dietary reconstruction of an early to middle holocene human population from the central california coast insights from advanced stable isotope mixing models the inherent sampling and preservational biases of the archaeological record make it difficult to quantify prehistoric human diets especially in coastal settings where populations had access to a wide range of marine and terrestrial food sources in certain cases geochemical proxies such as stable isotope ratios may be utilized to provide robust estimates on the relative proportions of various food resources consumed by prehistoric populations the harkins slough archaeological site scr 60 130 is an early to middle holocene coastal assemblage located on monterey bay in central ca the carbon d 13 c and nitrogen d 15 n isotope composition of human burials and associated archaeofauna excavated from the site were measured for input into a concentration dependent isotope mixing model that is able to statistically discriminate among multiple o3 food sources the human burials segregate into two distinct groups an early w7000 bp and middle w4500 bp holocene population with significant dietary differences stable isotope analyses indicate a 70e84 marine food source contribution for the early holocene group ehg but only a 48e58 marine dietary contribution for the middle holocene group mhg results also suggest that pinnipeds were an important marine food source for both groups modeling results are in agreement with archaeological evidence from southern ca suggesting that early holocene coastal populations were highly dependent on marine resources with the ability to procure both littoral and pelagic species further the use of terrestrial plant sources likely increased over time with the feasible contribution range doubling from the ehg 4e30 mean 19 to mhg 10e52 mean 38 this trend is supported by regional archaeological evidence for the advent of technological innovations linked to intensive terrestrial plant processing beginning in the middle holocene methodologically this work demonstrated the utility of a concentration dependent stable isotope mixing model in an iterative framework to provide feasible ranges of dietary contribution when the number of food sources is too high to allow a unique solution 2004 published by elsevier ltd

stable isotope composition of late pleistocene holocene eobania vermiculata muller 1774 pulmonata stylommatophora shells from the central mediterranean basin data from grotta d oriente favignana sicily abstract this paper presents stable isotopic results oxygen and carbon from both modern and late pleistocene holocene shells of the land snail eobania vermiculata muller 1774 from favignana island sicily it aims to contribute to the understanding of climate and vegetation history of this region during formation of upper palaeolithic mesolithic and meso neolithic deposits of grotta d oriente ort results from both an evaporative model fbm and an empirical regional isotopic model i e linear relation between oxygen isotopic composition of shells 18 os and those of local precipitation 18 op indicate that the 18 os values of modern specimens are mainly controlled by local temperature relative humidity and 18 op at the time of snail activity data also suggest that the modern snails are nocturnally active almost all year round in the study area the carbon isotopic compositions of shells 13 cs of the same specimens indicate a diet prevalently or exclusively composed of c3 vegetation the 18 os values of late pleistocene specimens suggest that climate conditions at 14 2 ka cal bp were similar to the present day in agreement with additional 18 os records from southern italy by contrast early middle holocene shells are notably 18 o depleted and suggest wetter conditions possibly combined with a decrease in isotopic composition of precipitation source compared to the present day when compared with regional palaeoclimatic records a large scale isotopic response to millennial scale changes in atmospheric and hydrological conditions e g enhanced rainfall in the central eastern mediterranean is observed during the early middle holocene the 13 cs of late pleistocene and holocene specimens are consistently higher than those of modern ones for the late pleistocene this could be reasonably explained in terms of water stressed vegetation on the other hand this seems to be less valid for holocene counterparts when the climate was wetter probably 13 cs values result from the combination of distinct competing factors involving atmospheric co 2 concentration seasonal water budget vegetation type cover and other carbon sources results reveal coherent relationships between regional 18 os and 13 cs demonstrating that late pleistocene holocene land snail shell remains from archaeological sites may provide useful snapshots of past seasonal climate conditions

holocene trends in 18o in land snail shells from the negev desert and their implications for changes in rainfall source areas abstract the 18o value of the carbonate of land snail shells is related to the 18o content of precipitation which in turn relates to the source region and trajectory of the rain bearing air masses analyses of 18o of the shell carbonate of 76 radiocarbon dated holocene samples of the land snail trochoidea seetzeni from the northern negev desert in southern israel were carried out and the results were compared to modern snails from the same region early holocene 18o values are similar to modern but during the period centered around 6500 6000 yr b p a depletion of some 2 below modern is observed a change in the atmospheric circulation pattern for this period is thus indicated most likely an increase in the frequency of storm systems reaching the region from north eastern africa by 3500 yr b p 18o values had reached modern levels and indicate a stable pattern of atmospheric circulation since that time

