analyzing earthquake clustering features by using stochastic reconstruction 1 on the basis of the epidemic type aftershock sequence etas model and the thinning procedure this paper gives the method about how to classify the earthquakes in a given catalogue into different clusters stochastically the key points of this method are the probabilities of one event being triggered by another previous event and being a background event making use of these probabilities we can reconstruct the functions associated with the characteristics of earthquake clusters to test a number of important hypotheses about the earthquake clustering phenomena we applied this reconstruction method to the shallow seismic data in japan and also to a simulated catalogue the results show the following assertions 1 the functions for each component in the formulation of the space time etas model are good enough as a first order approximation for describing earthquake clusters 2 a background event triggers less offspring in expectation than a triggered event of the same magnitude 3 the magnitude distribution of the triggered event depends on the magnitude of its direct ancestor 4 the diffusion of the aftershock sequence is mainly caused by cascades of individual triggering processes while no evidence shows that each individual triggering process is diffusive and 5 the scale of the triggering region is still an exponential law as formulated in the model but not the same one for the expected number of offspring

stationary rossby wave propagation in a baroclinic atmosphere observational studies of teleconnections in both soisticial seasons have suggested various patterns of behaviour linked mainly to westerly jets and equatorial westerlies these have been interpreted using barotropic rossby wave theory and simulated using stationary forcing in barotropic models linearized about 300 hpa flows in this paper the relevant propagation behaviour is investigated using a baroclinic model with three dimensional climatological basic states time integrations are performed using localized thermal forcing as a wavemaker the propagation results are qualitatively very similar to those obtained with the barotropic model though there are quantitative differences the westerly jets still act as strong waveguides the shorter wavelengths and smaller wave activity speeds found with the baroclinic model are generally in better agreement with observation propagation into and from the upper tropospheric equatorial westerlies in the east pacific propagation across north america and propagation from europe across the arabian gulf are all found the extent to which upper tropospheric westerlies reach towards the equator influences the propagation into those regions barotropic models can only represent such behaviour if the basic state reflects the near equatorial upper tropospheric zonal wind structure

when and where the aftershock activity was depressed contrasting decay patterns of the proximate large earthquakes in southern california 1 seismic quiescence has attracted attention as a possible precursor to a large earthquake however sensitive detection of quiescence requires accurate modeling of normal aftershock activity we apply the epidemic type aftershock sequence etas model that is a natural extension of the modified omori formula for aftershock decay allowing further clusters secondary aftershocks within an aftershock sequence the hector mine aftershock activity has been normal relative to the decay predicted by the etas model during the 14 months of available data in contrast although the aftershock sequence of the 1992 landers earthquake m 7 3 including the 1992 big bear earthquake m 6 4 and its aftershocks fits very well to the etas up until about 6 months after the main shock the activity showed clear lowering relative to the modeled rate relative quiescence and lasted nearly 7 years leading up to the hector mine earthquake m 7 1 in 1999 specifically the relative quiescence occurred only in the shallow aftershock activity down to depths of 5 6 km the sequence of deeper events showed clear normal aftershock activity well fitted to the etas throughout the whole period we argue several physical explanations for these results among them we strongly suspect aseismic slips within the hector mine rupture source that could inhibit the crustal relaxation process within shadow zones of the coulomb s failure stress change furthermore the aftershock activity of the 1992 joshua tree earthquake m 6 1 sharply lowered in the same day of the main shock which can be explained by a similar scenario

long term acceleration of aseismic slip preceding the mw 9 tohoku oki earthquake constraints from repeating earthquakes a decadal scale deformation transient preceding the 2011 mw 9 tohoku oki japan earthquake was reported from continuous gps data and interpreted as accelerating aseismic slip on the japan trench megathrust given the unprecedented nature of this transient independent confirmation of accelerating slip is required here we show that changes in the recurrence intervals of repeating earthquakes on the japan trench megathrust in the period 1996 to 2011 are consistent with accelerating slip preceding the tohoku oki earthquake all sequences of repeating earthquakes with statistically significant trends in recurrence interval at 95 confidence offshore south central tohoku occurred at an accelerating rate furthermore estimates of the magnitude of slip acceleration from repeating earthquakes are consistent with the completely independent geodetic estimates from a joint inversion of the gps and seismicity data we infer that a substantial portion of the megathrust experienced accelerating slip partly surrounding the eventual rupture zone of the mw 9 earthquake

