esr dating of fault movement using various defect centres in quartz the case in the western south fossa magna japan the dates of movements of the itoigawa shizuoka tectonic line i s t l and minobu fault in the western south fossa magna have been obtained by esr dating measurements were made on various lattice defects of the ohc ge al and e centres in quartz grains of fault clay and quartz veins intruded at the time of movement all the dates obtained from these centres in quartz grains from two localities of the i s t l and iwo localities of the minobu fault fall in the range of 0 30 0 55 ma this suggests that all the centres were annihilated completely and that the obtained age can be admitted as the actual data of the latest fault movement meanwhile esr dates of quartz vein and fault clay in other localities locations 3 6 7 are divided into 0 30 0 55 ma and 1 5 2 0 ma which suggest incomplete resetting the dates of 0 30 0 55 and 1 5 2 0 ma might correspond to the clino unconformities observed in plio pleistocene sequence of this region

the trochoid like track in typhoon dujuan 2003 1 the present study examines a prominent double eyewall case namely typhoon dujuan 2003 as it neared the island of taiwan this typhoon was unusual in that its double eye was not concentric it has been suggested that vertical wind shear caused the inner eye to drift away from the typhoon circulation center thus the inner eye tended to circulate due to the steering of the rotational flow in the moat with a period of 3 5 4 h the orbited inner eye motion superimposed on the typhoon motion as a whole resulted in a substantial oscillation or wobble and eventually manifested itself as a trochoid like track the orbiting inner eye also periodically produced additional abrupt wind increase up to 15 m s 1 for 1 2 hour and has been noted to be an important issue for nowcasting and hazard mitigations

thermochronologic record of pluton emplacement deformation and exhumation at courtright shear zone central sierra nevada california thermochronology and thermobarometry of two plutons and a ductile shear zone at their contact in the central sierra nevada california as defined over the range 700 to 300 c by 40 ar 39 ar dating of hornblende and biotite and u pb dating of zircon indicate that ductile shear coincided closely with dramatically increased cooling and possible decompression of both plutons deformation occurred as the younger 90 ma mount givens pluton was emplaced against the older 102 ma dinkey creek pluton which was softened by conductive heating during extension these events coincided with significant regional exhumation possibly a result of crustal inflation recorded by a major pulse of rapid sediment accumulation in contemporaneous fore arc strata of the great valley sequence

esr studies for absolute dating of fault movements the principle of absolute dating of fault movements is based on the initialization or resetting of some clock system by faulting in the case of esr dating heating is more effective in resetting esr signals than fracturing according to a computer simulation of resetting by shear heating during faulting the esr signals can never be completely reset at depths of less than 100 200 m below the surface of the earth therefore esr samples must be collected from depth by coring or tunnelling or from outcrop with consideration of the rate of exhumation of the fault outcrop in general unpaired electrons trapped at lattice defects in crystals can diffuse much more easily than atoms hence samples for other dating methods which are based on the diffusion of atoms should be collected at even greater depth on the other hand if no esr signal is observed from unfractured quartz in the wall rocks one may directly determine the age of the fault movement using esr signals in the fractured quartz whose precursors were formed by faulting the age obtained t should then satisfy the following relationship t b t t e where t b and t e are the ages of the beginning and end of the fault movements and it may show the time of a fault movement

helium chronometry of apatite and titanite using nd yag laser heating we developed a technique for extracting 4he from apatite and titanite using laser heating that permits measurement of u and th and hence u th he ages on a single sample aliquot unlike direct laser heating quantitative he extraction and u th retention can be achieved when samples are indirectly laser heated to temperatures below their melting point resulting he ages are consistent with those obtained from conventional furnace heating of larger samples the major advantages of this technique include faster analysis and far lower more reproducible he blanks that permit single crystal analyses single crystal dating opens a variety of new avenues for u th he chronometry

esr isochron dating of the nojima fault gouge southwest japan using icp ms an approach to fluid flow events in the fault zone

intra arc deformations with vertical rotation axes the case of the pre middle miocene terranes of southwest japan abstract various folds bends with vertical or subvertical rotation axes occur in the pre middle miocene terranes of southwest japan they are variable in shape conical folds accordion folds megakink bands and so on and some are accompanied with strike slip faults they range from several kilometers to more than 100 km in width and some of their hinge surfaces are traceable more than a few tens of kilometers their shapes which resemble megakink band or buckle folds indicate that they were produced by horizontal compression with vertical or subvertical 2 axes in a shallow level of the crust they were superimposed on the pre middle miocene fold and thrust structures or nappe melange complexes and are regarded to have been formed mostly during the middle miocene contemporaneous with the clockwise rotation of southwest japan related to the fan shaped opening of the sea of japan geometrical analysis clearly suggests that the drifting southwest japan behaved as a non rigid body and the formation of these structures resulted from the differential rotation of the terranes and the collision of the izu bonin arc with eastern southwest japan

doppler radar analysis of the rapid intensification of typhoon goni 2015 after eyewall replacement abstracta ground based doppler radar observed the rapid intensification ri of typhoon goni 2015 for 24 h immediately after it completed an eyewall replacement cycle goni s ri processes were examined by using radar reflectivity and wind fields retrieved by the ground based velocity track display gbvtd technique the maximum wind at 2 km altitude increased by 30 m s 1 during the first 6 h of ri and it further increased by 20 m s 1 during the subsequent 12 h around the onset of ri relatively strong outflow 2 m s 1 was present both inside and outside the radius of maximum wind rmw above the boundary layer bl suggesting the existence of supergradient flow in and just above the bl despite this outflow angular momentum increased inside the rmw the low level rmw contracted rapidly from 50 to 33 km causing the rmw to slope greatly outward with height the radius of maximum reflectivity was a few kilometers inside the rmw a budget analysis of absolute angular momentum showed that the outflow

