estimation of source rupture process and strong ground motion simulation of the 2002 denali alaska earthquake a m w 7 9 inland crustal earthquake occurred in the denali fault system alaska on 3 november 2002 at 22 12 utc in this study we estimated the source process of the 2002 denali earthquake by a multiple time window linear kinematic waveform inversion using strong motion and global positioning system gps measured static displacement data the obtained source model could explain both the observed strong motion waveforms and gps measured static displacements large slips on the fault plane are observed at approximately 80 90 km and 150 200 km east from the hypocenter these features are consistent with the observed surface rupture distribution and the other inversion results obtained using teleseismic body waves we also observed some portions of the whole fault with a local rupture propagation velocity of more than 4 0 km sec that exceeded the shear wave velocity of the source region the relation between the rupture area and seismic moment of this earthquake seems to follow the bilinear l model scaling rather than the self similar source scaling model the combined area of asperities is somewhat smaller than that expected from the empirical scaling relationship with seismic moments developed by compiling inverted source models finally we conducted a forward ground motion simulation using the finite difference method to estimate the influence of the heterogeneous source process obtained here on the spatial distribution of strong ground motions the calculated ground motions are relatively large above and around the large slip areas and also in the region east of the fault area because of the forward directivity effect of unilateral rupture propagation

source rupture process of the 2004 chuetsu mid niigata prefecture japan earthquake inferred from waveform inversion with dense strong motion data abstract the kinematic source rupture process of the 2004 chuetsu mid niigata prefecture japan earthquake is estimated from strong motion data by the linear waveform inversion method in order to develop appropriate green s functions one dimensional velocity structure models for each station are constructed by modeling the aftershock waveforms the estimated top of the bedrock is deeper at the western side of the fault and relatively shallow at the eastern side this tendency coincides with other investigations of seismic tomography and microtremor array observations the obtained source model shows large slips in the vicinity of the hypocenter the reverse slipping rupture originated from the deeper part of the fault and propagated toward the up dip and southwest directions the near surface slip is small two tests are demonstrated to check the stability of the obtained source model the first test examines the effects of the number of available stations on the solution and the second test examines how the difference in the target waveform type affects the solution the number of stations affects the variation of slip amount and more than 12 stations appear to be sufficient to obtain a stable solution in this case the difference in the target wave type in the data set does not significantly affect the solution if the number of stations is sufficient and the green s functions are well calibrated the model obtained using calibrated velocity structure models shows clear image of high slip area compared to the model obtained using a single velocity structure model

low frequency and broad band source models for the 2009 l aquila italy earthquake summary the 2009 l aquila italy earthquake mw 6 3 produced an unprecedented number of seismological records for a normal faulting event and hence represents an important case study of damaging moderate magnitude earthquakes occurring in densely inhabited areas we have investigated the source process of the 2009 l aquila earthquake in both the low and broad band frequency ranges by analysing the teleseismic and strong motion data a low frequency 0 5 hz source model has been determined by waveform inversion of teleseismic and near field strong motion data yielding slip distributions with a major asperity located about 8 km southeast of the hypocentre the broad band 0 2 10 hz source characteristics were estimated using the empirical green s function method providing the strong motion generation area of about 42 km2 located southeast of the hypocentre below the village of onna this coincides with the location of the asperity from the inversion analysis indicating that the low frequency and broad band ground motions produced during the earthquake were generated at similar locations on the fault plane the position of the strong motion generation area also correlates well with the distribution of observed macroseismic mcs intensities reported by ingv the maximum macroseismic intensities of ix x were reported southeast of the epicentre with an intensity of x measured in onna the source properties of the 2009 l aquila mainshock reveal the estimated size of the strong motion generation area to be in agreement with predictions made using empirical source scaling relation for inland crustal earthquakes implying a stress drop of approximately 10 mpa this further indicates that the 2009 l aquila earthquake involved a stress drop similar to that of previously recorded earthquakes in the central and southern apennines

validation of the recipe for broadband ground motion simulations of japanese crustal earthquakes the robustness of broadband ground motion simulation can promote seismic hazard assessment a broadband ground motion simulation technique called the recipe is used in the scenario earthquake shaking maps of the national seismic hazard maps for japan the recipe represents a fault rupture based on a multiple asperity model referred to as the characterized source model broadband ground motion time histories on the engineering bedrock are computed by a hybrid approach of the 3d finite difference method and the stochastic green s function method for the long 1 s and short period 70 km such conditions are outside of the target range of the recipe simulations using a 1d velocity structure model were also examined the simulation results for the 1d and 3d velocity structure models indicated that the 3d velocity structure models are important in reproducing pgv and the later phases with long duration especially on deep sediment sites

