanisms and rates of erosion that control topographic evolution apart from the obvious influence of humans does the resulting landscape bear an unmistakable stamp of life the influence of life on topography is a topic that has remained largely unexplored erosion laws that explicitly include biotic effects are needed to explore how intrinsically small scale biotic processes can influence the form of entire landscapes and to determine whether these processes create a distinctive topography

a more precise chronology of earthquakes produced by the san andreas fault in southern california improved methods of radiocarbon analysis have enabled us to date more precisely the earthquake ruptures of the san andreas fault that are recorded in the sediments at pallett creek previous dates of these events had 95 confidence errors of 50 100 calendar years new error limits are less than 23 calendar years for all but two of the dated events this greater precision is due to larger sample size longer counting time lower background noise levels more precise conversion of radiocarbon ages to calendric dates and better stratigraphic constraints and statistical techniques the new date ranges with one exception fall within the broader ranges estimated previously but our estimate of the average interval between the latest 10 episodes of faulting is now about 132 years variability about the mean interval is much greater than was suspected previously five of the nine intervals are shorter than a century three of the remaining four intervals are about two to three centuries long despite the wide range of these intervals a pattern in the occurrence of large earthquakes at pallett creek is apparent in the new data the past 10 earthquakes occur in four clusters each of which consists of two or three events earthquakes within the clusters are separated by periods of several decades but the clusters are separated by dormant periods of two to three centuries this pattern may reflect important mechanical aspects of the fault s behavior if this pattern continues into the future the current period of dormancy will probably be greater than two centuries this would mean that the section of the fault represented by the pallett creek site is currently in the middle of one of its longer periods of repose between clusters and sections of the fault farther to the southeast are much more likely to produce the next great earthquake in california the greater precision of dates now available for large earthquakes recorded at the pallett creek site enables speculative correlation of events between paleoseismic sites along the southern half of the san andreas fault a history of great earthquakes with overlapping rupture zones along the mojave section of the fault remains one of the more attractive possibilities

toward a unifying constitutive relation for sediment transport across environments abstract landscape evolution models typically parse the environment into different process domains each with its own sediment transport law e g soil creep landslides and debris flows and river bed load and suspended sediment transport sediment transport in all environments however contains many of the same physical ingredients albeit in varying proportions grain entrainment due to a shear force that is a combination of fluid flow particle particle friction and gravity we present a new take on the perspective originally advanced by bagnold that views the long profile of a hillsope river shelf system as a continuous gradient of decreasing granular friction dominance and increasing fluid drag dominance on transport capacity recent advances in understanding the behavior and regime transitions of dense granular systems suggest that the entire span of granular to fluid regimes may be accommodated by a single phase rheology this model predicts a material flow effective friction or viscosity that changes with the degree of shear rate and confining pressure we present experimental results confirming that fluid driven sediment transport follows this same rheology for bed and suspended load surprisingly below the apparent threshold of motion we observe that sediment particles creep in a manner characteristic of glassy systems we argue that this mechanism is relevant for both hillslopes and rivers we discuss the possibilities of unifying sediment transport across environments and disciplines and the potential consequences for modeling landscape evolution

quiet time variability of the gps tec and eej strength over indian region associated with major sudden stratospheric warming events during 2005 2006 1 this paper describes the quiet time variabilities of the ionospheric total electron content tec derived from the signals from global positioning satellite system gps recorded at several stations in india along with simultaneous observations of equatorial electrojet eej strength obtained from geomagnetic field variations during january march 2006 when sudden stratospheric warming ssw events occurred analysis of the observations presented here confirms that strong correlation exists among the variabilities in eej strength and gps tec observations investigations suggest that there exist large scale wave like structures with periodicity of quasi 16 day wave in the tec observations near the equatorial ionization anomaly eia crest quite similar to that of eej strength our observations also indicate the existence of morning enhancement and evening reduction of tec and eej strength and vice versa during ssw events similar to that reported elsewhere using these observations it is suggested that the quiet time variabilities seen in the gps tec over eia could be caused due to the nonlinear interaction of upward propagating planetary waves pws with atmospheric tides presence of similar periods in the eej strength and tec observations near the eia crest region supports the view that the large scale wave like structures seen in tec near the eia crest are associated with pws that are modifying the primary eastward electric field in the equatorial e region and hence the eej strength through non linear interactions with atmospheric tides

