an anticyclonic circulation above the northwest georgia rise southern ocean data from a variety of sources reveal a warm core anticyclonic circulation above the northwest georgia rise nwgr an similar to2000 m high bathymetric feature north of south georgia the sense of the circulation is opposite to the general cyclonic flow in the georgia basin the circulation shows the characteristics of a stratified taylor column dimensional analysis shows that the local bathymetry and hydrography are conducive to the formation of such ers2 altimeter data show that the column whilst not fully permanent is nonetheless a recurring feature high concentrations of chlorophyll a are observed at the centre of the circulation indicating that the modulation of the physical environment has significant consequences for the local biogeochemical system via enhanced primary production enhanced chlorophyll a extends in a long plume from the nwgr along pathways indicated by drifters this passive redistribution may have consequences for the larger basin scale ecosystem

sea level anomalies control phytoplankton biomass in the costa rica dome area 1 satellite data show that chlorophyll a concentration chl a in the northeastern tropical pacific is well correlated with sea level anomaly sla this correlation spans a wide spectrum of scales from large scale phenomena like enso to mesoscale cyclonic and anticyclonic eddies negative sla e g during la nina events and in cyclonic eddies is associated with the lifting of isopycnals in the nutricline and increased chl a due to enhanced phytoplankton growth while positive sla e g during el nino events and in anticyclonic eddies is associated with a deeper nutricline and reduced chl a due to decreased phytoplankton growth the coupling between sla and chl a anomaly in the costa rica dome crd area is tighter than has previously been recorded anywhere in the world ocean 70 of the interannual variations in chl a anomaly in the crd area is explained by a combination of the positive and negative effects of sla citation kahru m p c fiedler s t gille m manzano and b g mitchell 2007 sea level anomalies control phytoplankton biomass in the costa rica dome area geophys res lett 34 l22601 doi 10 1029 2007gl031631

holocene paleoseismicity temporal clustering and probabilities of future large m 7 earthquakes on the wasatch fault zone utah the chronology of m 7 paleoearthquakes on the central five segments of the wasatch fault zone wfz is one of the best dated in the world and contains 16 earthquakes in the past 5600 years with an average repeat time of 350 years repeat times for individual segments vary by a factor of 2 and range from about 1200 to 2600 years four of the central five segments ruptured between 620 30 and 1230 60 calendar years b p the remaining segment brigham city segment has not ruptured in the past 2120 100 years comparison of the wfz space time diagram of paleoearthquakes with synthetic paleoseismic histories indicates that the observed temporal clusters and gaps have about an equal probability depending on model assumptions of reflecting random coincidence as opposed to intersegment contagion regional seismicity suggests that for exposure times of 50 and 100 years the probability for an earthquake of m 7 anywhere within the wasatch front region based on a poisson model is 0 16 and 0 30 respectively a fault specific wfz model predicts 50 and 100 year probabilities for an m 7 earthquake on the wfz itself based on a poisson model as 0 13 and 0 25 respectively in contrast segment specific earthquake probabilities that assume quasi periodic recurrence behavior on the weber provo and nephi segments are less 0 01 0 07 in 100 years than the regional or fault specific estimates 0 25 0 30 in 100 years due to the short elapsed times compared to average recurrence intervals on those segments the brigham city and salt lake city segments however have time dependent probabilities that approach or exceed the regional and fault specific probabilities for the salt lake city segment these elevated probabilities are due to the elapsed time being approximately equal to the average late holocene recurrence time for the brigham city segment the elapsed time is significantly longer than the segment specific late holocene recurrence time

the unusual surface chlorophyll signatures of southern ocean eddies southern ocean mesoscale eddies play an important role in ocean circulation and biogeochemical cycling but their biological characteristics have not been well quantified at the basin scale to address this we combined a 15 year tracked eddy data set with satellite observations of ocean color sea surface temperature and autonomous profiling floats to quantify the surface and subsurface properties of eddies anomalies of surface temperature and chlorophyll were examined in eddy centric composite averages constructed from thousands of eddies normalized surface chlorophyll anomalies chlnorm vary seasonally and geographically cyclones typically show positive chlnorm while anticyclones have negative chlnorm the sign of chlnorm reverses during late summer and autumn for eddies between the subtropical and polar fronts the reversal is most obvious in the indian sector and we attribute this to a combination of eddy stirring deformation of surface gradients by the rotational velocity of an eddy and deeper winter mixing in anticyclones both chlnorm and sea surface temperature anomalies transition from dipole structures north of the subtropical front to monopole structures south of the subantarctic front sea surface temperature and chlnorm composites provide evidence for eddy trapping transporting of anomalies and eddy stirring this research provides a basin scale study of surface chlorophyll in southern ocean eddies and reveals counterintuitive biogeochemical signals

viscosity estimates for the crust and upper mantle from patterns of lacustrine shoreline deformation in the eastern great basin the deformed shorelines of lake bonneville constitute a classic source of information on lithospheric elastic thickness and upper mantle viscosity we describe and apply a new model to a recently augmented data set new data better constrain both the complex spatio temporal pattern of the lake load and the crustal deformation response to that load the history of lake level fluctuations has been significantly refined and somewhat modified this is due to both more radiocarbon dates from within the bonneville basin and to an improved calibration of the radiocarbon timescale itself the data which constrain the crustal deformation pattern consist of ages and shoreline elevations from several hundred points which sample three major levels of lake bonneville and corresponding elevations from the high stands of three smaller lakes situated to the west of lake bonneville the data from the smaller lakes help elucidate the pattern of deflection which occurred beyond the edge of the big lake the geometry of the earth model incorporates an arbitrary number of layers overlying a half space and the rheology of each level can accommodate an arbitrary number of maxwell viscoelastic elements in parallel the inverse modeling comprises three complementary approaches for the simplest configurations we performed a direct search of the parameter space and delineated the irregular boundary of the subspace of acceptable models for more complex configurations we constrained the elastic parameters to their seismically determined values and then solved for viscosity versus depth profiles by either expressing the log viscosity versus log depth profile as a series of specially constructed orthogonal polynomials or by allowing each of 8 10 layers plus the half space to have an independently determined viscosity we found that the data do not strongly support nor can they conclusively exclude a more complex rheology than simple maxwell viscoelasticity the orthogonal polynomial solution exhibits an essentially monotonic decrease in viscosity with depth the most rapid change occurs at shallow depths decreasing from 1023 pa s at 3 km to 102o pa s at 30 km the decrease is much more gradual below with only another factor of 5 decrease between 30 and 300 km depth the unconstrained solution exhibits a rapid decrease in viscosity with depth from 2x 10 24 pa s in the top 10 km to 4x 1017 pa s at a depth of 40 km a nearly isoviscous asthenospheric region extends from 40 to 150 km and is underlain by a mantle lithospheric region with increased viscosity 2x 102o pa s extending from 150 to 300 km depth and by a uniform viscosity 1019 pa s half space below