three dimensional ground motion modelling in the kachchh rift zone gujarat india abstract the strong motion dataset of the 6 april 2006 bhuj aftershock of mw5 5 from 16 three component accelerograph stations are used here to perform a detailed ground motion modelling in the kachchh rift basin first we estimate the 1 d velocity structure model down to the bedrock at 16 accelerograph sites through the genetic algorithm inversion of strong motion waveforms then a 3 d velocity structure model of the basin is constructed using the modelled 1 d velocity structure and constraints from earlier seismological vs30 estimation by ps logging and masw and seismic exploration studies in the region we modelled low frequency 0 1 1 hz ground motions excited by the 6 april 2006 event using the finite difference method fdm assuming a point source to access the robustness of the constructed velocity structure model at most of the stations the observed and simulated velocity waveforms are found to be in good agreement in terms of both amplitude and ground motion duration we also computed synthetic ground velocities at numerous locations within the basin for both the 2001 bhuj mainshock finite fault source and the 2006 aftershock point source cases using the 3 d velocity structure model for both the cases we notice significant amplifications of amplitudes and elongation of shaking at stations lying within the basin while smaller amplifications are noticed at stations away from the basin our fdm modelling for the 2001 bhuj mainshock at lower frequency

the 2004 mw6 0 parkfield california earthquake inversion of near source ground motion using multiple data sets on 28 september 2004 the m w 6 0 parkfield earthquake became the most densely recorded earthquake for near source ground motion to infer the kinematic nature of this event we invert the strong motion data the non linear global inversion yields slip amplitude slip rake average rupture velocity and rise time over the fault by using subsets of the data we study the dependence of the kinematic solutions on data input the inversions reveal that the slip amplitude was less than 0 65 m and outline two major areas of slip one that laterally surrounds the hypocenter preferentially extending to its se the other 10 to 20 km nw of the hypocenter at a depth between 2 and 8 km the slip amplitude we obtain for each point on the fault varies less than 0 15 m depending on data set used the rake angle variability is less than 40 degrees

stability of rapid finite fault inversion for the 2014 mw6 1 south napa earthquake local seismograms are useful for rapidly reconstructing kinematic finite fault sources but the results often depend not only on the data coverage but also on uncertainties of parameters e g hypocentral location and fault geometry used as a priori information during the inversion an automatic scheme was applied to offline tests for the 2014 south napa earthquake in the case of retrospective full waveform inversions a network with station spacing of 10 km within the epicentral distance of 30 km is able to provide adequate stable key source parameters if the preestimated hypocenter and fault orientation are accurate of 5 km and 15 respectively in simulated real time inversions the magnitude reaches mw6 0 at 13 s and the slip distribution matches that from the retrospective inversion at about 22 28 s after the origin time of the earthquake these results are meaningful for estimating the lead time of a catastrophic seismic event

imaging the source region of the 2004 mid niigata prefecture earthquake and the evolution of a seismogenic thrust related fold 1 the velocity structure and accurate aftershock distributions of the 2004 mid niigata prefecture earthquake are elucidated by inverting the arrival times from 716 aftershocks using double difference tomography fourteen temporal seismic stations were immediately deployed in and around the source region within 46 h of the occurrence of mainshock the seismic velocities in a hanging wall are lower than those in a footwall and the velocity contrast extends to a depth of approximately 10 km the aftershocks associated with the mainshock are distributed around the clear boundary between the low and high velocity structures it is interpreted that the mainshock fault plane of the mid niigata prefecture earthquake was reactivated as a reverse fault since the crustal shortening initiated at 3 5 ma crustal stretching or shortening along the japan coastline has created complex structures such as low velocity zones which can potentially control the seismic activities around the source region

source rupture process of the 2007 noto hanto japan earthquake estimated by the joint inversion of strong motion and gps data abstract the source rupture process during the 2007 noto hanto earthquake which was a reverse faulting event located near the western coast of the noto peninsula in central japan was estimated by the kinematic linear waveform inversion method the waveform inversion was conducted by jointly using velocity waveforms recorded at 12 near source strong motion stations and static horizontal displacements recorded at 19 global positioning system gps stations in order to implement reliable green s functions into the inversion a one dimensional underground velocity structure for each individual strong motion station was modeled through waveform modeling of an aftershock the waveform inversion result showed the following image of the source rupture process the larger slip concentrated in the vicinity of the hypocenter and it extended to the shallow portion of the source fault with a maximum slip of 5 1 m the whole source process was characterized by the total seismic moment of 1 57 10 19 n m m w 6 7 with the rupture duration of approximately 9 s the obtained source model explained observed strong ground motions and gps measured static horizontal displacements well the slip distribution correlated well with the spatiotemporal aftershock distribution and the northeast end of the rupture was blocked by the resistive structure in the crust from these facts the 2007 noto hanto earthquake could be concluded as reactivation of preexisting seafloor active faults f14 and f15 which were reported by the previous geophysical and geological surveys off the shore of the noto peninsula