dynamics of slow moving landslides from permanent scatterer analysis high resolution interferometric synthetic aperture radar insar permanent scatterer data allow us to resolve the rates and variations in the rates of slow moving landslides satellite to ground distances range changes on landslides increase at rates of 5 to 7 millimeters per year indicating average downslope sliding velocities from 27 to 38 millimeters per year time series analysis shows that displacement occurs mainly during the high precipitation season during the 1997 1998 el nino event rates of range change increased to as much as 11 millimeters per year the observed nonlinear relationship of creep and precipitation rates suggests that increased pore fluid pressures within the shallow subsurface may initiate and accelerate these features changes in the slope of a hill resulting from increases in the pore pressure and lithostatic stress gradients may then lead to landslides

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

modelling hillslope evolution linear and nonlinear transport relations many recent models of landscape evolution have used a diffusion relation to simulate hillslope transport in this study a linear diffusion equation for slow quasi continuous mass movement e g creep which is based on a large data compilation is adopted in the hillslope model transport relations for rapid episodic mass movements are based on an extensive data set covering a 40 yr period from the queen charlotte islands british columbia a hyperbolic tangent relation in which transport increases nonlinearly with gradient above some threshold gradient provided the best fit to the data model runs were undertaken for typical hillslope profiles found in small drainage basins in the queen charlotte islands results based on linear diffusivity values defined in the present study are compared to results based on diffusivities used in earlier studies linear diffusivities adopted in several earlier studies generally did not provide adequate approximations of hillslope evolution the nonlinear transport relation was tested and found to provide acceptable simulations of hillslope evolution weathering is introduced into the final set of model runs the incorporation of weathering into the model decreases the rate of hillslope change when theoretical rates of sediment transport exceed sediment supply the incorporation of weathering into the model is essential to ensuring that transport rates at high gradients obtained in the model reasonably replicate conditions observed in real landscapes an outline of landscape progression is proposed based on model results hillslope change initially occurs at a rapid rate following events that result in oversteepened gradients e g tectonic forcing glaciation fluvial undercutting steep gradients are eventually eliminated and hillslope transport is reduced significantly

upper atmosphere wind systems during reverse equatorial electrojet events days of reversed equatorial electrojet were identified at trivandrum india and in order to seek a global wind change in the dynamo region responsible for these events upper atmosphere winds at a height of 99 km at saskatoon canada were examined during northern winter and also in april and september the reversed electrojets were accompanied by reversals of the eastward wind at saskatoon the winter events generally occurred during a stratwarm no changes in the winds were detected during summer reversed electrojets

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

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

causes of the longitudinal differences in the equatorial vertical e b drift during the 2013 ssw period as simulated by the time gcm during stratospheric sudden warming ssw periods large changes in the low latitude vertical drift have been observed at jicamarca as well as in other longitudinal sectors in general a strengthening of the daytime maximum vertical drift with a shift from prenoon to the afternoon is observed during the january 2013 stratospheric warming significant longitudinal differences in the equatorial vertical drift were observed at jicamarca the previously reported ssw behavior prevails however no shift of the daytime maximum drift was exhibited in the african sector using the national center for atmospheric research thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm the possible causes for the longitudinal difference are examined the timing of the strong ssw effect in the vertical drift 15 20 january coincides with moderate geomagnetic activity the simulation indicates that approximately half of the daytime vertical drift increase in the american sector may be related to the moderate geophysical conditions kp 4 with the effect being negligible in the african sector the simulation suggests that the wind dynamo accounts for approximately 50 of the daytime vertical drift in the american sector and almost 100 in the african sector the simulation agrees with previous findings that the migrating solar tides and the semidiurnal westward propagating tide with zonal wave number 1 sw1 mainly contribute to the daytime wind dynamo and vertical drift numerical experiments suggest that the neutral wind and the geomagnetic main field contribute to the presence absence of a local time shift in the daytime maximum drift in the american african sector