criteria for complete zeroing of esr signals during faulting of the san gabriel fault zone southern california in using electron spin resonance esr to date the time of the last movement on a fault it is essential to demonstrate that the esr signal was fully zeroed at the time of faulting if the signal was not completely reset then the esr age obtained will be too great we have refined the criteria for complete zeroing of esr signals at the time of fault movement samples of fault rocks were collected from surface outcrops of the san gabriel fault zone in the little tujunga region near los angeles southern california using quartz grains of 250 m the estimated ages for either e or ohc signals in all fault rock samples analyzed decrease with grain size down to a plateau value for particles smaller than some critical grain size in some cases the al signal in the smallest grains yields the same age as the plateau age of either the e or ohc signal plateau ages of reactivated younger gouges were indeed smaller than those of the older fault host rocks within the plateau region different grain size fractions show different radiation sensitivity for a single esr signal but all converge to the same de equivalent dose value this indicates that the complete resetting probably occurred during fault movement the depth of fault rocks during fault movement can be estimated from uplift rates and the esr ages the estimated uplift rates was about 0 3 cm yr for the holocene and 0 03 cm yr for the late pleistocene menges et al 1979 the estimated plateau esr ages ranged from 1200 to 135 ka the depths at the time of the last fault movements in the little tujunga region were in the range of 68 360 m the measured maximum horizontal stresses at this depth in southern california range from 5 to 10 mpa for a depth of 70 m the calculated vertical stress is 1 16 mpa and measured maximum horizontal stress is about 5 mpa the angle between the strike of the san gabriel fault and the direction of maximum horizontal stress is about 85 using above values calculated shear stress on the fault is about 0 67 mpa and the normal stress to the fault is about 5 mpa if we assume mean displacements of 4 cm m 4 to 1 m m 7 these conditions were sufficient to reset esr signals in quartz below critical grain size at the time of fault activity

structural analysis of coseismic normal fault zones of the 2011 mw 6 6 fukushima earthquake northeast japan the 2011 m w 6 6 fukushima earthquake occurred in iwaki city 250 km southwest of the epicenter of the 2011 m w 9 0 tohoku japan earthquake and produced two subparallel 15 23 km long surface rupture zones with distinct displacements along two pre existing normal faults the shionohira and yunodake faults which strike north northwest south southeast and northwest southeast both dipping southwest respectively field investigations and structural analysis of the coseismic shear zones developed within the shionohira and yunodake fault zones reveal that 1 the coseismic shear zones consist of a fault core that includes a narrow fault gouge zone of 10 cm in width generally 1 5 cm a fault breccia zone of 50 cm in width and a damage zone of 5 50 m in width that is composed of cataclastic rocks fractures and subsidiary faults 2 the foliations characterized by s c fabrics developed in the shear zones indicate a dominantly normal fault slip sense consistent with that observed along the coseismic surface ruptures and 3 veinlet cataclastic rocks composed of unconsolidated fault gouges and fine grained materials occur as simple discrete veinlets and multiple cross cutting interconnected networks of veinlets these newly documented structural characteristics for two coseismic fault shear zones and associated cataclastic rocks indicate that the locations of coseismic slip zones associated with the 2011 fukushima earthquake were controlled by pre existing fault shear zones central to the shionohira and yunodake faults which have repeatedly moved as seismogenic normal faults since the timing of formation of associated cataclastic rocks our results demonstrate that the structural analyses of coseismic shear fault zones provide a powerful tool to study the nature and active faulting history of seismological faults

rapid filamentation zone in a numerically simulated tropical cyclone abstract in a recent study rozoff et al proposed a possible mechanism to explain the formation and maintenance of the weak echo annulus or moat outside of the primary eyewall of a tropical cyclone observed in radar images by this mechanism the moat is determined to be a region of the strain dominated flow outside of the radius of maximum wind in which essentially all fields are filamented and deep convection is hypothesized to be highly distorted and even suppressed this strain dominated region is defined as the rapid filamentation zone wherein the filamentation time is shorter than the overturning time of deep convection an attempt has been made in this study to test the hypothesis in a full physics tropical cyclone model under idealized conditions and to extend the concept to the study of the inner core dynamics of tropical cyclones the foci of this paper are the evolution of the rapid filamentation zone during the storm intensification the potential roles of rapid filamentation in the organiz

dating topography of the sierra nevada california using apatite u th he ages the upward motion of rock masses relative to the earth s surface has been documented for most of the main mountain belts using thermochronological and petrological techniques more fundamental to the physical processes of mountain building however is the motion of the earth s surface itself which remains elusive here we describe a technique for estimating the age of topographic relief by mapping the low temperature thermal structure imparted by river incision using the ages of apatites determined from their uranium thorium and helium contents the technique exploits horizontal variations in temperature in the shallow crust that result from range normal river drainages because cooling beneath ancient river valleys occurs earlier than beneath intervening ridges our results from the sierra nevada california indicate that two of the modern transverse drainages the kings and the san joaquin had developed deep canyons by the late cretaceous period suggesting that the high topography of the range is 50 60 million years older than generally thought

mesoscale and convective scale characteristics of mature hurricanes part i general observations by research aircraft abstract the analysis of instrumented aircraft data from four recent mature hurricanes reveals common mesoscale and convective scale features the structure and organization of the convection precipitation and wind flow are studied by combining the airborne observations using basic instrumentation with quantitative radar measurements three predominant precipitation features seen are 1 the eyewall 2 a stratiform rain region adjacent to and outside the eyewall and 3 rainbands that contain both convective and stratiform regions the eyewall is so named because it surrounds the rain free eye but several additional features distinguish it from other convective bands in the hurricane in particular the updraft tangential wind maximum and highest rainfall have preferred locations relative to each other with the updraft being radially inward from the rain and wind maxima the 10 dbz radar reflectivity contour indicative of the inner edge slopes substantially outward with height and there is evide