oxygen isotope signatures from land snail helix melanostoma shells and body fluid proxies for reconstructing mediterranean and north african rainfall abstract in this paper we show that oxygen isotope ratios from the shell carbonate of the land snail helix melanostoma reflect local rainfall parameters stable oxygen isotopes were measured in the body fluid 18 o body and shells 18 o shell of live collected h melanostoma along a north south transect across the gebel akhdar in northeast libya 18 o body ranged between 8 1 and 13 0 whilst 18 o shell ranged between 1 0 and 2 8 to investigate the relationship between snail oxygen isotope composition and climate these measurements were correlated with ambient air temperature relative humidity rainfall amount and the 18 o composition of rainwater 18 o rain strong and significant correlations were found between 18 o shell and 18 o rain and between 18 o shell and rainfall amount r 2 0 79 and 0 85 respectively suggesting that h melanostoma shells can be used as a proxy for past rainfall conditions when combined in multiple linear regressions 18 o rain and rainfall amount explained 90 of the variance in 18 o shell r 2 0 90 simple and multiple linear regressions were used to develop predictive models for these climate parameters as h melanostoma shells are commonly found in mediterranean and north african archaeological and geological deposits the predictive equations developed in this study hold great potential for reconstructing pleistocene to holocene rainfall and aridity patterns in the gebel akhdar and for assessing the relationship between environmental changes and human behavioural changes

the influence of diet on the δ13c of shell carbon in the pulmonate snail helix aspersa abstract the influence of diet and atmospheric co2 on the carbon isotope composition of shell aragonite and shell bound organic carbon in the pulmonate snail helix aspersa raised in the laboratory was investigated three separate groups of snails were raised on romaine lettuce c3 plant 13c 25 8 corn c4 plant 13c 10 5 and sour orange 12c enriched c3 plant 13c 39 1 the isotopic composition of body tissues closely tracked the isotopic composition of the snail diet as demonstrated previously however the isotopic composition of the acid insoluble organic matrix extracted from the aragonite shells does not track diet in all groups in snails that were fed corn the isotopic composition of the organic matrix was more negative than the body by as much as 5 whereas the matrix was approximately 1 heavier than the body tissues in snails fed a diet of c3 plant material these results indicate that isotopic composition of the organic matrix carbon cannot be used as an isotopic substrate for paleodietary reconstructions without first determining the source of the carbon and any associated fractionations the isotopic composition of the shell aragonite is offset from the body tissues by 12 3 in each of the culture groups this offset was not influenced by the consumption of carbonate and is not attributable to the diffusion of atmospheric co2 into the hemolymph the carbon isotopic composition of shell aragonite is best explained in terms of equilibrium fractionations associated with exchange between metabolic co2 and hco3 in the hemolymph and the fractionation associated with carbonate precipitation these results differ from previous studies based primarily on samples collected in the field that have suggested atmospheric carbon dioxide contributes significantly to the shell 13c the culture results indicate that the 13c of aragonite is a good recorder of the isotopic composition of the snail body tissue and therefore a better recorder of diet than is the insoluble shell organic carbon because the systematic fractionation of carbon isotopes within the snail is temperature dependent the 13c of the shell could provide an independent technique for estimating paleotemperature changes

inversion of complex body waves we have developed a method that inverts seismic body waves to determine the mechanism and rupture pattern of earthquakes the rupture pattern is represented as a sequence of subevents distributed on the fault plane this method is an extension of our earlier method in which the subevent mechanisms were fixed in the new method the subevent mechanisms are determined from the data and are allowed to vary during the sequence when subevent mechanisms are allowed to vary however the inversion often becomes unstable because of the complex trade offs between the mechanism the timing and the location of the subevents many different subevent sequences can explain the same data equally well and it is important to determine the range of allowable solutions some constraints must be imposed on the solution to stabilize the inversion we have developed a procedure to explore the range of allowable solutions and appropriate constraints in this procedure a network of grid points is constructed on the i plane where and i are respectively the onset time and the distance from the epicenter of a subevent the best fit subevent is determined at all grid points then the correlation is computed between the synthetic waveform for each subevent and the observed waveform the correlation as a function of and i and the best fit mechanisms computed at each i grid point depict the character of allowable solutions and facilitate a decision on the appropriate constraints to be imposed on the solution the method is illustrated using the data for the 1976 guatemala earthquake

