extracting time domain green s function estimates from ambient seismic noise 1 it has been demonstrated experimentally and theoretically that an estimate of the green s function between two seismic stations can be obtained from the time derivative of the long time average cross correlation of ambient noise between these two stations this tdgf estimate from just the noise field includes all tensor components of the green s function and these green s function estimates can be used to infer earth structure we have computed cross correlations using 1 to 30 continuous days of ambient noise recorded by over 150 broadband seismic stations located in southern california the data processing yielded thousands of cross correlation pairs for receiver separations from 4 500 km which clearly exhibit coherent broadband propagating dispersive wavetrains across frequency band 0 1 2 hz

valley fill alluviation during the little ice age ca a d 1400 1880 paria river basin and southern colorado plateau united states valley fill alluvium deposited from ca a d 1400 to 1880 is widespread in tributaries of the paria river and is largely coincident with the little ice age epoch of global climate variability previous work showed that alluvium of this age is a mappable stratigraphic unit in many of the larger alluvial valleys of the southern colorado plateau the alluvium is bounded by two disconformities resulting from prehistoric and historic arroyo cutting at ca a d 1200 1400 and 1860 1910 respectively the fill forms a terrace in the axial valleys of major through flowing streams this terrace and underlying deposits are continuous and interfinger with sediment in numerous small tributary valleys that head at the base of hillslopes of sparsely vegetated weakly consolidated bedrock suggesting that eroded bedrock was an important source of alluvium along with in channel and other sources paleoclimatic and high resolution paleoflood studies indicate that valley fill alluviation occurred during a long term decrease in the frequency of large destructive floods aggradation of the valleys ended about a d 1880 if not two decades earlier with the beginning of historic arroyo cutting this shift from deposition to valley entrenchment near the close of the little ice age generally coincided with the beginning of an episode of the largest floods in the preceding 400 500 yr which was probably caused by an increased recurrence and intensity of flood producing el nino events beginning at ca a d 1870

fluvial system response to late pleistocene holocene sea level change on santa rosa island channel islands national park california abstract santa rosa island sri is one of four east west aligned islands forming the northern channel islands chain and one of the five islands in channel islands national park california usa the island setting provides an unparalleled environment in which to record the response of fluvial systems to major changes of sea level many of the larger streams on the island occupy broad valleys that have been filled with alluvium and later incised to form steep to vertical walled arroyos leaving a relict floodplain as much as 12 14 m above the present channel the period of falling sea level between the end of the last interglacial highstand at 80 ka and the last glacial lowstand at 21 ka was marked by erosion and incision in the uplands and by deposition of alluvial sediment on the exposed marine shelf sea level rose relatively rapidly following the last glacial lowstand of 106 m triggering a shift from an erosional to a depositional sedimentary regime accumulation of sediment occurred first through vertical and lateral accretion in broad shallow channels on the shelf channel avulsion and delta sedimentation produced widespread deposition creating lobes or wedges of sediment distributed across relatively large areas of the shelf during the latest pleistocene backfilling of valleys onshore landward of present sea level appears to have progressed in a more orderly and predictable fashion throughout the holocene primarily because the streams were confined to their valleys vertical aggradation locally reduced stream gradients causing frequent overbank flooding and lateral channel shift by meandering and or avulsion local channel gradient and morphology short term climate variations and intrinsic controls also affected the timing and magnitudes of these cut fill and flood events and are reflected in the thickness and spacing of the episodic alluvial sequences floodplain aggradation within the valleys continued until at least 500 years ago followed by intensive arroyo cutting that abandoned the relict floodplains forming alluvial terraces sedimentary evidence points to overgrazing and drought followed by catastrophic flooding in the mid nineteenth century as factors that may have accelerated and dramatically enhanced arroyo formation on the island

a large california flood and correlative global climatic events 400 years ago a gray silt layer 1 2 cm thick in the central santa barbara basin dated by varve counts to a d 1605 5 yr implies an intensity of precipitation flooding of regional rivers and transport of terrigenous detritus unmatched in the last 1000 yr the inferred flood may correlate with the reported rare occurrence of a perennial lake 14c dated to 390 90 b p in california s mojave desert 300 km east of the area draining into the santa barbara basin the dating of the a d 1605 5 yr flood event is consistent with tree ring evidence for a wet and cold paleoclimate elsewhere in the region regional and global climate evidence indicates that much of the world also experienced rapid intense cooling around a d 1605 this cooling was probably accompanied by an equatorward shift of prevailing wind patterns and associated storm tracks

cosmic ray labeling of erosion surfaces in situ nuclide production rates and erosion models a number of in situ cosmogenic radionuclides and stable nuclides have been measured in natural exposed rock surfaces with a view to study their in situ production and rock erosion rates 1 the in situ radionuclides can be used for a high resolution tomography of the erosional history of an exposed surface two stable nuclides 3he 21ne and five radionuclides 10be 26al 36cl 14c 39ar having half lives in the range of 300 1 5 106 yr half life are measurable in many rock types a prerequisite for the application of the in situ nuclides for the study of erosional histories of surfaces is a knowledge of their production rates under different irradiation conditions altitude latitude irradiation geometry and shielding relative nuclide production rates can be determined fairly accurately using the extensive available data on cosmic ray neutrons 2 absolute nuclide production rates cannot generally be predicted with any accuracy because of lack of data on excitation functions of nuclides unless some normalization is possible as was done in the case of several cosmic ray produced isotopes in the atmosphere 3 based on a recent natural calibration experiment in which erosion free surfaces exposed to cosmic radiation for 11 000 yrs were sampled the absolute production rates of 10be and 26al in quartz have been accurately estimated for mountain altitudes in sierra nevada 4 the absolute production rates of 10be and 26al in quartz can therefore be estimated fairly accurately for any given latitude and altitude some measurements of 14c in rocks of low erosion rate 5 similarly allow an estimate of its production rate attempts made to measure the in situ production rates of 3he in rocks have not yet led to a convergent production rate in view of the importance of knowing the production rates of isotopes of he ne and ar i present here theoretical estimates of their production rates based on available cross section data i discuss the information that can be extracted from the study of the in situ nuclides in rocks useful parameters characterizing the exposure history of a rock surface are 1 the effective surface exposure age and 2 the time averaged erosion rate the implications of these parameters for single and multiple nuclide studies are discussed in terms of the erosion models considered

temporal changes of subsurface velocities during strong shaking as seen from seismic interferometry 1 we apply a deconvolution method to a strong motion data set recorded at the surface and in boreholes in northeast honshu japan we try to characterize the nonlinear effects of the subsurface soil during strong shaking and show the change of the subsurface velocity structure during the shaking the deconvolved waveforms reflect the subsurface velocity structure and their horizontal and vertical components correspond to s and p wave respectively traveling from the borehole to the ground surface the strong motion records with smaller values of peak acceleration do not include significant nonlinear effects so the deconvolved waveforms of the observed accelerations can be well simulated by the program shake91 for high acceleration motions during the shaking of two separate earthquakes large reductions of near surface velocities are seen in results for the 2008 iwate miyagi nairiku earthquake the large high frequency ground motions over 4g at one near source station caused a nonlinear response of the soil and the reduction of the average shear wave velocity reached 24 this corresponds to a stiffness change of over 75 the soil properties and the stiffness coefficient which changed during the shaking did not fully recover after the shaking leaving a static change