post 10 ma uplift and exhumation of the northern coast mountains british columbia apatite u th he ages reveal three distinct periods in the exhumation history of the northern coast mountains 54 n a well developed helium partial retention zone indicates little or no exhumation between ca 30 and 10 ma beginning at 10 ma and extending to at least 4 ma the range underwent steady but slow exhumation of 0 22 mm yr after which the exhumation rate increased by at least 70 an 85 km long he age traverse across the orogen at sea level shows that vertical offsets on post 10 ma faults are minor furthermore the sea level he ages 14 2 8 ma inversely correlate with local mean elevation along the traverse these data suggest that the coast mountains first appeared as a significant topographic feature only within the past few million years this history is not consistent with suggestions that uplift of the range resulted from formation of the queen charlotte basin in early middle miocene time we speculate that intense erosion by alpine and continental glaciation after 2 5 ma triggered isostatic uplift and creation of the modern topography of the coast mountains

microfractures within the fault damage zone record the history of fault activity 1 for faults without sedimentary covers there is no robust method to obtain paleoseismic data that is crucial for the prediction of future damaging earthquake events sudden failure along faults during earthquakes induces off fault damage surrounding such basement faults we showed that the quaternary active fault has the damage zone characterized by a fracture density that decays exponentially with distance from the fault for both healed and open microfractures in contrast quaternary inactive faults contain only healed microfracture damage zone cross cutting relationships between microfractures and a minimum healing temperature of 100 c suggest that healed microfractures formed before and at deeper levels than did unhealed microfractures the damage zone defined by open microfractures reflects the recent fault movement during exhumation associated with erosion and regional uplift from the maximum depth at which microfractures may remain unhealed microfracture analysis can therefore be used to examine the history of basement fault activity

stratospheric gravity waves generated by typhoon saomai 2006 numerical modeling in a moving frame following the typhoon abstract stratospheric gravity waves generated by typhoon saomai 2006 were simulated using a mesoscale model in a moving frame of reference following the typhoon waves with large amplitudes appear near the domain center because of strong convection in the eyewall of the typhoon convection bands propagating outward from the storm center also generate waves propagating to the stratosphere convective forcing is significant in various propagation directions with maximum power in slowly moving eastward components due to convection in the eyewall the forcing exhibits large amplitude at a speed of 8 16 m s 1 in the eastward direction in which spiral bands are mainly developed induced gravity waves in the stratosphere are dominant in the eastward northeastward and southeastward propagation directions since westward waves are mostly filtered by the background wind below z 25 km while the typhoon moves northwestward for 78 h the wave characteristics vary through time depending on the evolution of the

uranium lead isotopic ages from the sierra nevada batholith california this study provides new information on the timing and distribution of mesozoic magmatic events in the sierra nevada batholithic complex chiefly between 36 and 37 n latitude u pb ages have been determined for 133 zircon and 7 sphene separates from 82 samples of granitoid rocks granitoid rocks in this area range in age from 217 to 80 m y triassic intrusions are restricted to the east side of the batholith jurassic plutons occur south of the triassic plutons east of the sierra nevada as isolated masses within the cretaceous batholith and in the western foothills of the range cretaceous plutons form a continuous belt along the axis of the batholith and occur as isolated masses east of the sierra nevada no granitic intrusions were emplaced for 37 m y east of the sierra nevada following the end of jurassic plutonism however following emplacement of the eastern jurassic granitoids regional extension produced a fracture system at least 350 km long into which the dominantly mafic calc alkalic independence dike swarm was intruded 148 m y ago the dike fractures probably represents a period of regional crustal extension caused by a redistribution of the regional stress pattern accompanying the nevadan orogeny intrusion of cretaceous granitic plutons began in large volume about 120 m y ago in the western sierra nevada and migrated steadily eastward for 40 m y at a rate of 2 7 mm y this slow and constant migration indicates remarkably uniform conditions of subduction with perhaps downward migration of parent magma generation or a slight flattening of the subduction zone such steady conditions could be necessary for the production of large batholithic complexes such as the sierra nevada the abrupt termination of plutonism 80 m y ago may have resulted from an increased rate of convergence of the american and eastern pacific plates and dramatic flattening of the subduction zone u pb ages of the giant forest alaskite sequence in sequoia national park are all in the range 99 3 m y indicating a relatively short period of emplacement and cooling for this nested group of plutons u pb ages of a mafic inclusion and its host granodiorite indicate that both were derived from a common source or that the mafic inclusion was totally equilibrated with the granodioritic magma comparison of isotopic ages determined by different methods such as zircon u pb sphene u pb hornblende k ar and biotite k ar suggests that zircon u pb ages generally approximate the emplacement age of a pluton however some plutons probably contain inherited or entrained old zircons and the zircons of some samples are disturbed by younger thermal and metamorphic events the ages reported here are consistent with u pb age determinations previously made on granitic rocks to the north stern et al 1981 the age distribution of granitic belts determined here is in general agreement with those established by k ar dating evernden and kistler 1970 but does not differentiate the five epochs of plutonism determined in their study

erosion and tectonics at the margins of continental plateaus the topography across the eastern margin of the central andean plateau north of 18 s beni region bears a strong resemblance to the topography of the southern margin of the tibetan plateau nepal himalaya with both regions featuring a steep frontal slope and high peaks at the plateau edge in contrast the topography of the eastern margin of the central andean plateau south of 18 s pilcomayo region tapers toward the foreland more gently and has no line of high peaks at the margin both the himalayan and the beni regions have been the sites for large amounts of denudation and in both regions geologic evidence suggests that erosion has been sufficiently vigorous for the physiographic plateau margin to have retreated toward the plateau interior during the neogene we hypothesize that the steep frontal slope and high peaks of the beni region and himalayan front largely reflect the high orographic precipitation and high erosion rates occurring in these regions and that the more gentle topography of the semiarid pilcomayo region reflects a tectonic landform only slightly modified by erosion we propose that orographic precipitation impinging on a plateau margin will generally tend to drop moisture low on the slope eroding back the plateau while enhancing or maintaining the steep long wavelength slope a numerical model coupling orographic precipitation erosion and tectonic uplift demonstrates the plausibility of this hypothesis the erosional efflux in both the beni and nepal himalaya have been considerable and simple mass balance calculations for the himalaya suggest that during the neogene the erosional mass efflux has generally outpaced the tectonic mass influx this contrasts with the apparent prior domination of tectonic influx and may reflect a decrease in the rate of tectonic addition during the same period and or increased late cenozoic erosion rates

