stable isotopes δ18o and δ13c trace and minor element compositions of recent scleractinians and last glacial bivalves at the santa maria di leuca deep water coral province ionian sea special issue the aplabes programme physical chemical and biological characterization of deep water coral ecosystems from the ionian sea mediterranean 16 pages 13 figures 3 tables 2 appendix

variations in seawater sr ca recorded in deep sea bamboo corals 1 a depth transect of deep sea bamboo corals along the california margin provides evidence that coral strontium to calcium ratios sr cacoral record seawater sr ca ratios sr casw a calibration was constructed utilizing sr cacoral ratios and previously published pacific sr casw data r2 0 53 n 12 p 0 01 sr cacoral mmol mol 4 62 sr casw mmol mol 36 64 sr casw is ultimately governed by the remineralization of sr containing shells of surface water derived marine organisms e g acantharia at intermediate water depths california margin sr cacoral records from 792 and 1295 m document fluctuations in sr casw that appear decadal scale these results suggest that sr casw may not be as stable as previously assumed and may be influenced by surface productivity on short timescales

the relation between site amplification factor and surficial geology in central california abstract site amplification factors at frequencies of 1 5 3 6 and 12 hz were determined for 132 stations of the usgs seismic network in central california from coda waves of 185 local earthquakes in this area using a recursive stochastic inversion method we found that the site amplification at a station is systematically related to the geology underlying that station the site amplification is high for young quaternary sediments and decreases with increasing geologic age at all frequencies between 1 5 and 12 hz the rate of decrease varies with frequency where site amplification at low frequencies shows a faster rate of decrease with age than at higher frequencies to quantify the relation between site amplification factor and site geology the surface geology of station sites was classified into five groups namely 1 quaternary sediments 2 pliocene sediments 3 miocene through cretaceous sediments 4 franciscan formation and mesozoic granitic rocks and 5 pre cretaceous metamorphic rocks the station site amplification factors for each group were logarithmically averaged and the mean value was assigned to the median geologic age of that group a smooth power law relation was found between the mean site amplification and the median geologic age this relation provides a simple way of estimating site effect at a specific site with known surficial geology our site amplification factors were compared with magnitude station residuals determined by eaton 1990 for the same network a remarkable linear correlation was found between the logarithmic coda amplification factor and the magnitude station residual value confirming that the coda method provides an effective means of estimating site amplification factor comparison of our site amplification factor with strong motion results obtained from the loma prieta earthquake boore et al 1989 maley et al 1989 shakal et al 1989 chin and aki 1991 suggests that weak and strong motion site amplification factors correlate well in the region outside the epicentral source region beyond epicentral distances of about 50 km within the epicentral source region however the weak motion amplification factors estimated from coda waves do not agree with the observed for strong ground motion suggesting a nonlinear behavior at sediment sites these results together with studies on the correlation between weak motion site amplification and earthquake intensity borcherdt 1970 borcherdt and gibbs 1976 chavez garcia et al 1990 king et al 1990 demonstrate the importance of in situ determination of weak motion site amplification for seismic zonation

tributary trunk stream relations in a cut and fill landscape a case study from wolumla catchment new south wales australia at the time of european settlement of the south coast of new south wales australia in the mid nineteenth century river courses were discontinuous throughout wolumla catchment within a few decades of settlement intact valley fills had been transformed into incised channels along trunk streams this induced associated patterns of secondary incision into tributary valley fills three of the primary subcatchments in wolumla catchment became fully incised while an upland swamp and a floodout i e sand sheet deposits atop an intact valley floor remain in mid catchment of the fourth subcatchment of the 70 lower order tributaries which join the trunk streams in the four subcatchments 27 have incised 12 of which are discontinuously incised incision of tributary streams in wolumla catchment cannot be explained by subcatchment area and slope relations the position of the trunk stream channel within the valley floor trough is the key determinant of whether or not tributary streams have incised changes to river morphology since european settlement have altered the linkage of tributary streams to the trunk stream impacting directly on the within catchment transfer of water and sediment

late quaternary climates of the australian arid zone a review abstract aridity in australia has generally been associated with glacial intervals of the last few glacial cycles the causes and nature of aridity varied from north to south over the continent in northern and central australia reduced monsoon rain in global cold stages caused lakes and rivers to dry vegetation to become more sparse sand dunes to become active and dust advection to increase while the monsoon is correlated with warmer global temperatures and high sea levels overall the exact timing of the greatest development of the monsoon in stage 5 remains uncertain in southeastern australia the proxy records give a less clear picture while vegetation seems to have been more sparse in cold stages and sand dune activity and dust flux consequently greater records of runoff in rivers and lakes have mixed or opposite behaviour to northern or central australia the nature of aridity in southeastern australia is not analogous to conditions anywhere on the continent today greatly reduced temperatures over the central and southern interior greater influence of snow and periglaciation on runoff high groundwater tables lower rainfall and reduced atmospheric carbon dioxide levels may all have contributed to and interacted to produce the reconstructed picture of a cold sparsely vegetated arid landscape with large rivers and perennial lakes the largest changes in circulation patterns over the glacial cycle probably occurred in the location and or intensity of summer tropical convergence in northern australia over southern australia changes to the temperature and humidity of the westerly circulation have been more significant than the small fluctuations in latitude of the sub tropical high pressure ridge

the influence of skeletal micro structures on potential proxy records in a bamboo coral assessing the physicochemical variability of the deeper ocean is currently hampered by limited instrumental time series and proxy records bamboo corals isididae form a cosmopolitan family of calcitic deep sea corals that could fill this information gap via geochemical information recorded in their skeletons here we evaluate the suitability of high resolution chemical imaging of bamboo coral skeletons for temperature and nutrient reconstruction the applied elemental mapping techniques allow to verify the suitability of the chosen transect on the sample section for paleo reconstructions and enhance the statistical precision of the reconstruction we measured mg ca via electron microprobe at 1 m resolution and ba ca via laser ablation icp ms at 35 m resolution in a historic specimen of keratoisis grayi from the blake plateau off eastern florida long term growth temperatures of 7 1 3 4 c 2 sd that are in agreement with recent ambient temperature range can be reconstructed from mg ca ratios provided that anomalously mg enriched structural features around the central axis and isolated features related to tissue attachment are avoided for reconstruction skeletal ba ca measurements reflect mean seawater barium ba sw concentrations ba sw 51 24 nmol kg 1 2 sd in agreement with instrumental data 47 nmol kg 1 we show for the first time that ba ca forms concentric structures in a bamboo coral skeleton section our investigations suggest that while bamboo coral skeletons do record environmental parameters in their mean chemical composition the magnitude of environmental variability reconstructed from high resolution chemical maps exceeds that expected from instrumental time series this necessitates additional investigation of the factors driving bamboo coral skeletal composition

comparison of site classification from vs30 vs10 and hvsr in italy the aim of this work is to verify if 1 the average of shear wave velocity from the surface to 30 m depth vs30 is a good proxy of site amplification in a country with complex geology like italy 2 the grouping of vs30 in different soil classes and relevant spectra in the italian seismic codes is adequate and 3 shallow shear wave profiles vs10 could be a more economical tool for site classification to answer the first two questions we examined 40 estimates of vs30 derived from microzonation projects we performed in italy 27 obtained with downhole measurements plus 13 ve locity profiles obtained with surface techniques in all the sites we installed seismic instrumentation to record earthquakes and to estimate site response using horizontal to vertical spectral ratios hvsr the comparison between hvsr and vs30 showed in about one third of the sites that vs30 is not a good proxy of observed amplification effects if the site does not have a monotonically increasing velocity profile the reason vs30 does not provide satisfactory estimates in italy is linked to peculiar geological settings that are widespread in the country we then compared the observed ampli fications from earthquake hvsr data with the ones provided by the italian seismic code noting a substantial underestimation by the code a somewhat unsettling situa tion because hvsr is usually considered to be a lower bound for amplification es timated with other techniques finally we studied 45 vs downhole profiles to 30 m depth performed also at sites where earthquake recordings are not available on this data set we noticed that vs10 could predict site classification with the same performances of vs30 we consider al ternative soil classification schemes that include soil frequency besides the velocity profile in this two parameter approach vs10 could be substituted for vs30

investigation of site properties in adapazari turkey using microtremors and surface waves determination of suitable areas for new residential buildings is crucial to increase the resilience of buildings against earthquake hazards after the 1999 izmit earthquake mw 7 4 the city of sakarya has been expanding rapidly in terms of both the population and number of superstructures despite the fact that sakarya suffered several large earthquakes in the last two decades the geophysical properties of the region have not been adequately investigated in this study the site properties of sakarya university esentepe campus and its surrounding serdivan district which is one of the important parts of the city are determined using microtremor measurements and surface wave analysis nakamura s spectral ratio method spectral ratio between the horizontal and vertical components h v or hvsr was used to determine the fundamental frequency and site amplification values the shear wave velocity profiles of the studied sites were determined using the multichannel analysis of surface waves method seismic measurements were performed at 34 locations to record the surface waves in the area the fundamental frequency and site amplification values are determined as 1 02 11 68 and 1 33 5 96 hz respectively from the microtremor measurements the fundamental frequency is between 4 0 and 11 5 hz in the campus area and between 1 3 and 2 0 hz near the d 100 intercity highway the site amplification was determined to be 1 2 5 in the campus area the greatest site amplification 6 is obtained at thick alluvium deposits in the valley between hills the average shear wave velocity values are within the range of 300 and 1120 m s some parts located on the hill area have better soil condition b categories according to the national earthquake hazard reduction program and have comparatively high shear wave velocities in the range of 740 1080 m s whereas low velocity values are found at the thick alluvium deposits d we found that the geological properties and topographies play very important roles on the shear wave velocity and the amplification factors in the investigated area

ocean acidification trend in the tropical north pacific since the mid 20th century reconstructed from a coral archive abstract ocean acidification caused by anthropogenically elevated co 2 concentration in the atmosphere can pose a critical threat to calcifying marine organisms and coral reef ecosystems however because of temporally and spatially limited instrumental ph records little is known about the actual long term trend and natural variability of seawater ph during the past century we present an annually resolved time series of a ph proxy record for 1940 1999 using boron isotope composition 11 b in a modern massive porites coral from guam island nw pacific when superimposed onto interannual variability the data show a slightly decreasing trend of 0 39 equivalent to 0 05 0 08 ph units for surface water ph in the northwestern tropical pacific since the mid 20th century this first reported coral based reconstruction of long term open ocean ph is a unique archive for ocean acidification trend in the north pacific ocean for the past which along with 11 b records from south pacific corals can be an important key to ascertaining the extent and rapidity of actual acidification in the pacific ocean in the future

a next generation vs30 map for california based on geology and topography abstract correlations between geologic units and shear wave velocity form the basis of a series of maps developed over the past 15 years to estimate the time averaged shear wave velocity in the upper 30 m v s 30 the wills et al 2000 site condition map for california was found to correlate with seismic amplification field 2000 and was adopted as a standard depiction for many applications of seismic shaking estimates shakemap for example wills and clahan 2006 modified that map to show simplified geologic units and corresponding v s 30 values preparation of this map raised a number of questions on how best to distinguish units within younger alluvium wills and gutierrez 2011 found that a simple system based on surface slope could be used to subdivide the younger alluvium into three classes that have distinct v s 30 ranges the classes defined by slope have approximately the same variability in v s 30 as the previously defined classes but the total number of classes is reduced and the system can be easily applied to other tectonically active areas we have now applied the system of wills and gutierrez 2011 to create a new map of california using the most detailed available geologic maps use of more detailed geologic maps from 1 250 000 scale to 1 24 000 for much of california results in a much more detailed and accurate depiction of the surficial geology and we anticipate a more detailed and accurate depiction of seismic amplification due to the near surface materials online material site condition map of california at a scale of 1 1 500 000 as well as in arcgis formats