seismic velocity reduction and accelerated recovery due to earthquakes on the longmenshan fault various studies report on temporal changes of seismic velocities in the crust and attempt to relate the observations to changes of stress and material properties around faults although there are growing numbers of observations on coseismic velocity reductions generally there is a lack of detailed observations of the healing phases here we report on a pronounced coseismic reduction of velocities around two locked sections asperities of the longmenshan fault with a large slip during the 2008 mw 7 9 wenchuan earthquake and subsequent healing of the velocities the healing phase accelerated significantly at the southern asperity right after the nearby 2013 mw 6 6 lushan earthquake the results were obtained by joint inversions of travel time data at four different periods across the wenchuan and lushan earthquakes the rapid acceleration of healing in response to the lushan earthquake provides unique evidence for the high sensitivity of seismic velocities to stress changes we suggest that stress redistribution plays an important role in rebuilding fault strength after a fault ruptures the recovery of its strength may be accelerated by earthquakes that redistribute stress according to an analysis of temporal variation in crustal seismic velocity on the longmenshan fault in china

a geologically constrained monte carlo approach to modeling exposure ages from profiles of cosmogenic nuclides an example from lees ferry arizona we present a user friendly and versatile monte carlo simulator for modeling profiles of in situ terrestrial cosmogenic nuclides tcns our program available online at http geochronology earthsciences dal ca downloads models html permits the incorporation of site specific geologic knowledge to calculate most probable values for exposure age erosion rate and inherited nuclide concentration while providing a rigorous treatment of their uncertainties the simulator is demonstrated with 10be data from a fluvial terrace at lees ferry arizona interpreted constraints on erosion based on local soil properties and terrace morphology yield a most probable exposure age and inheritance of 83 9 14 1 19 1 ka and 9 49 2 52 1 21 104 atoms g 1 respectively 2 without the ability to apply some constraint to either erosion rate or age shallow depth profiles of any cosmogenic nuclide except for nuclides produced via thermal and epithermal neutron capture e g 36cl cannot be optimized to resolve either parameter contrasting simulations of 10be data from both sand and pebble sized clasts within the same deposit indicate grain size can significantly affect the ability to model ages with tcn depth profiles and when possible sand not pebbles should be used for depth profile exposure dating

nonlinear ground motion amplification by sediments during the 1994 northridge earthquake it has been known since at least 1898 ref 1 that sediments can amplify earthquake ground motion relative to bedrock for the weak ground motion accompanying small earthquakes the amplification due to sediments is well understood in terms of linear elasticity hooke s law 2 but there has been a long standing debate regarding the amplification associated with the strong ground motion produced by large earthquakes the view of geotechnical engineers based largely on laboratory studies is that hooke s law breaks down at larger strains causing a reduced nonlinear amplification seismologists on the other hand have tended to remain sceptical of this nonlinear effect mainly because the relatively few strong motion observations seemed to be consistent with linear elasticity although some recent earthquake studies have demonstrated nonlinear behaviour under certain circumstances3 4 the significance of nonlinearity for the type of stiff soil sites found in the greater los angeles region remains unresolved5 here we report that ground motion amplification due to sediments for the main shock of the 1994 northridge earthquake was up to a factor of two less than the amplification observed for its aftershocks these observations imply significant nonlinearity in such amplification and bring into question the use of measurements of weak ground motion to predict the strong ground motion at sedimentary sites

site effects on large ground motions at kik net iwase station ibrh11 during the 2011 tohoku earthquake abstract large horizontal ground motions with peak ground accelerations pgas of more than 800 cm s 2 and peak ground velocities of nearly 60 cm s were observed at a kik net station iwase ibrh11 during the 2011 m w 9 0 tohoku japan earthquake we investigated site effects on the large ground motions by inverting the subsurface structure and simulating ground motions considering soil nonlinearity the structure from the seismic bedrock to the surface in the linear regime was inverted from 1 array records of microtremors using rayleigh wave inversion 2 surface to borehole spectral ratios of weak motions using s wave inversion based on the 1d wave propagation theory and 3 horizontal to vertical spectral ratios of weak motions using the inversion based on the diffuse field theory for plane waves the main cause of the large ground motions was found to be a strong impedance contrast between soft layers with an s wave velocity v s of less than 381 m s and a layer with v s 2371 m s at a depth of 30 m the strong motions at the surface during the 2011 tohoku earthquake simulated by equivalent linear analysis using borehole records at a depth of 103 m are in reasonable agreement with the observed records whereas those simulated using linear analysis were approximately twice as large as the observed values the results showed that the nonlinearity of the surface soils reduced the amplification factors and the pgas by half compared with the values for the linear regime the pgas of the bedrock motions with v s 2371 m s were estimated using equivalent linear analysis to have reached approximately 500 cm s 2

stratigraphy and palaeoclimatic significance of late quaternary loess palaeosol sequences of the last interglacial glacial cycle in central alaska abstract loess is one of the most widespread subaerial deposits in alaska and adjacent yukon territory and may have a history that goes back 3 ma based on mineralogy and major and trace element chemistry central alaskan loess has a composition that is distinctive from other loess bodies of the world although it is quartz dominated central alaskan loess was probably derived from a variety of rock types including granites metabasalts and schists detailed stratigraphic data and pedologic criteria indicate that contrary to early studies many palaeosols are present in central alaskan loess sections the buried soils indicate that loess sedimentation was episodic or at least rates of deposition decreased to the point where pedogenesis could keep ahead of aeolian input as in china loess deposition and pedogenesis are likely competing processes and neither stops completely during either phase of the loess soil formation cycle loess deposition in central alaska took place before and probably during the last interglacial period during stadials of the mid wisconsin period during the last glacial period and during the holocene an unexpected result of our geochronological studies is that only moderate loess deposition took place during the last glacial period our studies lead us to conclude that vegetation plays a key role in loess accumulation in alaska factors favouring loess production are enhanced during glacial periods but factors that favour loess accumulation are diminished during glacial periods the most important of these is vegetation boreal forest serves as an effective loess trap but sparsely distributed herb tundra does not thus thick accumulations of loess should not be expected where tundra vegetation was dominant and this is borne out by modern studies near the treeline in central alaska much of the stratigraphic diversity of north american loess including that found in the central lowlands the great plains and alaska is explained by a new model that emphasizes the relative importance of loess production factors versus loess accumulation factors

the evolution of pleistocene climate a time series approach abstract in the later part of the pleistocene variations in global ice volume have been dominated by an approximate 100 000 year cycle analysis of 2 myr long oxygen isotope record from an equatorial pacific core indicates that this is true only for the last 900 000 years prior to this time the amplitude of the 100 000 year cycle is much reduced as is the variance of all oscillations with periods greater than 60 000 years based on results of time series analysis of this 2 myr long record the pleistocene glacial cycles can be divided into three sections 1 the late pleistocene 0 900 kyr b p where the variations in the isotope record are dominated by the 100 000 year cycle 2 the middle pleistocene 900 1450 kyr b p in which low frequency components are not as important as in the later period of the pleistocene and 3 the early pleistocene late pliocene 1450 2000 kyr b p where general reductions of importance at all frequencies is seen as compared to the later intervals recent modeling efforts which describe variations in global ice volume show that the dominant low frequency component observed in the late pleistocene can result from different time constants for the rate of glacial growth and decay in response to variations in the earth s orbital parameters it is hypothesized that during the early pleistocene the rate of growth and decay of glaciers were more similar and that continental erosion by successive glacial advances lowered the land surface in areas of ice cap formation to below sea level when the ice caps became marine based more rapid decay of the ice became possible