two paradigms of baroclinic wave life cycle behaviour two idealized baroclinic wave 6 life cycles examined here suggest a framework of opposite extremes a in which to view the behaviour of real synoptic scale disturbances in middle latitudes and b in which to interrelate the synoptic and wave theoretic viewpoints using the saturation propagation saturation sps picture of wave 6 life cycle behaviour the two life cycles dented by lc1 and lc2 are higher resolution versions of the simmons hoskins basic and anomalous cases showing strong and weak late decay of eddy kinetic energy eke they illustrate in varying degrees two extreme types of behaviour here disignated anticyclonic and cyclonic and epitomized by strongly contrasting upper air trough behaviour anticyclonic behaviour dominates the late stages of lc1 and is characterized by backward tilted thinning troughs being advected anticyclonically and equatorward as in the commoner cases of planetary scale mid stratospheric rossby wave breaking cyclonic behaviour dominates lc2 and is characterized by forward tilted broadening troughs wrapping themselves up cyclonically and poleward producing major cut off cyclones in high latitudes these morphologies are visualized by upper air maps of potential temperature on the nominal tropopause defined as a constant potential vorticity surface some atmospheric mid latitude disturbances examined here using the same visualization applied to operational analyses show the same two extreme types of trough behaviour together with intermediate cases the sps picture is re examined using eliassen palm and refractive index cross sections it is shown in particular by reference to a wave activity theorem of haynes that the late stages of lc2 can be looked upon as a remarkably clear and morphologically novel large amplitude counterpart of the nonlinear reflection scenario of rossby wave critical layer theory the late stages of lc1 by constrast look more akin to an nonlinear critical layer absorption scenario lc2 exhibits region of largely undular pv contours adjacent to a nonlinear of irreversiby deformen pv contous in the latter region pv rearrangement and hence absorption of rossby wave activity has largely ceased this accounts for the more persistent ekee in the lc2 case

rupture processes of the 2004 chuetsu mid niigata prefecture earthquake japan a series of events in a complex fault system 1 we relocated the hypocenters of the 2004 chuetsu earthquake sequence niigata japan using the double difference method the distribution of aftershocks reveals a complex fault system consisting of five different fault planes inversions of strong motion records for the five major events within the sequence indicate that the mainshock mw 6 6 and the largest aftershock mw 6 3 occurred on parallel wnw dipping fault planes the zones of large slip asperities of these two events are located near the hypocenters in contrast the three other large earthquakes mw 5 9 5 7 and 5 9 occurred on east dipping fault planes oriented perpendicular to the fault plane of the mainshock we used slip distributions deduced from waveform inversions to estimate the coulomb failure stress changes that occurred immediately prior to each event cff values were positive at the hypocenters and within the asperities of the major aftershocks these results suggest that stress changes resulting from individual earthquakes led directly to the occurrence of subsequent earthquakes within the complex fault system

asperity and barriers of the 2004 mid niigata prefecture earthquake revealed by highly dense seismic observations abstract a highly resolved velocity structure on the mainshock fault of the 2004 mid niigata prefecture earthquake was elucidated using arrival times from aftershocks observed by an extremely dense network of temporary seismic stations we evaluated the spatial relationship between the velocity structure and distributions of the slip stress change and aftershocks distributions of static stress drop on the fault were calculated from a kinematic slip model incorporating the 3d crustal structure a high velocity body with low aftershock activity was in proximity to the mainshock hypocenter and extended to the northeast side of the fault this high velocity body roughly coincided with an asperity where the amounts of coseismic slip and static stress drop were larger than those in the surrounding areas in contrast a zone of negative stress drop was observed on the shallow periphery of the high velocity body where the sediment thickness steeply increased southwestward and the aftershock activity was high we suggest that the structural heterogeneities of the host rocks surrounding the fault damaged zone have significant potentials to control dynamic rupture processes of the mainshock fault