late quaternary activity along the lone pine fault eastern california the lone pine fault is a north trending secondary break of the owens valley fault zone 1 4 km west of lone pine california this fault forms an east facing scarp as much as 6 5 m high across an abandoned outwash fan of the tioga latest pleistocene glaciation the fault experienced large right lateral and smaller vertical displacement during the 1872 owens valley earthquake knowledge of the character and amount of slip at this site in and before 1872 is necessary for evaluations of earthquake hazard near owens valley and may help us to understand earthquakes along other parts of the eastern front of the sierra nevada and in the great basin scarp profiles indicate a 1 to 2 m component of dip slip in 1872 thus three 1872 type earthquakes could have created the scarp this number of events is also indicated by desert varnish patterns on boulders in the fault scarp by scarp morphology and by sediments near the fault horizontal offset of a relict channel on the fan is 12 to 18 m 3 earthquakes horizontal offset of a younger debris flow is 10 to 12 m apparently 2 earthquakes average horizontal offset for each earthquake including that of 1872 is 4 to 6 m the age of the fan surface is bracketed by a 21 ka shoreline of former lake owens and by the time of abandonment of the fan about 10 ka an average recurrence interval for 3 earthquakes is 5 000 to 10 500 yr the average recurrence interval combined with the average oblique offset for each event of 4 3 to 6 3 m gives an average late quaternary slip rate of 0 4 to 1 3 mm yr for the lone pine fault if we add the average horizontal slip component for the lone pine fault to the 1872 horizontal slip reported for the adjacent main owens valley trace of 2 7 to 4 9 m the combined 1872 horizontal slip component for the owens valley fault zone is approximately between 7 and 11 m a large value the associated horizontal slip rate for the owens vallev fault zone is 0 7 to 2 2 mm yr

regional variations in the influence of mesoscale eddies on near surface chlorophyll eddies can influence biogeochemical cycles through a variety of mechanisms including the excitation of vertical velocities and the horizontal advection of nutrients and ecosystems both around the eddy periphery by rotational currents and by the trapping of fluid and subsequent transport by the eddy in this study we present an analysis of the influence of mesoscale ocean eddies on near surface chlorophyll chl estimated from satellite measurements of ocean color the influences of horizontal advection trapping and upwelling downwelling on chl are analyzed in an eddy centric frame of reference by collocating satellite observations to eddy interiors as defined by their sea surface height signatures the influence of mesoscale eddies on chl varies regionally in most boundary current regions cyclonic eddies exhibit positive chl anomalies and anticyclonic eddies contain negative chl anomalies in the interior of the south indian ocean however the opposite occurs the various mechanisms by which eddies can influence phytoplankton communities are summarized and regions where the observed chl response to eddies is consistent with one or more of the mechanisms are discussed this study does not attempt to link the observed regional variability definitively to any particular mechanism but provides a global overview of how eddies influence chl anomalies

thermoluminescence dating of sand dunes in rajasthan india we report here a new application of thermoluminescence tl for dating sand dunes this application assumes that exposure to sunlight causes bleaching of the geological tl of a sediment to a residual value and that tl accumulation starts again when the sediment is buried under fresh deposit and is thus shielded from the sun although the tl method has been applied to loess1 2 and ocean sediments3 4 the application of this technique to sand dunes provides the first reliable dating control for dune dynamics palaeoclimatology and spread of deserts

vertical structure of mesoscale eddies in the eastern south pacific ocean a composite analysis from altimetry and argo profiling floats 1 the mean vertical structure of mesoscale eddies in the peru chile current system is investigated by combining the historical records of argo float profiles and satellite altimetry data a composite average of 420 526 profiles acquired by argo floats that surfaced into cyclonic anticyclonic mesoscale eddies allowed constructing the mean three dimensional eddy structure of the eastern south pacific ocean key differences in their thermohaline vertical structure were revealed the core of cyclonic eddies ces is centered at 150 m depth within the 25 2 26 0 kg m 3 potential density layer corresponding to the thermocline in contrast the core of the anticyclonic eddies aes is located below the thermocline at 400 m depth impacting the 26 0 26 8 kg m 3 density layer this difference was attributed to the mechanisms involved in the eddy formation while intrathermocline ces would be formed by instabilities of the surface equatorward coastal currents the subthermocline aes are likely to be shed by the subsurface poleward peru chile undercurrent in the eddy core maximum temperature and salinity anomalies are of 1 c and 0 1 with positive negative values for aes ces this study also provides new insight into the potential impact of mesoscale eddies for the cross shore transport of heat and salt in the eastern south pacific considering only the fraction of the water column associated with the fluid trapped within the eddies each ce and ae has a typical volume anomaly flux of 0 1 sv and yields to a heat and salt transport anomaly of 1 3 1011 w and 3 8 103 kg s 1 respectively

reinterpretation of the exposed record of the last two cycles of lake bonneville western united states a substantially modified history of the last two cycles of lake bonneville is proposed the bonneville lake cycle began prior to 26 000 yr b p the lake reached the bonneville shoreline about 16 000 yr b p poor dating control limits our knowledge of the timing of subsequent events lake level was maintained at the bonneville shoreline until about 15 000 yr b p or somewhat later when catastrophic downcutting of the outlet caused a rapid drop of 100 m the provo shoreline was formed as rates of isostatic uplift due to this unloading slowed by 13 000 yr b p the lake had fallen below the provo level and reached one close to that of great salt lake by 11 000 yr b p deposits of the little valley lake cycle are identified by their position below a marked unconformity and by amino acid ratios of their fossil gastropods the maximum level of the little valley lake was well below the bonneville shoreline based on degree of soil development and other evidence the little valley lake cycle may be equivalent in age to marine oxygenisotope stage 6 the proposed lake history has climatic implications for the region first because the fluctuations of lake bonneville and lake lahontan during the last cycle of each were apparently out of phase there may have been significant local differences in the timing and character of late pleistocene climate changes in the great basin second although the bonneville and little valley lake cycles were broadly synchronous with maximum episodes of glaciation environmental conditions necessary to generate large lakes did not exist during early wisconsin time