variability in sediment delivery and storage along river courses in bega catchment nsw australia implications for geomorphic river recovery in many catchments in southeastern australia alluvial stores have been the dominant source of sediments mobilised in the period since european settlement in bega catchment on the south coast of new south wales nsw this has been reflected by dramatic changes to river morphology extensive volumes of material have been released and efficiently flushed to the lowland plain with a sediment delivery ratio of almost 70 however only 16 of these alluvial sediments have been flushed through to the estuary as antecedent controls on valley width have resulted in the lowland plain acting as a large sediment sink the changing nature of sediment source transfer and accumulation zones has varied markedly from subcatchment to subcatchment the volume of material supplied to the lowland plain from differing subcatchments is not related to subcatchment area rather the pattern of river types dictates the spatial variability in storage and transfer over 67 of sediment released has been sourced from just 25 of the catchment from subcatchments characterised by large valley fills cut and fill river style that previously stored extensive volumes of material at the base of the escarpment these parts of bega catchment were especially sensitive to disturbance sediment exhaustion from these parts of the catchment and from river courses elsewhere has major implications for the geomorphic recovery potential of rivers constraining what can be realistically achieved in terms of river rehabilitation

scenario shakemaps for ottawa canada ottawa ranks third among canadian urban areas in terms of seismic risk scenario shakemaps are generated for the ottawa region to study the expected ground shaking intensity distribution patterns for input to damage and risk studies variability in near surface geology plays an important role in earthquake ground shaking in the region the quarter wavelength method is used to generate frequency dependent amplification functions for typical generic soil profiles across the city using shear wave velocity and depth to bedrock data from 17 250 compiled soil profiles the methodology is validated using the ground motion and did you feel it records from the 2010 m 5 val des bois earthquake which occurred 60 km from ottawa it is noted that the calculated amplifications for typical ottawa soil profiles are often greater than generic national earthquake hazards reduction program factors as applied in building code applications for a scenario earthquake corresponding to the national building code of canada probability level of graphic 1 expected modified mercalli intensity values in soft soil areas of ottawa would be near 7 on average the impact of event location on expected ground motions and intensities was tested by considering the occurrence of a scenario earthquake a given magnitude event at various locations in the region the results of this study may be used as input to seismic risk studies for ottawa 1 embed inline graphic 1 gif

in stream wetlands and their significance for channel filling and the catchment sediment budget jugiong creek new south wales abstract evidence is presented here of recent and extensive infilling of the incised channel network of the jugiong creek catchment se australia the present channel network resulted from widespread stream and gully incision in the period between 1880 and 1920 our survey shows that gully floors have been colonised extensively by emergent macrophyte vegetation since before 1944 forming continuous dense in stream wetlands which now cover 25 of the channel network in the 2175 km 2 catchment and have so far trapped almost 2 000 000 t of nutrient enriched fine sediments this mass of sediments represents the equivalent of 4 7 years of annual sediment production across the catchment and in some tributaries more than 20 years of annual yield is stored within in stream wetlands previous work on the late quaternary stratigraphy of the region has shown that there were repeated phases of channel incision in the past following which the channels quickly stabilised by natural means and then filled with fine grained sediment to the point of channel extinction creating unchannelled swampy valley floors the current formation and spread of in stream wetlands is interpreted to be the onset of the next infill phase but it is not known whether present conditions will allow complete channel filling and reformation of the pre existing swampy valley floors nevertheless further spread of in stream wetlands is likely to increase the sediment trapping capacity and further reduce the discharge of sediments and nutrients into the murrumbidgee river the in stream wetlands may provide a significant capacity to buffer erosion from gullied catchments of considerable size up to 300 km 2 as an adjunct to current riparian management options they may also assist the recovery of sediment impacted channels downstream

evaluation of local site effects and their removal from borehole records observed in the sendai region japan abstract we present results from a borehole observation network composed of 12 borehole sites deployed in a 20 20 km area in the sendai region japan the subsurface quaternary layers vary with each site but a pliocene layer is commonly underlying at a depth of 0 to 80 m throughout the sendai region we define this pliocene layer whose s wave velocity is larger than 500 m sec and whose n value of the standard penetration test is greater than 50 as an engineering bedrock in the region once we characterize ground motions at the engineering bedrock we can either use these motions directly in the response analysis of whole soil building systems or use them in the nonlinear analysis of soft soil layers as an input the purpose of this study is to evaluate the local site effects due to surface layers overlying the engineering bedrock and to remove them by using one dimensional 1d soil models whose properties are determined by weak motion records of 18 events first we identify s wave velocities and frequency dependent quality factors q from amplification factors between surface records and borehole records observed at 10 sites at depths of several tens of meters the identified s wave velocities are very close to s wave logging values the identified q values show strong frequency dependence proportional to f 0 46 to 1 16 where f is frequency we confirm that the observed amplification factors in the frequency range from about 0 1 to 20 hz can be explained well by the theoretical ones based on the 1d wave propagation theory with the identified s wave velocities and q then we estimate the so called engineering bedrock waves which are supposed to be observed on the outcrop of the engineering bedrock from borehole records by using the 1d models with these identified soil constants we confirm that local site effects due to surface layers overlying the engineering bedrock are properly removed so that we have similar characteristics in the resultant engineering bedrock waves from records at different sites

cold water coral growth in the alboran sea related to high productivity during the late pleistocene and holocene abstract cold water corals are common along the moroccan continental margin off melilla in the alboran sea western mediterranean sea where they colonise and largely cover mound and ridge structures radiocarbon ages of the reef forming coral species lophelia pertusa and madrepora oculata sampled from those structures reveal that they were prolific in this area during the last glacial interglacial transition with pronounced growth periods covering the bolling allerod interstadial 13 5 12 8 ka bp and the early holocene 11 3 9 8 ka bp their proliferation during these periods is expressed in vertical accumulation rates for an individual coral ridge of 266 419 cm ka 1 that consists of coral fragments embedded in a hemipelagic sediment matrix following a period of coral absence as noted in the records cold water corals re colonised the area during the mid holocene 5 4 ka bp and underwater photographs indicate that corals currently thrive there it appears that periods of sustained cold water coral growth in the melilla coral province were closely linked to phases of high marine productivity the increased productivity was related to the deglacial formation of the most recent organic rich layer in the western mediterranean sea and to the development of modern circulation patterns in the alboran sea

site amplifications for generic rock sites seismic shear wave velocity as a function of depth for generic rock sites has been estimated from borehole data and studies of crustal velocities and these velocities have been used to compute frequency dependent amplifications for zero attenuation for use in simulations of strong ground motion we define a genetic rock site as one whose velocity at shallow depths equals the average of those from the rock sites sampled by the borehole data most of the boreholes are in populated areas for that reason the rock sites sampled are of particular engineering significance we consider two genetic rock sites rock corresponding to the bulk of the borehole data and very hard rock such as is found in glaciated regions in large areas of eastern north america or in portions of western north america the amplifications on rock sites can be in excess of 3 5 at high frequencies in contrast to the amplifications of less than 1 2 on very hard rock sites the consideration of unattenuated amplification alone is computationally convenient but what matters for ground motion estimation is the combined effect of amplification and attenuation for reasonable values of the attenuation parameter k 0 the combined effect of attenuation and amplification for rock sites peaks between about 2 and 5 hz with a maximum level of less than 1 8 the combined effect is about a factor of 1 5 at 1 hz and is less than unity for frequencies in the range of 10 to 20 hz depending on t using these amplifications we find provisional values of about ao 70 bars and k 0 0 035 sec for rock sites in western north america by fitting our empirically determined response spectra for an m 6 5 event to simulated values the borehole data yield shear velocities 033o of 618 and 306 rrdsec for rock and soil sites respectively when averaged over the upper 30 m from this we recommend that v30 equals 620 and 310 m sec for applications requiring the average velocity for rock and soil sites in western north america by combining the amplifications for rock sites and the site factors obtained from our analysis of strong motion data we derive amplifications for sites with 17 3o 520 m sec nehrp class c corresponding to a mix of rock and soil sites and v3o 310 and 255 m sec average soil and nehrp class d sites respectively for the average soil site the combined effect of amplification and attenuation exceeds a factor of 2 0 for frequencies between 0 4 and about 4 hz with a peak site effect of 2 4 the peak of the nehrp class d site effect is 2 7

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

near surface attenuation and site effects from comparison of surface and deep borehole recordings abstract near surface attenuation and site effects are investigated using the seismograms of 17 local earthquakes recorded at depths of 0 0 3 1 5 2 5 and 2 9 km in the cajon pass borehole southern california the borehole penetrates 500 m of miocene sandstone and then crystalline granitic basement rock previous estimates of site response have been limited to shallower holes where the surface reflection interferes with the upgoing direct wave and the deepest sensor is not below the severe near surface effects in bedrock spectral ratios of the direct p and s waves for each earthquake between the different recording levels are well modeled with frequency independent q and amplification at the borehole q p 27 8 and q s 21 7 in the upper 2 9 km increasing from q p 26 and q s 15 in the upper 300 m to q p 133 and q s 47 between 1 5 and 3 km one event was also recorded at a surface granite site less than 1 5 km from the wellhead comparison of the 2 9 km recording with that at this granite site gives q p 50 and q s 23 the similarity of these values with those of previous studies at a wide range of sites suggests that q is very low in the near surface independent of rock type near surface amplification appears considerably more site dependent at the wellhead the amplifications at 1 hz of the direct p and s waves are 12 7 and 13 7 respectively these values include the free surface effect and are in reasonable agreement with the impedance contrast from the borehole logs at the granite site amplification of both p and s waves is less than four direct wave amplification at the wellhead is therefore at least three times that of the granite site the spectra of the direct and coda waves of the one earthquake recorded at both the wellhead and granite sites are compared with the corresponding 2 9 km recording coda wave amplification is in good agreement with the direct wave at the rock site but at the borehole the coda wave amplification factor overestimates the direct wave amplification by a factor of 3

site amplification from s wave coda in the long valley caldera region california following the work of phillips 1985 we have computed site amplification factors for coda waves at many sites in the long valley region in the eastern sierra nevada we computed ratios of coda amplitudes measured at 15 stations in and around long valley caldera relative to a granitic site mmpm for six frequency bands centered at 1 5 3 0 6 0 9 0 12 0 and 15 0 hz all station sites located within the caldera experienced large ground motion amplification at 1 5 and 3 0 hz ranging between five and 17 times that of the reference site however at higher frequencies these same sites exhibited significantly less amplification than the reference granite site this is attributed to the competing effects of an impedance contrast between the basement rock and caldera fill and very high absorption in the caldera fill at high frequencies station mmlm located on top of a volcanic plug displayed the largest amplitudes of all the sites studied for frequencies between 9 0 and 15 0 hz a dike structure attached to the plug couples the basement rock to the surface at high frequencies the resulting large amplitudes at mmlm are not due to amplification resulting from a strong impedance contrast rather the absorption under this site is very low perhaps lower than at the reference site mmpm outside the caldera another hard rock site located at devil s postpile mdpm generally behaved like the reference site for all frequencies the lowest amplifications observed came from a site outside the caldera mdcm located on thin pyroclastic ash deposits overlying granitic basement this can be attributed to a dominance of absorption over the amplification caused by lower impedance of this layer variations among sites on similar surface geology may be due to small local variations in impedance and absorption under and adjacent to the site the range in the spectral decay parameter between caldera and rock sites are comparable to results of anderson and hough 1984 for sites on alluvium and rock in the san fernando region these surprisingly different amplifications support the need for additional site specific studies amplifications determined in this study for the frequency range 1 5 and 3 0 hz correlate remarkably well with eaton s 1990 residuals for duration magnitude fmag and amplitude magnitude xmag for the usgs northern california seismic array further supporting the use of coda waves in determining site specific amplification