late cenozoic uplift of mountain ranges and global climate change chicken or egg the high altitudes of most mountain ranges have commonly been ascribed to late cenozoic uplift without reference to when crustal thickening and other tectonic processes occurred deep incision and recent denudation of these mountain ranges abundant late cenozoic coarse sediment near them and palaeobotanical evidence for warmer climates where high mountain climates today are relatively cold have traditionally been interpreted as evidence for recent uplift an alternative cause of these phenomena is late cenozoic global climate change towards lower temperatures increased alpine glaciation a stormier climate and perturbations to humidity vegetative cover and precipitation

cross equatorial response to middle latitude forcing in a zonally varying basic state abstract a nonlinear model based on the shallow water equations is used to study cross equatorial propagation of forced waves in the presence of a longitudinally varying time mean basic state zonal wind field it is found that global scale planetary waves are unable to propagate past a critical latitude where the mean zonal wind speed vanishes however if the longitudinally asymmetric basic state includes a duet in which the zonal winds are westerly waves of zonal scale less than the zonal scale of the westerly duct may propagate from one hemisphere to the other even though the zonally symmetric mean zonal wind remains easterly in the equatorial region the amplitude of the response in one hemisphere to forcing in the opposite hemisphere increases strongly with the magnitude of the westerlies in the equatorial duct the existence and annual variations of a westerly duct region in the upper troposphere in the eastern pacific appear to account for some features of the low frequency variability in the no

the initial value problem for tropical perturbations to a baroclinic atmosphere large scale wave propagation ideas have proved extremely valuable in interpreting real and model data these ideas have been developed in the context of barotropic models and here the extension to baroclinic atmospheres is investigated the dispersion of waves from an initial large scale tropical perturbation to a baroclinic basic flow is studied using a direct approach a 15 level spectral primitive equation model is integrated forward in time even in baroclinically unstable flows it is found that for a period normally of order 12 days the model yields what can be considered to be the direct response to the tropical perturbations after this time baroclinic instability dominates the basic flows are a resting atmosphere a climatological westerly an equatorial longitudinal modification to this and a 3 d climatological december february state for the perturbations used here equatorial kelvin waves play only a very small role the large scale equatorial rossby wave shows only small dispersion and tends to move with a doppler shifted phase speed which allows it to accumulate to the east of an equatorial maximum of 10 ms 1 or more rossby wavetrains propagate into the middle and high latitude westerly regions with the climatological flow perturbations in the indian ocean west pacific sector trigger a modal structure in the north pacific and wavetrain across north america very much as barotropic theory would suggest and similar to observed pacific north america pna patterns in such a flow the middle latitude waves tend to extend to the equator in the westerly regions of the east pacific and atlantic in agreement with observed behaviour

absolute stress fields in the source region of the 1992 landers earthquake earthquake focal mechanisms are often inverted to obtain the deviatoric stress field because shear stress is equal to the frictional strength of the fault at the time of an earthquake six components of the absolute stress tensor at the hypocenter can be obtained from a focal mechanism by combining deviatoric stress fields with the coulomb failure criterion for a data set of focal mechanisms determined for southern california earthquakes including the 1992 landers earthquake sequence we calculated the absolute stress tensors at their hypocenters using a standard intrinsic friction coefficient under three pore pressure conditions parameterized by the reference pore pressure at the optimally oriented faults to the stress field three absolute stress fields were obtained for southern california immediately before the landers main shock by applying each data set of the stress tensors to an inversion scheme based on bayesian statistical inference and akaike s bayesian information criterion the coseismic stress field was calculated to obtain the absolute stress fields immediately after the main shock the variations of the coseismic stress rotation were related to the reference pore pressure comparing this relation with that obtained through stress inversion we determined the absolute stress field and the most plausible reference pore pressure to be hydrostatic on average the maximum shear stresses immediately before the main shock were 44 15 and 79 24 mpa at depths of 5 and 10 km respectively earthquakes on the off plate boundary faults in southern california occur on faults that are loaded by anderson byerlee stress conditions