thermal conductivity of unconsolidated sediments with geophysical applications a theoretical model for the prediction of the thermal conductivity of unconsolidated granular sediments with application to sand shale mixtures is presented the sediment is modeled as an assemblage of grains of thermal conductivity s immersed in a pore fluid of thermal conductivity in order to take into account for the thermal interactions between the grains a differential effective medium approach is used to provide a relationship between the effective thermal conductivity of the isotropic mixtures of grains saturated by the pore fluid the porosity and the thermal conductivities of the grains and pore fluid the influence of the topology of the interconnected pore space is accounted for through the use of the electrical cementation exponent m which is related to the electrical formation factor f by f m where is the interconnected porosity the main assumption of the model lies in the small contiguity between the grains this assumption holds well for unconsolidated sand shale mixture sediments as demonstrated by comparing the model to available experimental data the model offers the possibility to derive thermal conductivity profiles from downholes measurements of natural radioactivity electrical resistivity and bulk density

a quantitative approach for estimating coseismic displacements in the near field from strong motion accelerographs the translational accelerations recorded by strong motion seismometers are often contaminated by baseline offsets that prevent recovering theground displace ments by double integration detailed analysis of the k net95 strong motion seis mometer and the improvement of the visual display of the recorded accelerations fourier transform by addition of long zero pads to the acceleration records made it possible to distinguish the origins of the long period noise that contaminate the translational accelerations recorded in the near field of two studied earthquakes the 2004 niigata ken chuetsu earthquake and the 2007 niigata ken chuetsu oki earthquake japan they are the residual rotation of the instrument residual tilt or the 1 f digital semiconductor noise the quantification of these two terms allows us to discuss the low frequency content of the records and to describe when it is possible to obtain realistic displacement time histories it happens when the residual tilt is removed in the time domain or when the 1 f semiconductor noise overshadows the translational acceleration records up to sufficiently small frequencies as a check of the method displacement time histories obtained from acceleration records are compared with nearby 1 hz gps data good similitudes are obtained in the near field for collocated instruments online material figures showing acceleration velocity and displacement time series and acceleration spectra for 18 records

tropical storm formation in a baroclinic environment abstract an analysis is presented of the large scale conditions associated with the initial development of tropical storm diana september 1984 in a baroclinic environment ordinary extratropical wave cyclogenesis began along an old frontal boundary east of florida after 0000 utc 7 september and culminated in tropical cyclogenesis 48 h later water vapor satellite imagery showed that the initial cyclogenesis and incipient tropical storm formation was nearly indistinguishable from a classical midlatitude development cyclogenesis occurred in three stages a large scale cold trough and associated frontal system crossed the atlantic coast while a small potential vorticity maximum aloft fractured off the main trough and stalled over central florida in the first stage as the main trough sheared off eastward cyclogenesis began along the southwestern end of the stalled frontal zone east of florida anticyclogenesis to the north in the wake of the shearing trough allowed a surge of cooler and drier air to flo

the role of synoptic scale flow during tropical cyclogenesis over the north atlantic ocean abstract the synoptic scale flow during tropical cyclogenesis and cyclolysis over the north atlantic ocean is investigated using compositing methods genesis and lysis are defined using the national hurricane center nhc now known as the tropical prediction center best track data genesis lysis occurs when nhc first last identifies and tracks a tropical depression in the final best track dataset storm centered composites are created with the analysis of the tropical oceanic lower level atoll 900 hpa and 200 hpa winds for june november produced by nhc for the years 1975 93 results show that significant regional differences exist in 200 hpa flow during genesis across the atlantic basin composites of genesis in the western part of the basin show a 200 hpa trough ridge located to the west east of the atoll disturbance in the eastern half of the basin composites of genesis show a sprawling 200 hpa ridge centered northeast of the atoll disturbance the major axis of this elliptically shaped 20

atlantic subtropical storms part i diagnostic criteria and composite analysis abstract subtropical cyclones st have only recently gained attention as damaging weather systems a set of criteria for identifying and classifying these systems is introduced here and employed to identify 18 st cases forming in the 1999 2004 hurricane seasons to be classified as an st these systems must have near surface gale force winds and show hybrid structure for more than one diurnal cycle the 18 st cases are partitioned into four classes based upon their genesis environments genesis over waters with sst in excess of 25 c is observed in almost 80 of warm season cases in contrast with only 55 in an st climatology presented in a companion study the low shear magnitude constraint recognized for tropical cyclogenesis is less apparent for st formation with over 50 forming in the two partitions characterized by shear in excess of 10 m s 1 this relatively high shear environment corresponds to equatorward intrusion of upper troughs over the relatively warm sst present in the mid late hurricane s