a catalogue of late cenozoic tephra beds in the klondike goldfields and adjacent areas yukon territory preece s j westgate j a froese d g pearce n j g perkins w t 2011 a catlogue of late cenozioc tephra beds in the klondike goldfields and adjacent areas yukon canadian journal of earth sciences 48 10 1386 1418

time lapse changes of seismic velocity in the shallow ground caused by strong ground motion shock of the 2000 western tottori earthquake japan as revealed from coda deconvolution analysis abstract a large earthquake shock often drops the seismic velocity of the shallow ground however it is not clear whether the dropped velocity recovers shortly after the earthquake shock or not the purpose of this article is to report the time lapse changes of seismic velocity in the shallow ground after the 2000 western tottori earthquake japan we deconvolve the coda record of small earthquakes registered on the ground surface by that registered at the 100 m depth in a borehole at a station that experienced a strong shock from the mainshock because coda waves are mostly composed of randomly scattered s waves deconvolution of the two coda records enables us to obtain a robust image of the ground structure assuming that the shear modulus was reduced at the depth of 0 11 m we estimate the shear modulus change in each time period after the mainshock by fitting synthetic coda deconvolution to the observed one from 1 to 16 hz as a result the shear modulus dropped to 52 of the value obtained before the mainshock a few minutes after the strong earthquake shock this caused a decrease in the s wave velocity of 30 and an increase in s wave travel time of 17 msec the shear modulus continued to recover for over 1 yr following the logarithm of the lapse time it recovered to 69 83 87 and 97 of the value obtained before the mainshock in the periods of 0 to 1 week 1 week to 1 month 1 month to 1 yr and 1 to 4 yr after the mainshock respectively

permafrost response to last interglacial warming field evidence from non glaciated yukon and alaska abstract we present stratigraphic observations from three sites in eastern beringia ch ijee s bluff in northern yukon and nearby exposures on the old crow river the palisades on the yukon river in alaska and placer mining exposures at thistle creek in west central yukon which provide insight into the response of permafrost to regional warming during the last interglaciation chronology is based on the presence of old crow tephra an important regional stratigraphic marker that dates to late marine isotope stage 6 supplemented by paleoecology and non finite 14c ages on wood rich organic silts old crow tephra overlies several relict ice wedges at the palisades and thistle creek indicating that permafrost at these sites did not thaw completely during the last interglaciation prominent deposits of last interglacial wood rich organic silt are present at multiple sites in eastern beringia and probably represent accumulations of reworked forest vegetation due to thaw slumping or deposition into thermokarst ponds or depressions consistent stratigraphic relations between these deposits old crow tephra and ice wedge pseudomorphs at our three study sites and at least six other sites in eastern beringia suggest that thaw of shallow permafrost was widespread during the last interglaciation limited stratigraphic evidence suggests that thaw was probably on the order of meters rather than 10s of meters the ubiquity of shallow permafrost degradation during the last interglaciation suggests that current ground warming may foreshadow widespread near surface thaw under even modest future warming scenarios however the persistence of relict pre last interglacial ice wedges highlights the potential for the regional antiquity of discontinuous permafrost and provides compelling field evidence for the long term resilience of deep permafrost during sustained periods of warmer than present climate

variability in nonlinear sediment response during the 1994 northridge california earthquake abstract spectral ratios between sediment sites and rock sites for strong and weak ground motion are compared to infer the extent of nonlinear sediment response in the los angeles area during the 1994 northridge earthquake northridge mainshock records form the strong motion database and aftershock records form the weak motion database the degree of nonlinearity is evaluated at 25 locations in and around the san fernando and los angeles basins based on the ratio of weak to strong spectral amplification factors wsaf values of wsaf vary greatly from site to site and for a given site from one frequency band to another over the range from 0 75 to 20 hz this complexity is attributed to differences in several factors material properties under the sites and the amplitude and frequency content of the input ground motions given these observations it is not possible to assign an acceleration or velocity level at which nonlinearity initiates for all the stiff soil sites analyzed however no nonlinearity is seen below a peak acceleration of about 200 to 300 cm sec 2 or peak velocity of 20 to 30 cm sec nonlinearity is seen at all sites in or near the san fernando valley nonlinearity in the los angeles basin is limited to a few isolated sites for the northridge earthquake even sites with strong nonlinearity still show amplification levels greater than 1 0 relative to rock sites for frequencies below 10 hz

role of in situ cosmogenic nuclides 10be and 26al in the study of diverse geomorphic processes the central premises of applications of the in situ cosmogenic dating method for studying specific problems in geomorphology are outlined for simple and complex exposure settings in the light of these general models we discuss the information that can be derived about geomorphic processes utilizing concentrations of in situ produced cosmogenic radionuclides 10be half life 1 5 ma and 26a1 half life 0 7 ma in a variety of geomorphic contexts glacial polish and tills meteorite impact craters alluvial fans paleo beach ridges marine terraces sand dunes and bedrock slopes we also compare 10be 26al data with results obtained by other dating methods we conclude that the technique of measuring in situ cosmic ray produced nuclides holds promise for quantitative studies of processes and time scales in a wide range of geomorphological problems

cosmogenic nuclide age constraints on middle stone age lithics from niassa mozambique abstract the late phases of the middle stone age msa in the east african rift system ears are known for their evolutionary shifts and association with bottlenecks transcontinental expansion and climatic fluctuations the chronology of msa sites contemporaneous with these eco demographic upheavals is uncertain because of the scarcity of datable sites and the poor understanding of their depositional and erosional histories we apply terrestrial cosmogenic nuclide dating in a stratigraphic section with a complex exposure history to the study of the luchamange beds a widespread sedimentological unit underlying msa sites from the shores of lake niassa mozambican ears we use an innovative approach which may be applicable elsewhere to calculate their age using a monte carlo based bayesian model that links depth profiles of 26al and 10be and uses other geomorphic and cosmogenic nuclide age constraints on episodic erosion and burial the age of the basal luchamange beds is 42 77 15 ka and the msa occupation on top is 29 3 11 ka these dates suggest temporal overlap between msa and the earliest later stone age and diversity in cultural manifestations at the end of the msa

micromorphology and development of some central yukon paleosols canada abstract this paper focusses on the wounded moose and diversion creek paleosols which developed in the central yukon territory of northern canada wounded moose paleosols developed during the pre illinoian interglacial period and contain well developed reddish void and grain argillans in the bt horizons diversion creek paleosols developed in the sangamonian period and also contain void and grain argillans but these argillans are weakly developed brownish in colour and occur only rarely both of these paleosols have been exposed to one or more cold periods during which cryogenic processes dominated the soil development these cryogenic processes produced papules embedded grain argillans aggregates silt cappings and oriented fabrics the reddish argillans that are found in some diversion creek paleosols are thought to have originated from the former wounded moose paleosols when the pre reid illinoian glacial ice overrode them and incorporated them into the diversion creek parent material the development of the micromorphological features during the various glacial and interglacial periods is given with reference to the climate of the time