precursory seismic anomalies and transient crustal deformation prior to the 2008 mw 6 9 iwate miyagi nairiku japan earthquake 1 the epidemic type aftershock sequence etas model has been widely used for detecting seismicity anomalies such as quiescence and activation during aftershock sequences of large earthquakes and background levels of seismicity the causes of such anomalies are thought to be associated with spatiotemporal changes in stress even tiny perturbation of local stress here we analyze the seismic activity during the decade prior to the 2008 iwate miyagi inland earthquake of m7 2 mw6 9 to fit the etas model to the seismicity from various regions around the source over northern honshu japan from the viewpoint of the analyses with the etas model we find northern honshu is divided into three areas of distinctive behaviors increased seismicity decreased seismicity and normal seismicity relative to the etas prediction as in other previously published papers here we hypothesize that coulomb stress changes caused by a few years of precursory slip of the iwate miyagi earthquake resulted in the seismicity changes in and around the 2008 source region the confirmed significant seismic anomalies in respective regions are consistent with the increments of the coulomb failure stress of the corresponding regions that are calculated by the assumed slow slip on the southern part of the faults of the main shock the local crustal deformations observed from a dense global positioning system network including a station right above the focal fault supports that slow slip on the fault had been taking place for about 5 years prior to the occurrence of the focal earthquake and suggests that the slip terminated or migrated to down dip extension of the fault around 1 year before the rupture

teleconnections in the geopotential height field during the northern hemisphere winter abstract contemporaneous correlations between geopotential heights on a given pressure surface at widely separated points on earth referred to as teleconnections in this paper are studied in an attempt to identify and document recurrent spatial patterns which might be indicative of standing oscillations in the planetary waves during the northern hemisphere winter with time scales on the order of a month or longer a review of existing literature on the subject reveals the existence of at least four such patterns the north atlantic and north pacific oscillations identified by walker and bliss 1932 a zonally symmetric seesaw between sea level pressures in polar and temperature latitudes first noted by lorenz 1951 and what we will refer to as the pacific north american pattern which has been known to operational long range forecasters in this country since the 1950 s a data set consisting of nmc monthly mean sea level pressure and 500 mb height analyses for a 15 year period is used as a basis fo

a decadal scale deformation transient prior to the 2011 mw 9 0 tohoku oki earthquake gps time series in northeast japan exhibit nonlinear trends from 1996 to 2011 before the mw 9 0 2011 tohoku oki earthquake after removing reference frame noise we model time series as linear trends plus constant acceleration correcting for coseismic and postseismic effects from the numerous mw 6 5 earthquakes during this period we find spatially coherent and statistically significant accelerations throughout northern honshu large areas of japan outside the tohoku region show insignificant accelerations demonstrating that the observation is not due to network wide artifacts while the accelerations in northern tohoku sanriku area can be explained by decaying postseismic deformation from pre 1996 earthquakes the accelerations in south central tohoku appear unrelated to postseismic effects the latter accelerations are associated with a decrease in average trench normal strain rate and can be explained by increasing slip rate on the japan trench plate interface and or updip migration of deep aseismic slip in the decades before the 2011 tohoku oki earthquake

anomalies of seismic activity and transient crustal deformations preceding the 2005 m 7 0 earthquake west of fukuoka if aseismic slip occurs on a fault or its deeper extension both seismicity and crustal deformation around the source would be affected anomalous phenomena of this kind are revealed from earthquake occurrence data and geodetic records during a period of 10 years leading up to the march 2005 m 7 0 earthquake west of fukuoka that occurred off the northern coast of kyushu japan seismicity rate anomalies quiescence and activation took place relative to the rates expected by the etas model in a number of seismic zones in and around the kyushu district the seismic zone of the relative quiescence and activation consistently corresponds to the zone of the negative and positive cfs coulomb failure stress change respectively assuming the precursory aseismic slips on the m 7 0 source fault in addition we consider the time series of geodetic baseline distances between permanent gps stations in the kyushu district for the same period which also supports the possible precursory slips rather than the known slow slips beneath the bungo straight off the eastern coast of kyushu

the climate of the mis 13 interglacial according to hadcm3 the climate of the marine isotopic stage 13 mis 13 is explored in the fully coupled atmosphere ocean general circulation model the hadley centre coupled model version 3 hadcm3 it is found that the strong insolation forcing at the time imposed a strengthened land ocean thermal contrast resulting in an intensified summer monsoon over asia the addition of land ice over north america and eurasia results in a stationary wave feature across the eurasian continent this leads to a high pressure anomaly over the sea of japan with increased advection of warm moist air onto the chinese landmasses this in turn reinforces the east asian summer monsoon easm highlighting the counterintuitive notion that depending on the background insolation and its size ice can indeed contribute to strengthening the easm the modeling results support the geological record indication of a strong easm 500 000 years ago furthermore arctic oscillation el nino southern oscillation and indian ocean dipole like teleconnection features are discussed in the mis 13 environment it is shown that the change in the tropical pacific sea surface temperature has the potential to impact the north atlantic climate through an atmospheric bridge