southern ocean eddy phenomenology mesoscale eddies are ubiquitous features in the southern ocean yet their phenomenology is not well quantified to tackle this task we use satellite observations of sea level anomalies and sea surface temperature sst as well as in situ temperature and salinity measurements from profiling floats over the period 1997 2010 we identified over a million mesoscale eddy instances and were able to track about 105 of them over 1 month or more the antarctic circumpolar current acc the boundary current systems and the regions where they interact are hot spots of eddy presence representing also the birth places and graveyards of most eddies these hot spots contrast strongly to areas shallower than about 2000 m where mesoscale eddies are essentially absent likely due to topographical steering anticyclones tend to dominate the southern subtropical gyres and cyclones the northern flank of the acc major causes of regional polarity dominance are larger formation numbers and lifespans with a contribution of differential propagation pathways of long lived eddies areas of dominance of one polarity are generally congruent with the same polarity being longer lived bigger of larger amplitude and more intense eddies extend down to at least 2000 m in the acc eddies show near surface temperature and salinity maxima whereas eddies in the subtropical areas generally have deeper anomaly maxima presumably inherited from their origin in the boundary currents the temperature and salinity signatures of the average eddy suggest that their tracer anomalies are a result of both trapping in the eddy core and stirring

the influence of nonlinear mesoscale eddies on near surface oceanic chlorophyll oceanic rossby waves have been widely invoked as a mechanism for large scale variability of chlorophyll chl observed from satellites high resolution satellite altimeter measurements have recently revealed that sea surface height ssh features previously interpreted as linear rossby waves are nonlinear mesoscale coherent structures referred to here as eddies we analyze 10 years of measurements of these ssh fields and concurrent satellite measurements of upper ocean chl to show that these eddies exert a strong influence on the chl field thus requiring reassessment of the mechanism for the observed covariability of ssh and chl on time scales longer than 2 to 3 weeks the dominant mechanism is shown to be eddy induced horizontal advection of chl by the rotational velocities of the eddies

preferential burial of permafrost derived organic carbon in siberian arctic shelf waters the rapidly changing east siberian arctic shelf esas receives large amounts of terrestrial organic carbon oc from coastal erosion and russian arctic rivers climate warming increases thawing of coastal ice complex deposits icd and can change both the amount of released oc as well as its propensity to be converted to greenhouse gases fueling further global warming or to be buried in coastal sediments this study aimed to unravel the susceptibility to degradation and transport and dispersal patterns of oc delivered to the esas bulk and molecular radiocarbon analyses on surface particulate matter pm sinking pm and underlying surface sediments illustrate the active release of old oc from coastal permafrost molecular tracers for recalcitrant soil oc showed ages of 3 4 13 14c ky in surface pm and 5 5 18 14c ky in surface sediments the age difference of these markers between surface pm and surface sediments is larger i in regions with low oc accumulation rates suggesting a weaker exchange between water column and sediments and ii with increasing distance from the lena river suggesting preferential settling of fluvially derived old oc nearshore a dual carbon end member mixing model showed that i contemporary terrestrial oc is dispersed mainly by horizontal transport while being subject to active degradation ii marine oc is most affected by vertical transport and also actively degraded in the water column and iii oc from icd settles rapidly and dominates surface sediments preferential burial of icd oc released into esas coastal waters might therefore lower the suggested carbon cycle climate feedback from thawing icd permafrost

on the rheology of till the deformation of subglacial till is instrumental in causing certain glacier surges the motion of rapid ice streams in ice sheets and ice sheet surges which are associated with heinrich events and consequent rapid climatic shifts during the last ice age it may also be the means whereby drumlins are formed and these in turn may act as a brake on large scale ice flow it is therefore important in building models to understand the rate at which till deforms and how this controls the basal ice velocity in recent years two paradigms have emerged on the one hand theoreticians have tended to use a viscous rheology though this lacks quantitative support on the other hand field and laboratory studies suggest that till behaves plastically in this paper i will examine some of the dynamic consequences of this latter assumption and show how the dichotomy between viscous and plastic may be less clearcut than previously thought

neotectonic fault activity in hong kong evidence from seismic events and thermoluminescence dating of fault gouge hong kong lies within a major ne trending fault zone that has been reactivated during several tectonic episodes since the palaeozoic three main faults sets are recognized in hong kong a dominant ne trending set an ene varying to e trending set and a subordinate nw trending set over the last 1000 years within a distance of 350 km of hong kong there have been about 40 earthquakes with magnitudes of over 4 75 and of these 11 had magnitudes of over 6 0 microseismic events in the last ten years are diffuse but may be associated with a major ne trending fault and a fault intersection thermoluminescence tl dates of fault gouge suggest that there have been three episodes of recent fault activity in hong kong these occurred at approximately at 100 000 190 000 and 270 000 years bp tl dating of alluvial sediments also indicates fault activity in the late pleistocene

surface faulting accompanying the borah peak earthquake and segmentation of the lost river fault central idaho on the morning of 28 october 1983 the ms 7 3 borah peak earthquake struck central idaho and formed a y shaped zone of surface faults that is divided into a southern a western and a northern section the total length of the surface faults is 36 4 3 1 km and the maximum net throw is 2 5 to 2 7 m the near surface net slip direction determined from the rakes of striations in colluvium averaged 0 17 m of sinistral slip for 1 00 m of dip slip the 20 8 km long southern section is the main zone of surface faulting and coincides with the thousand springs segment of the lost river fault it has the largest amount of net throw most complex rupture patterns and best evidence of sinistral slip the surface faults include zones of ground breakage as much as 140 m wide en echelon scarps with synthetic and antithetic displacements and individual scarps that are nearly 5 m high the 14 2 km long western section diverges away from the lost river fault near the northern end of the southern section the net throw on this section is generally less than 0 5 m but locally is as much as 1 6 m the new ruptures are poorly developed across the crest and north flank of the willow creek hills they are mostly downhill facing arcuate scars perhaps incipient landslides that may overlie a deeper zone of tectonic movement the northern section at least 7 9 km long is on the warm spring segment of the lost river fault and has a maximum net throw of about 1 m the pattern of surface faulting on this section is simple compared to the other sections a 4 7 km long gap in 1983 surface faults separates the northern and southern sections but contains an older scarp of late pleistocene age geologic seismologic and geodetic data from the earthquake suggest that barriers confined the primary coseismic rupture to the thousand springs segment of the fault the rupture propagated unilaterally to the northwest from a hypocenter near the southeastern end of the segment the southeastern boundary of the segment is marked by an abrupt bend in the range front a 4 km long gap in late quaternary scarps and transverse faults of eocene age that intersect the lost river fault the northwestern boundary of the thousand springs segment is at the junction of the willow creek hills and the lost river fault here the southern and western sections of surface faults diverge and there is a gap in the 1983 scarps during the first few weeks after the main shock the large magnitude and large stress drop aftershocks clustered near this barrier later aftershocks were mainly northwest of the barrier on the warm spring and challis segments and showed that strain adjustments eventually affected the entire northern part of the lost river fault fault scarp morphology and the bedrock geology suggest that the boundary between the thousand springs and warm spring segments has probably ruptured less frequently and had less net slip during much of the late cenozoic than the interior of the adjacent segments the 1983 faulting shows that although segment boundaries can stop or deflect primary ruptures secondary surface faulting can occur on adjacent segments of the main fault a late pleistocene scarp in the 1983 gap suggests that infrequent earthquakes perhaps larger than the 1983 event might break through a segment boundary and thus release strain on two adjacent segments