sediment transport in the san francisco bay coastal system an overview abstract the papers in this special issue feature state of the art approaches to understanding the physical processes related to sediment transport and geomorphology of complex coastal estuarine systems here we focus on the san francisco bay coastal system extending from the lower san joaquin sacramento delta through the bay and along the adjacent outer pacific coast san francisco bay is an urbanized estuary that is impacted by numerous anthropogenic activities common to many large estuaries including a mining legacy channel dredging aggregate mining reservoirs freshwater diversion watershed modifications urban run off ship traffic exotic species introductions land reclamation and wetland restoration the golden gate strait is the sole inlet connecting the bay to the pacific ocean and serves as the conduit for a tidal flow of 8 10 9 m 3 day in addition to the transport of mud sand biogenic material nutrients and pollutants despite this physical biological and chemical connection resource management and prior research have often treated the delta bay and adjacent ocean as separate entities compartmentalized by artificial geographic or political boundaries the body of work herein presents a comprehensive analysis of system wide behavior extending a rich heritage of sediment transport research that dates back to the groundbreaking hydraulic mining impact research of g k gilbert in the early 20th century

sediment yield from the tectonically active semiarid western transverse ranges of california sediment yields from the world s rivers are generally highest from steep drainage basins with weak lithology active tectonics or severe land use impacts here we evaluate sediment yields from the western transverse ranges of california in an attempt to explain why they are two to tenfold greater than the surrounding areas of california we found that suspended sediment yields across the gauged basins of the western transverse range during 1969 1999 varied by approximately an order of magnitude 740 5300 t km2 yr similarly fine sediment concentrations for normalized discharge rates varied by almost two orders of magnitude e g 1 3 110 g l for the mean annual flood for 11 previously unmonitored drainages of the santa ynez mountains areas with high sediment yields consistently have weakly consolidated bedrock quaternary pliocene marine formations and are associated with the highest rates of tectonic uplift of the region 5 mm yr these regions are important to the sediment discharge budgets because 50 of the total suspended sediment discharge from the western transverse range is estimated to be generated within these regions even though they represent only 10 of the total watershed area previous estimates of suspended sediment discharge from the ventura river have likely been underestimated by 50 because the gauging station is located immediately upstream of a high sediment yield region we also found a significant and positive correlation between sediment yield and the percentage of a watershed with grassland and agricultural land use these results suggest that there is adequate variation within the lithology tectonics and land use of the broader western transverse range geologic province to induce large variations in sediment yield at the local scale

an extensive late cenozoic terrestrial record of multiple glaciations preserved in the tintina trench of west central yukon stratigraphy paleomagnetism paleosols and pollenthis is a companion paper to barendregt et al also in this issue geological survey of canada contribution 20100035 the tintina trench in west central yukon is a late miocene graben formed along the antecedent early tertiary tintina fault since its formation the trench has served as a sediment trap for alluvial and glacial deposits an extensive record of preglacial glacial and interglacial sediments spanning the late pliocene to late pleistocene has been preserved and is exposed today in modern landslide scars this sedimentary record comprises multiple sequences of tills outwash mudflows loess and paleosols the glacial sediments are the product of both local montane and regional cordilleran ice advances that channeled into the trench while loess and well developed paleosols brunisols and luvisols reflect nonglacial and interglacial conditions respectively the tintina trench exposures provide the most complete record of glaciations for the region paleomagnetism paleosols and palynology provide age constraints for the geological events a formal stratigraphic nomenclature is proposed for this region

the california storm of january 1862 abstract the greatest storm in the written history of california struck the region in the winter of 1861 1862 the unusual weather began on christmas eve 1861 and persisted for some 45 days as a series of middle latitude cyclones made landfall along the california coast episodes of very cold and very warm temperatures occurred both during the storm and in the spring of 1862 as meridional flow prevailed heavy precipitation swelled the santa ana river to more than triple the highest estimated discharge in this century high water levels in coastal streams between los angeles and san diego persisted into the spring lakes were created in the los angeles basin and the mojave desert arroyos were cut sediments from the flood may be preserved in offshore basins

contributions and unrealized potential contributions of cosmogenic nuclide exposure dating to glacier chronology 1990 2010 abstract this paper reviews the application of cosmogenic nuclide exposure dating to glacier chronology exposure dating of glacial landforms has made an outsize impact on this field because the technique filled an obvious need that had already been recognized by glacial geologists by now hundreds of studies have used cosmogenic nuclide exposure dating to date glacial deposits and in fact it is rare to find a study of glacial geology or glacier chronology or any paleoclimate synthesis that makes use of such studies that does not involve exposure dating these developments have resulted in major contributions to glacier chronology and paleoclimate in particular i reconstructing antarctic ice sheet change ii establishing the chronology of late pleistocene and holocene glacier change in mountain regions where it was previously unknown iii establishing the broad chronological outlines of mountain glaciations prior to the last glacial maximum and iv gaining insight into subglacial erosional processes through the observation that many glaciated surfaces preserve cosmogenic nuclide inventories from long past ice free periods as well as the present one an important potential future contribution will be the application of the large data set of exposure dated glacier chronologies to better understand global and regional climate dynamics during lateglacial and holocene millennial scale climate changes however this contribution cannot be realized without significant progress in two areas i understanding and accounting for geologic processes that cause apparent exposure ages on glacial landforms to differ from the true age of the landform and ii minimizing systematic uncertainties in exposure ages that stem from cosmogenic nuclide production rate estimates and scaling schemes at present there exists an enormous data set of exposure ages on glacial deposits but these data cannot be used to their full potential in paleoclimate syntheses due to an inadequate understanding of geologic scatter and production rate uncertainties the intent of this paper is to highlight this situation and suggest some strategies for realizing this potential

production of cosmogenic radionuclides at great depth a multi element approach abstract for the last two decades in situ produced cosmogenic nuclides are increasingly applied in earth sciences to quantify surface processes in parallel significant reduction of the analytical uncertainties linked to advances in accelerator mass spectrometry ams allows more precise measurements however among all the published works on cosmogenic nuclides only few studies are dedicated to a better understanding of their production systematic or to a better constrain of the physical parameters involved in their production thus an approach to investigate in situ produced cosmogenic nuclides 10 be 26 al and 36 cl along a single 11 meter long core drilled from the surface and composed of carbonates and quartzose conglomerates has been launched these measurements have been used to quantify muon induced productions based on natural samples for each studied nuclide contrary to the current most oftenly used calculation of muon induced production parameters which are based on irradiation experiments at discrete energies productions based on natural samples are considering the entire energy range of particles reaching the ground surface the evolution of 36 cl concentrations with depth needs to agree with those parameters deduced from 10 be and 26 al data this is optimized when considering a fast muon induced 36 cl production contribution and a spallation production rate at sea level high latitude slhl of 42 0 2 0 atoms 36 cl g ca 1 a 1 1 sigma uncertainty

coseismic velocity change in and around the focal region of the 2008 iwate miyagi nairiku earthquake 1 the 2008 m7 2 iwate miyagi nairiku earthquake occurred in ne japan where dense seismic networks exist using the data from these networks we determined the coseismic seismic velocity change associated with this earthquake by two different methods ambient noise interferometry and vertical array interferometry of coda wave the purpose of this article is to reveal the spatial distribution and the cause of the velocity change by integrating these two approaches ambient noise interferometry revealed a coseismic velocity decrease of rayleigh wave by 0 1 0 5 at 0 25 0 5 hz we also estimated the spatial distribution of the velocity change by a tomographic inversion the velocity decrease was distributed in and around the focal area in the second method we applied cross correlation analysis to coda waves observed by the kik net vertical array we detected a shear velocity decrease of approximately 5 in shallow layers up to a few hundred meters depth quantitative comparison of the two results reveals that the 5 shear velocity decrease in shallow layers can explain the 0 1 0 5 decrease of rayleigh wave velocity the distribution of the velocity decrease is similar to that of the strong ground motion and the static stress change however a significant velocity increase is not observed in the compression area where a velocity increase is expected based on the observations we consider that the primary factor affecting the velocity change is damage in shallow layers due to strong motion the effect of the static stress change might be masked by the larger effect of the strong motion