monitoring of anomaly in the aftershock sequence of the 2005 earthquake of m7 0 off coast of the western fukuoka japan by the etas model monitoring of aftershock sequences to detect lowering activity relative to the modeled rate the relative quiescence becomes realistic and practical in predicting the enhancement of the likelihood of having a substantially large aftershock or even another earthquake of similar size or larger a significant relative quiescence in the aftershock sequence of the 2005 march earthquake of m7 0 off the western coast of fukuoka japan was reported two weeks before the largest aftershock of m5 8 that also hit the kyushu district the relative quiescence was discussed in relation to the stress shadowing as inhibiting the activity due to probable precursory slips which are retrospectively speculated in more detail

horizontal structure of 500 mb height fluctuations with long intermediate and short time scales abstract maps of standard deviations and one point correlation maps based on twice daily data subjected to a variety of temporal filters are presented in order to document the horizontal structure of 500 mb height fluctuations with different time scales the filters have been chosen to isolate fluctuations with long time scales periods much longer than 30 days intermediate time scales 10 30 day periods and short time scales 2 5 6 day periods the one point correlation maps for long time scales resemble the teleconnection patterns described by wallace and cutzler these patterns are strongly regionally dependent with meridionally oriented dipole structures in the jet exit regions over the oceans indicative of strong fluctuations in the zonal wind for intermediate time scales the dominant patterns consist of more zonally oriented wave trains which originate in the jet entrance regions and cross the jet streams as they curve southeastward into the tropics another important distinction between th

detection of anomalous seismicity as a stress change sensor 1 anomalous seismicity such as quiescence and activation is defined by a systematic deviation of seismic activity from the predicted rate by the epidemic type aftershock sequence etas model that represents the normal occurrence rate of earthquakes in a region indicating the empirical triggering effect by the previous events the model is fitted to a data set of origin times and magnitudes of earthquakes or aftershocks during may august 2003 in and around northern japan the detected quiescence and activation relative to the predicted seismicity rate are consistent with the coseismic changes of coulomb failure stress cfs in the corresponding regions transferred from certain strong earthquakes few results in this paper agree with the claim that there should be a threshold value of cfs capable of affecting seismic changes thus we expect that significant deviation of actual activity from the predicted rates is sensitive enough to detect a slight stress change furthermore i offer a similar interpretation of the detected seismicity lowering relative to the modeled rates preceding the strong earthquakes assuming some aseismic slips

a non stationary epidemic type aftershock sequence model for seismicity prior to the december 26 2004 m 9 1 sumatra andaman islands mega earthquake 1 we study temporal changes in seismicity in sumatra andaman islands region before the m 9 1 earthquake of december 26 2004 we applied the epidemic type aftershock sequence etas models to the seismicity the two stage non stationary etas model with a single change point provides a better statistical fit to the seismicity data than the stationary etas model throughout the whole period we made further change point analysis of data sets by dividing into two sub regions the best fitted models suggest that the seismic activation relative to the etas rates started in the middle of july 2000 about 4 5 years before the m 9 1 earthquake this includes an increase in the background seismicity rates particularly in the southern part of the seismogenic zone near the epicenter a space time etas model also suggests that the background seismicity throughout the entire sumatra andaman islands area had increased after the change point time

seismicity and geodetic anomalies in a wide area preceding the niigata ken chuetsu earthquake of 23 october 2004 central japan 1 the ordinary short term occurrence rate of earthquakes in a region is predicted using the epidemic type aftershock sequence etas model of triggering seismicity any anomalous seismic activity such as quiescence and activation can be quantified by identifying significant deviation from the predicted rate such anomalies are revealed to have occurred during the three year period leading up to the 2004 chuetsu earthquake of m6 8 mw6 6 central japan the quiescence and activation which took place in the zone of negative and positive increments of the coulomb failure stress respectively were possibly caused by aseismic slip on or near the focal fault plane such slip is further supported by transient crustal movement around the rupture source time series records of the baseline distances between permanent gps stations deviated from the predicted trends with the deviations mostly consistent with the coseismic horizontal displacements of the stations due to the chuetsu earthquake the cumulated preceding slip is estimated to be roughly equivalent to mw6