current challenges to esr dating abstract electron spin resonance dating is applicable to a wide range of materials found at quaternary sites and which can generally be assured to exhibit zero signals at the time to be dated t 0 local inhomogeneity in external dose rates may contribute to dispersion in apparent dates but average dates may still be good estimates of site ages testing of u uptake models by u series measurements shows that both early and continuous uptake can occur possibly even in the same site problems of signal lifetime determination and diagenesis are reviewed

esr dating of the subsidiary faults in the yangsan fault system korea abstract the yangsan fault system is located near heavy industrial complexes and nuclear power plants in the korean peninsula we carried out esr dating of fault rocks from the wonwonsa and ihwa faults two subsidiary faults of the yangsan fault system esr ages are divided into three groups in order of decreasing confidence multiple plateau esr ages single plateau esr ages and maximum esr ages the wonwonsa fault was reactivated at least 4 times and the ihwa fault at least 2 times within the quaternary period long term cyclic fault activity of some subsidiary faults of the yangsan fault system occurred in the pleistocene and suggests the possibility of continued activity on this fault system

the kinematic structure of a hurricane with sea level pressure less than 900 mb abstract a national oceanic and atmospheric administration aircraft recorded the first doppler radar data in a tropical cyclone with a minimum sea level pressure mslp 50 m s 1 extended to 12 km higher than has been reported in previous hurricanes the inner eyewall contained weak

esr dating of fault gouge the effect of grain size abstract esr signals of quartz grains in fault gouge have been partially or completely reset by movements on the fault which allows the dating of the last fault movement in order to better understand the zeroing process we have studied the variation in esr signal ad and age in various grain sizes since it can be expected that larger grains will be less affected by stress than smaller grains we propose that a plateau of constant lower age for the smallest grains indicates total resetting this is confirmed in gouge from a fault in california only such samples should be used for dating

dating of a volcanic rock by electron spin resonance the age of a volcanic rock has been determined by esr dating using the ge center in quartz the total dose of natural radiation and the age obtained from the ge center are 460 krad and 2 07 0 50 ma respectively and those from the unidentified defect at g 2 011 are 484 krad and 2 16 0 21 ma respectively these dates agree well with the age of 2 0 0 5 ma determined by the fission track method high stress or temperature destroy these accumulated defects but in the same time produce a lot of new diamagnetic precursors which enable us to observe the clear esr signal

tropical cyclone kinematic structure retrieved from single doppler radar observations part iii evolution and structures of typhoon alex 1987 abstract this paper is the third of a series that focuses on the applications of the ground based velocity track display gbvtd technique and the gbvtd simplex center finding algorithm developed in the previous two papers to a real tropical cyclone tc the evolution and structure of typhoon alex 1987 including full tangential winds mean radial winds one component of the mean flow and their derived axisymmetric angular momentum and perturbation pressure fields are reconstructed from 16 volume scans 6 5 h of data with a 2 h gap from the civil aeronautic administration caa doppler radar while typhoon alex moved across the mountainous area in northern taiwan this analysis retrieves a plausible and physically consistent three dimensional primary circulation of a landfalling tc using a single ground based doppler radar highly asymmetric wind structures were resolved by the gbvtd technique where the maximum relative tangential wind at z 2 km evolved from 52 m s 1 before landfall to less than

increase of radiation sensitivity of esr centres by faulting and criteria of fault dates abstract the esr spectra and ages of the fractured rocks along the itoigawa shizuoka tectonic line a major fault in japan were measured the esr signal intensities tend to become larger with decreasing distance from the fault boundary because the radiation sensitivities of the esr centres have increased by faulting according to fracturing and heating experiments when the radiation sensitivities of esr centres have visibly increased the signals may have been almost completely reset by faulting as a result of the increase of radiation sensitivity the error range of the td values for incompletely reset esr signals is comparatively large whereas it is smaller in the case of completely reset signals therefore by assessing the error range of td values we can determine whether esr signals were completely reset at the time of faulting

rapid intensification eyewall contraction and breakdown of hurricane charley 2004 near landfall 1 the rapid intensification and decay in hurricane charley 2004 was sampled by the wsr 88ds in key west and tampa charley s axisymmetric wind fields vertical vorticity perturbation pressure and reflectivity were derived from the ground based velocity track display gbvtd technique charley s rapid intensification was accompanied by a contracting eyewall the central pressure dropped 33 hpa in three hours the vortex was unstable possessed a ring vorticity profile during the eyewall contraction while the vortex became stable monopole vorticity profile after charley reached its peak intensity charley s eyewall broke down during the decaying stage after the land fall this study demonstrates the powerful combination of the gbvtd technique and coastal wsr 88d data in monitoring landfalling tropical cyclones