use of a new 10be and 26al inventory method to date marine terraces santa cruz california usa marine terraces along active continental margins reflect the interplay between sea level oscillations and rock uplift well dated marine terraces record the timing of sea level highstands and delimit both uplift and geomorphic rates cosmogenic radionuclides provide a new tool for dating previously undatable terraces because the five marine terraces north of santa cruz california are capped by well developed soils formed in regressive marine sands both predepositional cosmogenic radionuclide inheritance and bioturbation of the profile must be accounted for we present a new cosmogenic radionuclide inventory method that uses the depth integrated cosmogenic radionuclide concentration to determine the terrace age this method yields terrace ages that correlate well with sea level highstands of marine oxygen isotope stages 3 5a 5c 5e and 7 the implied uplift rate is steady at 1 1 mm yr and is two to three times higher than rates suggested by earlier studies

paleomagnetic evidence for multiple late cenozoic glaciations in the tintina trench west central yukon canadathis article is a companion paper to duk rodkin et al also in this issue the tintina trench in west central yukon has preserved an extensive record of late cenozoic preglacial glacial and interglacial deposits these deposits comprise multiple sequences of tills outwash loesses and paleosols the sediments that were laid down directly by ice tills are of both local montane and regional cordilleran provenance the tintina trench area was impacted repeatedly by montane ice from the southern ogilvie mountains to the northwest 2500 m above sea level asl and also repeatedly along its southern extent by cordilleran ice from the selwyn mountains to the east 2759 m asl the latter forming the continental divide in this region we report here the magnetostratigraphy of three sections rock creek 64 13 n 139 07 w west fifteenmile river 64 29 n 139 55 w and east fifteenmile river 64 23 n 139 48 w the majority of the units identified at these sections record late pliocene to mid pleistocene glaciations although relatively thin surficial sequences of late mid

a signature of transience in bedrock river incision rates over timescales of 10 4 10 7 years measured rates of river incision into bedrock are commonly interpreted as proxies for rates of rock uplift see refs 1 and 2 for example and indices of the strength of climatic forcing of erosion over time see refs 3 and 4 for example this approach implicitly assumes that river incision rates are in equilibrium with external forcings over a wide range of timescales here we directly test this assumption by examining the temporal scaling of bedrock river incision from 155 independent measurements of river incision compiled from 14 sites of these sites 11 exhibit a negative power law dependence of bedrock river incision rate on measurement interval a relationship that is apparent over timescales of 10 4 10 7 years and is independent of tectonic and geomorphic setting thus like rates of sediment accumulation rates of river incision into bedrock exhibit non steady state behaviour even over very long measurement intervals non steady state behaviour can be explained by episodic hiatuses in river incision triggered by alluvial deposition if such hiatuses have a heavy tailed length distribution regardless of its cause the dependence of incision rate on measurement interval complicates efforts to infer tectonic or climatic forcing from changes in rates of river incision over time or from comparison of rates computed over different timescales

nonlinear behavior of soils revealed from the records of the 2000 tottori japan earthquake at stations of the digital strong motion network kik net acceleration records of the tottori earthquake 6 october 2000 pro vided by stations of the digital strong motion network kik net show clear evidence of the nonlinearity of soil response at sites located in near fault zones in this study records of the mainshock of the tottori earthquake are analyzed and stresses and strains induced by the strong motion in the upper 100 or 200 m of soil are recon structed at sites located within 80 km from the fault plane for reconstructing stresses and strains the method is applied which we developed and used previously for studying the response of soils during the 1995 kobe earthquake nonlinear time dependent stress strain relations in the soil layers are estimated based on vertical array records a good agreement between the observed and simulated accelerograms of the tottori earthquake testifies to the validity of the obtained vertical distributions of stresses and strains in the soil layers we also evaluated variations of the shear moduli of the soil layers caused by the strong motion at stations located at different distances from the fault plane changes in the rheological properties of the upper soil layers were found at the stations closest to the fault plane a similarity in stress strain relations describing the behavior of similar soils during the 1995 kobe earth quake and the 2000 tottori earthquake was obtained indicating the possibility of precasting soil behavior in future earthquakes at sites where profiling data are available

estimating near surface shear wave velocities in japan by applying seismic interferometry to kik net data 1 we estimate shear wave velocities in the shallow subsurface throughout japan by applying seismic interferometry to the data recorded with kik net a strong motion network in japan each kik net station has two receivers one receiver on the surface and the other in a borehole by using seismic interferometry we extract the shear wave that propagates between these two receivers applying this method to earthquake recorded data at all kik net stations from 2000 to 2010 and measuring the arrival time of these shear waves we analyze monthly and annual averages of the near surface shear wave velocity all over japan shear wave velocities estimated by seismic interferometry agree well with the velocities obtained from logging data the estimated shear wave velocities of each year are stable for the niigata region we observe a velocity reduction caused by major earthquakes for stations on soft rock the measured shear wave velocity varies with the seasons and we show negative correlation between the shear wave velocities and precipitation we also analyze shear wave splitting by rotating the horizontal components of the surface sensors and borehole sensors and measuring the dependence on the shear wave polarization this allows us to estimate the polarization with the fast shear wave velocity throughout japan for the data recorded at the stations built on hard rock sites the fast shear wave polarization directions correlate with the direction of the plate motion

loess of the upper mississippi valley driftless area abstract loess of the driftless area includes four distinct late quaternary lithostratigraphic units the wyalusing new loveland roxana and peoria formations erosion has removed parts or all of the pre late wisconsian loess at many sites these formations consist largely of loess and retransported loess that typically occurs on uplands terraces and valley margins in the region the oldest widespread formation probably 125 000 yr b p is here formally named the wyalusing formation the three younger formations correlate with the loveland probably 125 000 yr b p roxana 55 000 25 000 yr b p and peoria 25 000 12 000 yr b p loesses recognized elsewhere in the midcontinental united states the soil stratigraphic morphology of the wyalusing loveland and roxana peoria couplets appears to represent two distinct loess sedimentation sequences related to major expansion and contraction of the laurentide ice sheet during oxygen isotope stages 6 and 3 2 respectively the occurrence frequency of loess units is inversely related to age illustrating the erosional nature of the driftless area landscape the occurrence of four loess units at some sites in driftless area stratigraphic sections corroborates loess stratigraphy along the length of the mississippi valley where typically not more than four or five loess units are found and they represent only the late and middle pleistocene

application of seismic interferometry to extract p and s wave propagation and observation of shear wave splitting from noise data at cold lake alberta canada we extract downward propagating p and s waves from industrial noise generated by human and or machine activity at the surface propagating down a borehole at cold lake alberta canada and measure shear wave splitting from these data the continuous seismic data are recorded at eight sensors along a downhole well during steam injection into a 420 470 m deep oil reservoir we crosscorrelate the waveforms observed at the top sensor and other sensors to extract estimates of the direct p and s wave components of the green s function that account for wave propagation between sensors fast high frequency and slow low frequency signals propagating vertically from the surface to the bottom are found for the vertical and horizontal components of the wave motion which are identified with p and s waves respectively the fastest s wave polarized in the east northeast west southwest direction is about 1 9 faster than the slowest s wave polarized in the northwest southeast direction the direction of polarization