topographic form of the coast ranges of the cascadia margin in relation to coastal uplift rates and plate subduction the coast ranges of the cascadia margin are overriding the subducted juan de fuca gorda plate we investigate the extent to which the latitudinal trend in average topography of the coast ranges is a function of the latitudinal change in attributes related to the subduction process these attributes include the variable age of the subducted slab that underlies the coast ranges and average vertical crustal velocities of the western margin of the coast ranges for two markedly different time periods the last 45 years and the last 100 kyr these vertical crustal velocities are computed from the resurveying of highway bench marks and from the present elevation of shore platforms that have been uplifted in the late quaternary respectively topography of the coast ranges is in part a function of the age and buoyancy of the underlying subducted plate this is evident in the fact that the two highest topographic elements of the coast ranges the klamath mountains and the olympic mountains are underlain by youngest subducted oceanic crust the subducted blanco fracture zone in southernmost oregon is responsible for an age discontinuity of subducted crust under the klamath mountains the northern terminus of the topographically higher klamaths is offset to the north relative to the position of the underlying blanco fracture zone the offset being in the direction of migration of the fracture zone as dictated by relative plate motions vertical crustal velocities at the coast derived from bench mark surveys are as much as an order of magnitude greater than vertical crustal velocities derived from uplifted shore platforms this uplift rate discrepancy indicates that strain is accumulating on the plate margin to be released during the next interplate earthquake in a latitudinal sense average coast range topography is relatively high where bench mark derived short term vertical crustal velocites are highest because the shore platform vertical crustal velocites reflect longer term permanent uplift we infer that a small percentage of the interseismic strain that accumulates as rapid short term uplift is not recovered by subduction earthquakes but rather contributes to rock uplift of the coast ranges the conjecture that permanent rock uplift is related to interseismic uplift is consistent with the observation that those segments of the subduction zone subject to greater interseismic uplift rates are at approximately the same latitudes as those segments of the coast ranges that have higher magnitudes of rock uplift over the long term

space time model for regional seismicity and detection of crustal stress changes 1 the regional occurrence rate of earthquakes is modeled as a function of previous activity the specific form of which is based on empirical laws in time and space such as the modified omori formula and the utsu seki scaling law of aftershock area against magnitude respectively its parameters including the p value of the aftershock decay rate vary from place to place in such a way that for example the regional p value at the locations around the main shock is similar to the one estimated from the corresponding individual aftershock sequence the estimated space time model is used to visualize features of the regional seismic activity the utility is demonstrated by applying the model to the events of m 5 in and around japan for the period 1926 1995 among the parameters of the model this paper is particularly concerned with the normalized k value of the modified omori function indicating the aftershock productivity this takes high values around the boundaries of asperities that are estimated in the wide area off the east coast of tohoku district japan by the inversion of historical strong motion seismograms furthermore this space time model enables us to identify the anomalous period and regions where the actual occurrence rates deviate systematically from the modeled one such an anomaly activation and quiescence relative to the model could sensitively reveal the change of stresses in the regions we attempt to relate this relative activation and lowering of the seismicity to the pattern of coulomb stress changes due to a rupture or silent slip elsewhere for example such anomalies seen in the seismic activity in the central japan m 2 5 during 1995 1999 and during 2001 are respectively likely the consequence of the coulomb stress changes due to the 1995 kobe rupture and the interplate aseismic slip during 2001 beneath the western tokai region

periodic slow slip triggers megathrust zone earthquakes in northeastern japan both aseismic and seismic slip accommodate relative motion across partially coupled plate boundary faults in northeastern japan aseismic slip occurs in the form of decelerating afterslip after large interplate earthquakes and as relatively steady slip on uncoupled areas of the subduction thrust here we report on a previously unrecognized quasi periodic slow slip behavior that is widespread in the megathrust zone the repeat intervals of the slow slip range from 1 to 6 years and often coincide with or precede clusters of large magnitude m 5 earthquakes including the 2011 m 9 tohoku oki earthquake these results suggest that inherently periodic slow slip events result in periodic stress perturbations and modulate the occurrence time of larger earthquakes the periodicity in the slow slip rate has the potential to help refine time dependent earthquake forecasts