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

overview of the oxygen isotope systematics of land snails from north america continental paleoclimate proxies with near global coverage are rare land snail 18o is one of the few proxies abundant in quaternary sediments ranging from the tropics to the high arctic tundra however its application in paleoclimatology remains difficult attributable in part to limitations in published calibration studies here we present shell 18o of modern small 10 mm snails across north america from florida 30 n to manitoba 58 n to examine the main climatic controls on shell 18o at a coarse scale this transect is augmented by published 18o values which expand our coverage from jamaica 18 n to alaska 64 n results indicate that shell 18o primarily tracks the average annual precipitation 18o shell 18o increases 0 5 0 7 for every 1 increase in precipitation 18o and 0 3 0 7 for every 1 c increase in temperature these relationships hold true when all taxa are included regardless of body size ranging from 1 6 to 58 mm ecology herbivores omnivores and carnivores or behavior variable seasonal active periods and mobility habits future isotopic investigations should include calibration studies in tropical and high latitude settings arid environments and along altitudinal gradients to test if the near linear relationship between shell and meteoric precipitation 18o observed on a continental scale remains significant

contribution of radar interferometry to a two step inversion of the kinematic process of the 1992 landers earthquake we study the rupture process of the 1992 landers earthquake to limit the trade off between slip amplitude and rupture time that affects solutions using only seismological data we adopt a two step approach we first constrain the slip distribution and its uncertainty by independent geodetic data to recover in the second step the temporal details of the rupture propagation the first step consists of an inversion of interferometric data and global positioning system measurements both independently and together to constrain slip distribution on a three segment fault model along both strike and dip direction we use a genetic algorithm to test the uniqueness of the solution and a least squares formulation to find the model which best fits the data we conclude from the results of these geodetic inversions that interferometric data are rich enough to access the slip distribution in the case of the landers earthquake since the surface deformations are more sensitive to shallow slip in our configuration the slip amplitude is better resolved near the surface than at depth the resulting slip distribution is in agreement with geological observations at the surface and confirms the heterogeneous nature of the landers earthquake most of the slip occurs at shallow depths on the homestead valley fault second segment with a maximum value of around 7 m another high slip zone is observed on the johnson valley fault first segment at 8 km depth in the second step we invert strong motion data with the a priori final slip amplitude and its uncertainty deduced from geodetic data to constrain the time history of the rupture process this second step emphasizes a strong variation of the temporal development of the earthquake fast rupture front velocities appear within high slip zones and the rupture slows when it encounters a resistance along the fault on average the rupture front propagates with velocities close to the s wave velocity and terminates about 20 s after initiation the large variations in both slip amplitude and rupture velocity suggest that the rupture process is better described by successively breaking asperities than by a pulse propagating with constant velocity

empirical relationships between elevation and the stable isotope composition of precipitation and surface waters considerations for studies of paleoelevation change a compilation of 68 studies from throughout many of the world s mountain belts reveals an empirically consistent and linear relationship between change in elevation and change in the isotopic composition of precipitation along altitudinal transects the isotopic composition of precipitation decreases linearly with increasing elevation in most regions of the world except in the himalayas and at elevations 5000 m there are no significant differences in isotopic lapse rates from most regions of the world 0 28 permil 100 m except at the extreme latitudes where isotopic lapse rates are higher given information on past changes in the isotopic composition of precipitation preserved in pedogenic or authigenic minerals this global isotopic lapse rate can be used to place numerical constraints on the topo graphic development of some ancient mountain belts or plateaus there are many complicating factors that can confound interpretation of paleoel evation change based on stable isotopes and many of these are unique to specific mountain belts or time periods relevant to all stable isotope based paleoelevation change studies is the temperature dependent isotope fractionation between a pedo genic or authigenic mineral and the water from which it forms in cases where isotopic proxy minerals are sampled from localities where temperature will change simulta neously with elevation change the apparent change in the isotopic composition of precipitation may be dampened by several permil this suggests that samples taken from the rainshadow side of an emerging orographic barrier may be more likely to preserve isotopic changes resulting from mountain uplift than samples taken from atop a rising mountain range or plateau