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

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

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

longitudinal and interhemispheric ionospheric response to 2009 and 2013 ssw events in the african european and indian east asian sectors

case studies of electrical and electromagnetic methods applied to mapping active faults beneath the thick quaternary it is of considerable importance to explore the geological structure around active faults especially near surface unconsolidated layers to estimate the faults activity there are numerous case studies to investigate active faults using geophysical exploration methods however only a few cases have been verified in detail by comparison with other geological information we have applied electric and electromagnetic methods which can be effective for exploring to several hundred meters depth to reveal geological structures covered by thick quaternary formations at four active fault sites in japan in this paper we used the controlled source audio frequency magnetotelluric csamt method the direct current dc resistivity method and the resistivity tomography method the resistivity profiles were analyzed by two dimensional inversion techniques and the resulting models were verified by comparison with geological evidence obtained by drilling or trenching our results are as follows 1 csamt is an effective method for defining an outline of geological structures around a fault to several hundred meters deep it enables us to define a resistivity boundary between different kinds of bedrock with a fault contact 2 the dc resistivity method distinguishes each sedimentary unit as a different resistivity zone and detects the vertical displacement in the quaternary formations 3 the resistivity tomography method is useful to determine in more detail the flexure structure produced by faulting using these latter two methods we can select drilling positions and trenching locations in addition it is verified from the data measured along trench walls and electrical logging that the resistivity of soft sedimentary layers and clayey cataclastic bedrock conforms to the relationship established between the resistivity and the clay content these resistivity methods have the advantages of detecting clayey layers as very low resistivity zones the overall conclusion is that the combination of these resistivity methods provides us with more detailed and accurate information for estimating fault activity

particle motion on burned and vegetated hillslopes climate change is causing increasingly widespread frequent and intense wildfires across the western united states many geomorphic effects of wildfire are relatively well studied yet sediment transport models remain unable to account for the rapid transport of sediment released from behind incinerated vegetation which can fuel catastrophic debris flows this oversight reflects the fundamental inability of local continuum based models to capture the long distance particle motions characteristic of steeplands probabilistic particle based nonlocal models may address this deficiency but empirical data are needed to constrain their representation of particle motion in real landscapes here we present data from field experiments validating a generalized lomax model for particle travel distance distributions the model parameters provide a physically intuitive mathematical framework for describing the transition from light to heavy tailed distributions along a continuum of behavior as particle size increases and slopes get steeper and or smoother we show that burned slopes are measurably smoother than vegetated slopes leading to 1 lower rates of experimental particle disentrainment and 2 runaway motion that produces the heavy tailed travel distances often associated with nonlocal transport our results reveal that surface roughness is a key control on steepland sediment transport particularly after wildfire when smoother surfaces may result in the preferential delivery of coarse material to channel networks that initiate debris flows by providing a first order framework relating the statistics of particle motion to measurable surface characteristics the lomax model both advances the development of nonlocal sediment transport theory and reveals insights on hillslope transport mechanics