thermoluminescence dating of fault scarp derived colluvium deciphering the timing of paleoearthquakes on the weber segment of the wasatch fault zone north central utah the timing of middle to late holocene faulting on the weber segment of the wasatch fault zone utah is constrained by thermoluminescence tl and radiocarbon age estimates on fine grained fault related colluvial sediments the stratigraphy in two trenches excavated across fault scarps is characterized by a stack of three colluvial wedges deposited in response to three separate faulting events the oldest of which buried a soil developed on a middle holocene debris flow thermoluminescence age estimates by the partial and total bleach methods and the regeneration method on fine grained colluvium from the trenches agree within 1 sigma and are concordant with the radiocarbon chronology a synthesis of the tl and 14c age estimates indicate that these three faulting events occurred sometime between 4500 and 3500 between 3200 and 2500 and between 1400 and 1000 years ago detailed investigation of a sequence of fine grained scarp derived distal colluvium shows that much of the sediment was deposited during 600 year intervals immediately after faulting the sedimentation rate of colluvium is inferred to increase shortly after faulting and tl dating of these sediments provides additional information to constrain the timing of faulting events

late quaternary earthquake chronology from luminescence dating of colluvial and alluvial deposits of the arava valley israel abstract luminescence ages help provide a time scale for recurrent surface ruptures on a normal fault in the southern arava israel the dated samples come from alluvium and colluvium along a fault scarp north of elat the ages obtained mainly by infrared stimulation of sand size potassium feldspar grains accord with geomorphic age estimates from soils and degraded scarps four large earthquakes occurred between 37 000 and 14 000 yr ago five smaller earthquakes occurred thereafter continuing until recent times the mean recurrence interval for earthquakes of magnitudes greater than 6 is about 4000 yr

paleoseismological investigation of the oblique normal ekkara ground rupture zone accompanying the m 6 7 7 0 earthquake on 30 april 1954 in thessaly greece archaeological and geochronological constraints on ground rupture recurrence 1 observations in trenches excavated across the ekkara rupture zone erz the longest of the sporadic ground ruptures that accompanied the m 6 7 7 0 earthquake of 30 april 1954 on the domokos fault zone dfz identify a left lateral oblique normal fault with a slip vector aligned with the regional extension direction verifying the tectonic origin of the erz the paleoseismological interpretation of stratigraphic soil stratigraphic and tectonic features is discussed with emphasis on the issues related to strongly oblique fault kinematics two pre 1954 events of ground rupture are recognized e1 and e2 and an event of ground cracking only e1a shortly after e1 event e2 was accompanied by larger displacement than e1 and 1954 but this does not necessarily imply a stronger earthquake archaeological dating of transported ceramic sherds constrains e1 between 6750 and 4450 b p more likely 6450 5750 b p luminescence dating of colluvial deposits and 14c dating of pedogenic carbonates stone coatings place e2 at 17 500 2500 b p preferred age in the hazard wise most conservative interpretation recent recurrence intervals of erz activations exceed 3195 years the sporadic nature of the 1954 ruptures precludes certainty on whether the erz has recorded every past activation of the dfz unless data are also collected from other dfz rupture zones minimum limiting estimates of 0 3 0 5 mm yr slip rate are derived for the erz and the true slip rate is not expected to exceed 1 mm yr slip rate estimates for the erz may be minima for the dfz slip rate however because coseismic deformation in the past may have been distributed to more than one rupture zones at the surface

satellite observations of mesoscale eddy induced ekman pumping abstractthree mechanisms for self induced ekman pumping in the interiors of mesoscale ocean eddies are investigated the first arises from the surface stress that occurs because of differences between surface wind and ocean velocities resulting in ekman upwelling and downwelling in the cores of anticyclones and cyclones respectively the second mechanism arises from the interaction of the surface stress with the surface current vorticity gradient resulting in dipoles of ekman upwelling and downwelling the third mechanism arises from eddy induced spatial variability of sea surface temperature sst which generates a curl of the stress and therefore ekman pumping in regions of crosswind sst gradients the spatial structures and relative magnitudes of the three contributions to eddy induced ekman pumping are investigated by collocating satellite based measurements of sst geostrophic velocity and surface winds to the interiors of eddies identified from their sea surface height signatures on average e

soil catenas to estimate ages of movements on normal fault scarps with an example from the wasatch fault zone utah usa trenches excavated across fault scarps on a 13 ka delta surface at brigham city utah usa document four types of soil catena phenomena first the relict summit soil is eroded at the scarp crest and its components incorporated into the accumulating colluvial wedge at the scarp base second the pre faulting soil weakens laterally as it is traced scarpward beneath the colluvial wedge from a relict position beyond the scarp toe third soils developed on individual colluvial wedges and on the underlying pre faulting surface merge downslope to form a cumulative soil profile at the scarp toeslope fourth soil horizons thicken downslope probably due to the combined affect of more available moisture water infiltration and sediment accumulation two soil catenas were used to evaluate the applicability of a continuity approach to paleoearthquake dating by which percentages of total development time represented by each soil at a fault scarp footslope could be estimated the continuity approach sets total soil development at the scarp footslope including any buried pre faulting soil plus the sum development of all colluvial wedge soils corrected by a slope factor f equal to total soil development at the scarp summit soil development was characterized by profile development index pdi and pedogenic clay parameters using facies models to estimate parent material values for genetically different colluvial units and recognizing inherited soil components in colluvial wedges as parent material properties the f slope factor used to correct colluvial wedge soils for development attributable to slope position rather than age was checked by using a nearby fluvial scarp as an independent control our soil data when compared to independent age estimates imply that rates of soil development have not been constant over the last 13 ka at brigham city but rather were considerably higher than average between 13 ka and 8 3 ka higher rates are probably due to a relatively high influx of eolian dust during the late pleistocene to early holocene following the lowering of lake bonneville a large paleolake in the western usa these variable rates of soil development preclude using the continuity approach for paleoearthquake dating at brigham city however promising results showing that generally consistent f factors can be calculated for fault and fluvial scarps leave open the possibility that in areas where soil development rates have been relatively constant over the time period in question the continuity approach may be a broadly applicable method for paleoearthquake dating