short baseline variations in site response and wave propagation effects and their structural causes four examples in and around the santa clara valley california abstract ground motion records of local and regional events from a portable array are used to investigate the structural causes of variations in ground motion over distances of a few hundred meters to a few kilometers in the sedimentary basin environment of the santa clara valley california and its margins arrays of portable seismic stations are used to target four study areas with different ground motion patterns 1 an edge of the alluvial basin extending up onto a marginal ridge blossom hill 2 a cenozoic basin with a nearly flat bottom cupertino basin 3 a long narrow cenozoic basin with a steep v profile evergreen basin and 4 a line perpendicular to the trace of the hayward fault average peak velocities on blossom hill from local earthquakes are a factor of 2 5 times higher than nearby valley sites three dimensional 3d modeling is used to conclude that the majority of the amplification is due to lower shear wave velocities along a local fault zone shannon berrocal site amplification over the cupertino basin in the frequency band 0 5 4 hz is generally low less than 2 0 relative to a mesozoic rock site and spatially uniform this response is attributed to the shallow flat bottomed shape of the basin and the uniform flat laying sedimentary fill in contrast site amplification in the evergreen basin generally exceeds 3 0 and is attributed to the deep v shaped geometry of the basin and younger sedimentary fill 3d waveform modeling shows the elongated shape of the evergreen basin causes more efficient trapping of long period waves for sources along the long axis of the basin a low velocity zone is postulated along the hayward fault with a width between 100 and 200 m based on elevated site response along the fault trace and 4 5 hz fault zone guided waves on the horizontal components of stations near the fault

crustal heterogeneity in the source region of the 2004 mid niigata prefecture earthquake inversion analysis of coda envelopes the 2004 mid niigata prefecture earthquake mjma 6 8 and its aftershock sequences generated complicated i e several conjugate fault planes in their source region in order to understand the generating process of these earthquakes we estimated a 3 d distribution of relative scattering coefficients in the source region the large slip area during the main shock rupture seems to be bounded by strong heterogeneous zones with larger scattering coefficients hypocenters of the main shock and major large aftershocks with m 5 6 classes tend to be located close to stronger scattering areas we found that one of these strong heterogeneities already existed before the occurrence of the m 5 9 aftershock on november 8 we suppose that heterogeneous structures in the source region of this earthquake sequence affected the initiation and growth of ruptures of the main shock and major large aftershocks

a new nonlinear finite fault inversion with three dimensional green s functions application to the 1989 loma prieta california earthquake 1 we present a new procedure to invert for kinematic source parameters on a finite fault on the basis of the reciprocity relation of the green s functions we use a newly developed fourth order viscoelastic finite difference algorithm to calculate three dimensional 3 d green s functions actually the tractions on the fault we invert the data for the unknown source parameters at the nodes or corners of the subfaults the source parameters within a subfault area are allowed to vary this variation is calculated through bilinear interpolation of the four nodal quantities we have developed a global nonlinear inversion algorithm that is based on simulated annealing methods to solve efficiently for the nodal parameters we apply this method to the 1989 loma prieta california m 6 9 earthquake for both a 1 d and 3 d velocity structure we show 1 the bilinear interpolation technique reduces the dependence of inversion results on the subfault size by naturally including the effects of nearby subfaults 2 while the number of synthetic seismograms that must be computed is greatly increased by the bilinear interpolation the structure of the inversion method minimizes the actual numbers of computations 3 as expected complexity in the velocity structure is mapped into the source parameters that describe the rupture process there are significant differences between faulting models derived from 1 d and 3 d structural models

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

imaging the seismic structure and stress field in the source region of the 2004 mid niigata prefecture earthquake structural zones of weakness and seismogenic stress concentration by ductile flow 1 we deployed a dense temporal seismic network in the source region of the 2004 mid niigata prefecture earthquake thrust fault japan a detailed velocity structure and accurate aftershock distributions were elucidated by inverting aftershock arrival times using double difference tomography a stress tensor inversion using the first motion data was also conducted in order to investigate the stress field the seismic velocities in the hanging wall above the main shock fault are lower than those in the footwall with the velocity contrast extending to a depth of approximately 10 km the aftershocks along the main shock rupture zone are distributed around the sharp boundary between the low and high velocity bodies furthermore aftershocks associated with the largest aftershock appear to be aligned on a boundary between low and high velocity zones in the footwall the orientation of maximum principal stress 1 is consistent with the regional compressional strain rate axis inferred from gps data except in the southwestern side of the main shock hypocenter where the azimuth of 1 rotates approximately 20 counterclockwise the main shock hypocenter was located roughly at the transition zone where the structure of the hanging wall changes laterally and the azimuth of 1 rotates heterogeneous structures of the seismic velocity and the stress field combined with the ductile deformation of the upper crust may have concentrated seismogenic stress around the hypocenter area to cause the complex distributions of aftershock sequence on structural boundaries