evaluation of methods for estimating linear site response amplifications in the los angeles region we have evaluated two methods of estimating linear site response amplifications and the standard index for classifying sites by comparing the results of each technique to observed ground motions at 33 sites in the los angeles region using velocity and density profiles from 33 boreholes we evaluated the use of the average 30 m shear wave velocity and associated site classifications the quarter wavelength method and the haskell propagator matrix method we correlated the average 30 m shear wave velocity and nehrp site classification at the borehole sites colocated within 290 m of a site with observed ground motion the observed data follow the expected trend of higher ground motion amplifications for lower average shear wave velocities but there is a significant degree of variability also there is a great deal of scatter in the observed amplifications within each national earthquake hazards reduction program nehrp class we used the velocity and density information in the database to calculate the average frequency dependent site response in the frequency ranges 1 3 hz 3 5 hz and 5 7 hz for a one dimensional flat layered structure using the haskell propagator matrix method and the quarter wavelength method there is a general correlation with the ground motion data however once again there is a great degree of scatter although slightly less for the quarter wavelength method we note that both the observed and predicted amplifications can change dramatically over a distance as small as 1 km or less even though all techniques considered give results that follow the expected trend of higher amplifications for softer sediments the predicted site response at any particular site with the current level of information may not be representative of the shaking that will actually occur during an earthquake the disparity between observed and predicted amplifications appears to be a result of oversimplification inherent in the amplificationestimation methods such as the use of average or assumed values for the site conditions in the absence of measured values the smoothing effect of using an average velocity limiting the properties considered to the uppermost 30 m of material and complexities in the wave propagation that are not addressed by these methods

the character and age structure of valley fills in upper wolumla creek catchment south coast new south wales australia extensive valley fills at the base of the escarpment in upper wolumla creek on the south coast of new south wales australia have formed from a combination of cut and fill processes the valley fills comprise series of alternating horizontally bedded sand and mud units reflecting reworking of detritus from deeply weathered granites of the bega batholith sand units are deposited as sand sheets or splays on floodplain surfaces or in floodouts that form atop intact valley fill surfaces downstream of discontinuous gullies alternatively sands are deposited from bedload and form bars or part of the valley floor within channel fills organic rich mud units are deposited from suspension in swamps or in seepage zones at the distal margin of floodouts within 5 km of the escarpment valley deposits grade downstream from sand sheet and splay deposition in floodouts to mud deposition in swamp and seepage zones radiocarbon dates indicate that virtually the entire valley fill of upper wolumla creek was excavated prior to 6000 years bp remnant terraces are evident at valley margins the valley subsequently filled between 6000 years bp and 1000 years bp producing valley fills around 12 m deep but no greater than 300 m wide reincision into the valley fill on a scale smaller than the present incision phase is indicated at around 1000 years bp following which the channel refilled portion plans dated from 1865 refer to the study area as wolumla big flat and show large areas of swampy terrain suggesting that the valley fill had re established by this time within a few decades of european settlement the valley fill incised once more upper wolumla creek now has a channel over 10 m deep and 100 m wide in places draining a catchment area of less than 20 km2 1998 john wiley sons ltd

the recent history of erosion and sedimentation on the southern tablelands of southeastern australia sediment flux dominated by channel incision abstract as in other regions colonised from europe within the last few centuries australia s vegetation and soils have been dramatically changed by clearing cropping and grazing in southeastern australia particularly on the southern tablelands the impacts of european settlement are clearly manifested by channel incision by using stratigraphic and documentary evidence in conjunction with aerial photographs sediment budgets for the post settlement period have been constructed to define the fluxes and stores of sediment for each of the major geomorphic components of the 136 km2 catchment of jerrabomberra creek near canberra using these budgets and some plausible assumptions it has been possible to approximate the history of both the sediment delivery ratio and sediment yield for this catchment while the quantities estimated in this analysis are approximations the trends through time are credible sediment yield increased rapidly to a peak after european settlement and has returned to a level between the peak and the pre european value the delivery ratio has followed a similar trend the most general conclusion to emerge is that in this landscape both the total sediment flux and the sediment yield of the catchment have been dominated by channel erosion this result is contrary to the findings in many parts of the world where sheet and rill erosion dominates the fluxes the soil conservation implication of these results is clear to control off site effects of erosion the focus must be on the channels

reproducibility of trace element profiles in a specimen of the deep water bamboo coral keratoisis sp abstract bamboo corals order gorgonacea family isididae are attractive prospects for deep sea paleoceanographic reconstruction capturing trace elements in their calcitic skeletons that may serve as environmental proxies with subdecadal resolution over multi century timescales we study the reproducibility and fidelity of trace element profiles ba mg sr mn u pb in a 420 year old specimen of the bamboo coral keratoisis sp from the se usa using laser ablation icp ms to obtain multiple replicate profiles we use spectral techniques to distinguish noise and irreproducible variations from fully reproducible geochemical fluctuations that are candidates for environmental signals by quantifying variability between profiles we assess the fidelity with which the corals potentially record environmental information barium is the most reproducible element in the skeleton with large fluctuations along different growth radii reproducing to within 4 both mg and sr have very uniform levels within the coral but display low amplitude irreproducible variations that might represent an internal biological process in the case of mg which has been proposed as a paleotemperature proxy this irreproducibility would represent an intrinsic uncertainty of 0 1 to 0 4 c both mn and pb contain some irreproducibility superimposed upon broad reproducible profiles that may be environmental signals some of the irreproducible pb fluctuations correlate with cracks and dark bands in the sample suggesting detrital or surface contamination uranium displays large amplitude variations which are not reproducible along different radii this suggests that uranium cannot be used for paleoenvironmental reconstruction and may show signs of early diagenesis a possibility that could complicate attempts to date young keratoisis sp samples by u series geochemistry the highly reproducible ba signal allows precise alignment of profiles and thus we can show that growth rate along one radius can vary by a factor of two relative to growth along a different radius there is no evidence that this large variation in relative growth rate affects either the mg or sr incorporation in addition geochemical anomalies in ba and mg indicate that the very central axis of the specimen may represent a different mode of growth this study suggests that keratoisis sp corals are imperfect recorders of geochemical information but do contain reproducible variations which are good candidates for environmental signals

site amplification factors in central and southern california determined from coda waves abstract site amplification factors at frequencies of 1 5 3 6 and 12 hz were determined for 158 stations of the southern california seismic network scsn from coda waves of 306 local earthquakes using a recursive stochastic inverse method our results for southern california are consistent with those of central california obtained by su et al 1992 in that the site amplification at a station is systematically related to the surface geology of the station site the site amplification is high for young quaternary sediments and decreases with increasing geologic age at all frequencies between 1 5 and 12 hz this decreasing rate is higher for younger rock sites gradually becomes lower with increasing geologic age and appears to be insignificant when the site reaches mesozoic age or older the relationship between site amplification and geologic age obtained for southern california agrees with that for central california amplification factors at 158 sites in southern california were combined with those at 132 sites in central california through a common reference site the result is a unique data base of site specific uniformly referenced amplification factors throughout central and southern california

holocene valley aggradation and gully erosion in headwater catchments south eastern highlands of australia late quaternary stratigraphy of a 50 km2 catchment on the south eastern highlands of australia reveals processes and history of denudation and helps resolve a long standing debate about factors controlling episodic valley aggradation and degradation during holocene times valley sedimentation occurred when swampy vegetation fully colonized valley floors and obliterated all channels promoting aggradation for periods of several thousand years with most incoming sediment being trapped in swampy meadows much of the sediment was reworked from late pleistocene alluvial fan and valley fill deposits and primary hillslope erosion was minor during the holocene differing sedimentation patterns between the late pleistocene holocene and post european settlement periods reflect regional changes in sediment supply and transport capacity as a result of major environmental change within the holocene however valley fill stratigraphy is controlled by massive episodic gully erosion terminating aggradation gully initiation appears to be controlled more by thresholds of incision into vegetated valley floors than by changes to sediment supply whether the thresholds are exceeded because of climatic change autonomous change or extreme events cannot yet be determined overall the holocene history represents continuing complex response to events of the late pleistocene and does not support the k cycle concept which has strongly influenced late quaternary geomorphology in australia

gully formation and the role of valley floor vegetation southeastern australia attempts to understand the causes of gully erosion have been hampered by a poor understanding of quantitative changes to the force of flows and the resistance to scour we used flume experiments on an unincised valley floor to determine flow resistance and the critical shear stress for scour under natural and degraded vegetation covers applying the results to sites of gully formation in southeastern australia demonstrates the crucial role that reduced vegetation cover plays in increasing the susceptibility of valleys to channel incision widespread and rapid gully formation in the 19th century required degradation of valley floor vegetation and was not solely the result of land use or climatically induced increases in discharge

discontinuous ephemeral streams abstract many ephemeral streams in western north america flowed over smooth valley floors before transformation from shallow discontinuous channels into deep arroyos these inherently unstable streams of semiarid regions are sensitive to short term climatic changes and to human impacts because hillslopes supply abundant sediment to infrequent large streamflow events discontinuous ephemeral streams appear to be constantly changing as they alternate between two primary modes of operation either aggradation or degradation may become dominant attainment of equilibrium conditions is brief disequilibrium is promoted by channel entrenchment that causes the fall of local base level and by deposition of channel fans that causes the rise of local base level these opposing base level processes in adjacent reaches are maintained by self enhancing feedback mechanisms the threshold between erosion and deposition is crossed when aggradational or degradational reaches shift upstream or downstream extension of entrenched reaches into channel fans tends to create continuous arroyos upvalley migration of fan apexes tends to create depositional valley floors with few stream channels less than 100 years is required for arroyo cutting but more than 500 years is required for complete aggradation of entrenched stream channels and valley floors discontinuous ephemeral streams have a repetitive sequence of streamflow characteristics that is as distinctive as sequences of meander bends or braided gravel bars in perennial rivers the sequence changes from degradation to aggradation headcuts concentrate sheetflow a single trunk channel conveys flow to the apex of a channel fan braided distributary channels end in an area of diverging sheetflow and converging sheetflow drains to headcuts the sequence is repeated at intervals ranging from 15 m for small streams to more than 10 km for large streams lithologic controls on the response of discontinuous ephemeral streams include 1 amount and size of sediment yielded from hillslopes 2 infiltration capacity of valley floor alluvium that influences both the unit stream power available for upstream headcut migration and the attenuation of flashy streamflow events by riparian vegetation in sheetflow reaches and 3 cohesiveness of alluvium which affects headcut and streambank morphology and rates of arroyo extension downcutting and widening initiation of arroyo cutting may be too complex to be attributed to a single cause such as change in mean annual precipitation or grazing by livestock but is most likely associated with a decrease in density of protective plant cover on hillsides and along valley floors relatively larger unit stream power makes downstream reaches more susceptible to initial entrenchment during floods than headwaters reaches and favors persistent arroyos entrenchment continues until an equilibrium longitudinal profile is briefly attained then channel widening occurs streambanks are undercut and aggradation begins

vs30 mapping and soil classification for seismic site effect evaluation in dinar region sw turkey summary the dinar earthquake m s 6 1 of 1995 october 1 killed 90 people and destroyed more than 4000 buildings despite the moderate size of the earthquake the level of damage was extremely high which led to many studies that were carried out in the region the majority of these studies concluded that the main reasons for the damage were the construction errors and the poor soil conditions however at that time no appropriate soil condition map based on extended high density measurements was available shear wave velocity is an important parameter for evaluating the dynamic behaviour of soil in the shallow subsurface thus site characterization in calculating seismic hazards is usually based on the near surface shear wave velocity values the average shear wave velocity for the top 30 m of soil is referred to as v s 30 for earthquake engineering design purposes both the uniform building code ubc and eurocode 8 ec8 codes use v s 30 to classify sites according to the soil type the v s 30 values calculated by using multichannel analysis of surface waves masw were used to create a new soil classification map of the dinar region surface seismic measurements were carried out at 50 locations mostly in dinar city and its surroundings the dispersion data of the recorded rayleigh waves were inverted using a genetic algorithm ga method to obtain shear wave velocity profiles of the investigated sites thus the derived v s 30 map of the dinar region was transformed to the ubc and ec8 standards soil classification results show that most parts of the region located in alluvial basin have low shear wave velocity values these values are within the range of 160 240 m s 1 and thus fall into the s d and s e categories according to the ubc and the c and d categories according to ec8 within the region some parts located on the hill zone and the transition zone have better soil conditions corresponding to s c ubc and b ec8 categories and have comparatively high shear wave velocities in the range of 500 740 m s 1 and 350 450 m s 1 respectively v s 30 and soil classification maps were compared with the damage distribution associated with the earthquake in possession of a detailed shear wave velocity map of dinar city in general the results show that there is a correlation between the v s 30 values and the damage distribution of the region in addition to the low v s 30 values the likely causes of the damage were investigated and it is observed that one of the major factors for high levels of damage is 3 d variations of geological structures