the evolution of hurricane danny 1997 at landfall doppler observed eyewall replacement vortex contraction intensification and low level wind maxima danny made landfall as a minimal hurricane on the alabama coast on 19 july 1997 after drifting over mobile bay for over 10 h danny s unusually close proximity to the doppler radar wsr 88d in mobile provided an unprecedented view of the storm s complex and dramatic evolution during a prolonged landfall event over a 1 day period base reflectivity and velocity products were combined with aircraft reconnaissance information to detail the formation of concentric eyewalls and complete evolution of an eyewall replacement cycle this highly symmetric hurricane then underwent a rapid asymmetric transition in mobile bay during which a small eyewall mesovortex developed adjacent to intense convection in the western eyewall radar estimated rainfall increased dramatically during the asymmetric phase rates exceeded 100 mm h21 for nine consecutive hours west of the center while precipitation nearly vanished to the east changes in the distribution of precipitation corresponded with changes in the low level wind velocity structure a 25 h temporal composite of wsr 88d base velocities displayed axisymmetric intensification and contraction of danny s core during the eyewall replacement cycle later the asymmetric phase was dominated by further contraction and intensification on the west side only in the western eyewall a persistent boundary layer wind maximum evolved and contracted to a radius of only 10 13 km from the center concurrently eastside boundary layer winds diminished as the maximum winds rose to 1 1 5 km altitude and the radius expanded danny reached maximum intensity during this asymmetric phase in mobile bay with base velocities 44 m s21 85 kt at 600 m elevation eyewall contraction in the meandering storm combined with climatologically elevated ssts in shallow mobile bay probably played significant roles in danny s continued intensification there discrepancies arose in determining danny s structural patterns intensity and evolution during landfall interpretation varied depending on the type of platform used to observe the storm the continual sampling of the storm by the nearby wsr 88d provided detail not available from aircraft data alone doppler base velocities in the intense westside convection were much stronger than measured at flight level yet the opposite was true in the storm s drier east side doppler radar showed that the westside base velocity maxima were confined to the boundary layer 600 700 m and represented a slightly conservative estimate of maximum surface gusts recorded at dauphin island during the passage of danny s convective eyewall thus winds probably were even stronger at boundary layer levels below the wsr 88d s lowest scan elevation the shallowness and persistence of danny s boundary layer velocity maxima stressed the need for accurate wind information in the lowest few hundred meters of a tropical cyclone s eyewall for a better indication of the storm s true intensity and near surface wind velocities

tropical cyclone kinematic structure retrieved from single doppler radar observations part ii the gbvtd simplex center finding algorithm abstract this paper is the second of a series and focuses on developing an algorithm to objectively identify tropical cyclone tc vorticity centers using single doppler radar data the first paper dealt with the formulation of a single doppler radar tc wind retrieval technique the ground based velocity track display gbvtd and the results are verified using analytical tcs it has been acknowledged that the quality of the gbvtd retrieved tc circulation strongly depends on accurately knowing its center position however existing single doppler radar center finding algorithms are limited to estimate centers for axisymmetric tcs the proposed algorithm uses a simplex method to objectively estimate the tc vorticity center by maximizing gbvtd retrieved mean tangential wind when tested with a number of axisymmetric and asymmetric analytical tcs the accuracy of the tc centers estimated by the gbvtd simplex algorithm is 340 m from the true center when adding 5 m s 1 random noise to the doppler velocities

cenozoic thermal evolution of the central sierra nevada california from uth he thermochronometry apatite u th he cooling ages are reported for igneous apatite samples from the central sierra nevada and compared to published apatite fission track ages and track length data from the same mineral separates helium ages are youngest at low elevations and increase systematically toward higher elevations ranging from 43 to 84 ma at yosemite valley 32 to 74 ma at kings river canyon and 23 to 75 ma at mt whitney helium ages from high elevation samples are generally concordant with corresponding fission track ages while lower elevation helium ages are substantially younger cooling histories inferred from present laboratory derived fission track annealing and helium diffusion models do not match well suggesting that either helium diffusion rates or fission track annealing rates are miscalibrated at temperatures below about 60 c for geologic exposure periods unlike the fission track results the helium data do not indicate a very low geothermal gradient in the sierra nevada during early to middle tertiary time

relative and absolute dating of land surfaces abstract the dating of land surfaces has long posed problems for geomorphologists relative methods stratigraphic geomorphic topographic are sound and convincing exhumed forms may complicate identification and relationships for both epigene and etch forms have been buried and exhumed but in tectonically undisturbed areas the higher surfaces are older than those preserved at lower levels also surfaces have an age range the relationship of surfaces with volcanic deposits old shorelines and genetically related sedimentary sequences provides sound ages and correlation with dated duricrusts and faults is also useful there are no temporal limits to relative dating for the methods are equally applicable to the dating say of proterozoic surfaces as of those of pleistocene age the disadvantage of such methods is that the necessary evidence is frequently either not preserved or not exposed the so called absolute physical numerical methods and especially those based on exposure age dating with in situ cosmogenic radionuclides are appealing because they produce direct numerical ages and appear to be widely applicable but there are severe temporal limitations and sampling problems complicate and may invalidate interpretation absolute age determinations must be consistent with the stratigraphic and geomorphologic settings the best results are obtained when physicists and earth scientists pool their knowledge and experience a background in local and regional geology is especially important

tropical cyclone kinematic structure retrieved from single doppler radar observations part i interpretation of doppler velocity patterns and the gbvtd technique abstract deducing the three dimensional primary circulation of landfalling tropical cyclones tcs from single ground based doppler radar data remains a difficult task the evolution and structure of landfalling tcs and their interactions with terrain are left uncharted due to the lack of dual doppler radar observations existing ground based single doppler radar tc algorithms provide only qualitative information on axisymmetric tc center location and intensity in order to improve understanding of the wind structures of landfalling tcs using the widely available wsr 88d data along the u s coastal region a single ground based radar tc wind retrieval technique the ground based velocity track display gbvtd technique is developed part i of this paper presents 1 single doppler velocity patterns of analytic asymmetric tcs 2 derivation of the gbvtd technique and 3 evaluation of the gbvtd retrieved winds using analytic tcs the doppler velocity patterns of asymmetric tcs display more complex structu