stable carbon isotope record of middle to late holocene climate changes from land snail shells at hinds cave texas abstract stable carbon isotope ratios of shell carbonate and shell organic matter from land snails rabdotus alternatus from hinds cave texas are used to reconstruct the climate history of the drier western part of the southern great plains present mean annual rainfall of 400 mm over the last ca 5000 yr ams radiocarbon analyses of four individual shells from each of two strata indicate that there are no problems of reworking or age mixtures within strata however burning is evident in many shells amino acid composition and racemization were used to identify shells that had been significantly heated and these were rejected for isotopic analysis because of possible alteration of the isotopic signal fourteen samples of snails from hinds cave each consisting of 2 6 individual shells from the same provenience were radiocarbon dated by ams and analyzed for stable carbon isotopes in addition a sample collected alive ca ad 1890 from a nearby site was analyzed to represent modern conditions the shells show no decrease in organic content with age indicating good preservation of shell organic matter both the organic and carbonate isotope values show similar temporal trends the oldest samples 4100 4600 cal yr bp are relatively depleted in 13 c maximum 13 c values are reached at ca 3500 cal yr bp thereafter there is a regular depletion in 13 c with the recent sample showing the lowest 13 c value the change in the isotopic values over time is quite large range of 4 5 for organic matter and indicates substantial climatic changes the variations in isotopic values are interpreted as resulting primarily from changes in moisture conditions affecting the abundance of drought adapted cam crassulacean acid metabolism plant species enriched in 13 c thus relatively moist mid holocene conditions are indicated with increasingly dry conditions reaching a maximum at ca 3500 cal yr bp followed by progressively moister conditions through the late holocene

a hybrid source mechanism of the 2017 mw 6 5 jiuzhaigou earthquake revealed by the joint inversion of strong motion teleseismic and insar data abstract as occurred during the tourist season the 2017 mw 6 5 jiuzhaigou china earthquake led to destructive damages the seismogenic fault of this event was merely speculated to be the northern extension of the huya fault while no apparent surface ruptures were discovered in the field investigation previous studies and released moment tensor solutions indicated the jiuzhaigou earthquake was dominated by left lateral strike slip with partial normal slip component it seems unintelligible that the normal slip occurred in this event as the epicenter was located near the boundary of convergent blocks hence a reasonable and elaborate source rupture model is necessary to investigate such a blind fault and the role it plays in the complex fault system of this region combining space based geodetic teleseismic or regional seismic observations can provide detailed information about earthquake ruptures we first attempted to determine the fault geometry using the bayesian approach with synthetic aperture radar interferograms insar and then the fault geometry was refined based on the relocated aftershock distribution and a two segment fault model was constructed based on the two segment model we resolved the source rupture process of the 2017 jiuzhaigou earthquake through the joint inversion of strong motion teleseismic body wave and insar data the inversion results reveal a hybrid source mechanism in which normal and thrust slips coexist besides the strike slip component we suggest that the eastward motion with the extrusion of the lower crustal flow in the northeastern margin of the bayan har block is responsible for such a faulting behavior the co seismic coulomb stress changes show a significant stress loading in the western segment of the tazang fault increasing its seismic hazard due to the lack of aftershocks to the southeast of the seismogenic fault the probably enhanced seismicity in the northern segment of the huya fault is also worth further attention

evidence of nonlinear elasticity of the crust from the mw7 6 manyi tibet earthquake satellite synthetic aperture radar sar interferometry shows that the magnitude 7 6 manyi earthquake of 8 november 1997 produced a 170 kilometer long surface break with up to 7 meters of left lateral slip reactivating a n76 e quaternary fault in western tibet the radar interferometric map reveals asymmetric along strike displacement profiles between the two sides of the surface rupture a pattern that cannot be explained with linear elastic theory this observation suggests that the elastic moduli of the crust in tension and in compression are different because of the presence of cracks in the crust at shallow depth a model indicates that a ratio of 2 between compressive and tensile elastic moduli can account for the observed asymmetry a ratio that is consistent with laboratory and borehole measurements