empirical site response and comparison with measured site conditions at anss sites in the vicinity of reno nevada we empirically evaluate spectral amplification relative to a nearby rock site at 18 advanced national seismic system strong motion stations within the basin containing the urban areas of reno and sparks nevada the near surface site conditions have a strong effect on ground motion which is clearly demonstrated through analysis of weak motion the study uses multiple regional earthquake events of varying azimuth averages of these empirical amplifications grouped by generalized geological formations volcanic rock pliocene and early to mid quaternary sediments and younger quaternary sedimentary sites show dependence on the geology however when the stations are grouped according to v s 30 values the mean amplifications are more distinct indicating that v s 30 is a more useful predictor of amplification for the reno sparks nevada urban area spectral amplifications computed from ground motions of the local mogul nevada 2008 earthquake swarm m l 0 6 4 7 anderson et al 2009 have similar spectral shapes for 8 of the 12 stations where comparisons could be made but the absolute amplitudes are slightly inconsistent four stations show unexplained peaks in the amplitude spectral ratios from the mainshock ground motions the comparisons verify that multiple regional ground motions can be used to obtain relative site response amplification functions for seismic hazard applications but the discrepancies are a reminder that directional effects contribute uncertainty to the amplification functions online material tables describing earthquakes recorded in the vicinity of reno nevada and figures of the fourier spectral ratios fsrs and of the amplitude and basin depth relationships

accounting for site effects in probabilistic seismic hazard analyses of southern california overview of the scec phase iii report this article presents an overview of the southern california earthquake center scec phase iii effort to determine the extent to which probabilistic seismic hazard analysis psha can be improved by accounting for site effects the contri butions made in this endeavor are represented in the various articles that compose this special issue of bssa given the somewhat arbitrary nature of the site effect distinction it must be care fully defined in any given context with respect to psha we define the site effect as the response relative to an attenuation relationship averaged over all damaging earthquakes in the region a diligent effort has been made to identify any attributes that predispose a site to greater or lower levels of shaking the most detailed maps of quaternary geology are not found to be helpful either they are overly detailed in terms of distinguishing different amplification factors or present southern california strong motion observations are inadequate to reveal their superiority a map based on the average shear wave velocity in the upper 30 m however is found to delineate significantly different amplification factors a correlation of amplification with basin depth is also found to be significant implying up to a factor of two difference between the shallowest and deepest parts of the los angeles basin in fact for peak accel eration the basin depth correction is more influential than the 30 m shear wave ve locity questions remain however as to whether basin depth is a proxy for some other site attribute in spite of these significant and important site effects the standard deviation of an attenuation relationship the prediction error is not significantly reduced by making such corrections that is given the influence of basin edge induced waves subsur face focusing and scattering in general any model that attempts to predict ground motion with only a few parameters will have a substantial intrinsic variability our best hope for reducing such uncertainties is via waveform modeling based on first principals of physics finally questions remain with respect to the overall reliability of attenuation re lationships at large magnitudes and short distances current discrepancies between viable models produce up to a factor of 3 difference among predicted 10 in 50 yr exceedance levels part of which results from the uncertain influence of sediment nonlinearity

new views of tropical paleoclimates from corals abstract corals offer a rich archive of past climate variability in tropical ocean regions where instrumental data are limited and where our knowledge of multi decadal climate sensitivity is incomplete in the eastern equatorial pacific coral isotopic records track variations in enso related changes in sea surface temperature further west corals record variability in sea surface temperature and rainfall that accompanies zonal displacement of the indonesian low during enso events these multi century records reveal previously unrecognised enso variability on time scales of decades to centuries outside the enso sensitive equatorial pacific long term trends towards recent warmer wetter conditions suggest the tropics respond to global forcings new coral paleothermometers indicate that surface ocean temperatures in the tropical southwestern pacific were depressed by 4 6 c during the younger dryas climatic event and rose episodically during the next 4000 yr high temporal resolution measurements of sr ca and 18 o in corals provide information about the surface ocean hydrologic balance and can resolve the seasonal balance between precipitation and evaporation radiocarbon measurements in corals coupled with ocean circulation models may be used to reconstruct near surface ocean circulation past mixing rates and the distribution of fossil fuel co2 in the upper ocean most recently seasonal to interannual variations in the radiocarbon of corals from the equatorial pacific have been linked to the redistribution of surface waters associated with the enso

resolving shallow shear wave velocity structure beneath station cbn by waveform modeling of the mw 5 8 mineral virginia earthquake sequence abstract the 23 august 2011 m w 5 8 mineral virginia earthquake was the largest earthquake in the central and eastern united states in the past 100 years and it was well recorded by strong motion and broadband seismometers thus providing abundant ground motion data for earthquake ground motion studies the largest recorded ground motion among advanced national seismic system stations was at station cbn but the site effects at station cbn need to be understood because the strong motions recorded there do not represent bedrock site conditions on the radial component of these recordings the initial p wave is very weak and is followed by a strong signal 0 3 s later which is interpreted to be the s wave converted from the p wave ps at the interface between the sediments and bedrock we first estimate the subsurface shear wave velocity by modeling the ratio of the radial to vertical components of the initial p waves and then resolve the velocity structure and thickness of the unconsolidated sediments by modeling the ps wave the subsurface shear wave velocity is found to be approximately 300 m s consistent with field survey results the shear wave velocity at the bottom of the sediments is constrained to be in the range of 320 780 m s from which the thickness of the layer is estimated to be 100 230 m the estimates of shear wave velocity structure and thickness of the sediments are further improved by modeling the oscillatory waveforms between the p and s waves this study suggests that site characterization for the estimation of ground motion amplification at a site can be achieved inexpensively and noninvasively by modeling local p waveforms recorded at the site

determination of site amplification in the los angeles urban area from inversion of strong motion records abstract the amplification of strong ground motion at sites in the greater los angeles california region is determined using the generalized inverse method of andrews 1986 site amplification estimates are determined at 281 strong motion sites that provided horizontal component accelerograms from the 1971 san fernando 1987 whittier narrows 1991 sierra madre or 1994 northridge mainshocks the estimates are determined relative to the spectral level recorded at a single reference site in a second inversion a source site interaction term is added to andrews9s 1986 model to quantify the effect selected mainshock records have on site amplification estimates the source site interaction term is applied to the san fernando valley sites9 records of the northridge earthquake and to three los angeles basin sites9 records of the whittier narrows mainshock site amplification spectra are averaged within two frequency bands the intermediate frequency band ifb from 0 5 to 1 5 hz and the high frequency band hfb from 2 to 6 hz results are displayed on maps of surficial geology average spectral levels are correlated with average shear wave velocity in the uppermost 30 m a geotechnical parameter used by the national earthquake hazards reduction program nehrp to characterize site amplification statistically significant correlation is found in both frequency bands average spectral amplification levels for nehrp class b c and d sites in the la urban area are determined these averages display an expected increase in spectral amplification with category with a more pronounced variation in the ifb than in the hfb considerable overlap in the one standard deviation range of the c and d site levels is found in both ifb and hfb suggesting that site specific spectral amplification is influenced by more than just near surface shear wave velocity average site amplification levels are compared with those obtained from northridge aftershock records at 28 collocated sites and are found to be in reasonably good agreement in both frequency bands some interesting outliers that is sites for which the mainshock and aftershock determined amplifications differ significantly are identified as sites that experienced ground failure during the northridge mainshock

a site conditions map for california based on geology and shear wave velocity one simple way of accounting for site conditions in calculating seismic hazards is to use the shear wave velocity in the shallow subsurface to classify materials the average shear wave velocity to 30 m v 30s has been used to develop site categories that can be used for modifying a calculated ground motion to account for site conditions we have prepared a site category map of california by first classifying the geologic units shown on 1 250 000 scale geologic maps our classification of geologic units is based on v 30s measured in 556 profiles and geological similarities between units for which we have v s data and the vast majority of units for which we have no data we then digitized the geologic boundaries from those maps that separated units with different site classifications v s data for california shows that several widespread geologic units have ranges of v 30s values that cross the boundaries between nehrp ubc site categories the franciscan complex has v 30s values across ubc categories b and c with a mean value near the boundary between those two categories older alluvium and late tertiary bedrock have v 30s values that range from about 300 to about 450 m sec across the boundary between categories c and d to accommodate these units we have created intermediate categories which we informally call bc and cd geologic units that have or are interpreted to have v 30s values near the boundary of the ubc categories are placed in these intermediate units in testing our map against the available v 30s measurements we have found that 74 of the measured v 30s values fall within the range assigned to the v s category where they fall on the map this ratio is quite good considering the inherent problems in plotting site specific data on a regional map and the variability of physical properties in geologic units we have also calculated the mean and distribution of v 30s for each of our map units and prepared composite profiles showing the variation of v s in the upper 100 m from the available v s data these data show that the map categories that we have defined based on geologic units have different v s properties that can be taken into account in calculating seismic hazards

basin structure effects on long period strong motions in the san fernando valley and the los angeles basin from the 1994 northridge earthquake and an aftershock the strong ground motions recorded within the san fernando valley and in the los angeles basin during the 17 january 1994 northridge earthquake show complex waveforms and complicated patterns of peak acceleration and veloc ity this complexity persists even at long periods 1 to 10 sec we investigate basin structure effects on long period wave propagation in the san fernando valley and in the los angeles basin by the two dimensional finite difference modeling of the mainshock and one selected aftershock with m 4 1 the aftershock ground motion records in the san fernando valley and in the los angeles basin can be explained by basin structure effects assuming a simple point source model the structural effects and a source model composed of two subevents can explain the most prominent characteristics of the strong motion waveforms ob served during the mainshock at sites south of the epicenter while such a combination is not enough to explain the large strong motions observed in the north this result suggests that the rupture propagation effects significantly amplified the ground mo tions at sites north of the epicenter

proliferation and demise of deep sea corals in the mediterranean during the younger dryas abstract uranium series and radiocarbon ages are reported for deep sea corals madrepora oculata desmophyllum dianthus lophelia pertusa and caryophyllia smithii from the mediterranean sea u series dating indicates that deep sea corals have persisted in the mediterranean for over 480 000 years especially during cool interstadial periods the most prolific period of growth however appears to have occurred within the younger dryas yd period from 12 900 to 11 700 years bp followed by a short 330 years phase of post yd coral growth from 11 230 to 10 900 years bp this indicates that deep sea corals were prolific in the mediterranean not only during the return to the more glacial like conditions of the yd but also following the rapid deglaciation and transition to warmer conditions that followed the end of the yd surprisingly there is a paucity last glacial maximum lgm coral ages implying they were largely absent during this period when cold water conditions were more prevalent radiocarbon ages show that the intermediate depth waters of the mediterranean generally had 14 c compositions similar to surface waters indicating that these waters were extremely well ventilated the only exception is a narrow period in the yd 12 500 100 years bp when several samples of lophelia pertusa from the ionian sea had 14 c values falling significantly below the marine curve using a refined approach isolation ages isol of 300 years to 500 years are estimated for these intermediate 800 1000 m depth waters relative to surface marine waters indicating a reduction or absence of deep water formation in the ionian and adjacent adriatic seas during the yd contrary to previous findings we find no evidence for widespread intrusion of low 14 c atlantic waters into the mediterranean prolific growth of deep sea corals in the mediterranean ended abruptly at 10 900 years bp with many of the coral bearing mounds on the continental slopes being draped in a thin veneer of mud their demise is attributed to a number of factors including the direct loss of habitat due to high sedimentation that accompanied glacial meltwater pulses together with rising temperatures that would have finally pervaded the deeper water of the mediterranean following the onset of holocene warming