residual luminescence in modern debris flow deposits from western taiwan a single grain approach abstract in an active fold and thrust belt sediment is commonly transported in the form of debris and colluviums and the ages of such deposits can be important for seismic hazard assessment these sediments are mainly transported by high concentration flows that travel very short distances before burial and therefore have very few opportunities for daylight exposure and bleaching which limits the application of luminescence dating in such environments luminescence studies on modern debris flow deposits and channel sediments in central taiwan indicate a mixed population of bleached and unbleached grains the well bleached grains constitute a small proportion of the sediments and could only be identified using the single grain dating technique doing single aliquot analysis may result in overestimation of the age of such sediments by 3 25 ka the data reveal that outwash sediments are better bleached than debris flow sediments our results show that quartz that has experienced partial resetting can be used for luminescence dating only through the use of the single grain technique

role of mesoscale eddies in cross frontal transport of heat and biogeochemical tracers in the southern ocean abstractthis study examines the role of processes transporting tracers across the polar front pf in the depth interval between the surface and major topographic sills which this study refers to as the pf core a preindustrial control simulation of an eddying climate model coupled to a biogeochemical model gfdl climate model version 2 6 cm2 6 simplified version of the biogeochemistry with light iron nutrients and gas minibling 0 1 ocean model is used to investigate the transport of heat carbon oxygen and phosphate across the pf core with a particular focus on the role of mesoscale eddies the authors find that the total transport across the pf core results from a ubiquitous ekman transport that drives the upwelled tracers to the north and a localized opposing eddy transport that induces tracer leakages to the south at major topographic obstacles in the ekman layer the southward eddy transport only partially compensates the northward ekman transport while below the ekman layer the sout

optical dating of tsunami laid sands abstract the ages of some tsunami deposits can be determined by optical dating a key requirement being that the deposits are derived from sediment that was reworked and exposed to daylight by tidal currents waves wind or bioturbation during the last years before the tsunami measurements have been made using 1 4 ev infrared excitation of k feldspar grains separated from samples of prehistoric tsunami sand sheets and modern analogs of tsunami source sediments at four sites in washington state and british columbia source sands gave equivalent doses indicative of recent exposure to daylight tsunami sand at cultus bay washington yielded an optical age of 1285 95 yr calendric years before a d 1995 1 at 2 this age overlaps the range of from 1030 to 1100 yr determined through a combination of high precision radiocarbon dating and stratigraphic correlation tsunami sands at three sites near tofino and port alberni on vancouver island british columbia have optical ages of 260 20 325 25 and 335 45 yr historical records and radiocarbon dating show that the sand at each of the three sites is between 150 and 400 yr old these optical ages support the hypothesis that the vancouver island sands were deposited by a tsunami generated by a large earthquake on the cascadia subduction zone about 300 yr ago

late quaternary faulting and thermoluminescence dating of the east cache fault zone north central utah the east cache fault zone ecfz the southernmost of five en echelon quaternary normal faults between the wasatch and teton faults displays evidence of two large paleoearthquakes in the last 15 000 years 15 ka stratigraphic data from a trench on the central segment of the ecfz are augmented with one radiocarbon date the regional radiocarbon chronology and 14 thermoluminescence tl age estimates of the 14 tl analyses performed by alpha analytic inc only 8 satisfied our criteria for statistical acceptability 20 per cent coefficient of variation 50 per cent extrapolation to residual tl level the tl age estimates broadly bracket the earlier faulting event at between 8 7 1 0 and 17 4 3 0 ka and the later event at between 2 5 0 5 and 8 7 1 0 ka one radiocarbon age further constrains the earlier event to be younger than 15 540 130 yr bp correlation of local quaternary deposits to the regional radiocarbon chronology provides indirect but more tightly limiting age constraints of ca 4 to ca 7 ka for the later event and ca 13 ka to 15 540 130 yr bp for the earlier event both events had small vertical displacements at the trench site 0 8 to 1 8 m but the cumulative net vertical tectonic displacement elsewhere is up to 4 2 m suggesrive of m s 6 9 to 7 1 paleoearthquakes single event displacements and the extent of fault scarps suggest that these two paleoearthquake ruptures were probably limited to the 20 kin long central segment of the east cache fault zone near logan utah the elapsed time since the most recent event on the central segment ca 4 to ca 7 ka is somewhat less than the estimated recurrence interval between the latest two paleoearthquake 8 6 3 0 ka however comparison of only a single poorly constrained recurrence interval with the elapsed time does not result in a confident assessment of future earthquake potential

satellite observations of chlorophyll phytoplankton biomass and ekman pumping in nonlinear mesoscale eddies nonlinear mesoscale eddies can influence biogeochemical cycles in the upper ocean through vertical and horizontal advection of nutrients and marine organisms the relative importance of these two processes depends on the polarity of an eddy cyclones versus anticyclones and the initial biological conditions of the fluid trapped in the core of the eddy at the time of formation eddies originating in the eastern south indian ocean are unique in that anticyclones typically associated with downwelling contain elevated levels of chlorophyll a enhanced primary production and phytoplankton communities generally associated with nutrient replete environments from analysis of 9 years of concurrent satellite measurements of sea surface height chlorophyll phytoplankton carbon and surface stress we present observations that suggest eddy induced ekman upwelling as a mechanism that is at least partly responsible for sustaining positive phytoplankton anomalies in anticyclones of the south indian ocean the biological response to this eddyinduced ekman upwelling is evident only during the austral winter during the austral summer the biological response to eddy induced ekman pumping occurs deep in the euphotic zone beyond the reach of satellite observations of ocean color