magmatic arc asymmetry and distribution of anomalous plutonic belts in the batholiths of california effects of assimilation crustal thickness and depth of crystallization in order to better understand geologic fac tors controlling pronounced regional variations in whole rock chemistry mineralogy and mineral chemistry in the batholiths of california we calculate the magmatic intensive variables f hf f h 2 o f hf f hcl and f o 2 regional scale west to east increases in f oh in mafic silicates corresponding to the systematic i wc to i mc and i sc progression reflect orders of magnitude increase in f hf f h 2 o attending pluton crystallization low f hf f h 2 o of formation of western i wc types is consistent with their derivation from low fluorine source rocks in subducted oceanic slabs or the upper mantle in contrast higher f hf f h 2 o of crystallization of i mc and i sc types to the east implies the involvement of 1 progressively greater amounts of continental crustal source material such as biotite bearing metamorphic rocks their unweathered sedimentary derivatives retaining f rich mafic minerals or their fusion products and or 2 source materials which become more f rich toward the continental interior the regional distribution of i mc and i sc types suggests that the precambrian craton of western north america or derivative sediments may extend farther north in california and be morphologically more complex than previously thought from seemingly out of place occurrences of i wc plutons on the eastern slopes of the sierra nevada batholith we infer the existence of regions where precambrian basement was thin or absent in mesozoic time which prevented extensive cratonal contamination of subducted slab or upper mantle derived magmas new methods for estimating t f o 2 relations in the magmas demonstrate that i scr granites crystallize at oxygen fugacities as much as five orders of magnitude lower than those of i wc i mc and i sc types under conditions at or below the maximum stability limit of graphite in equilibrium with a c o h s gas phase the local scale formation of i scr granites in plutonic belts within specific wall rock terranes containing highly reducing sediments or metasediments may occur by contamination of i types with graphitic pelite or in some cases by the direct fusion of this reducing pelitic wall rock the spatial distribution of i scr granite provinces therefore is controlled simply by wall rock lithology amphibole geobarometry demonstrates a general west to east decrease in crystallization pressure across the sierra nevada batholith in contrast the peninsular ranges batholith displays a west to east crystallization pressure increase the bulk of the california batholiths crystallized at pressures less than 4 5 kb and depths less than about 15 19 km in the southern sierra nevada batholith the san gabriels and the eastern peninsular ranges however plutons crystallized at pressures exceeding 6 kb at deep crustal levels 23 km reconstruction of the pre erosion top of the batholith shows that in an east west cross section the central sierra nevada batholith was a horizontal tabular body with an aspect ratio of at least five to one

concentric eye walls secondary wind maxima and the evolution of the hurricane vortex abstract research aircraft observations in recent hurricanes support the model of shapiro and willoughby 1982 for the tropical cyclone s response to circularly symmetric convective heat sources convective rings in both nature and the numerical model the tangential wind commonly increases rapidly just inside the radius of maximum wind and decreases inside the eye near the central axis of the vortex thus both secondary outer wind maxima and eyewall wind maxima often contract as they intensify this response is independent of the horizontal spatial scale of the maximum an outer maximum is frequently observed to constrict about a pre existing eye and replace it this chain of events often coincides with a weakening or at least a pause in intensification of the vortex as a whole the concentric eye phenomenon is a common but by no means universal feature of tropical cyclones it is most frequently observed in intense highly symmetric systems

electron spin resonance esr dating abstract esr dating has been systematically applied in earth sciences and archaeology since 1975 when ikeya dated a stalactite from the akiyoshi cave in japan in the meantime this new technique has been successfully applied to the dating of materials such as speleothems spring deposited travertines mollusc shells corals and tooth enamel the present research focuses on the dating of quartz which allows the age assessment of heated ceramics volcanic rocks intrafault material or windblown sediments esr dating is based on the measurement of the number of paramagnetic centers in a mineral these centers are generated by alpha beta and gamma radiation of the matural radioelements such as u th and k and have accumulated over time two parameters have to be determined the accumulated dose ad and the dose rate d to which the sample was exposed this review comprises three major parts a introduction into esr dating b application of the method and c appendices giving detailed description of dose rate calculation physical basis of electron spin resonance the esr spectrometer and esr lines the major emphasis lies on the outline of the application of esr dating this includes the discussion of the esr signals of the various materials sampling sample preparation and measurement techniques

applicability of esr dating using multiple centres to fault movement the case of the itoigawa shizuoka tectonic line a major fault in japan abstract no direct method for dating the fault movement has been hitherto established except esr dating whose applicability is disputed however the most serious question in esr dating is whether accumulated esr signals are completely reset at the time of fault movement when the defect centres are partially preserved at the time of previous faulting the date obtained is uncertain we have shown fukuchi et al 1985 1986 however that we can judge correctly whether esr signals were completely reset or not when the esr signal counting is done for multiple esr centres of different stabilities for resetting from the data for completely reset centres actual date of fault movement can be calculated this multiple centre method was tested with samples whose esr signal intensities are judged to be about zero at the time of fault movement the result which confirms the applicability for the fault movement dated back to 100 ka bp is presented in this paper

lithospheric gravitational potential energy and past orogenesis implications for conditions of initial basin and range and laramide deformation gravitational body forces i e buoyancy forces have come to be seen as critical to the evolution of orogens nevertheless constraining the role of body forces in specific geologic scenarios is made difficult by the substantial number of poorly constrained physical parameters needed to fully relate forces to deformation by separating the calculation of buoyancy forces from the calculation of the resulting deformation models based on relatively simple descriptions of the lithosphere can yield geologically useful constraints among these are the importance of paleoelevation in driving syn and postcontractional extension and in localizing contractional strain although such phenomena have been considered in more complex models of continental deformation the simpler analysis presented here clearly establishes first order limits on lithospheric structures and paleoelevations consistent with buoyancy driven deformation in the early cenozoic great basin of the western united states we show that the low elevations inferred in much of the geologic literature are inconsistent with a body force origin for observed extensional tectonism east of the colorado plateau localization of laramide deformation coincides with pre laramide subsidence of the western interior seaway this subsidence prestressed the lithosphere making the southern rocky mountains the weak link in responding to regional compressional stress

observations on the micro texture and esr spectra of quartz from fault gouge abstract we have investigated fault gouge samples from a variety of sites in eastern china with esr optical and scanning electron microscopy sem x ray diffraction and cathodoluminescence the results reveal two different types of quartz a macrocrystalline and a microcrystalline variety the macrocrystalline samples show increasing esr intensities of the e centre with increasing grain size whilst the microcrystalline samples show the opposite trend we also found that the dissolution of quartz grains and secondary quartz precipitation on the surface of the grains is significant in some samples indicating active chemical weathering in these fault zones the occurrence of secondary quartz has serious implications for the reliability of any dating attempt