the non tropical coral cladocora caespitosa as the new climate archive for the mediterranean high resolution weekly trace element systematics abstract high resolution weekly laser ablation icp ms trace element analyses b sr u mg ba are reported for the scleractinian coral cladocora caespitosa collected from the northern adriatic sea geochemical ratios sr ca b ca mg ca u ca ba ca were measured in a 38 mm long 10 years growth external coralline portion wall region and generally exhibit a close relationship with the in situ measured weekly fortnightly data on sea surface temperature sst available for the last 6 years in particular b ca ratios tuned to fine scale variations in sst show a high degree of correlation r 0 856 n 136 with sst and indicate that coral calcification only occurs above a minimum temperature threshold of 14 16 c in addition the ranges of trace element variability are larger than those typically recorded in tropical corals consistent with the large seasonal variations in sst of the adriatic this study thus demonstrates the feasibility of extracting and exploiting high resolution geochemical records from non tropical corals such as c caespitosa as a proxy for sst

quantifying the ph vital effect in the temperate zooxanthellate coral cladocora caespitosa validation of the boron seawater ph proxy boron isotopic and elemental systematics are used to define the vital effects for the temperate shallow water mediterranean coral cladocora caespitosa the corals are from a range of seawater ph conditions pht 7 6 to 8 1 and environmental settings 1 naturally living colonies harvested from normal ph waters offshore levanto 2 colonies transplanted nearby a subsea volcanic vent system and 3 corals cultured in aquaria exposed to high 700 atm and near present day 400 atm pco2 levels b ca compositions measured using laser ablation inductively coupled mass spectrometry la icpms show that boron uptake by c caespitosa cultured at different pco2 levels is independent of ambient seawater ph being mainly controlled by temperature dependent calcification in contrast the boron isotope compositions 11bcarb of the full suite of corals determined by positive thermal ionisation mass spectrometry ptims shows a clear trend of decreasing 11bcarb from 26 7 to 22 2 with decreasing seawater ph reflecting the strong ph dependence of the boron isotope system the 11bcarb compositions together with measurements of ambient seawater parameters enable calibration of the boron ph proxy for c caespitosa by using a new approach that defines the relationship between ambient seawater ph phsw and the internally controlled ph at the site of calcification phbiol c caespitosa exhibits a linear relationship between phsw and the shift in ph due to physiological processes ph phbiol phsw giving the regression phclad 4 80 0 52 phsw for this species we further apply this method ph phsw to calibrate tropical species of porites acropora and stylophora reported in the literature the temperate and tropical species calibrations are all linearly correlated r2 0 9 and the biological fractionation component ph between species varies within 0 2 ph units our ph phsw approach provides a robust and accurate tool to reconstruct palaeoseawater phsw for both temperate and tropical corals further validating the boron fractionation factor b3 b4 1 0272 determined experimentally by klochko et al 2006 and the boron isotope ph proxy both of which have been the foci of considerable debate

the information content of high frequency seismograms and the near surface geologic structure of hard rock recording sites due to hardware developments in the last decade the high frequency end of the frequency band of seismic waves analyzed for source mechanisms has been extended into the audio frequency range 20 hz in principle the short wavelengths corresponding to these frequencies can provide information about the details of seismic sources but in fact much of the signal is the site response of the nearsurface several examples of waveform data recorded at hard rock sites which are generally assumed to have a flat transfer function are presented to demonstrate the severe signal distortions includingfmax produced by near surface structures analysis of the geology of a number of sites indicates that the overall attenuation of high frequency 1 hz seismic waves is controlled by the whole path q between source and receiver but the presence of distinctfmax site resonance peaks is controlled by the nature of the surface layer and the underlying near surface structure models of vertical decoupling of the surface and nearsurface and horizontal decoupling of adjacent sites on hard rock outcrops are proposed and their behaviour is compared to the observations of hard rock site response the upper bound to the frequency band of the seismic waves that contain significant source information which can be deconvolved from a site response or an array response is discussed in terms offmax and the correlation of waveform distortion with the outcrop scale geologic structure of hard rock sites it is concluded that although the velocity structures of hard rock sites unlike those of alluvium sites allow some audio frequency seismic energy to propagate to the surface the resulting signals are a highly distorted limited subset of the source spectra

the holocene evolution and geomorphology of a chain of ponds southeast australia establishing a physical template for river management abstract chains of ponds are a discontinuous river type found in australia their unusual morphology important ecological functions and increasing rarity make them a priority for conservation and yet very little research has investigated their physical structure behaviour and evolution this paper reconstructs the holocene evolution and environmental history of crisp s creek a headwater chain of ponds in the southern tablelands of nsw australia this history establishes baseline information on the physical template that can be used to assess a range of other biophysical processes and design appropriate river rehabilitation and management strategies for these rivers sedimentary aggradation began in the late holocene at least 3 7 1 3 ka broadly synchronous with aggradation phases at other sites in southeast australia since european arrival in the nineteenth century parts of the river incised destroying intact ponds and smothering formerly swampy floodplains with post incision alluvium however sections unaffected by incision provide a rare opportunity to examine the evolutionary trajectory of an intact variant of these rivers this research deepens our understanding of the evolutionary context for contemporary river behaviour as relevant for designing appropriate and effective conservation and rehabilitation strategies for chains of ponds

unexpected values of qs in the unconsolidated sediments of the mississippi embayment we studied the attenuation of shear waves at three sites in the mississippi embayment using data recorded in boreholes drilled to depths of up to 60 m the source was a highly repeatable compressed air driven hammer to estimate attenuation we used a spectral ratio technique for fixed depth and variable frequency the best fit line for each depth z gives a measure of the cumulative attenuation indicated by z then we fit a straight line to z for a range of values of z the slope of this line gives an estimate of the average attenuation per distance and was used to determine an average q s for one of the sites newport northeastern arkansas q s ranges between 34 1 5 m z 44 2 m and 44 1 5 m z 51 8 m these values are significantly higher than the more typical value of about 10 determined for unconsolidated sediments by other authors in addition these high values correspond to sediments with low average shear wave velocity about 300 m sec in contrast average q s and velocity for sediments in shelby forest near memphis tennessee are 22 and 348 m sec 22 6 m z 60 1 m respectively therefore these results go against the conventional wisdom that low velocity implies low q for the third site marked tree northeastern arkansas average q s and velocity are 18 and 251 m sec 9 8 m z 33 6 m respectively this site is about 75 km from newport and the differences in attenuation appear related to differences in lithology manuscript received 5 april 2001

holocene hydrologic variability in temperate southeastern australia an example from lake george new south wales lake george is one of the largest freshwater lakes in australia when full and provides one of the most complete records of quaternary sedimentation in the southeastern part of the continent the lake is currently ephemeral but sediments within the basin preserve evidence of multiple permanent and dry lake conditions in the past we present an optically stimulated luminescence osl chronology of recent lake shoreline sediments in order to reconstruct holocene hydrologic variability at lake george providing past climatic context for the presently ephemeral lake conditions the osl chronology indicates three distinct periods of permanent lake conditions up to 15 18 m depth over the holocene period at approximately 10 8 6 2 4 and 0 7 0 3 ka with lower lake levels occurring in between those events there appears to be a trend towards lake regression over this period despite relatively recent high lake levels the chronology is broadly synchronous with comparable records of holocene climatic variability across southeastern australia we also investigate the intrinsic luminescence characteristics of different sediment types as diagnostic tools but these appear not to be appropriate in this context or form

late quaternary river evolution of floodplain pockets along mulloon creek new south wales australia valley confinement along upper middle reaches of mulloon creek in the upper shoalhaven catchment of southern new south wales australia restricts floodplain development to a series of distinct pockets these pockets comprise a downstream thinning wedge of vertically accreted fine grained deposits atop basal gravels some time before 12500 years ago a bedload dominated river was transformed into a suspended load system in the mid late holocene swamps developed in the middle lower part of each floodplain pocket within a few decades of european settlement of this region circa ad 1820 discontinuous watercourses in some floodplain pockets had incised to form a low sinuosity gravel bed channel wedge shaped units of post incisional alluvium that thicken downstream overlie the swamp and floodplain deposits in the downstream part of these pockets in the downstream most pocket incision commenced prior to colonization while upstream swamps retain a continuous swamp across the valley floor the late quaternary evolution of this variant of discontinuous watercourse is summarized in a schematic model

site response for urban los angeles using aftershocks of the northridge earthquake ground motion records from aftershocks of the 1994 northridge earthquake are used to estimate site response in the urban los angeles area over 1300 shear wave records from 61 sources and 90 sites are used in a linear inversion for source and site response spectra the methodology makes no assumptions about the shape of the source spectrum to obtain a stable unique inverse a q model and geometrical spreading factor are assumed in addition the site response at a hard rock site is constrained to be approximately 1 0 with a kappa of 0 02 the site response spectra compare favorably with the results of previous and on going investigations in los angeles a couple of first order effects are lower site response in the surrounding mountains dominated by mesozoic and tertiary rocks and higher values in the san fernando and los angeles basins containing surficial pleistocene and holocene alluvial deposits results show good correlation of high site response spectral values with localized areas of severe damage interstate 10 collapse sherman oaks northridge interstate 5 14 collapse however widespread trends in site response across the sedimentary basins are not obvious the data suggest that site responses are lower near the southern margin of the san fernando valley for sources to the north due to north dipping sedimentary structures but the general pattern of site response is characterized by high variability on length scales less than a kilometer variations of a factor of 2 in site response are observed over the length scale of 200 m and for the same surficial geologic unit for some of the alluvial basin sites surface wave generation is a significant contributor to elevated site response at lower frequencies below 2 hz the total damage pattern for the northridge earthquake is influenced by strong source directivity to the north and strong local site effects the correlation of weak motion site response estimates with areas of significant damage demonstrates the value of these field measurements in future urban planning and in the reduction of seismic risk in urban areas

peatlands in eastern australia sedimentology and age structure of temperate highland peat swamps on sandstone thpss in the southern highlands and blue mountains of nsw australia temperate highland peat swamps on sandstone thpss are a form of topogenous mire found on the plateau areas of eastern australia they are well recognised for their ecological value but our under

a core top screen for trace element proxies of environmental conditions and growth rates in the calcite skeletons of bamboo corals isididae abstract we test for trace element proxies in the high magnesium calcite fraction of bamboo coral internodes by comparing environmental conditions and growth rates to the specimen mean compositions of 73 corals that were live caught at depths ranging from 3 to 3950 m and collected from habitats ranging from tropical coral reefs to the antarctic slope comparisons were done at a large geographic scale lgs and for a well sampled area south of australia across depths at a single site in order to help separate the effects of environmental variables that co vary at one spatial scale but not the other thirty seven trace elements were measured using solution based sector field icp ms of which seventeen were significantly detected in more than a third of the specimens only eight element calcium ratios correlated significantly with any environmental variable at the large geographic scale and only four did so at the local level at the lgs the highest correlation was between ambient temperature and mg ca which accounted for 89 of the variance across specimens spanned all four isidid sub families and was independently significant in the two best sampled sub families the predictive geometric mean relationship is t c 23 9 2 46 0 34 0 25 mg ca mmol mol spanning a temperature range of 1 9 to 26 8 c mg ca ratios from 58 6 to 155 1 mmol mol and an uncertainty rms of 2 78 c the numbers in parentheses are 95 cis the slope of the regression does not differ significantly from that of abiotic high mg calcites which suggests that the temperature dependent incorporation of mg into the carbonate results from kinetic reactions at the crystal surface analysis at the sh scale for the sub set of specimens for which we had data suggests is also affected by growth rates there were no obvious trace element correlates at either spatial scale of salinity or oxygen levels that could not be accounted for by covariance between these environmental parameters and in most cases temperature single and multiple correlation analyses also confirm previous suggestions that ba ca in bamboo coral calcite is a proxy for seawater barium and hence refractory nutrients suggest that sr ca is influenced by specimen mean mg ca ratios and water temperature as well as possibly seawater sr ca and falsify for bamboo corals p ca as well as p cd and cd ca as a proxy for seawater phosphate levels the predictive relationship between isidid skeletal mean ba ca and seawater silicate concentrations appears to be linear and is given by silicate mol kg 1 56 7 20 8 9217 1632 ba ca mmol mol spanning a silicate range of 0 5 to 120 mol kg 1 a ba ca range of 0 0042 to 0 0195 mmol mol and with an uncertainty rms of 33 1 mol kg 1 mn ca differences among specimens and sites are highly significant and appear to reflect seawater mn suggesting a proxy for this micronutrient the compilation of growth rate data across 34 specimens indicates a wide range of growth rates even among con familial specimens from within a single habitat and suggests both ambient temperature and food availability underlie at least part of this variability