an evaluation of thermoluminescence dating of paleoearthquakes on the american fork segment wasatch fault zone utah the accuracy of the thermoluminescence tl method for dating holocene paleoearthquakes was tested on fine grained sediments from three trenches excavated across the american fork segment of the wasatch fault zone utah sediments exposed in the trenches targeted for tl dating include a horizons of buried soils loessial silts and sag pond muds this study indicates that these sediments were fully light bleached prior to deposition and are suitable for tl dating equivalent dose estimates by the regeneration total and partial bleach methods are in general agreement and mean tl age estimates are concordant with radiocarbon ages combined radiocarbon and tl age estimates indicate three major episodes of faulting at 5 3 0 3 2 6 0 3 and 0 5 0 2 kyr ago

applications and limitations of thermoluminescence to date quaternary sediments abstract the thermoluminescence tl method dates sediment by quantifying time dependent dosimetric properties of mineral grains sunlight exposure of the sediment during transportation and deposition or heating resets the tl clock to time zero after burial of the mineral grains ionizing radiation from the decay of radioisotopes imparts a tl signal this accumulated tl signal is proportional to the equivalent dose ed which is a measure of radiation exposure during the burial period a tl age estimate is determined from the ratio of the ed to the environmental radiation dose rate the calculation of an ed is influenced by the susceptibility of sediments to optical bleaching the emission spectra of minerals and possible long and short term fading there are three basic methods for determining an ed regeneration total and partial bleach the regeneration technique may yield under estimates because of sensitivity changes with laboratory bleaching the latter two techniques are most useful for well and partially light bleached sediments respectively a number of sediments can be dated by the tl method eolian and a variety of terrestrial sediments yield apparently accurate tl age estimates though there are possible complications associated with pedogenesis it appears that some fluvial sediment can be accurately dated by tl but little is known about the efficiency of optical bleaching for fluvial depositional systems till and glacier proximal deposits are inadequately light bleached to be dated by tl sediments deposited distal from the glacier margin which are at least partially bleached are preferred for dating future research is needed to understand better the relationship between sedimentary environments and the extent of light bleaching also studies should concentrate on dating feldspar extracts from well dated sequences to more fully ascertain the temporal limitations of the method only by understanding the interplay of sedimentology tl dosimetry and environmental radiation can the tl method be effectively applied to the myriad of depositional environments spanning the late to middle pleistocene

earthquake recurrence in nw and central himalaya abstract in this study we compare himalayan seismic moment release estimates derived from strain rate observations with those derived from large historical earthquakes and to this end we use a reassessed catalogue of historical earthquakes from western and central himalaya since the beginning of the 16th century we have computed seismic moment rates within six contiguous segments along the himalayan arc and compared these using kostrov s formula with moment rates computed from recent global strain rate estimates and regional studies while the ratios between strain based moment rate estimates and those inferred from observed seismicity vary significantly between the segments we find on the average consistently larger strain based values by about a factor of two based on seismicity from the last 515 years the moment rate ratio is however significantly reduced when shorter catalogues are used to 1 28 for the last 215 years and to 1 05 for the last 115 years which is an almost perfect match the possible inclusion of afterslip in the model would further improve the 515 year match this is indicating that a significant part of the difference possibly most of it is likely to be caused by incompleteness of the longer earthquake catalogue possibly combined with underestimated magnitudes the difference between geodetic and seismic estimates for the more complete part of the catalogue is smaller than previously reported along the western himalayan frontal thrust in fact the only region where a significant moment rate difference is found in our study is in se himachal pradesh in terms of seismic hazard it is found that the moment rate reduction of about a factor of two when going from 115 to 515 years leads to a reduction in the 475 year pga of about 26 it is also found that using 50 years of usgs seismicity data between 1963 and 2012 leads to a 40 lower hazard as compared to using moment release for the last 115 years

eddy induced carbon transport across the antarctic circumpolar current the implications of a mesoscale eddy for relevant properties of the southern ocean carbon cycle are examined with in situ observations we explored carbon properties inside a large 190 km diameter cyclonic eddy that detached from the subantarctic front saf south of tasmania in march 2016 based on remote sensing the eddy was present for 2 months in the subantarctic zone saz an important region of oceanic carbon dioxide co2 uptake throughout the annual cycle and carbon subduction i e where mode and intermediate waters form before it was reabsorbed into the saf the eddy was sampled during the middle of its life 1 month after it spawned comparatively the eddy was 3 c colder 0 5 practical salinity unit fresher and less biologically productive than surrounding saz waters the eddy was also richer in dissolved inorganic carbon dic and had lower saturation states of aragonite and calcite than the surrounding saz waters as a consequence it was a strong source of co2 to the atmosphere with fluxes up to 25 mmol c m 2 d 1 compared to the saf waters from which it originated dic concentration in the eddy was 20 mol kg 1 lower indicating lateral mixing small scale recirculation or eddy stirring with lower dic saz waters by the time the eddy was observed as they are commonly spawned from the antarctic circumpolar current and as 50 of them decay in the saz the rest being reabsorbed by the saf n these types of eddies may represent a significant south north transport pathway for carbon across the acc and may alter the carbon properties of saz waters

soils as a tool for estimating ages of quaternary fault scarps in a hyperarid environment the southern arava valley the dead sea rift israel abstract on the alluvial fan of nahal shehoret in the extremely arid region of the negev desert israel reg soils developed on stable alluvial surfaces in colluvium along terrace risers and in colluvial units on a complex fault scarp were compared the degree of soil profile development provided an age estimate of the surface that was faulted a maximum age estimate of the scarp or terrace riser and an estimate of the maximum recurrence intervals of faulting events irsl dates of the tectonically displaced alluvial surfaces and colluvial units at the same site enabled us to re evaluate the use of reg soils for relative dating the major faulting event started at 34 8 4 3 ka it displaced a late pleistocene surface of the nahal shehoret alluvial fan dated at 56 10 8 ka renewed fluvial activity and deposition of alluvium on the downfaulted block had almost terminated by 13 6 2 3 ka the scarp was formed during the latest pleistocene and was followed by smaller faulting events which had only minor effects on the fault scarp morphology the similarity of age estimates from irsl dating and the degree of soil development in this environment indicates that soils can be used to date surfaces and colluvial units