stable isotope δ18o δ13c and δd signatures of recent terrestrial communities from a low latitude oceanic setting endemic land snails plants rain and carbonate sediments from the eastern canary islands abstract stable isotopes of oxygen and carbon extracted from fossil land snail shells have been used increasingly to interpret past environments to evaluate the utility of this approach for low latitude oceanic islands populations of the modern helicid land snail theba geminata a species also abundant in the quaternary fossil record of the region were sampled at ten low altitude d and 2 v smow for 18 o ranging from 11 to 2 v smow and from 2 6 to 0 7 v smow respectively the local vegetation is heterogeneous including c 3 c 4 and cam plants 13 c values vary from 13 0 to 29 0 v pdb across plant species of the 24 species five are c 4 15 are c 3 and four are cam plants the 18 o values for shells represent a narrow range of values from 0 3 to 2 5 v pdb which is consistent with the low climate seasonality typifying low latitude oceanic settings hypothetical model of the expected 18 o value for shell aragonite precipitated in equilibrium suggests that the most negative 18 o shell represent the closest estimate for 18 o rain water the 13 c values of shells range from 9 4 to 1 7 v pdb the most positive 13 c values are attributed to a diet based on c 4 plants the comparison of 13 c values of soft tissues and shells suggests that snails ingested notable amounts from 20 up to 40 of foreign carbonates consequently fossil shells with the most negative 13 c values should be selected for radiocarbon dating in future geochronological studies of the region the 13 c values of body tissues vary from 12 0 to 27 2 v pdb indicating that land snails consumed c 3 and c 4 plants indiscriminately the mean carbon isotopic composition averaged across multiple fossil specimens may thus provide a useful tool for reconstructing paleoclimates and paleoenvironments throughout the quaternary history of the canary islands and other comparable low latitude oceanic settings

late glacial to holocene transition in northern spain deduced from land snail shelly accumulations abstract shells of the helicid cepaea nemoralis were studied using taphonomic isotopic and morphometric measurements to estimate late glacial holocene 12 1 6 3 cal ka bp environmental conditions in northern spain higher taphonomic alteration among holocene shells suggests lower sedimentation rates or higher shell destruction rates than during glacial conditions shells preserved the aragonitic composition despite differing degree of skeleton damage shell 13 c values were 10 3 1 1 8 2 2 3 and 7 3 1 6 for modern holocene and late glacial individuals respectively higher 13 c values during the late glacial and some holocene periods imply higher water stress of c 3 plants and or higher limestone contribution than today intrashell 13 c values were higher during juvenile stages suggesting higher limestone ingestion to promote shell growth shell 18 o values were 1 1 0 7 0 9 0 8 and 0 1 0 7 for modern holocene and late glacial specimens respectively a snail flux balance model suggests that during 12 1 10 9 cal ka bp conditions were drier and became wetter at 8 4 6 3 cal ka bp and today intrashell 18 o profiles reveal that glacial individuals experienced more extreme seasonality than interglacial shells despite possible larger hibernation periods shell size correlated positively with 18 o values suggesting that growth rates and ultimate adult size of c nemoralis may respond to climate fluctuation in northern spain

surface displacements and source parameters of the 2003 bam iran earthquake from envisat advanced synthetic aperture radar imagery 1 the mw 6 6 26 december 2003 bam iran earthquake was one of the first earthquakes for which envisat advanced synthetic aperture radar asar data were available using interferograms and azimuth offsets from ascending and descending tracks we construct a three dimensional displacement field of the deformation due to the earthquake elastic dislocation modeling shows that the observed deformation pattern cannot be explained by slip on a single planar fault which significantly underestimates eastward and upward motions se of bam we find that the deformation pattern observed can be best explained by slip on two subparallel faults eighty five percent of moment release occurred on a previously unknown strike slip fault running into the center of bam with peak slip of over 2 m occurring at a depth of 5 km the remainder occurred as a combination of strike slip and thrusting motion on a southward extension of the previously mapped bam fault 5 km to the east