rates of surface processes on slopes slope retreat and denudation results taken from 270 publications on rates are summarized and collated with those from 149 publications reviewed previously young 1969 1974 the data are classified by major climatic zone normal or steep relief and consolidated or unconsolidated rocks representative rates and their ranges are given for soil creep solifluction surface wash solution chemical denudation rock weathering slope retreat cliff free face retreat marine cliff retreat and denudation the last being compared with representative rates of uplift solifluction is of the order of 10 times faster than soil creep but both cause only very slow ground loss solution is an important cause of ground loss for siliceous rocks on which it may be half as rapid as on limestones total denudation brought about mainly by surface wash reaches a maximum in the semi arid and probably also the tropical savanna zones acceleration of natural erosion rates by human activities ranges from 2 3 times with moderately intense land use to about 10 times with intensive land use and considerably higher still where there is recognized accelerated soil erosion where there is active uplift typical rates are of the order of 10 times faster than denudation although in some high steep mountain ranges these may approach equality

gopher bioturbation field evidence for non linear hillslope diffusion it has generally been assumed that diffusive sediment transport on soil mantled hillslopes is linearly dependent on hillslope gradient fieldwork was done near santa barbara california to develop a sediment transport equation for bioturbation by the pocket gopher thomomys bottae and to determine whether it supports linear diffusion the route taken by the sediment is divided into two parts a subsurface path followed by a surface path the first is the transport of soil through the burrow to the burrow opening the second is the discharge of sediment from the burrow opening onto the hillslope surface the total volumetric sediment flux as a function of hillslope gradient is found to be qs cm3 cm 1 a 1 176 dz dx 3 189 dz dx 2 68 dz dx 34 dz dx 0 4 this result does not support the use of linear diffusion for hillslopes where gopher bioturbation is the dominant mode of sediment transport a one dimensional hillslope evolution program was used to evolve hillslope profiles according to non linear and linear diffusion and to compare them to a typical hillslope the non linear case more closely resembles the actual profile with a convex cap at the divide leading into a straight midslope section copyright 2000 john wiley sons ltd

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

late mesozoic cenozoic strike slip and block rotation in the inner belt of southwest japan abstract the inner belt of southwest japan is located in the region north of the median tectonic line mtl which is the largest strike slip fault in the japanese islands belonging to an island arc system the inner belt is divided into ten or more small blocks bounded by active faults and geological tectonic lines the blocks are 20 to 80 km in width and approximately 200 km in length the width and the length have remained nearly constant during the long history since the late cretaceous significant igneous activity has occurred along boundaries of the blocks from the late cretaceous to the present with the use of a geometrical strike slip and block rotation model the small blocks were rotated in such a way that they are to be rearranged in parallel with each other at the time of the block formation the inner belt of southwest japan was then placed north of its present location to the position occupied in mid cretaceous time with this configuration the inner belt is found to be situated between two major strike slip faults the mtl and the sikhote alin fault faulting and igneous activity that occurred from the late cretaceous to the present can be geometrically interpreted by the strike slip and block rotation model which induces left lateral slip movement of the two major bounding faults main plutonic activity occurs at triangle gaps generated by the block rotation other igneous activity occurred along block terminations block boundary faults and riedel shear fractures inside the block bending of southwest japan occurred along three block boundaries the itoigawa shizuoka tectonic line the tsurugawan isewan tectonic line and the hanaore kongo fault line during the opening of the sea of japan blocks raised by underthrusting during the rotation of the inner belt due to the opening of the sea of japan at about 15 ma have continued to tilt even at present most earthquake faults were generated along block boundary faults while a few earthquake faults also appearing along riedel shear fractures that originated from the block boundary faults