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

changes in holocene paleoseismic activity in the hula pull apart basin dead sea rift northern israel abstract paleoseismic analysis of the azaz fault segment of the dead sea fault northern israel indicates that this region was subjected to intermittent periods of strong seismicity and quiescence during the latest pleistocene and the holocene the azaz fault forms the eastern margin of the hula valley a pull apart basin between two left stepping segments of the dead sea fault the fault is currently inactive but it displaces a 25 30 ka travertine in the northeastern corner of the hula valley and near surface marsh sediments inside the valley two trenches excavated across a 15 20 m high fault scarp near kefar szold expose fluvial and colluvial sequences showing clear evidence of recent tectonics one trench exposes well sorted bedded alluvial sediments comprising two upward fining units each capped by a weakly developed paleosol the sediments were deposited on the down faulted block and are bounded in the east by the fault scarp the second trench uncovers fine colluvial sediments cross cut by a wide fault parallel fissure filled by collapsed sediments in both trenches the lower sedimentary unit is capped by a coarse colluvium containing boulders up to 1 5 m in size the colluvium shows no clear bedding and has a weakly developed paleosol on top optically stimulated luminescence dating of the lower fluvial sequence shows that its age ranges between 12 ka at the base to 6 ka at the top while the middle part of the overlying colluvium is ca 4 8 ka the relation between the lower fluvial units and the fault indicates that at least two large scale earthquakes occurred in the early holocene each one resulting in a 1 1 5 m high fault scarp during this seismically active period no coarse colluvial sediments were deposited along the fault trace and thus the region must have had low tectonic relief the clear contact with the overlying coarse colluvium reflects a middle holocene rapid change to the present high steep relief this change was achieved by frequent strong seismic events which triggered colluvial processes and prevented stratification and soil formation on the slope the soil on the present slope reflects a quiescent period that has lasted at least several hundred years during which stress has accumulated and seismic risk increased

late quaternary faulting on the manas and hutubi reverse faults in the northern foreland basin of tian shan china abstract the tian shan range lies in the actively deforming part of the india asia collision zone in the northern foreland basin of tian shan the strata were intensively deformed by cenozoic folding and faulting slip rate studies along these faults are important for understanding the dynamics of crustal deformation and evaluating the seismic hazards in the region two reverse faults the manas and hutubi faults in the northern foreland basin were investigated due to past faulting events along these faults the terrace treads along the manas river were ruptured forming fault scarps several meters in height loess deposits were trapped and preserved at the surface ruptures along these scarps the thickness of the trapped loess is dependent on the size of the ruptures the minimum and maximum ages of these scarps are constrained by dating the loess preserved at the surface ruptures and the terrace treads respectively using the quartz optically stimulated luminescence osl dating technique our dating results suggest that the loess trapped at the ruptures was deposited from the early to mid holocene at the hutubi fault and from the mid to late holocene at the manas fault the vertical displacements of the faults were evaluated by measuring the topographic profiles across the investigated fault scarps using the differential global position system dgps our results suggest that during the late quaternary in the studied region the vertical slip rates of the manas fault were between 0 74 mm yr and 1 6 mm yr while the hutubi fault had a much lower vertical slip rate between 0 34 mm yr and 0 40 mm yr the tectonic implications of our results are discussed

comparison of amino acid racemization geochronometry with lithostratigraphy biostratigraphy uranium series coral dating and magnetostratigraphy in the atlantic coastal plain of the southeastern united states the results of an integrated study comprising litho and biostratigraphic investigations uranium series coral dating amino acid racemization in molluscs and paleomagnetic measurements are compared to ascertain relative and absolute ages of pleistocene deposits of the atlantic coastal plain in north and south carolina four depositional events are inferred for south carolina and two for north carolina by all methods the data suggest that there are four pleistocene units containing corals that have been dated at about 100 000 yr 200 000 yr 450 000 yr and over 1 000 000 yr some conflicts exist between the different methods regarding the correlation of the younger of these depositional events between charleston and myrtle beach lack of good uranium series dates for the younger material at myrtle beach makes the correlation with the deposits at charleston more difficult

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

response of the antarctic circumpolar current to atmospheric variability abstract historical hydrographic profiles combined with recent argo profiles are used to obtain an estimate of the mean geostrophic circulation in the southern ocean thirteen years of altimetric sea level anomaly data are then added to reconstruct the time variable sea level and this new dataset is analyzed to identify and monitor the position of the two main fronts of the antarctic circumpolar current acc during the period 1993 2005 the authors relate their movements to the two main atmospheric climate modes of the southern hemisphere the southern annular mode sam and the el nino southern oscillation enso the study finds that although the fronts are steered by the bathymetry which sets their mean pathway on first order in flat bottom areas the fronts are subject to large meandering because of mesoscale activity and atmospheric forcing while the dominant mode of atmospheric variability in the southern hemisphere sam is relatively symmetric the oceanic response of the fronts is not show

circumpolar response of southern ocean eddy activity to a change in the southern annular mode 1 analysis of satellite altimeter data reveals anomalously high eddy kinetic energy eke in the antarctic circumpolar current acc during the period 2000 2002 around 2 3 years earlier 1998 the circumpolar eastward wind stress as quantified by the southern annular mode sam showed a significant positive peak and we have shown previously that the acc peaked around 1998 in response an eddy resolving ocean model is used to investigate the delay between wind forcing and the eddy response and demonstrates that the lag is due to the time taken to influence the deep circulation of the acc winds over the southern ocean have shown a strong climatic increase over the past few decades if this increase in winds is also reflected as an increase in eddy activity as our analysis suggests it might then the increased poleward heat flux may have played a significant role in the observed warming of the southern ocean citation meredith m p and a m hogg 2006 circumpolar response of southern ocean eddy activity to a change in the southern annular mode geophys res lett 33 l16608 doi 10 1029 2006gl026499

the potential of using thermoluminescence to date buried soils developed on colluvial and fluvial sediments from utah and colorado u s a preliminary results the natural tl intensity for surface and buried holocene and pleistocene a horizons developed on flood plain silts near denver colorado exponentially decreases with time this signal is approaching saturation by ca 130 ka the a horizon of the modern flood plain soil is not fully light bleached the tl properties and age estimates are presented for radiocarbon dated eolian enriched buried a horizons developed on fault derived colluvium from the american fork segment of the wasatch fault zone utah dating of these buried soils provide a close age estimate on paleoearthquake events mean tl age estimates by regeneration and total bleach techniques for buried a horizons are 0 5 0 1 ka and 2 7 0 4 ka which are in agreement with corresponding radiocarbon dates of 980 70 years bp and 2620 70 years bp a surface sag pond mud formed within an antithetic grabben is well light bleached and yielded a tl age estimate by the total bleach method of 240 60 years bp in agreement with its known age of 300 years bp this study indicates that relatively brief periods of pedogenesis are not sufficient to light bleach sediment and that eolian additions enhance the reduction of tl in soils