study of the diet effect on δ13c of shell carbonate of the land snail helix aspersa in experimental conditions abstract this study aims to demonstrate the influence of the metabolic co2 derived from the diet and of the atmospheric co2 on the shell carbonate 13c of the pulmonate snail helix aspersa maxima raised under controlled conditions adult snails were analyzed and compared with three hatching and 1 day old young snails stemming from the same breeding one day after the 2 day old individuals were raised during 1 month three groups of gastropods were fed with fresh lettuce c3 plant 13c 27 49 three groups with corn c4 plant 13c 11 7 and three groups ate alternately both c3 c4 the difference between the average 13c values of the adult snails on the one hand and the hatched and 1 day old snails on the other hand indicates a depletion of 2 47 therefore the isotopic parents offspring signal is not preserved the depleted ingested albumen by the snail embryo in the egg during the building of the shell could explain this depletion the c3 diet experiment gave the expected isotopic composition difference between the diet lettuce and the shells average 13cshell lettuce 13 75 0 52 this result shows a clear diet effect on the isotopic composition of the snail shells for the c4 experiment the difference in carbon isotope composition between the corn and the shell 13cshell corn yielded an average value of 4 89 0 87 the main result is that 13c is not constant and appears to depend on the type of ingested food several hypotheses can arise from this study to explain the different fractionations a differences in the quality of the two diets b differences in turnover rate for c3 and c4 feeders the groups regularly fed with mixed diet yielded 13c values showing a preferential use of c3 food for most values the c3 c4 mixed dietary alternation probably led snails to use mainly the lettuce instead of the corn powder

joint inversion of gps insar and teleseismic data sets for the rupture process of the 2015 gorkha nepal earthquake using a generalized abic method abstract various observations are made to invert for the source model of the 2015 gorkha earthquake previously published slip models involve different slip distributions and slip amplitudes to obtain a robust model we jointly invert for the rupture process of the gorkha earthquake using three types of observations global positioning system gps interferometric synthetic aperture radar insar and teleseismic p wave data three constraints i e spatial and temporal smoothness and minimum moment constraints are applied to regulate the rupture process the weight ratios between data sets and prior constraints are determined from a new developed generalized akaike s bayesian information criterion gabic weight determination method this gabic method can simultaneously and objectively weigh various kinds of observations and prior constraints rather than being limited to the two types in the traditional abic method the inverted slip model reveals the seismic moment of the earthquake is 9 40 10 20 n m released primarily in the first 60 s equivalent to mw 7 92 the rupture front propagates unilaterally along the strike direction and spreads in both the strike and dip directions the slip distribution shows one large slip patch with two peaks along the strike direction with a maximum slip amplitude of approximately 7 6 m and identifies large slips 2 m that occur in the updip section of the main himalayan thrust mht fault plane our results indicate that the released slip amplitude is larger than the accumulated slip amplitude since 1833 so the 2015 earthquake likely does not overlap with the 1833 earthquake

coseismic and postseismic slip of the 2004 parkfield earthquake from space geodetic data we invert interferometric synthetic aperture radar insar data jointly with campaign and continuous global positioning system gps data for slip in the coseismic and postseismic periods of the 2004 parkfield earthquake the insar dataset consists of eight interferograms from data collected by the envisat and radarsat satellites spanning the time of the earthquake and variable amounts of the postseismic period the two datasets complement each other with the insar providing dense sampling of motion in the range direction of the satellite and the gps providing more sparse but three dimensional measurements of ground motion the model assumes exponential decay of the postseismic slip with a decay time constant of 0 087 years determined from time series modeling of continuous gps and creepmeter data we find a geodetic moment magnitude of m 6 2 for a 1 day coseismic model and m w 6 1 for the entire postseismic period the coseismic rupture occurred mainly in two slip asperities one near the hypocenter and the other 15 20 km north postseismic slip occurred on the shallow portions of the fault and near the rupture areas of two m 5 0 aftershocks a comparison of the geodetic slip models with seismic moment estimates suggests that the coseismic moment release of the parkfield earthquake is as little as 25 of the total this underlines the importance of aseismic slip in the slip budget for the parkfield segment online material complete data tables and supplemental tables

paleoclimatic implications of the spatial patterns of modern and lgm european land snail shell δ18o abstract the oxygen isotopic composition of land snail shells may provide insight into the source region and trajectory of precipitation last glacial maximum lgm gastropod shells were sampled from loess from belgium to serbia and modern land snail shells both record 18 o values between 0 and 5 there are significant differences in mean fossil shell 18 o between sites but not among genera at a single location therefore we group 18 o values from different genera together to map the spatial distribution of 18 o in shell carbonate shell 18 o values reflect the spatial variation in the isotopic composition of precipitation and incorporate the snails preferential sampling of precipitation during the warm season modern shell 18 o decreases in europe along a n s gradient from the north sea inland toward the alps modern observed data of isotopes in precipitation gnip demonstrate a similar trend for low altitude sites lgm shell 18 o data show a different gradient with 18 o declining toward the ene implying a mid atlantic source due to increased sea ice and a possible southern displacement of the westerly jet stream balkan lgm samples show the influence of a mediterranean source with 18 o values decreasing northward