from extreme rainfall to drought 250 years of annually resolved sediment deposition in santa barbara basin california abstract the mediterranean climate of southern california is marked by droughts and extreme precipitation events here we use elemental variations generated by scanning x ray fluorescence xrf to identify droughts and floods in recently deposited 1755 2008 sediments of santa barbara basin sbb from box core spr0901 04bc the first principal component pc1 of the scanning xrf elements has high loadings for elements associated with the lithogenic component of sbb laminae couplets while the second pc2 is associated with biogenic components we interpret pc1 as a proxy for river runoff and pc2 as a proxy for marine productivity high values of pc1 are associated with el nino events and positive warm phases of the pacific decadal oscillation pdo while low values of pc2 are associated with el nino events and negative cool phases of the pdo droughts such as the 1934 40 1949 56 and 1989 91 events coincide with low pc1 values in addition to distinguishing interannual and decadal variability in the elemental composition of sbb sediments several historic floods can be recognized including a gray flood layer associated with the 1861 62 flood and a peak in pc1 associated with the flood following the st francis dam disaster in 1928

fractional seismic velocity change related to magma intrusions during earthquake swarms in the eastern izu peninsula central japan 1 we investigated temporal changes in seismic velocity associated with active seismic swarms and crustal deformations that occurred in 2006 and 2009 in the eastern izu peninsula of japan to detect changes in seismic velocity during and after these swarm episodes we used a passive image interferometry technique by estimating the phase shift of auto correlation functions of continuous seismic waveforms in a frequency band of 1 3 hz during the 2006 and 2009 swarm episodes a significant velocity decrease 0 3 was detected at the station nearest the swarm area this velocity decrease occurred when the volumetric strain change at the surface due to magma intrusion was larger than 10 6 we could not however find a clear correlation between the velocity decrease and the peak ground acceleration caused by moderate earthquakes m 5 that occurred during the swarms we also found that during the interseismic period the velocity decrease gradually recovered and appears to be proportional to displacement at the surface measured by gps stations these results suggest that the change in the subsurface velocity structure in the eastern izu peninsula strongly reflects strain changes caused by magma intrusion into the crust

age erosion constraints on an early pleistocene paleosol in yukon canada with profiles of 10be and 26al evidence for a significant loess cover effect on cosmogenic nuclide production rates abstract wounded moose type paleosols developed on remnant deposits of late pliocene to early pleistocene pre reid cordilleran ice sheet cis glaciations in central yukon canada it is an important regional soil geomorphic marker at the boundary between early cis advances and the non glaciated regions of yukon and alaska yet at present its age is poorly constrained between the reid 0 2 ma and earliest 2 84 ma cis advances here we apply depth profiles of in situ produced cosmogenic 26al and 10be to obtain both a minimum exposure age 1 12 0 44 0 36 ma 2 and maximum erosion rate 1 1 0 9 0 5 m myr 1 for the wounded moose paleosol our results show that this soil formed under exceptionally stable conditions max erosion rate similar to polar bedrock erosion rates and that it pre dates the emergence of the 100 ka eccentricity climate cycle contrasting our results from single and joint nuclide depth profile models reveals a significant discrepancy between calculated and effective 10be and 26al production rates 40 65 of expected values we interpret this discrepancy as the result of intermittent loess cover with a time averaged depth between 60 and 110 cm which significantly reduced apparent exposure ages obtained from the single nuclide model the observation of such a significant loess cover effect on cosmogenic nuclide production has implications for exposure dating in glacial and periglacial environments a multi nuclide sampling strategy is required to quantify this effect

mid pleistocene cosmogenic minimum age limits for pre wisconsinan glacial surfaces in southwestern minnesota and southern baffin island a multiple nuclide approach abstract paired 10 be and 26 al analyses n 14 indicate that pre wisconsinan glaciated bedrock surfaces near the northern baffin island and southern minnesota paleo margins of the laurentide ice sheet have long and complex histories of cosmic ray exposure including significant periods of partial or complete shielding from cosmic rays using the ratio 26 al 10 be we calculate that striated outcrops of sioux quartzite in southwestern minnesota southern margin were last overrun by ice at least 500 000 years ago weathered bedrock tors on the once glaciated uplands of baffin island northern margin are eroding no faster than 1 1 m myr 1 the equivalent of at least 450 000 years of surface and near surface exposure our data demonstrate that exposure ages and erosion rates calculated from single nuclides can underestimate surface stability dramatically because any intermittent burial and the resultant lowering of nuclide production rates and nuclide abundances will remain undetected

interferometry by deconvolution part 2 theory for elastic waves and application to drill bit seismic imaging deconvolution interferometry successfully recovers the impulse response between two receivers without the need for an independent estimate of the source function here we extend the method of interferometry by deconvolution to multicomponent data in elastic media as in the acoustic case elastic deconvolution interferometry retrieves only causal scattered waves that propagate between two receivers as if one acts as a pseudosource of the point force type interferometry by deconvolution in elastic media also generates artifacts because of a clamped point boundary condition imposed by the deconvolution process in seismic while drilling swd practice the goal is to determine the subsurface impulse response from drill bit noise records most swd technologies rely on pilot sensors and or models to predict the drill bit source function whose imprint is then removed from the data interferometry by deconvolution is of most use to swd applications in which pilot records are absent or provide unreliable estimates of bit excitation with a numerical swd subsalt example we show that deconvolution interferometry provides an image of the subsurface that cannot be obtained by correlations without an estimate of the source autocorrelation finally we test the use of deconvolution interferometry in processing swd field data acquired at the san andreas fault observatory at depth safod because no pilot records were available for these data deconvolution outperforms correlation in obtaining an interferometric image of the san andreas fault zone at depth

riser diachroneity lateral erosion and uncertainty in rates of strike slip faulting a case study from tuzidun along the altyn tagh fault nw china 1 at late quaternary timescales offset fluvial terrace risers are among the most common landforms used to determine rates of strike slip faulting although diachroneity in the age of riser segments on opposite sides of the fault has been noted previously an unexplored source of uncertainty associated with deriving slip rates from these markers centers on quantifying the size of the displacement uncertainty such diachroneity introduces to evaluate the impact of riser diachroneity we investigated the tuzidun site 37 73 n 86 72 e along the cherchen he reach of the active central altyn tagh fault the east bank of the channel is flanked by a left laterally offset terrace riser while the measured offset is 54 3 m geochronologic measurements and analysis of riser topography indicate that the downstream riser segment formed between 6 0 0 8 ka and 5 7 0 4 ka while the upstream riser segment may have been laterally refreshed as recently as 0 5 0 2 ka a valley wall on the west bank of the channel places a maximum limit of 38 6 m on the amount of possible lateral erosion of the upstream riser this bound in turn limits the total offset since formation of the downstream riser to range from 54 3 to 89 7 m together these observations bracket the millennial altyn tagh fault slip rate to range from 9 0 1 3 to 15 5 1 7 mm a 1 more generally this investigation shows that the observed riser displacement does not necessarily correlate with the age of either riser segment downstream or upstream of the fault in cases where one segment is displaced while the other is subjected to lateral erosion if this diachroneity goes undetected erroneous slip rate measurements are likely to result