sea surface temperature and salinity reconstruction from coral geochemical tracers massive scleractinian corals secrete an aragonitic skeleton which incorporates a large array of chemical tracers corals present several advantages for palaeoclimate research they grow continuously and can live up to 1000 years they are easy to date and they can be sampled at high resolution weekly to monthly resolution both live and fossil corals can be collected in the field in the past two decades significant efforts have been made to identify robust tracers of sea surface temperature sst and salinity sss in corals to date sr ca and 18o are considered to be the most reliable sst tracers although changes in seawater 18o can significantly alter sst reconstructed from coralline 18o because these variations in seawater 18o can be linked to sss changes this initial problem can in fact be turned into an advantage and provide us with an sss tracer the sst component in the coral 18o signal can either be evaluated through sr ca measurements or in some case simply filtered out however there is still much uncertainty concerning the exact mode of incorporation of trace elements and stable isotopes into the coral skeleton the effects of growth rate light intensity feeding habits ph and water chemistry are still poorly documented a review of the strength and weaknesses of sr ca and 18o is presented together with some examples of sst and sss reconstructions other potential sst tracers are also reviewed it is expected that the ability to grow corals in aquarium under controlled conditions and that the development of sophisticated analytical techniques at the micrometric level should help us understand better the robustness of each tracers and the factors controlling their incorporation in coral aragonite

228ra 226ra and 226ra ba ratios in the western mediterranean sea barite formation and transport in the water column 226ra 228ra and ba distributions as well as 228ra 226ra and 226ra ba ratios were measured in seawater suspended and sinking particles at the dyfamed station in the western mediterranean sea at different seasons of year 2003 in order to track the build up and fate of barite through time the study of the 228raex 226raex ratios raex ra activities corrected for the lithogenic ra of suspended particles suggests that baex baex ba concentrations corrected for the lithogenic ba mostly barite formation takes place not only in the upper 500 m of the water column but also deeper i e throughout the mesopelagic layer temporal changes in the 228raex 226raex ratios of sinking particles collected at 1000 m depth likely reflect changes in the relative proportion of barite originating from the upper water column with a high 228ra 226ra ratio and formed in the mesopelagic layer with a low 228ra 226ra ratio 228raex 226raex ratios measured in sinking particles collected in the 1000 m trap in april and may suggest that barite predominantly formed in the upper water column during that period while barite found outside the phytoplankton bloom period february and june appears to form deeper in the water column combining ratios of both the suspended and sinking particles provides information on aggregation disaggregation processes high 226raex baex ratios were also found in suspended particles collected in the upper 500 m of the water column because celestite is expected to be enriched in ra bernstein r e byrne r h and schijf j 1998 acantharians a missing link in the oceanic biogeochemistry of barium deep sea res ii 45 491 505 acantharian skeletons may contribute to these high ratios in shallow waters the formation of both acantharian skeletons and barite enriched in 226ra may thus contribute to the decrease in the dissolved 226ra activity and 226ra ba ratios of surface waters observed between february and june 2003 at the dyfamed station

a geology based 3d velocity model of the los angeles basin sediments abstract seismic hazard studies of the los angeles basin area require a realistic seismic velocity model we use geologic information about depth to crystalline basement depths to sedimentary horizons uplift of sediments and surface geology in a velocity depth age function to construct a three dimensional velocity model in earthquake location tests the model predicts travel times satisfactorily and in earthquake ground motion simulations the model correctly determines the timing and amplitude of late arriving waves

microtremors hvsr and its correlation with surface geology and damage observed after the 2010 maule earthquake mw 8 8 at talca and curico central chile nowadays microtremors horizontal to vertical spectral ratio hvsr has been extensively used in the estimation of the predominant vibration frequency of soils mainly for microzonation purposes in the present study we show results from extensive microtremor measurements performed at the cities of talca and curico central chile we found a strong correlation between surface geology and microtremors hvsr even in complex geological settings considering the damage produced by the 2010 maule earthquake mw 8 8 we also estimated high density macroseismic intensities at these cities with values ranging from vi up to viii on the msk64 scale we believe that the main responsible of these variations are the surface geological conditions also reflected in the variations of the resonance frequencies of the soils the evidence presented here supports the use of microtremors hvsr in combination with surface geology to improve seismic microzonation studies particularly in an andean context

elemental systematics of the calcitic skeleton of corallium rubrum and implications for the mg ca temperature proxy abstract the high mg calcite skeleton of corallium rubrum was analyzed from living colonies collected from a wide range of depths 15 m to 607 m and environmental settings in the mediterranean sea an overarching goal was to better understand the calcification process and incorporation of elements into the slow growing skeleton of both shallow and deep water specimens and more specifically to clarify the veracity of geochemical proxies for reconstructing seawater temperatures the coral internal structure including growth bands were determined by scanning electronic microscopy sem and petrographic techniques trace elements li b mg sr and ba compositions of the coral skeleton were obtained by solution and laser ablation inductively coupled plasma mass spectrometry icp ms results show that the skeleton of the deep water specimens has an internal microstructure similar to shallow water colonies with the medullar and the annular zones clearly distinguishable in both shallow and deep water specimens in general the bands of the deep water samples are very thin and equidistant compared to the irregular banding of the shallow water specimens banding differences relate to the contrasting environmental dynamics with the shallow water specimens being exposed to large seasonal fluctuations compared to the relative stable conditions of those inhabiting bathyal depths the inner medullar and outer annular portions differ in their trace element concentrations mg ca sr ca and li ca ratios are higher in the medullar zone and seem to be influenced by growth kinetics whereas b ca and ba ca are similar in both zones and hence unaffected by growth rate the variability of elemental ratios is lower in the deep water specimens growth bands are highly correlated to mg ca sr ca and li ca suggesting common mechanism s controlling the incorporation of these elements into the coral skeleton mg ca ratios were especially depleted in the dark bands although the mean mg ca of each specimen is positively correlated to ambient seawater temperature the intra annual variations and amplitudes differ and do not correlate to the band widths these findings suggest that intra and inter annual variations of mg ca cannot be used to reconstruct a continuous time series of long term seasonal temperature records however the mean mg ca composition can serve as a valuable proxy to estimate mean palaeoseawater temperature at a given site within the mediterranean

combining bulk sediment osl and meteoric 10be fingerprinting techniques to identify gully initiation sites and erosion depths deep erosional gullies dissect landscapes around the world existing erosion models focus on predicting where gullies might begin to erode but identifying where existing gullies were initiated and under what conditions is difficult especially when historical records are unavailable here we outline a new approach for fingerprinting alluvium and tracing it back to its source by combining bulk sediment optically stimulated luminescence bulk osl and meteoric 10be 10bem measurements made on gully derived alluvium samples in doing so we identify where gully erosion was initiated and infer the conditions under which such erosion occurred as both 10bem and bulk osl data have distinctive depth profiles in different uneroded and depositional settings we are able to identify the likely incision depths in potential alluvium source areas we demonstrate our technique at birchams creek in the southeastern australian tablelands a well studied and recent example of gully incision that exemplifies a regional landscape transition from unchanneled swampy meadow wetlands to gully incision and subsequent wetland burial by post european settlement alluvium we find that such historic alluvium was derived from a shallow erosion of valley fill upstream of former swampy meadows and was deposited down the center of the valley incision likely followed catchment deforestation and the introduction of livestock which overgrazed and congregated in valley bottoms in the early 20th century during a period of drought as a result severe gully erosion was likely initiated in localized compacted and oversteepened reaches of the valley bottom

variability of site response in the los angeles urban area this article addresses the variability of site response in the los angeles area and possible structural causes for the observations aftershock records from 231 sites in the san fernando and los angeles basins and the surrounding mountains are used in this study spectral ratios taken with respect to a low amplitude reference site are used to document the variation in site amplification in the frequency range 2 to 6 hz both spatially and with backazimuth to the source at higher frequencies 6 to 10 hz spectral ratios are shown to have greater spatial variability interstation spectral ratios are used to measure the standard deviation among source as a function of station separation an increase in the variation in ground motion is shown to take place at a station separation of 1 km relative site response estimates between nearby stations are used to demonstrate that preferred directions of motion can exist even in areas with no surface topographic effects significant variations in site response exist over short baselines up to a factor of 2 over 200 m that are not explained by differences in surficial geology or shallow shear wave velocity a variety of investigative approaches is used including spectral ratios arrival time variations 1d and 2d waveform modeling and comparison with seismic reflection lines to determine the most likely causes of these observations a correlation is demonstrated between late arrival times of p and s waves and larger site amplification in sherman oaks and northridge this observation in conjunction with waveform modeling and seismic reflection profiles is used to infer that sedimentary structures in the upper 1 to 2 km and topography on the sediment basement interface play an important role in determining site amplification these structures in the form of folds and buried basins focus energy in spatially restricted areas at the surface comparison of displacement waveforms at nearby stations having disparate site amplifications complemented by known shallow shear wave velocities at selected sites is used to support the argument that these structures in some cases can be the dominant factor in the modification of local ground motions

what is a reference site many methods for estimating site response compare ground motions at sites of interest to a nearby rock site that is considered a reference motion the critical assumption in these methods is that the surface rock site record reference is equivalent to the input motion at the base of the soil layers data collected in this study show that surface rock sites can have a site response of their own which could lead to an underestimation of the seismic hazard when these sites are used as reference sites data were collected from local and regional earthquakes on digital recorders both at the surface and in boreholes at two rock sites and one basin site in the san jacinto mountains southern california the two rock sites keenwild and pinon flat are located on granitic bedrock of the southern california peninsular ranges batholith the basin site garner valley is an ancestral lake bed with watersaturated sediments on top of a section of decomposed granite which overlies the competent bedrock ground motion is recorded simultaneously at the surface and in the bedrock at all three sites when the surface rock sites are used as the reference site i e the surface rock motion is used as the input to the basin the computed amplification underestimates the actual amplification at the basin site for frequencies above 2 to 5 hz this underestimation by a factor of 2 to 4 depending on frequency and site results from the rock sites having a site response of their own above the 2 to 5 hz frequencies the near surface weathering and cracking of the bedrock affects the recorded ground motions at frequencies of engineering interest even at sites that appear to be located on competent crystalline rock the bedrock borehole ground motion can be used as the reference motion but the effect of the downgoing wave field and the resulting destructive interference must be considered this destructive interference may produce pseudo resonances in the spectral amplification estimates if one is careful the bedrock borehole ground motion can be considered a good reference site for seismic hazard analysis even at distances as large as 20 km from the soil site

first generation site response maps for the los angeles region based on earthquake ground motions abstract ground motion records from aftershocks of the 1994 northridge earthquake and mainshock records from the 1971 san fernando 1987 whittier narrows 1991 sierra madre and 1994 northridge earthquakes are used to estimate site response relative to a rock site for the urban los angeles area site response is estimated at 232 mainshock and 201 aftershock sites relative to a low amplitude site in the santa monica mountains average amplification values are calculated for the frequency bands 1 to 3 3 to 5 and 5 to 7 hz these bands are chosen based on limitations in aftershock recording equipment at lower frequencies and reduced significance to the building inventory at higher frequencies site amplification factors determined at the instrumented locations are grouped by the surficial geology and contoured to produce a continuous spatial estimation of amplification the maps in this article represent the first attempt to produce estimates of site amplification based on observations of ground motion for such a large areal extent of the los angeles region these maps are expected to evolve as more data become available and more analysis is done