carbon isotope signatures from land snail shells implications for palaeovegetation reconstruction in the eastern mediterranean in this study we compare carbon isotope values in modern helix melanostoma shell carbonate 13cshell from the gebel al akhdar region of libya with carbon isotope values in h melanostoma body tissue 13cbody local vegetation 13cplant and soil 13csoil all vegetation in the study area followed the c3 photosynthetic pathway however the 13cplant values of different species formed two distinct isotopic groups this can be best explained by different water use efficiencies with arid adapted species having significantly more positive 13cplant values than less water efficient species the ranges and means of 13cbody and 13cplant were statistically indistinguishable from one another suggesting that 13cbody was primarily a function of local vegetation composition h melanostoma 13cshell reflected the 13cplant of local vegetation with a positive offset between body diet and shell of 14 5 1 4 therefore in the gebel al akhdar where only c3 plants are present higher mean 13cshell values likely reflect greater abundances of water efficient c3 plants in the snails diet and therefore in the landscape whilst lower mean 13cshell values likely reflect the consumption of less water efficient c3 plants the distribution of these plants is in turn affected by environmental factors such as rainfall these findings can be applied to archaeological and geological shell deposits to reconstruct late pleistocene to holocene vegetation change in the southeast mediterranean

oxygen isotope composition of living land snail shells data from italy sixty seven shells of living land snails were selected from 31 different localities across italy to investigate the relationships between their oxygen isotopic composition 18os and the mean value of local rainfall 18op despite the difficulty for some localities to correctly estimate the oxygen isotopic composition of local rainfall a good relationship was found this indicates that the oxygen isotopic composition of environmental water used by the snails is in italy strictly related to that of the local meteoric precipitation however the relationship found is substantially different from that previous established for central europe indicating that regional climatic conditions are important in defining the final isotopic composition of land snail shells moreover these equations may not hold for different climatic conditions existing during for instance glacial and interglacial periods the data also show that isotopic differences among species are relatively narrow and that they may depend on ecological factors i e style of life rather than any clearly identifiable different vital offset

source model for the mw 6 7 23 october 2002 nenana mountain earthquake alaska from insar 1 the 23 october 2002 nenana mountain earthquake mw 6 7 occurred on the denali fault alaska to the west of the mw 7 9 denali earthquake that ruptured the same fault 11 days later we used 6 interferograms constructed using radar images from the canadian radarsat 1 and european ers 2 satellites to determine the coseismic surface deformation and a source model data were acquired on ascending and descending satellite passes with incidence angles between 23 and 45 degrees and time intervals of 72 days or less modeling the event as dislocations in an elastic half space suggests that there was nearly 0 9 m of right lateral strike slip motion at depth on a near vertical fault and that the maximum slip in the top 4 km of crust was less than 0 2 m the nenana mountain earthquake increased the coulomb stress at the future hypocenter of the 3 november 2002 denali earthquake by 30 60 kpa

post seismic motion following the 1997 manyi tibet earthquake insar observations and modelling summary on november 8 1997 a mw 7 6 earthquake occurred in the manyi region of northern tibet near the western end of the kunlun fault over 7 m of left lateral slip occurred on a 200 kmlong fault here we use insar observations of post seismic surface deformation following the manyi earthquake to investigate possible causal mechanisms time series of deformation are constructed from 26 interferograms covering the entire length of the fault for nearly 4 yr after the earthquake three different modelling approaches are used to try and understand the observed variations in surface displacement first order poroelastic models predict displacement fields which do not match those observed modelling of viscoelastic stress relaxation in a half space with standard linear solid rheology beneath an elastic lid provides a reasonable fit to the observations and demonstrates that two relaxation times are needed to characterize the post seismic transient the best fitting viscosity is 4 10 18 pa s and the fully relaxed shear modulus is 32 per cent of the purely elastic value a model with a maxwell viscoelastic halfspace underlying the lid cannot explain the observations at later times larger viscosities are required than at earlier times this increase in effective viscosity with time may be consistent with stress relaxation occurring in a power law rheology the time series are also inverted for distributed afterslip on an extension of the coseismic rupture along strike correlation of coseismic and post seismic slip maxima suggests that afterslip is a plausible mechanism the maximum slip in the afterslip model is 0 72 m after 3 yr and the equivalent moment release is approximately 20 per cent of the coseismic moment this study shows that it is possible to rule out certain mechanisms as the dominant post seismic process but with the current insar data set it is difficult to distinguish between other plausible options