the relationship between late cenozoic tectonic events and stress field and basin development in northeast japan the regional tectonic stress field basin development and crustal deformation of the ne japan arc in the interval between 32 ma to the quaternary can be synthesized based on dike vein and fault orientation data as well as on the compilation of the regional geology an extensional stress field became prevalent from 32 ma and major normal faulting started at 25 20 ma which resulted from back arc rifting normal faulting trending nearly parallel to the arc propagated from the present japan sea coast to the forearc side following the trenchward migration of the main volcanic field from 20 to 15 ma normal faults with an oblique trend to the arc developed due to the counterclockwise rotation of ne japan the rapid clockwise rotation of sw japan since 16 ma produced a nw se directed transtensional stress regime in the ne japan arc due to crustal stretching associated with this pull apart movement the back arc side of the ne japan arc subsided rapidly to middle bathyal environments after the termination of the opening of the japan sea at about 14 ma a neutral stress regime prevailed which included phases of both weak extension and compression lithospheric cooling eventually led to thermal subsidence of the back arc region and igneous underplating caused uplift of the axial zone of the volcanic arc the increase in velocity of the westward motion of the pacific plate at around 4 ma produced strong compression across the arc reactivating most of the miocene normal faults and uplifting the volcanic arc the greatest crustal shortening occurred in areas that were stretched the most in the miocene within the volcanic arc which implies tectonic inversion

baroclinically induced tropical cyclogenesis abstract the authors investigate the transition of numerous subtropical cyclones into late season tropical storms and hurricanes during the 2000 and 2001 atlantic tropical cyclone seasons in all transitioning cases 10 the 900 200 hpa wind shear was initially near or in excess of the upper limit of vertical shear deemed suitable for tropical cyclogenesis in many of these cases the vertical shear decreased markedly near or prior to the time of tropical cyclone formation in cases that did not become named tropical cyclones either the tropospheric vertical shear remained in excess of 15 20 m s 1 or the underlying sea surface temperature sst dropped below about 26 c prior to or during the weakening of the shear cases in which the shear remained large featured multiple short wave upper tropospheric troughs interacting with the developing lower tropospheric disturbance such that classical occlusion did not occur through detailed analysis and simulation of the development of hurricane michael in 2000

synthetic source inversion tests with the full complexity of earthquake source processes including both supershear rupture and slip reactivation recent studies in dynamic source modeling and kinematic source inversion show that earthquake rupture may contain greater complexity than we previously anticipated including multiple slipping at a given point on a fault finite source inversion methods suffer from the nonuniqueness of solutions and it may become more serious if we aim to resolve more complex rupture models in this study we perform synthetic inversion tests with dynamically generated complex rupture models including both supershear rupture and slip reactivation to understand the possibility of resolving complex rupture processes by inverting seismic waveform data we adopt a linear source inversion method with multiple windows allowing for slipping from the nucleation of rupture to the termination at all locations along a fault we regularize the model space effectively in the bayesian framework and perform multiple inversion tests by considering the effect of inaccurate green s functions and station distributions we also perform a spectral stability analysis our results show that it may be possible to resolve both a supershear rupture front and reactivated secondary slipping using the linear inversion method if those complex features are well separated from the main rupture and produce a fair amount of seismic energy it may be desirable to assume the full complexity of an earthquake rupture when we first develop finite source models after a major event occurs and then assume a simple rupture model for stability if the estimated models do not show a clear pattern of complex rupture processes

rupture process of the 1944 tonankai earthquake ms 8 1 from the inversion of teleseismic and regional seismograms 1 we digitized teleseismic and regional records of the 1944 tonankai earthquake we used the multiple time window method to invert these records for the spatial and temporal distribution of slip and rake we assume a 220 140 km fault with a spacing of 20 20 km and a maximum rupture velocity of 2 5 km s the inversion resolved an asperity along the accretionary wedge and under the shima and atsumi peninsulas the rupture propagated from southwest to northeast and there was little slip near the hypocenter consistent with the absence of uplift in the overlying submarine forearc basin the peak slip is 2 3 m and the total seismic moment is 2 4 1028 dyn cm mw 8 2 we compared the predicted and observed vertical geodetic displacements and inferred that the limit of rupture is consistent with the change from subsidence to uplift west of the atsumi peninsula this suggested that the earthquake did not rupture the plate interface in the tokai gap we modeled the tsunami using sea bottom displacements generated from this slip model the tide gauge amplitudes and frequency content are consistent with those predicted resolution tests from inverting synthetic seismograms computed using a simplified slip model indicated that the combination of teleseismic and regional data sets best recovers the asperity locations and peak slips given similar station geometry and degrees of freedom an inversion of the synthetic regional data set indicates that slip artifacts can occur early in the rupture process due to many clipped records while the inversion of synthetic teleseismic data set had less resolution and recovered only 50 of the peak slip