changes in seismic activity following the 2011 tohoku oki earthquake effects of pore fluid pressure abstract we examined the effects of pore fluid pressure on seismicity changes following the 2011 off the pacific coast of tohoku tohoku oki earthquake through the analysis of aftershocks based on the coulomb failure criterion background tectonic stress fields in northeast japan are generally characterized by e w compression after the tohoku oki earthquake as expected from decrease in the coulomb failure function shear stress 0 4 normal compressive stress seismicity in the upper crust of northeast japan decreased except some restricted regions where we observed many aftershocks with unfavourable focal mechanisms to the background stress fields by mapping the focal mechanisms of aftershocks on the 3 d mohr diagram region by region we confirmed that the aftershocks occurred on optimally oriented faults in some regions but on misoriented faults in other regions the aftershocks on optimally oriented faults indicate the increase in regional ambient fluid pressure caused by the flow of over pressurized fluid from a deep reservoir on the other hand the aftershocks on misoriented faults which cannot be attributed to coseismic stress rotation indicate the increase in fault confined fluid pressure relative to the ambient fluid pressure

fault plane geometry in the source region of the 1994 sanriku oki earthquake abstract we present the results of a seismic refraction experiment conducted off eastern aomori northeastern japan forearc region where the detailed crustal structure was poorly known an objective analysis using high quality survey data allowed us to obtain the seismic velocity structure to about 30 km depth and in particular to obtain a well constrained geometry of the plate boundary in the source region of the 1994 sanriku oki earthquake our results show that the subducting pacific oceanic plate increases its dip from about 5 to approximately 15 around the longitude of 143 5 e 80 km landward of the trench axis near the latitude of 40 n the location of this bend in the plate is 40 km east of the bending point previously proposed on the basis of hypocenter distribution a cluster of aftershocks of the 1994 sanriku oki earthquake occurred around the bending point this is because the bending of the subducting plate appears to affect the stress state in the vicinity of the plate boundary furthermore the plate geometry is also considered to be related to the coupling or slip features along the plate boundary as the bending point correlates with the spatial distribution of repeating earthquakes our results will lead to more reliable determinations of asperity areas because an accurate dip angle of the fault plane is necessary for slip distribution studies

barotropic wave propagation and instability and atmospheric teleconnection patterns abstract a global barotropic model linearized about the 300 mb climatological mean january flow is perturbed by applying a series of localized forcings distributed throughout the tropics and subtropics structures which resemble the observed pacific north american and east atlantic teleconnection patterns noted by wallace and gutzler 1981 tend to recur in the responses similar patterns are found to result from the dispersion of isolated initial perturbations placed at a variety of locations in the tropics and midlatitudes it is shown that these structures are related to the most rapidly growing mode associated with barotropic instability of the zonally varying climatological basic state in the absence of damping this mode has an e folding time of about a week and a period close to 50 days in localized regions the instantaneous growth rates can be competitive with those of baroclinic instability these episodes of rapid local barotropic growth are interspersed with intervals in which the local

pre seismic anomalies in seismicity and crustal deformation case studies of the 2007 noto hanto earthquake of m6 9 and the 2007 chuetsu oki earthquake of m6 8 after the 2004 chuetsu earthquake of m6 8 summary if aseismic slip occured on a fault or its deeper extension both seismicity and crustal deformation around the source would be affected such anomalies are determined from earthquake occurrence data and geodetic records during the periods leading up to the 2007 march noto hanto earthquake of m6 9 and the 2007 july chuetsu oki earthquake of m6 8 which successively occurred after the 2004 october chuetsu earthquake of m6 8 on the japan sea coast assuming such aseismic slips seismic zones corresponding to negative and positive increments of the coulomb failure stress show seismic quiescence and activation respectively relative to the rate predicted by the epidemic type aftershock sequence model these interpretations are further supported by transient crustal movements around the sources preceding the ruptures for example the time series of baseline distances between permanent global positioning system stations deviated from their long term linear trends in a manner that is consistent with the assumed slip in particular this paper emphazes on the investigation of the interacting tectonic processes within such a narrow area and a short period considering the precursory slow slips on the focal faults or their downdip extensions based on the observed anomalies in seismicity and crustal movement

the effect of the madden julian oscillation on the north atlantic oscillation using idealized numerical experiments abstractthe aim of the paper is to investigate the influence of the madden julian oscillation mjo on the north atlantic oscillation nao using a quasigeostrophic model on the sphere a simplifie