hurricane intensity and eyewall replacement observations made during the historic 2005 hurricane season document a case of eyewall replacement clouds outside the hurricane eyewall coalesce to form a new eyewall at a greater radius from the storm center and the old eyewall dies the winds in the new eyewall are initially weaker than those in the original eyewall but as the new eyewall contracts the storm reintensifies understanding this replacement mechanism is vital to forecasting variations in hurricane intensity processes in the moat region between the new and old eyewall have been particularly unclear aircraft data now show that the moat becomes dynamically similar to the eye and thus is converted into a region inimical to survival of the inner eyewall we suggest that targeting aircraft to key parts of the storm to gain crucial input to high resolution numerical models can lead to improvements in forecasting hurricane intensity

esr plateau dating of fault gouge abstract the use of esr dating to determine the time of last motion on a fault requires that the signals must have been fully zeroed at the time of last motion zeroing can be demonstrated by comparing the ages of successively finer grain sizes of quartz if a plateau of low ages is found for the finest grains this should represent the age of last motion testing this model on various strands of the san gabriel fault zone in southern california we find low age plateaus in all samples and also convergence of ages for two different esr signals in most samples esr dating of single samples of quartz with larger grains than those of the plateau will result in too large an age of last motion and may fail to observe convergence between ages given by two or more esr signals

reconstructing the paleotopography of mountain belts from the isotopic composition of authigenic minerals the paleorelief of mountain belts can be estimated from the 18 o value of authigenic minerals development of relief during mountain building often creates lee side rain shadows in which precipitation is depleted in 18 o and d the magnitude of this rain shadow effect is strongly correlated to relief a compilation of 18 o data from surface waters throughout the globe shows a linear relationship between net elevation change and 18 o r 2 0 79 through the use of this relationship we investigated the timing and magnitude of elevation change in the southern alps of new zealand and the sierra nevada of california the 18 o values of kaolinites from new zealand show an 6 decrease in the early pliocene that corresponds to an 2 km elevation change in the southern alps the 18 o of smectites from the sierra nevada show little change since 16 ma suggesting that these mountains have been a long standing topographic feature

direct esr dating of fault gouge using clay minerals and the assessment of fault activity abstract the esr dating method has been applied to the fault gouge of the nojima fault the outcrop of which arose due to the southern hyogo prefecture earthquake on january 17th 1995 and to the fault gouge of the median tectonic line mtl which is a major active fault in japan without considering the resetting of esr signals the esr ages obtained for clay minerals in the fault gouges are considered to indicate the age of the beginning of the fault movements at the outcrop assuming no radon loss and the general values of water content and ray efficiency the esr ages of the fault gouges of the nojima fault and mtl are estimated as 0 55 1 16 and 6 76 9 28 ma respectively the esr age of the nojima fault is consistent with the age of the beginning of the rokko movements in the kinki districts estimated geologically on the other hand the esr age obtained from the mtl is younger than the k ar age about 11 ma which is presumably overestimated due to the existence of the source minerals in the k ar dating sample since it is geologically known that the mtl at the outcrop had moved until the late pleistocene holocene the fault movement of the mtl at this outcrop probably began at 6 76 9 28 ma b p after the intrusion of the felsitic dyke 12 16 ma which is the source rock of the fault gouge into the fault boundary the esr dating of clay minerals in the fault gouge may be effective for assessing fault activity if no quaternary deposit exists at the outcrop the younger the esr age of the fault gouge is the higher the fault activity is if not indurated and the freshest clay gouge can be collected at the outcrop the esr age of the most recent movement may be obtained from the clay gouge

gnss based statistical analysis of ionospheric anomalies during typhoon landings in taiwan japan using the global navigation satellite system gnss differenced total electron content dtec series the traveling ionosphere disturbances tids of 22 typhoons registered in taiwan japan between 2013 and 2016 were studied the horizontal speed of the first tid during a typhoon landing can be estimated by a two station method with the ionosphere anomaly indicator in total electron count units tecus dtec 0 15 tecu the horizontal speed of the tids was from 155 to 210 m s and with an average speed of 168 70 m s the estimated tid speeds of typhoons soudelor 205 93 m s and megi 158 47 m s are not consistent with each other even though they had very similar trajectories when cross through taiwan island moreover the propagation velocity of the typhoon ionospheric anomaly showed a significant positive correlation r 0 78 0 05 with the change rate of the typhoon central air pressure and a negative correlation r 0 52 0 05 with the central pressure before landing gravity waves were generated by land friction terrain blocking and strong wind shear transport energy into the atmosphere from the near surface to the mesosphere and thermosphere which is the main cause of ionosphere disturbances during typhoon landing

single doppler radar observation of the concentric eyewall in typhoon saomai 2006 near landfall 1 landfalling typhoon saomai 2006 was observed by the cinrad wsr 98d radar on the southeast coast of china this study documents the formation and evolution of a concentric eyewall episode using the axisymmetric circulation derived from the ground based velocity track display technique saomai s outer eyewall formed after reaching its peak intensity 5 hours before landfall updraft tangential wind maximum and shallow low level inflow coincided with the high reflectivity and voriticity ring in both inner and outer eyewalls surrounding a moat region characterized by weak downward motion and lower reflectivity the subsidence and rain free moat region between the two eyewalls was filled with rain and upward motion prior to landfall indicating a breakdown in the outer eyewall which was a barrier to radial inflow meanwhile the outer vorticity maximum flattened and the central pressure dropped 9 hpa the eyewall replacement cycle didn t complete probably due to the landfall