rapid warming and ostracods mass extinction at the lower toarcian jurassic of central spain abstract here we present the results of the study of two lower toarcian carbonate sections located in the iberian range of central spain analyses of stable isotope on belemnite calcite allowed calculation of seawater palaeotemperature variations which were compared with the stratigraphical distribution of ostracods these organisms are particularly sensitive to ratios of temperature and salinity variations and hence are good indicators of climate changes from a cooling interval with seawater temperatures of 13 2 c recorded at the pliensbachian toarcian transition seawater temperature began to rise in the lowermost toarcian tenuicostatum zone reaching average temperatures between 14 6 c and 16 3 c during the time of deposition of this zone coinciding with this seawater warming up to 85 of the ostracods species progressively disappeared during a period of approximately 300 kyr marking the extinction interval the extinction boundary located around the tenuicostatum serpentinum zonal boundary coincides with a marked increase in temperature in the serpentinum zone on which average seawater temperatures of 22 c have been calculated warming continued through part of the middle toarcian bifrons zone reaching average temperatures of 24 7 c readjustment of the ostracod population allowed recovery of these faunas in the upper serpentinum zone although the extinction of a major ostracod group the healdioids was also recorded the correlation between mass extinction and warming infers a causal relationship comparison of the results with the records of stable isotopes in belemnites and in bulk carbonates as well as toc and facies analysis suggests that the anoxia linked to the early toarcian oceanic anoxic event was not the main responsible for the ostracod mass extinction

mechanisms for vertical nutrient transport within a north atlantic mesoscale eddy abstract prompted by observational evidence for an enhanced source of surface nutrients within an anticyclonic eddy in the ne atlantic we investigate vertical transport processes that may produce such a phenomenon for the eddy investigated the dominant mechanism is found to be ageostrophic circulation resulting from a perturbation of the circular flow of the eddy this can produce upwelling velocities of order 10 m d 1 ekman pumping due to wind stress on the eddy also produces upwelling within but on a smaller scale of 0 5 m d 1 there is no evidence that self propagation of the eddy leads to an enhanced nutrient flux by displacement upwards of nutrient laden deeper isopycnals over the core of the eddy deeper winter mixing within the eddy relative to the surroundings however may contribute to the elevated nutrient levels

luminescence dating of hillslope deposits a review abstract luminescence dating determines the last exposure to light of quartz and feldspar mineral grains and thus the time a sediment was laid down prerequisite is that the sediment grains were sufficiently exposed to light prior to deposition for eolian deposits this seems a fair assumption although exceptions may well exist for other depositional environments light exposure prior to burial is often restricted in duration intensity and spectral composition and may result in an age overestimation recent developments now allow dating of sediments that were exposed to only little light prior to deposition the main developments are single aliquot techniques and statistical tests that allow extraction of valid age estimates even from deposits in which bleached and unbleached grains are mixed these developments in combination with the fact that the great majority of sediments near the earth s surface are not of eolian origin have resulted in the large interest in the luminescence dating of non eolian deposits here we review possibilities and challenges of luminescence dating of colluvial deposits we summarize techniques for the detection and handling of insufficiently bleached sediments a common condition in colluvial deposits we give an overview how luminescence dating has been applied on hillslope sediments for reconstructing landscape response to climate change to analyze past fault activity and unravel human induced soil erosion we discuss sampling strategies and give guidelines as to which techniques are best suited to establish luminescence chronologies for colluvium

active tectonic studies in the united states 1987 1990 the techniques and instrumentation used in active tectonic studies are discussed and recent results are reviewed it is suggested that a critical mass of data on several particular regions has been accumulated making possible critical debates and attempts to assess earthquake hazards particular attention is given to studies of the pacific northwest region basin and range deformation studies and distributed deformation and hidden earthquake sources also included is a comprehensive bibliography for the period

topographic constraints on deviatoric stress field in the indo eurasian collision region seismo tectonic implications the deviatoric stress field are computed from the inversion of gravitational potential energy gpe for the indo eurasian plate collision region including the himalaya and the tibet plateau the resulting stress pattern in combination with stress and strain rates obtained by inverting respectively the focal mechanism solution of large earthquakes and gps derived plate motions are used to study the nature of the present day deformations a narrow belt bordering the himalayan collision zone from the south is characterized by strong compressive stresses the variations in stress pattern along this belt coincide with arc normal ridges extending into the himalaya and are able to explain arc parallel segmentation of seismicity gravitational collapse seems to play an important role in the southeastern tibet plateau depth sensitivity of the seismic derived stresses and gps derived surface strain rates coupled with evidence of arcuate shaped high electrical conductivity favour strong ductile flow around the eastern himalaya syntaxis ehs at mid crustal depth the deflection of crustal flow indicted by the viscous resistance offered by the rigid sichuan basin adds to the traction stresses to cause clockwise rotation of the block around ehs

reevaluation of holocene faulting at the kaysville site weber segment of the wasatch fault zone utah the 1978 kaysville utah trench excavated by swan and others 1980 across a large graben of the weber segment of the wasatch fault zone was reexcavated in 1988 to reevaluate the timing and nature of holocene faulting relogging of the trench reveals evidence for five or six faulting events younger than the provo phase of lake bonneville circa 13 000 14c years b p geometric reconstruction of net vertical offset in the last three events suggests a variation in coseismic vertical displacement at this site ranging from a net of 1 4 3 4 m per event the three latest faulting events occurred at shortly before 0 6 0 8 ka 2 8 0 7 ka and circa 3 8 7 9 ka earlier events cannot be directly dated because older graben fill sediments yielded thermoluminescence ages older than the time of deposition and some scarp derived colluvial wedges beneath the trench floor were not exposed the two younger faulting events we recognize at kaysville correlate reasonably well with faulting events on the same segment 25 km north near east ogden utah at circa 0 8 1 2 ka and 2 5 3 0 ka forman and others 1991 whereas the earlier kaysville event is significantly older than the earliest 3 5 4 0 ka event dated at east ogden the 3 5 4 0 ka ground rupture recognized at east ogden may have died out at a subsegment boundary between the two trench sites within the 61 km long weber segment