pre and postseismic slow slip surrounding the 2011 tohoku oki earthquake rupture abstract slow aseismic slip that accommodates part of the long term plate motion on subduction megathrusts is thought to be strongly related to the occurrence of large earthquakes on the same fault zone however the temporal evolution and spatial distribution of the aseismic slip before major earthquakes and of accelerated postseismic afterslip are largely unconstrained we estimate cumulative offsets of small repeating earthquakes that are interpreted to reflect the in situ aseismic slip history on the subduction zone offshore northeastern japan these data reveal contrasting aseismic slip patterns between the coseismic rupture area of the mw 9 0 tohoku oki earthquake and surrounding portions of the subduction thrust the rupture area is characterised by low and variable slip rates before 2008 and the slip stopped almost completely after the earthquake the region surrounding the rupture area exhibited higher aseismic fault slip rates before the earthquake and clear postseismic slip of up to 1 6 m within 9 months following the main shock the frictional fault properties and complete relief of ambient stress in the central rupture zone of the main shock probably control the observed distribution the postseismic slip shows a more abrupt increase in the region closer to the source suggesting outwards propagation of afterslip small but distinct increases in the slip rate in the 3 yr before the earthquake near the area of large coseismic slip suggests preseismic unfastening of the locked area in the last stage of the earthquake cycle

long term glacial erosion of active mountain belts example of the chugach st elias range alaska an emerging paradigm that equates glaciers to buzz saws of exceptional erosional efficiency has been strengthened by short term 10 2 yr sediment yields from southern alaska new low temperature cooling ages from this area the glaciated chugach st elias mountains constrain long term 10 6 yr exhumation rates vertically averaged exhumation rates reach 3 mm yr but are an order of magnitude lower than rates based on short term sediment yields whereas these exhumation rates are not exceptional for oro genic belts denudation patterns are strongly correlated with the distribution of glaciers and erosion appears to keep pace with con vergence and uplift these findings imply a coupling between gla cially dominated erosion and tectonics

statistical model for standard seismicity and detection of anomalies by residual analysis abstract a statistical point process model is derived to describe the standard activity of earthquake occurrences by assuming that general seismicity is given by the superposition of aftershock sequences the parameters are estimated ty the maximum likelihood method using the estimated model the residual point process of the data is defined and used to find the anomalies which are included in the data set but not captured in the considered model for the standard seismicity for instance seismic quiescences can be measured quantitatively by using the residual process some examples are provided to illustrate such analyses furthermore a time series of the magnitudes on the residual point process is considered to investigate its dependence either on the time or on the history of the seismicity by assuming the exponential distribution at each time and modelling of the b value we can examine such dependences and estimate them two practical examples are shown

preceding coseismic and postseismic slips of the 2011 tohoku earthquake japan 1 we estimated the spatial and temporal evolution of the preceding aseismic slip from january 2003 to january 2011 the coseismic slip of the tohoku earthquake and the postseismic slip after the earthquake based on global positioning system gps data time dependent analysis indicates aseismic slip offshore of miyagi and fukushima prefectures from 2004 associated with a series of subduction earthquakes that overlap the aseismic slip area these preceding aseismic and coseismic slip areas are centered between the centers of the coseismic and afterslip areas of the tohoku earthquake offshore of miyagi prefecture while they overlap the coseismic and afterslip areas of the tohoku earthquake off fukushima prefecture the timing of moment magnitude nine mw9 class earthquakes appears to be controlled by multiple preceding slip events smaller earthquakes and their afterslip the preceding aseismic and coseismic slip decreased the coupling rate off the tohoku coast suggesting the possibility that the preceding slip represented a precursive stage of the tohoku earthquake the afterslip of the tohoku earthquake occurred in an area where the coseismic slip was not large complementing the large coseismic slip zone the afterslip along iwate miyagi extends up to 80 km in depth and is currently the sole mechanism of strain release in this depth range the source region of the anticipated miyagi oki earthquake shows small postseismic slip after the tohoku earthquake reflecting the energy release at the time of the earthquake aftershock activity is roughly governed by an afterslip process

interactions between enso transient circulation and tropical convection over the pacific abstract the interannual variability of transient waves and convection over the central and eastern pacific is examined using 30 northern winters of ncep ncar reanalyses 1968 69 1997 98 and satellite outgoing longwave radiation data starting in 1974 there is a clear signal associated with the el nino southern oscillation such that differences in the seasonal mean basic state lead to statistically significant changes in the behavior of the transients and convection with periods less than 30 days which then feed back onto the basic state during a warm event el nino phase the northern hemisphere subtropical jet is strengthened over the central pacific the region of upper tropospheric mean easterlies over the tropical western pacific expands eastward past the date line and the upper tropospheric mean westerly duct over the tropical eastern pacific is weakened the transients tend to propagate along the almost continuous waveguide of the subtropical jet equatorward propagation into the westerly