electron spin resonance esr dating of pre quaternary faults in the sichuan basin sw china abstract the electron spin resonance esr dating method is thought to be limited to the quaternary period in this study we attempt to expand the esr dating range to the pre quaternary using three fault zone samples collected from faults in the sichuan basin and its surroundings we adopt a ray radiation dose of up to 2 104 gy which is much greater than that typically employed and find that the esr intensity of the e1 center a type of signal for esr dating in quartz continuously increases with the ray dose and is slightly influenced by the radiation dose rate this indicates the potential of esr to date pre quaternary faults by simulating environmental radiation under geological burial conditions we use esr to date the latest extension event in the western hubei and hunan thrust belt to 9 17 0 76 ma and the thrusting of the longmenshan fault zone toward the sichuan basin to approximately 6 14 0 73 ma conversely the saturated esr intensity of fault zone samples from the daba fault zone suggests a lack of strong tectonic activity in the southern daba fault zone in the last 10 ma our results are consistent with fission track ages and the regional tectonic evolution history therefore esr is a practical method for dating pre quaternary faults in structural and petroleum geology applications

experimental investigations on dating the last earthquake event using osl signals of quartz from fault gouges abstract obtaining a reliable age of the latest seismic slip event along an active fault is important for seismic hazard assessment here we observe changes in the optically stimulated luminescence osl signal of quartz crystals due to frictional heating in artificial fault gouges comprising a mixture of quartz grains and ca bentonite powder the fault gouge was deformed using a high velocity rotary shear apparatus at room temperature and room humidity at a seismic slip rate of 1 31 m s 1 intense slip localization occurred along a very thin layer 300 m thick within the simulated fault zones 1 mm thick the estimated temperature of the slip localized layer sll increased by 475 c from frictional heating the quartz osl signals of the gouges were fully reset most noticeably for the sll in contrast there was rare slip localization at subseismic slip rates 0 06 0 001 m s 1 for which the estimated temperature rise in the sll was 120 c hence the quartz osl signal was not reset under this condition the results suggest that quartz osl dating can be used to constrain the age of the latest seismic event in natural quartz bearing fault zones where a sll occurs

temporal changes of the primary circulation in tropical cyclones abstract more than 900 radial profiles of in situ aircraft observations collected in 19 atlantic hurricanes and tropical storms over 13 years confirm that the usual mechanism of tropical cyclone intensification involves contracting maxima of the axisymmetric swirling wind radar shows that annuli of convective echoes accompany the wind maxima these features called convective rings exist and move inward because latent heat released in the rings leads to descent adiabatic warming and rapid isobaric height falls in the area they enclose the radial change in rate of isobaric height fall is concentrated at the inner edge of the wind maximum causing the gradient wind to increase there and the maximum to contract vigorous convection organized in rings invariably causes well defined inward moving wind maxima but when convection is weak the rings are also weak or even absent in this case the swirling wind may be nearly constant with radius and change slowly in time hurricanes that have a single vigor

polygonal eyewalls asymmetric eye contraction and potential vorticity mixing in hurricanes hurricane eyewalls are often observed to be nearly circular structures but they are occasionally observed to take on distinctly polygonal shapes the shapes range from triangles to hexagons and while they are often incomplete straight line segments can be identified other observations implicate the existence of intense mesovortices within or near the eye region is there a relation between polygonal eyewalls and hurricane mesovortices are these phenomena just curiosities of the hurricane s inner core circulation or are they snapshots of an intrinsic mixing process within or near the eye that serves to determine the circulation and thermal structure of the eye as a first step toward understanding the asymmetric vorticity dynamics of the hurricane s eye and eyewall region these issues are examined within the framework of an unforced barotropic nondivergent model polygonal eyewalls are shown to form as a result of barotropic instability near the radius of maximum winds after reviewing linear theory simulations with a high resolution pseudospectral numerical model are presented to follow the instabilities into their nonlinear regime when the instabilities grow to finite amplitude the vorticity of the eyewall region pools into discrete areas creating the appearance of polygonal eyewalls the circulations associated with these pools of vorticity suggest a connection to hurricane mesovortices at later times the vorticity is ultimately rearranged into a nearly monopolar circular vortex while the evolution of the finescale vorticity field is sensitive to the initial condition the macroscopic end states are found to be similar in fact the gross characteristics of the numerically simulated end states are predicted analytically using a generalization of the minimum enstrophy hypothesis in an effort to remove some of the weaknesses of the minimum enstrophy approach a maximum entropy argument developed previously for rectilinear shear flows is extended to the vortex problem and end state solutions in the limiting case of tertiary mixing are obtained implications of these ideas for real hurricanes are discussed

paleo geomorphology of the sierra nevada california from u th he ages in apatite new apatite u th he ages from the central sierra nevada california place limits on the morphology and evolution of longitudinal profiles of major transverse river drainages developed in the late cretaceous helium ages from a new orogen parallel constant elevation sample transect are relatively uniform 60 ma and not correlated with topography unlike those from a similar lower elevation transect approx 15 km to the west we interpret the marked difference in the two orogen parallel profiles to reflect a headward decrease in long wavelength transverse relief at the time of cooling consistent with either a concave up stream gradient typical of those observed near the headwaters of modern sierran trunk streams or a convex gradient like those found along slope breaks of eroding plateau edges from the san joaquin drainage we obtained a new helium age versus elevation profile which has a comparable slope to those previously reported for the yosemite valley kings canyon and mt whitney areas this new profile yields slightly older ages at a given elevation as expected from its position adjacent to the largest major drainage the age versus elevation profiles imply that the mean denudation rate of the region in the cenozoic was about 0 04 to 0 05 mm yr we show that long wavelength 70 km relief inferred from longitudinal helium age variations is a strong function of erosion rate such that even relatively subdued relief is detectable with helium age profiling provided that denudation rates were low using the rate implied by sierran age versus elevation profiles we infer long wavelength relief of 1500 500 m in the late cretaceous by analogy with modern orogenic plateaus this value of long wavelength relief suggests a cretaceous interior cordilleran plateau lay at an elevation of at least 3000 m

the impact of t trec retrieved wind and radial velocity data assimilation using enkf and effects of assimilation window on the analysis and prediction of typhoon jangmi 2008