microearthquake s wave observations from 0 to 1 km in the varian well at parkfield california abstract high gain three component seismometers from 0 to 1 km deep along the varian a 1 well at parkfield california were used to record the waveforms of nearby microearthquakes despite being in the thick tertiary sediments of the parkfield syncline the s wave amplification at this site is only about a factor of 3 the spectral content and spectral ratios of s waves along the well show that the average qs in the top 1 km at this site is 37 with the qs in different subintervals varying between 8 and 65 based on initial s wave polarizations a complex s wave velocity structure must exist at and below the varian site this structure appears to include position dependent anisotropy as well as steep lateral velocity gradients at a depth of 1 km s wave splitting parallel and normal to the san andreas fault zone is consistently observed this splitting scales at roughly 0 01 sec km subsequent to the split s waves the particle motion seems to be controlled by event focal mechanism above 1 km the upgoing s waves attenuate and change directions of polarization with a new splitting rate of 0 1 sec km uniquely for some events on the san andreas fault immediately below the varian site large post s wave signals with normal dispersion are present we propose that these phases are fault zone guided waves channeled from the san andreas fault to the varian site along the gold hill fault

mind the gap an absence of valley fill deposits identifying the holocene hypsithermal period of enhanced flow regime in southeastern australia the holocene sedimentary record in southeastern australia is present in a range of landscape settings such as upland swamps dells internally drained lake basins alluvial fans and mid catchmen

lithium in the aragonite skeletons of massive porites corals a new tool to reconstruct tropical sea surface temperatures previous studies have demonstrated the potential for the li content of coral aragonite to record information about environmental conditions but no detailed study of tropical corals exists here we present the li and mg to ca ratios at a bimonthly to monthly resolution over 25 years in two modern porites corals the genus most often used for paleoclimate reconstructions in the tropical indo pacific a strong relationship exists between coral li ca and locally measured sst indicating that coral li ca can be used to reconstruct tropical sst variations however li ca ratios of the skeleton deposited during 1979 1980 do not track local sst well and are anomalously high in places the mg ca ratios of this interval are also anomalously high and we suggest li ca can be used to reconstruct tropical sst only when mg ca data are used to carefully screen for relatively rare biological effects mg li or li mg ratios provide little advantage over li ca ratios except that the slope of the li mg temperature relationship is more similar between the two corals the mg li temperature relationship for the coral that experienced a large temperature range is similar to that found for cold water corals and aragonitic benthic foraminifera in previous studies the comparison with data from other biogenic aragonites suggests the relationship between li mg and water temperature can be described by a single exponential relationship despite this hint at an overarching control it is clear that biological processes strongly influence coral li ca and more calibration work is required before widely applying the proxy

site amplification in the san fernando valley california variability of site effect estimation using the s wave coda and h v methods during the months that followed the 17 january 1994 m 6 7 northridge california earthquake portable digital seismic stations were deployed in the san fernando basin to record aftershock data and estimate site amplification factors this study analyzes data recorded on 31 three component stations from 38 aftershocks ranging from m 3 0 to m 5 1 and depths from 0 2 to 19 km site responses from the 31 stations are estimated from coda waves s waves and ratios of horizontal to vertical h v recordings for the coda and the s waves site response is estimated using both direct spectral ratios and a generalized inversion scheme results from the inversions indicate that the effect of qs can be significant especially at high frequencies site amplifications estimated from the coda of the vertical and horizontal components can be significantly different from each other depending on the choice of the reference site the difference is reduced when an average of six rock sites is used as a reference site in addition when using this multi reference site the coda amplification from rock sites is usually within a factor of 2 of the amplification determined from the direct spectral ratios and the inversion of the s waves however for nonrock sites the coda amplification can be larger by a factor of 2 or more when compared with the amplification estimated from the direct spectral ratios and the inversion of the s waves the h v method for estimating site response is found to extract the same predominant peaks as the direct spectral ratio and the inversion methods the amplifications determined from the hiv method are however different from the amplifications determined from the other methods finally the stations were grouped into classes based on two different classifications general geology and a more detailed classification using a quaternary geology map for the los angeles and san fernando areas average site response estimates using the site characterization based on the detailed geology show better correlation between amplification and surface geology than the general geology classification

influence of temperature on the composition of magnesian calcite overgrowths precipitated from seawater a constant disequilibrium technique was used to determine the composition of magnesian calcite overgrowths precipitated on pure calcite seeds from artificial seawater at 5 25 and 40 c the amount of magnesium incorporated in the overgrowths at a given temperature is independent of the precipitation rate over a wide range of saturation states and is believed to correspond to a composition in true equilibrium with seawater the distribution coefficient of magnesium dmg2 c in the magnesian calcite overgrowths increases almost linearly with temperature being 0 0121 0 0013 at 5 c 0 0172 0 0022 at 25 c and 0 0271 0 0013 at 40 c these values apply only to magnesian calcites precipitated from standard composition seawater since a previous study has shown dmg2 c to be a function of the mg2 ca2 ratio in the parent solution results of this study are compared with values reported previously by other workers and with the compositional distribution of naturally occurring magnesian calcite cements and ooids found in seawater it appears that variations in temperature are not sufficient to account for the compositional variability of naturally occurring inorganic marine magnesian calcite cements

earthquake site response estimation a weak motion case study using weak motion recordings of aftershocks of the 1989 loma prieta earthquake recorded in oakland california near the failed nimitz freeway two methods have been applied to estimate the site response of an alluvium site and three mud over alluvium sites the first estimate is the traditional spectral ratio and the second utilizes the cross spectrum recordings obtained at a nearby bedrock site are used as estimates of the sediment site input motions while the two site response estimates produce similar peaks and troughs there is an approximate factor of 2 difference in amplitudes this discrepancy is evidence that there is a much greater level of noise than would be expected from the pre event ambient noise we interpret this as signal generated noise produced by scattering from heterogeneities which causes the true sediment site input to differ significantly from the bedrock site recording given this level of noise the cross spectrum estimate suffers a severe downward bias by a factor of 2 in this study and should probably not be used when the input motion is estimated from a bedrock site recording the spectral ratio estimates are relatively unbiased but the level of noise introduces a large degree of uncertainty therefore inferences about site response from individual spectral ratios should probably be avoided on the other hand ensemble averages of the estimates significantly reduce the scatter to reveal resonances that agree quite well in frequency and overall shape with those of one dimensional models whose parameters were determined independently a discrepancy of higher observed amplitudes than predicted by theory remains unexplained but most likely results from the effects of boundary layer topography which are not accounted for by the simple one dimensional models

shear wave velocity structure of the shallow sediments in the bohai sea from an ocean bottom seismometer survey abstractto investigate the seismic velocity structure of the shallow sediments in the bohai sea of china we conducted a shear wave velocity inversion of the surface wave dispersion data from a survey of 12 ocean bottom seismometers obss and 377 shots of a 9000 in3 air gun with obs station spacing of approximately 5 km and air gun shot spacing of approximately 190 m high quality scholte wave data were recorded by the obss within 0 4 5 km offset we retrieved the scholte wave phase velocity dispersion for the fundamental mode and first overtone in the frequency band of 0 9 3 0 hz with the phase shift method and inverted for the shear wave velocity structure of the shallow sediments with a damped iterative least squares algorithm pseudo 2d shear wave velocity profiles with a depth of approximately 400 m revealed coherent features of relatively weak lateral velocity variation we also estimated the uncertainty in shear wave velocity structure based on the pseudo 2d profiles from six trial inversions wi

characterization of near surface geology at strong motion stations in the vicinity of reno nevada abstract we evaluate site conditions at each of the 21 advanced national seismic system anss strong motion stations in the reno sparks nevada area shallow shear wave velocities are measured using the refraction microtremor remi technique louie 2001 average velocities to depths of 30 and 100 m are compared with local geological and soil classifications generalized 1 250 000 scale geological classifications show some variations in unit averages of the measured velocities but variations between units are much smaller than the standard deviations of velocities within units having multiple measurements site velocities are weakly correlated with the weight percent of gravel sand silt and clay in the soil unit at the surface predictions of site velocities based on these soil sediment percentages fall within 20 of measured values for all but two of the 21 sites

a probabilistic approach to seismic hazard in metropolitan france in this study we applied a probabilistic methodology to seismic hazard assessment in metropolitan france for that purpose we determined an attenuation law adapted to the french context this law holds for peak ground acceleration on stiff bedrock for earthquakes with local magnitudes between 2 5 and 5 6 recorded in near field at distances between 3 and 50 km geological conditions are taken into account by means of a three categories classification of lithologies based on a 1 1 000 000 geological map the seismotectonic zonation consists of areas of diffuse seismicity characterized by a frequency magnitude distribution in southeastern france active faults are considered in a test case and are assumed to follow the characteristic earthquake model we performed hazard curves for six french cities and maps of peak horizontal ground accelerations expected for return periods of 475 975 and 1975 years in the country sensitivity tests have been performed the uncertainty introduced by ground motion variability seems minor compared with that due to the choice of the attenuation law this study points to the importance of testing internal consistency of the various data and laws used in any seismic hazard analysis in particular here the type of magnitude used to predict ground motion if not some systematic bias is introduced that may result in systematic errors on peak ground acceleration determination we also show that the introduction of possibly very large and infrequent events known only from paleoseismic investigations may have a dramatic impact on the hazard especially when long periods of time are considered

coral li mg thermometry caveats and constraints abstract the coral li mg temperature proxy is revisited through an in depth trace element analysis of scleractinians collected live from tropical to polar environments the dataset consists of li ca mg ca sr ca and li mg ratios from 64 coral specimens belonging to 8 different taxa including both reef building zooxanthellate and cold water non zooxanthellate species from a wide range of water temperature 1 to 29 5 c salinity 34 71 to 38 61 and depth 3 to 670 m our results showed that the reliability of the li mg temperature proxy is strongly limited by the organic matter associated with the coral skeleton which is most evident within the green bands observed in tropical corals organic rich bands can double the mg content otherwise present in the skeleton which may ultimately lead to a temperature overestimation exceeding 15 c we found that this bias can be overcome by the treatment of coral skeletons with a specific oxidizing cleaning protocol we also detected the presence of calcite deposits within the aragonite skeleton of some antarctic living coral specimens which strongly affects the robustness of the li mg proxy given its temperature sensitivity of 1 5 c 1 calcite therefore to obtain reliable reconstructions a correction needs to be applied when organic matter and or calcite contamination is present which requires the scrupulous assessment of the integrity of the aragonite prior to geochemical analyses given that some species entrap more organic matter than others and that some are more prone to calcite contamination a taxon related effect is apparent here we show that the tropical species porites spp pseudodiploria strigosa and orbicella annularis and the cold water species madrepora oculata caryophyllia antarctica and flabellum impensum are all suitable candidates for reconstructing seawater temperatures the integrated results across a wide temperature range from extreme cold to tropical shallow waters yield an overall precision for the li mg temperature proxy of 1 0 c as quantified by the standard error of estimates if calculated from the 95 prediction intervals the uncertainty of the temperature estimates is 0 9 c at 1 c 1 5 c at 12 c and 2 6 c at 25 c however the uncertainty for the tropical corals e g porites can be reduced to 0 6 c if a li mg and sr ca multi regression approach is applied