paleoseismic evidence of clustered earthquakes on the san andreas fault in the carrizo plain california exposures we have excavated across the san andreas fault contradict the hypothesis that part of the fault in the carrizo plain is unusually strong and experiences relatively infrequent rupture the exposures record evidence of at least seven surface rupturing earthquakes which have been approximately dated by accelerated mass spectrometry radiocarbon analysis of detrital charcoal and buried in situ plants five large earthquakes have occurred since 1218 a d the most recent earthquake event a was the 1857 fort tejon earthquake which we have associated with 6 6 10 m of dextral slip along the main fault trace the penultimate earthquake event b most likely occurred within the period a d 1405 1510 slip from either events b and c combined or from event b alone totals 7 11 m three earthquakes events c d and e occurred in a temporal cluster prior to event b and after approximately a d 1218 the average recurrence interval within this cluster is 73 116 years depending on assumptions events f and g occurred after 200 years b c a depositional hiatus between events e and f may hide evidence of additional earthquakes events b and d within the carrizo cluster of a d 1218 1510 may correlate with events t a d 1329 1363 and v a d 1465 1495 at pallett creek on the mojave segment of the fault this suggests two fault ruptures similar in length to that of 1857 events c and e apparently did not rupture the mojave section which suggests that the carrizo segment has ruptured independently or in combination with segments to the north irregular repeat times of large earthquakes suggest a pattern of clustered events at the end of seismic supercycles

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

sudden stratospheric warming event signatures in daytime exb drift velocities in the peruvian and philippine longitude sectors for january 2003 and 2004 1 this paper first describes the technique that has been developed to obtain realistic daytime vertical exb drift velocities in the equatorial ionosphere using two ground based magnetometers one on the magnetic equator and the other located 6 9 away in latitude this technique is then employed to study the unique exb drift signatures associated with sudden stratospheric warming events ssw in both the peruvian and philippine longitude sectors occurring in january 2003 and january 2004 it is found that the semidiurnal shaped signature first appears in the peruvian sector and 3 days later appears in the philippine sector in both sectors the exb drift signature lasts for approximately 5 days

rain splash of dry sand revealed by high speed imaging and sticky paper splash targets 1 rain splash transport of sediment on a sloping surface arises from a downslope drift of grains displaced ballistically by raindrop impacts we use high speed imaging of drop impacts on dry sand to describe the drop to grain momentum transfer as this varies with drop size and grain size and to clarify ingredients of downslope grain drift the splash of many grains involves ejection of surface grains accelerated by grain to grain collisions ahead of the radially spreading front of a drop as it deforms into a saucer shape during impact for a given sand size splash distances are similar for different drop sizes but the number of displaced grains increases with drop size in proportion to the momentum of the drop not infiltrated within the first millisecond of impact we present a theoretical formulation for grain ejection which assumes that the proportion of ejected grains within any small azimuthal angular interval dq about the center of impact is proportional to the momentum density of the spreading drop within dq and that the momentum of ejected grains at angle q is on average proportional to the momentum of the spreading drop at q this formulation consistent with observed splash distances suggests that downslope grain transport involves an asymmetry in both quantity and distance more grains move downslope than upslope with increasing surface slope and on average grains move farther downslope this latter effect is primarily due to the radial variation in the surface parallel momentum of the spreading drop surface parallel transport increases approximately linearly with slope

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

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

effect of sudden stratospheric warming on lunar tidal modulation of the equatorial electrojet 1 using the equatorial electrojet eej peak current intensity as deduced from champ magnetic observations from the years 2001 through 2009 we investigated the relationship between sudden stratospheric warming ssw and lunitidal signatures in the tropical ionosphere there is a practically one to one correspondence between midwinter ssw periods and the strongest 13 day modulation of the eej strength as observed by champ that is all the midwinter ssw periods from december 2001 to august 2009 were accompanied by an enhanced 13 day modulation of the eej strength no other geophysical phenomenon brought about as strong a 13 day modulation as those of the midwinter ssw periods during each midwinter ssw period the amplified 13 day modulation of the eej strengths starts roughly within 1 week around the first peak in stratospheric temperature difference an oscillation with a period of 13 26 days is predicted by the lunitidal equation when considering the precession of the champ orbit when fitting the lunitidal equation to the eej modulations during the midwinter ssw periods consistent phase delays of 4 4 0 3 days of the tidal signal emerge for all the cases the results suggest that the pronounced 13 day modulation of the eej strength is related to an enhancement of the lunar tide in the ionosphere by the ssw effect