along dip variation in seismic radiation of the 2011 ibaraki oki japan earthquake m w 7 9 inferred using a multiple period band source inversion approach

numerical simulations of the genesis of hurricane diana 1984 part i control simulation abstract the complete transformation of a weak baroclinic disturbance into hurricane diana is reproduced by numerical simulations using the fifth generation pennsylvania state university national center for atmospheric research mesoscale model three distinct phases of the evolution are evident first baroclinic and barotropic development strongly modified by the effects of latent heating occurs during the latter part of this phase the low level circulation is strengthened through the axisymmetrization of remote potential vorticity anomalies that are generated by condensational heating and then advected toward the incipient storm the axisymmetrization process evinces properties of both nonlinear discrete vortex merger and vortex rossby wave dynamics the transformation from cold core to warm core vortex occurs in this development stage in the second phase lasting 10 12 h little deepening occurs spiral bands of convection begin to form and the core of the storm moistens eventually reaching 95

source scaling of inland crustal earthquake sequences in japan using the s wave coda spectral ratio method we estimate corner frequencies and stress drops for 298 events ranging from m w 3 2 7 0 in 17 inland crustal earthquake sequences in japan to investigate the source scaling and variation in stress drops we obtain the source spectral ratio from observed records by the s wave coda spectral ratio method the advantage of using the s wave coda is in obtaining much more stable source spectral ratios than using direct s waves we carefully examine the common shape of the decay of coda envelopes between event pair records the corner frequency and stress drop are estimated by modeling the observed source spectral ratio with the omega square source spectral model we investigate the dependences of stress drops on some tectonic effects such as regionality focal mechanism and source depth the principal findings are as follows 1 a break in self similar source scaling is found in our dataset events larger than m w 4 5 show larger stress drops than those of smaller events 2 stress drops of aftershocks are mostly smaller than those of mainshocks in each sequence 3 there are no systematic differences between stress drops of events occurring inside and outside the niigata kobe tectonic zone in japan 4 clear dependence of the faulting type on stress drops cannot be seen 5 stress drops of aftershocks depend on their source depth 6 the crack size obtained from the corner frequency corresponds to the total rupture area of heterogeneous slip models for large events

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

characterization of stress drops on asperities estimated from the heterogeneous kinematic slip model for strong motion prediction for inland crustal earthquakes in japan dense strong motion observation networks provided us with valuable data for studying strong motion generation from large earthquakes from kinematic waveform inversion of seismic data the slip distribution on the fault surface of large earthquakes is known to be spatially heterogeneous because heterogeneities in the slip and stress drop distributions control the generation of near source ground motion it is important to characterize these heterogeneities for past earthquakes in constructing a source model for reliable prediction of strong ground motion the stress changes during large earthquakes on the faults recently occurring in japan are estimated from the detailed slip models obtained by the kinematic waveform inversion the stress drops on and off asperities are summarized on the basis of the stress change distributions obtained here in this paper we define the asperity to be a rectangular area whose slip is 1 5 or more times larger than the average slip over the fault according to the previous study for inland crustal earthquakes the average static stress drops on the asperities of the earthquakes studied here are in the range 6 23 mpa whereas those off the asperities are below 3 mpa we compiled the stress drop on the asperities together with a data set from previous studies of other inland earthquakes in japan and elsewhere the static stress drop on the asperity depends on its depth and we obtained an empirical relationship between the static stress drop and the asperity s depth moreover surface breaking asperities seemed to have smaller stress drops than buried asperities simple ground motion simulations using the characterized asperity source models reveal that deep asperities generate larger ground motion than shallow asperities because of the different stress drops of the asperities these characteristics can be used for advanced source modeling in strong ground motion prediction for inland crustal earthquakes