alluvial sedimentation rates from southeastern australia indicate post european settlement landscape recovery increased catchment sediment yields are common following the introduction of european style agriculture to relatively undisturbed landscapes catchment erosion rates generally increase immediately after disturbance and then decline over time consequently where a catchment currently sits along this disturbance recovery sequence will strongly influence future catchment sediment yields and river morphology in this study field stratigraphy optical dating and hydraulic modelling are used to investigate changes in catchment sediment yield and storage in the lake burragorang catchment in australia with emphasis placed upon changes occurring since european settlement in a d 1820 on the southern tablelands and the upper cox s river subcatchment a large volume of sediment was liberated by gully erosion early in the post settlement period much of which was deposited at break of slope positions below the catchment s headwaters or stored in alluvial benches adjacent to the channel but within the confines of older holocene alluvium a lack of substantial sediment deposition over the last 20 to 40 years is evidence that catchment sediment yields have strongly declined this is consistent with both reduced erosion rates and re aggradation of the incised gullies that in their erosive phase dominated the catchment s post settlement sediment flux collectively these characteristics indicate the catchment is undergoing a phase of landscape recovery

the effect of quaternary alluvium on strong ground motion in the coyote lake california earthquake of 1979 abstract the effect of alluvium on strong ground motion can be seen by comparing two strong motion records of the coyote lake california earthquake of 6 august 1979 m l 5 9 one record at a site on franciscan bedrock had a peak horizontal acceleration of 0 13 g and a peak horizontal velocity of 10 cm sec the other at a site 2 km distant on 180 meters of quaternary alluvium overlying franciscan had values of 0 26 g and 32 cm sec amplifications by factors of 2 and 3 horizontal motions computed at the alluvial site for a linear plane layered model based on measured p and s velocities show reasonably good agreement in shape with the observed motions but the observed peak amplitudes are greater by a factor of about 1 25 in acceleration and 1 8 in velocity about 15 per cent of the discrepancy in acceleration and 20 per cent in velocity can be attributed to the difference in source distance the remainder may represent focusing by refraction at a bedrock surface concave upward there is no clear evidence of nonlinear soil response fourier spectral ratios between motions observed on bedrock and alluvium show good agreement with ratios predicted from the linear model in particular the observed frequency of the fundamental peak in the amplification spectrum agrees with the computed value indicating that no significant nonlinearity occurs in the secant shear modulus computations show that nonlinear models are compatible with the data if values of the coefficient of dynamic shear strength in terms of vertical effective stress are in the range of 0 5 to 1 0 or greater the data illustrate that site amplification may be less a matter of resonance involving reinforcing multiple reflections and more the simple effect of the low near surface velocity application of traditional seismological theory leads to the conclusion that the site amplification for peak horizontal velocity is approximately proportional to the reciprocal of the square root of the product of density and shear wave velocity

european impacts on downstream sediment transfer and bank erosion in cobargo catchment new south wales australia abstract upland valley fills in cobargo catchment on the south coast of new south wales represent substantial sediment source zones contemporary channels within these fills are up to 8 m deep and 50 m wide for catchment areas 2 virtually all banks are eroding downstream of this sediment source zone sediment transfer zones are characterised by sinuous channels that are partially choked by sands released from upland valley fills coarse sands stored in point bars deflect flow to outer banks where colluvial footslopes are eroded approximately 50 of banks are eroding in this section of the catchment other than the 10 km river reach upstream of the river mouth the remainder of the catchment is a bedrock confined sediment throughput zone characterised by fluctuations in channel bed elevation the downstream 10 km of the catchment is a sediment accumulation zone in which erosion is restricted to occasional concave banks prior to european settlement of cobargo catchment upland valley fills were largely unincised and middle transfer reaches of the catchment comprised swamps vegetation clearance along with disturbance and drainage of swamps transformed discontinuous water courses into continuous channels working from a base point of intact upland valley fills almost 50 of available material has been removed from the upper catchment sediment source zone contributing 2 9 10 6 m 3 of material to the lower catchment of this roughly 65 has been stored along the channel bed and floodplain this gives a total sediment contribution to the delta of 1 0 10 6 m 3 sufficient materials are stored in transient storage units along transfer zones to maintain current rates of sediment throughput to the delta for several decades cobargo catchment experienced dramatic acceleration of channel incision and bank erosion processes within a few decades following european settlement of the catchment i e around 1830 transition in landscape form and associated sediment delivery were rapid with a negligible lag interval i e within a few decades of disturbance however given the extensive volume of sediment released from upland valley fills landscape recovery i e refilling of upland valleys will likely take thousands of years

proteinaceous corals as proxy archives of paleo environmental change abstract high resolution marine data are critical to evaluating anthropogenic impacts on our environment considering the spatial and temporal limitations of direct instrumental measurements proxy data extracted from marine environmental archives are necessary to separate anthropogenic changes from those that would occur naturally the majority of late holocene high resolution environmental reconstructions are derived from marine carbonates including tropical scleractinian corals bivalves crustose coralline algae and sclerosponges however these archives are restricted to the top hundreds of meters of the water column and only preserve environmental variability that is captured by calcium carbonate skeletons at a very few select locations marine sediments archive annual environmental variability in organic and inorganic materials recently additional types of corals are proving to yield information complimentary to these traditional marine archives including cold water scleractinian corals and proteinaceous corals a taxonomically diverse group the proteinaceous corals are broadly defined as those having a branching gross morphology with skeleton comprised at least partly of protein rich organic material they encode characteristics of their food and ambient environment into the chemical and physical composition of their skeleton this environmental encoding combined with their banded skeleton and significant longevity means that proteinaceous corals hold information in their skeleton that helps fill the spatial and temporal gaps in our knowledge of past and present ocean conditions here i review the environmental reconstructions derived from geochemical measurements of the proteinaceous coral skeletons this information is grouped into the mesopelagic environmental variability captured in the skeleton of bamboo corals surface processes captured in the organic skeletons of corals across all ocean depths and environmental variability documented by skeletal radiometric isotopes we include animals from two separate subclasses within the class anthozoa including the parasitic zoanthids that secrete a sclero proteic skeleton since the proteinaceous corals are taxonomically diverse we consider the unique features that define this group of corals including their distribution morphology nutrition and longevity we find that uncertainty surrounding biological parameters limits the precision of reconstructions derived from the calcitic skeleton in contrast analytical effort and cost constrain the number of reconstructions from the organic skeleton through this discussion we provide insights into the uses challenges and directions for future research for this important environmental archive

refining trace metal temperature proxies in cold water scleractinian and stylasterid corals abstract the li mg sr ca and oxygen isotopic 18 o compositions of many marine biogenic carbonates are sensitive to seawater temperature corals as cosmopolitan marine taxa with carbonate skeletons that can be precisely dated represent ideal hosts for these geochemical proxies however efforts to calibrate and refine temperature proxies in cold water corals 18 o and carbon isotope 13 c data from live collected specimens of aragonitic scleractinian corals balanophyllia caryophyllia desmophyllum enallopsammia flabellum lophelia and vaughanella both aragonitic and high mg calcitic stylasterid genera stylaster and errina and shallow water high mg calcite crustose coralline algae lithophyllum hydrolithon and neogoniolithon we interpret these data in conjunction with results from previously explored taxa including aragonitic zooxanthellate scleractinia and foraminifera and high mg calcite octocorals we show that li mg ratios covary most strongly with seawater temperature both for aragonitic and high mg calcitic taxa making for reliable and universal seawater temperature proxies combining all of our biogenic aragonitic li mg data with previous calibration efforts we report a refined relationship to temperature li mgall aragonite 5 42 exp 0 050 t c r 2 0 97 this calibration now permits paleo temperature reconstruction to better than 3 4 c 95 prediction intervals across biogenic aragonites regardless of taxon from 0 to 30 c for taxa in this study aragonitic stylasterid li mg offers the most robust temperature proxy li mgstylasterid arag 5 64 exp 0 046 t c r 2 0 95 with a reproducibility of 2 3 c for the first time we show that high mg calcites have a similar exponential relationship with temperature but with a lower intercept value li mg 0 63 exp 0 050 t c r 2 0 92 this calibration opens the possibility of temperature reconstruction using high mg calcite corals and coralline algae the commonality in the relationship between li mg and temperature transcends phylogeny and suggests a similar abiogenic trace metal incorporation mechanism

downstream changes in dryland river channels the northern plains of arid central australia abstract many dryland rivers undergo marked downstream changes owing to factors such as infrequent floods flow transmission losses and typically few tributary inflows beyond the headwaters along the sandover bundey sandover bundey and woodforde rivers on the northern plains of arid central australia downstream channel changes are broadly similar in upland zones small rocky channels transporting sand and gravel gradually increase in size before entering piedmont zones where channels and narrow floodplains are confined by bedrock alluvial terraces or aeolian dunes in lower gradient lowland zones channels and floodplains remain confined and in the absence of tributary inflows channel cross sectional areas and discharges decrease downstream confining landforms are not present in floodout zones which results in splay formation increased floodplain widths and marked overall downstream decreases in cross sectional areas eventually channelised flow and bedload transport terminate although occasional large floods continue across extensive unchanneled alluvial surfaces termed floodouts these broad similarities apart downstream changes along the three rivers differ in detail the sandover is largely a single thread channel whereas many reaches of the sandover bundey and woodforde are anabranched on the small woodforde river downstream decreases in parameters such as cross sectional area and width are roughly linear on the larger sandover and sandover bundey downstream changes are more irregular particularly through the floodout zones where there are marked fluctuations in widths depths and bed slopes the irregular downstream changes typical of the lower reaches of these large rivers may be due to the reduced influence of vegetation on bankline stability and width adjustment relative to that of smaller rivers on the northern plains as in other drylands complex interactions between discharge sediment transport slope patterns of tributary drainage bank sediment type and vegetation result in variable patterns of downstream channel change

bamboo coral ba ca calibration of a new deep ocean refractory nutrient proxy abstract it is poorly understood how intermediate water masses are affected by decadal scale climate via biogeochemical cycling export production and changes in circulation ventilation to this end a geochemical nutrient proxy from deep sea bamboo corals would provide decadal to centennial scale records of deep and intermediate water nutrient dynamics seawater barium basw has a nutrient like distribution in the water column similar to silicate so ba ca records in foraminifera shallow water surface corals and other deep sea corals have been used to trace refractory nutrients here we present the first calibration of a nutrient proxy from skeletal barium preserved in the calcitic internodes of deep sea bamboo corals collected from intermediate water depths a calibration was calculated from a broadly distributed suite of isidella and keratoisis corals spanning a silicate and basw gradient n 33 corals 300 2800 m ba ca b a m b o o c o r a l mol mol 0 079 0 008 ba sw nmol kg 4 205 0 870 r 2 0 77 n 33 the strong linear correlation between ba cabamboo coral and basw suggests that coral ba ca is a reliable recorder of seawater barium and therefore silicate we find a distribution coefficient dba for ba cabamboo coral of 1 3 0 2 similar to that of other corals surface and deep sea dwelling and inorganic calcium carbonate precipitation experiments dba 1 2 1 5 this suggests that ba incorporation is primarily driven by cationic substitution in bamboo corals and holds promise as a globally applicable refractory nutrient proxy we find interannual decadal scale variability in a ba cabamboo coral timeseries from a california margin coral san juan seamount 1295 m these data suggest that additional high resolution ba cabamboo coral records may reveal a connection between regional scale intermediate water biogeochemistry and low latitude surface ocean atmospheric climate

the distribution and climatic implications of periglacial landforms in eastern australia mapping of over 4000 block deposits and scree slopes in eastern australia is used to determine the extent of past strong freeze thaw activity freeze thaw landforms are common in the high country as far north as 30 degrees s there is a clear association between the locations of relict periglacial landforms and areas that receive more than 50 modern frost days we infer about 10 5 degrees c cooling north of 35 degrees s in the diving range about 9 degrees c in the australian alps and about 5 degrees c in tasmania during the phases when the lowest block deposits were active an unexpected observation is the importance of precipitation in the distribution of block deposits north of 35 degrees s here the majority of block deposits have a southerly or westerly aspect and lie in a narrow modern precipitation band of ca 900 1050 mm to the east high elevation areas appear to have weaker diurnal oscillations limiting freezethaw activity to the west block deposits are absent probably due to insufficient moisture to drive freeze thaw processes we cannot define specific last glaciation precipitation but the maintenance of a strong east west precipitation gradient during glacial times is consistent with the maintenance of onshore easterlies during cold periods copyright c 2015 john wiley sons ltd