single grain osl dating of glaciofluvial quartz constrains reid glaciation in nw canada to mis 6 abstract improved chronological control on the penultimate advance of the cordilleran ice sheet in northwest canada the reid glaciation is required for a better understanding of late quaternary palaeoclimatic and palaeoenvironmental change in eastern beringia however reliable dating of glaciation events beyond the last glacial maximum is commonly hindered by a lack of directly dateable material in this study we i provide the first combined minimum and maximum age constraint on the reid glaciation at ash bend its reference locale in the stewart river valley northwestern canadian cordillera using single grain optically stimulated luminescence dating of quartz and ii compare the timing of the reid glaciation with other penultimate ice sheet advances in the region with the aim of establishing improved glacial reconstructions in eastern beringia we obtain ages of 158 18 ka and 132 18 ka for glaciofluvial sands overlying and underlying the reid till respectively these ages indicate that the reid advance at its reference locale occurred during mis 6 this precludes an earlier mis 8 age and suggests that the reid advance may have been synchronous with the delta glaciation of central alaska and is likely correlative with the mirror creek glaciation in southern yukon

extracting earth s elastic wave response from noise measurements recent research has shown that noise can be turned from a nuisance into a useful seismic source in seismology and other fields in science and engineering the estimation of the system response from noise measurements has proven to be a powerful technique to convey the essence of the method we first treat the simplest case of a homogeneous medium to show how noise measurements can be used to estimate waves that propagate between sensors we provide an overview of physics research dating back more than 100 years showing that random field fluctuations contain information about the system response this principle has found extensive use in surface wave seismology but can also be applied to the estimation of body waves because noise provides continuous illumination of the subsurface the extracted response is ideally suited for time lapse monitoring we present examples of time lapse monitoring as applied to the softening of soil after the 2011 tohoku oki earthquake the detection of a precursor to a landslide and temporal changes in the lunar soil

coastal flooding and the 1861 2 california storm season abstract a series of large storms attributed to atmospheric river conditions struck the california coast in the winter of 1861 2 although historical accounts document inland flooding little is known about how the 1861 2 storms impacted the now heavily developed california coast here we show that the 1861 2 storms emplaced a deposit of beach sand up to 50 cm thick over 450 m inland within a southern california salt marsh this deposit is unprecedented in the post european sediments of the marsh and more extensive than that derived from any other historical event it is comparable in scale to hurricane and tsunami washover fans in back barrier environments along other coastlines the presence of overwash deposits in carpinteria suggests that the 1861 2 storm season was erosive enough to remove coastal barriers allowing for inundation of parts of the coastline currently developed efforts to prepare for a recurrence of an 1861 2 like storm season should address potential coastal impacts likewise interpretations of past washover deposits should consider these unusually prolonged stormy periods in addition to hurricane and tsunami inundation

explicit treatment of inheritance in dating depositional surfaces using in situ 10be and 26al we describe a new strategy for dating depositional landscape surfaces using in situ produced cosmogenic radionuclides crns that removes the complication of nuclide inheritance by clasts prior to depositon two amalgamated samples each consisting of 30 clasts one from the surface and one from a fixed depth in the subsurface constrain this crn inheritance and date the surface the inheritance may be used to estimate minimum exhumation rates and maximum transport times within the geomorphic system we test the technique using sup 10 be and sup 26 al to date the third fr3 of five terraces along the fremont river utah and the third wr3 of 15 along the wind river wyoming whereas effective ages based solely upon the surface samples yield 118 138 ka fr3 and 93 ka wr3 the subsurface samples reveal that inheritance accounts for 22 wr3 to 43 fr3 of the total crn concentration taking this into account yeilds terrace ages of nearly 61 81 ka for fr3 and nearly 67 76 ka for wr3 we explore the dependence of age estimates on the accumulation history of the terrace silt caps 22 refs 3 figs 1 tab

late holocene alluvial history of the cuyama river california usa dryland river deposits are archives of past changes in fluvial system form and process chronostratigraphic reconstruction of the late holocene alluvial history of the cuyama river in west central california reveals past spatial and temporal variation in dryland channel form and process the modern cuyama river consists of a wide braided reach in the upper drainage basin a narrower arroyo reach in the middle of the drainage basin and a bedrock canyon reach in the lower drainage basin that drains to the santa maria coastal plain along the arroyo reach late holocene stratigraphy is well exposed and is the focus of this study between ca 1700 and 350 yr b p two widespread deposits of tabular bedded clay silt and fine sand were deposited separated by a buried soil formed between 950 and 700 yr b p channel incision occurred between 550 and 350 yr b p next deposition of massive to bedded sands occurred in a pattern alternating between poorly confined deposition on top of older deposits onto the broad valley floor and channelized deposition along the valley axis inset into older deposits the superposed deposits now underlie the main valley terrace and the valley axis deposits are preserved as inset fill terraces historical arroyo cutting then formed a 65 km long arroyo ca 150 yr b p based on correlation to regional paleoclimate records channel aggradation occurred during periods of relative aridity and low peak discharge events while wet periods possibly floods after drought led to fluvial incision these cycles are superimposed on a transition from a wide silt and fine sand dominated fluvial system to a modern narrow sand and gravel dominated arroyo channel the relationship between times of fluvial process change and climate change in cuyama valley bears considerable similarity to other well studied dryland rivers in the southwestern united states however the complex sedimentology and geometry of preserved fluvial deposits suggest that a wider range of fluvial modes occurred along the cuyama river than has been reported in simpler cut and fill dominated channels elsewhere these spatial and sedimentological complexities underscore the need to link fluvial deposits and their bounding unconformities along a channel in order to fully understand the spatial and temporal evolution of ancient fluvial systems

dating sediment burial with in situ produced cosmogenic nuclides theory techniques and limitations abstract dating sediment burial over million year time scales is crucial in many areas of the earth sciences and archeology but is often difficult using traditional techniques sediment burial can be dated by the radioactive decay of cosmogenic nuclides provided that the sediment was exposed to cosmic rays prior to burial dating calculations are straightforward if sediment is buried deeply and rapidly enough to prevent cosmogenic nuclide production after burial however the analysis can be complicated by postburial production if sediment is insufficiently shielded from secondary cosmic ray nucleons and muons this paper discusses how buried sediments can be dated over timescales up to 5 myr using 26 al and 10 be in quartz

coseismic and postseismic elastic wave velocity variations caused by the 2008 iwate miyagi nairiku earthquake japan 1 we analyze coseismic and postseismic velocity variations caused by the june 13 2008 iwate miyagi nairiku earthquake mw 6 9 using passive image interferometry pii seismic noise is correlated in order to reconstruct the green s function between two sensors shear wave velocity changes are determined by relating the coda parts of the daily green s functions to a long term reference green s function our study extends from january 2008 to august 2010 and includes the correlations for 190 station pairs in three different frequency ranges from 0 125 to 1 0 hz we show that combining the 9 different component cross correlation functions stabilizes the velocity change estimation and increases analysis resolution the observed velocity change curves can be fitted by model time series consisting of a coseismic velocity drop followed by logarithmic postseismic recovery and seasonal velocity variations the coseismic velocity drops are stronger at higher frequencies and are concentrated in the southern part of the fault zone a tomography algorithm was developed to reproject the observed velocity variations of the different sensor pairs onto the single sensors the depth distribution of coseismic changes was modeled for the three stations with the largest velocity drops at two stations the coseismic velocity changes are located in the upper several hundred meters the third station shows indications for deeper changes in the order of kilometers postseismic recovery takes significantly longer than the analyzed two year period seasonal velocity variations with periods of one year are observed at all analyzed frequencies for most station pairs