numerical simulations of the genesis of hurricane diana 1984 part ii sensitivity of track and intensity prediction abstract the authors examine numerous simulations that probe the dynamics governing the intensification and track of tropical cyclone diana 1984 simulated in part i the development process is fundamentally dependent on a preexisting upper tropospheric trough ridge couplet this couplet focuses mesoscale vertical motion that in turn produces lower tropospheric potential vorticity pv anomalies which form the seed for the tropical storm removal of this trough ridge couplet from the initial conditions eliminates cyclogenesis the simulated rate of development of diana in the prehurricane phase depends principally on choices of cumulus parameterization boundary layer treatment sea surface temperature and grid spacing simulations with cumulus schemes that allow more grid scale precipitation on the 9 km grid exhibit unrealistic grid scale overturning and slower intensification primarily due to production of cyclonic vorticity anomalies at large radii use of an innermost nest with 3 km grid spacing

western north pacific tropical cyclone characteristics stratified by genesis environment abstractthe characteristics of tropical cyclones tcs in the summer and autumn seasons over the western north pacific that are associated with different environmental factors that influence tc genesis tcg were studied we objectively categorized factors into the five tcg factors classified by ritchie and holland 1999 monsoon shear line sl monsoon confluence region cr monsoon gyre gy easterly wave ew and the rossby wave energy dispersion from a preexisting tc ptc the gy tcs tended to develop slowly and the highest rates of occurrence of rapid intensification ri were found for the cr tcs whereas the gy tcs rarely experienced ri the average storm size of the gy tcs at the time of formation was the largest of the averages of the other tc types while the ew and ptc tcs were smaller although these differences disappeared at the mature time there were no significant differences in the sea surface temperature sst beneath the tcs but the tropical cyclone heat potential tchp of t

numerical study of convection observed during the winter monsoon experiment using a mesoscale two dimensional model abstract a two dimensional version of the pennsylvania state university mesoscale model has been applied to winter monsoon experiment data in order to simulate the diurnally occurring convection observed over the south china sea the domain includes a representation of part of borneo as well as the sea so that the model can simulate the initiation of convection also included in the model are parameterizations of mesoscale ice phase and moisture processes and longwave and shortwave radiation with a diurnal cycle this allows use of the model to test the relative importance of various heating mechanisms to the stratiform cloud deck which typically occupies several hundred kilometers of the domain frank and cohen s cumulus parameterization scheme is employed to represent vital unresolved vertical transports in the convective area the major conclusions are ice phase processes are important in determining the level of maximum large scale heating and vertical motion because there is a strong anvil componen

detailed imaging of the fault planes of the 2004 niigata chuetsu central japan earthquake sequence by double difference tomography abstract imaging of the hypocentral faults of the niigata chuetsu earthquake sequence was performed by double difference tomography using data obtained by a temporary aftershock observation network densely deployed in the hypocentral region two parallel unfavorly oriented fault planes steeply inclined to the wnw are revealed that of the main shock and that of the largest aftershock as well as a zone of velocity change between the high velocity footwall and the low velocity hanging wall for both p and s waves this suggests that the main shock and the largest aftershock are caused by the reactivation of normal faults in the miocene under the current compressional stress regime parts of the fault planes are also found to be located within the low velocity zone this low velocity zone continues to the lower crust which is imaged by an inversion from the regional data and would correspond with highly fractured zone around the fault plane with high fluid pressure which reactivated the unfavorly oriented fault and triggered the present earthquake large coseismic slip area appears to extend to the northeastern portion with relatively high velocity this suggests that the asperity large coseismic slip area of the main shock possibly correspond with a higher velocity region along the fault plane

rupture process of the 1964 mjma 7 5 niigata earthquake estimated from regional strong motion records the source rupture process of the 1964 niigata earthquake m jma 7 5 japan is inferred in detail from regional strong motion data recorded with low gain mechanical displacement seismographs a fault plane model with high angle dipping to the west is assumed as a result of reinvestigating the aftershock distribution and the thickness of the fault zone is determined from recent high resolution seismicity in the source region to develop appropriate green s functions a one dimensional velocity structure model for each station is constructed by modeling the waveforms from recent small earthquakes in the source region a multiple time window technique is applied to invert the observed waveforms for the spatial and temporal slip distribution the obtained source model indicates large slips mainly in the northern part of the fault plane and secondary slips in the vicinity of the hypocenter and slightly expanding to the south the total moment release reached graphic 1 m w 7 6 and the rupture velocity of the first time window sweep was 1 5 km s the static stress drop was estimated to be 8 9 mpa by assuming a circular fault model the crustal deformation estimated from the slip distribution agrees well with the tsunami generating area the sea bottom movement and the uplift measurement at awashima island located above the fault plane 1 embed inline graphic 1 gif