response of planetary waves to stationary tropical heating in a global atmosphere with meridional and vertical shear abstract the response of planetary waves to stationary tropical heating in a stratified global atmosphere linearized with respect to a basic zonal mean flow is investigated the basic zonal wind has meridional and vertical shear the basic equations are solved by using the method of three dimensional normal mode expansion forced solutions to a prescribed tropospheric equatorial heating distribution with a specific wavenumber in longitude are examined without the basic zonal flow the internal vertical modes whose equivalent depths are on the order of a few hundred meters are favorably excited but the response of the external mode barotropic mode is relatively small with the inclusion of a zonal flow the vertical shear of the zonal wind permits the coupling of the external mode with the internal vertical modes as a result of the coupling a significant response occurs in the external mode due to the excitation of the baroclinic internal modes by tropical heating the meridional structures of in

co seismic slip post seismic slip and largest aftershock associated with the 1994 sanriku haruka oki japan earthquake 1 we analyzed continuous gps data to investigate the spatio temporal distribution of co seismic slip post seismic slip and largest aftershock associated with the 1994 sanriku haruka oki japan earthquake mw 7 7 to get better resolution for co seismic and post seismic slip distribution we imposed a weak constraint as a priori information of the co seismic slip determined by seismic wave analyses we found that the post seismic slip during 100 days following the main shock amount to as much moment release as the main shock and that the sites of co seismic slip and post seismic slip are partitioning on a plate boundary region in complimentary fashion the major post seismic slip was triggered by the mainshock in western side of the co seismic slip and the extent of the post seismic slip is almost unchanged with time it rapidly developed a shear stress concentration ahead of the slip area and triggered the largest aftershock

systematic multiscale models for the tropics systematic multi scale perturbation theory is utilized to develop self consistent simplified model equations for the interaction across multiple spatial and or temporal scales in the tropics one of these models involves simplified equations for intraseasonal planetary equatorial synoptic scale dynamics ipesd this model includes the self consistent quasi linear interaction of synoptic scale generalized steady matsuno webster gill models with planetary scale dynamics of equatorial long waves these new models have the potential for providing self consistent prognostic and diagnostic models for the intraseasonal tropical oscillation other applications of the systematic approach reveal three different balanced weak temperature gradient wtg approximations for the tropics with different regimes of validity in space and time a synoptic equatorial scale wtg sewtg a mesoscale equatorial wtg mewtg which reduces to the classical models treated by others and a new seasonal planetary equatorial wtg spewtg both the spewtg and mewtg model equations have solutions with general vertical structure yet have the linearized dispersion relation of barotropic rossby waves thus these models can play an important role in theories for midlatitude connections with the tropics the models are derived both from the equatorial shallow water equations in a simplified context and also as distinguished limits from the compressible primitive equations in general

timing and nature of late quaternary mountain glaciation compilations of regional to subcontinental scale mountain glacier chronologies from five continents plus hawaii examine the temporal and spatial patterns of mountain glaciation the compilations yield key insights into the nature of past fluctuations in temperature and precipitation in mountains and adjacent regions and provide baseline data for examining the dynamics of glacier responses to climate change key insights from these compilations include the wide variability of glacier responses to fluctuations in insolation temperature and precipitation and the regionally specific variations in climatic variables through late quaternary time the compilations highlight the need to improve the density and quality of geochronological data and to enhance the understanding of the links between climate and glaciation copyright 2008 john wiley sons ltd

change in seismicity along the japan trench 1990 2011 and its relationship with seismic coupling we investigate the temporal evolution of the background seismicity rate related to the subduction of the pacific plate in northeast japan at latitudes 34o to 42o for the 1 1 1990 9 3 2011 period two declustering methods are used to identify robust features we find that the dominant behaviour is a lowering down of activity especially in the northern half of our studied area where changes appear related to the cycle of m7 5 earthquakes in particular the 1968 tokachi and the 1994 sanriku earthquakes acceleration of background seismicity is observed offshore the kanto region and could mark a long term decoupling of the pacific and the philippine sea plates over a 100 km long segment along the sagimi trough which cannot be simply explained by the earthquake cycle model our analysis further suggests that changes in background seismicity are plausibly related to changes in seismic coupling and thus further strengthens the recent observation that seismic coupling does vary at the time scales of tens of years for the japanese subduction zone