atmospheric scaling of cosmogenic nuclide production climate effect 1 absorption of cosmic rays by atmospheric mass varies temporally due to a redistribution of atmospheric pressure by ice sheets during glaciations the compression and expansion of the atmosphere due to cooling and warming and changes in katabatic winds near large ice masses these atmospheric processes can result in changes in production rates of cosmogenic nuclides which when integrated over long exposure durations may result in 0 to 5 adjustments in site production rates depending on location combining a ccm3 model with imbedded ice sheets for 20 ka we show that production rates changes relative to today are greatest at high elevations 6 7 at 5 km altitude due to atmospheric compression from decreased temperature production rates at specific times for sites near ice sheet margins can be reduced more than 10 due to a combination of katabatic winds draining off the ice sheet margins and atmospheric cooling nunatak settings may be significantly affected by the climate effect due to persistent glacial atmospheric conditions atmospheric variability may explain some of the disparities among cosmogenic nuclide production rate calibrations

near surface weakening in japan after the 2011 tohoku oki earthquake 1 the magnitude mw 9 0 tohoku oki earthquake on 11 march 2011 was one of the largest in recent history ground motion caused by the seismicity around the time of the main shock was recorded by kik net the strong motion network that covers most of japan by deconvolving waveforms generated by earthquakes that are recorded at the surface and in a borehole at kik net station fksh18 we detect a reduction of shear wave velocity in the upper 100 m of about 10 and a subsequent healing that varies logarithmically with time using all available borehole and surface records of more than 300 earthquakes that occurred between 1 january 2011 and 26 may 2011 we observe a reduction in the shear wave velocity of about 5 in the upper few hundred meters after the tohoku oki earthquake throughout northeastern japan the area of the velocity reduction is about 1 200 km wide which is much wider than earlier studies reporting velocity reductions following other larger earthquakes the reduction of the shear wave velocity is an indication that the shear modulus and hence the shear strength is reduced over a large part of japan

dating fluvial terraces with and profiles application to the wind river wyoming abstract fluvial strath terraces provide a record of river incision and the timing of climatic perturbations to the fluvial system dating depositional surfaces like terraces that are older than the range of 14 c however is difficult we employ a cosmogenic radionuclide crn profile technique that addresses a major problem of crn dating on such surfaces nuclide inheritance by measuring 10 be and 26 al profiles we constrain the exposure age and the mean crn inheritance for the deposit the crn profile also yields a self check on the assumptions underlying the method we report our attempts to date terraces along the wind river wy like many sequences of western north american fluvial terraces these are inferred to reflect oscillation between glacial and interglacial conditions in the headwaters previous dating of some of these terraces and the associated terraces and glacial deposits makes this a unique location to compare dating methods dates from five sites along the bull lake glacial correlative terrace wr 3 are 118 125 ka which agrees with dates on bull lake age moraines and independent age estimates on the terrace and is consistent with the model of terrace glacial relationship crn inheritance is significant and highly variable requiring it be considered despite the additional sampling complexity assuming all inheritance in wr 3 deposits arises during exhumation in the headwaters we obtain minimum mean rates of exhumation of 13 130 m my for the source rocks alternatively assuming the crns are inherited during clast transport the time of fluvial transport from source to terrace is 10 ka it increases downstream and is lower for sand than cobbles the crn ages for older terraces wr 7 300 ka and wr 15 510 ka are lower by 50 than previous estimates based on tephrochronology the most plausible explanation is eolian deflation of a once thicker loess cover on the terrace surfaces mean thicknesses of loess of 0 5 1 5 m are required to reconcile these concentrations of crn with the previous estimates of age difficulty in dating the older terraces emphasizes that geologic caution independent estimates of age and multiple sample sites should still be part of dating depositional surfaces with crns even when employing the inheritance correction technique

downhole receiver function a case study receiver function is defined as the spectral ratio of the radial component and the vertical component of the ground motion it is used to characterize converted waves we extend the use of the receiver function to downhole data using waves recorded in a borehole excited by an earthquake of magnitude 4 0 near san fran cisco california on 26 june 1994 the focal depth of the event was 6 6 km and the epicenter was located at a distance of 12 6 km from the borehole array six three component sensors were located at different depths in a borehole to extract a co herent response of the near surface from the incoherent earthquake waves we de convolve the waves recorded by the sensors at different depths with the waves recorded by the sensor on the surface deconvolution applied to the waves in the s time window recorded by the radial component result in an upgoing and adowngoing wave propagating with s wave velocity for the waves in the p time window re corded by the radial component deconvolution also gives an upgoing and a down going wave propagating with s wave velocity this interesting result suggests a p to s conversion at a depth below the deepest sensor to diagnose this we compute the receiverfunction forthe borehole recording of the earthquakewaves thereceiver function shows an upgoing wave with an arrival close to time t 0 for the deepest sensor the agreement of the upgoing wave in the receiver function with the travel time curve for the p to s converted wave calculated using the p and the s wave velocity profile supports the hypothesis of a pronounced p to s conversion we present a synthetic example to illustrate that the first arrival of the receiver function applied to borehole data gives the upward propagating p to s converted wave to corroborate the observation of the mode conversion we apply receiver function to a different earthquake data recorded by the same borehole array in 1998 the focal depth of the event was 6 9 km and the epicenter was located at a distance of 13 km from the borehole array the receiver function for these data also show an upgoing wave with a pulse close to time t 0 at the deepest sensor the moveout of the upgoing wave agrees with the travel time curve for the p to s converted wave hence supporting our observation of the mode conversion

combination of hi net and kik net data for deconvolution interferometry abstract application of deconvolution interferometry to wavefields observed by kik net a strong motion recording network in japan is useful for estimating wave velocities and s wave splitting in the near surface at the location of the borehole accelerometer of each kik net station a velocity sensor is also installed as a part of a high sensitivity seismograph network hi net i present a technique that uses both hi net and kik net records for computing deconvolution interferometry the deconvolved waveform obtained from the combination of hi net and kik net data is similar to the waveform computed from kik net data only this similarity in the waveforms indicates that one can use hi net wavefields for deconvolution interferometry because hi net records have a high signal to noise ratio snr and high dynamic resolution snr and quality of amplitude and phase of deconvolved waveforms can be improved with hi net data these advantages are especially important for short time moving window seismic interferometry and deconvolution interferometry using coda waves

gold run tephra a middle pleistocene stratigraphic and paleoenvironmental marker across west central yukon territory canada gold run tephra has been found at thistle creek sixtymile river and the klondike goldfields of west central yukon canada it is a hornblende bearing rhyolitic tephra with thicknesses of up to 10 cm at each site suggesting a widespread distribution across interior alaska and the yukon territory given the long distance to the nearest volcanic centre old crow flat creek and ta tephra beds are stratigraphically associated with gold run tephra at our study sites and have distinctive compositions gold run tephra is not accommodated by the current classification scheme for late cenozoic distal tephra beds in alaska and the yukon territory a scheme based on the physical and chemical attributes so that its provenance is unknown an early middle pleistocene age is supported by a glass fission track age of 0 74 0 06 ma a normal remanent magnetic polarity for the enclosing loess and the presence of a late irvingtonian faunal assemblage in the associated organic rich silts at thistle creek hence gol