new constraints on the rupture process of the 1999 august 17 izmit earthquake deduced from estimates of stress glut rate moments summary this paper illustrates the use of integral estimates given by the stress glut rate moments of total degree 2 for constraining the rupture scenario of a large earthquake in the particular case of the 1999 izmit mainshock we determine the integral estimates of the geometry source duration and rupture propagation given by the stress glut rate moments of total degree 2 by inverting long period surface wave lpsw amplitude spectra kinematic and static models of the izmit earthquake published in the literature are quite different from one another in order to extract the characteristic features of this event we calculate the same integral estimates directly from those models and compare them with those deduced from our inversion while the equivalent rupture zone and the eastward directivity are consistent among all models the lpsw solution displays a strong unilateral character of the rupture associated with a short rupture duration that is not compatible with the solutions deduced from the published models with the aim of understand this discrepancy we use simple equivalent kinematic models to reproduce the integral estimates of the considered rupture processes including ours by adjusting a few free parameters controlling the western and eastern parts of the rupture we show that the joint analysis of the lpsw solution and source tomographies allows us to elucidate the scattering of source processes published for this earthquake and to discriminate between the models our results strongly suggest that 1 there was significant moment released on the eastern segment of the activated fault system during the izmit earthquake 2 the apparent rupture velocity decreases on this segment

fault geometry and distribution of asperities of the 1997 manyi china mw 7 5 earthquake integrated analysis from seismological and insar data 1 the integration of seismic and insar interferogram data allows us to have a comprehensive understanding of the earthquake fault geometry and distribution of asperities for a remote event namely the 1997 manyi china earthquake we first obtained the slip distribution from teleseismic stations for several fault models and then made synthetic interferograms in order to determine the optimum fault geometry our results show that the 1997 manyi earthquake ruptured bilaterally with two segments dipping north and south for the western and eastern segments respectively the south dip of the eastern segment is essential for a better interpretation of the stations near the nodal plane and a reversal of dip between the west and east segment is necessary to explain the pattern of observed insar interferograms due to the broader distribution of asperities the fault rupture extended 170 km with maximum displacement of 6 1 m and a total seismic moment of 2 24 10 20 nm mw 7 5

the 1994 sefidabeh eastern iran earthquakes revisited new evidence from satellite radar interferometry and carbonate dating about the growth of an active fold above a blind thrust fault in 1994 three shallow earthquakes of mw 6 occurred close together on blind thrusts near sefidabeh in eastern iran in an earlier study of the teleseismic waveforms the geomorphology and the faulting in the epicentral region it was suggested that these earthquakes were associated with the growth of a ridge above a blind thrust fault system whose activity could be detected by its effect on the surface drainage in this study we present a sar interferogram that precisely determines the location and amount of coseismic surface displacements showing that the earthquakes in the sefidabeh sequence probably occurred on en echelon fault segments associated with three stepping ridges we also present u th dates of 100 ka for lake deposits uplifted by the growing ridge from the cumulative dated uplift and knowledge of the surface displacements due to an earthquake sequence we estimate that 120 such events have occurred in the past 100 ka with an average recurrence interval of 830 yr and an average convergence rate of 1 5 mm yr 1 on the sefidabeh thrust each estimate has an uncertainty of a factor of two either way we argue that the sefidabeh fault originally formed by coalescence of many small fault segments and has grown in length at about 2 cm yr 1 in the past 100 ka though the coseismic surface deformation observed in the sar interferogram closely resembles folding the overall topography does not because of inherited topography associated with earlier geological deformation in spite of this the activity of the buried thrust fault can easily be detected by its effect on the surface drainage a significant lesson when interpreting landscapes that are not entirely due to the present day deformation

holocene paleoenvironment 7200 4000 cal bp of the los castillejos archaeological site se spain inferred from the stable isotopes of land snail shells abstract neolithic copper age and modern land snail shells from the los castillejos archeological site 37 20 n se iberian peninsula were analyzed for 13 c 12 c and 18 o 16 o ratios to estimate the paleoenvironmental conditions during shell deposition modern and ancient 13 c values ranged from 9 2 to 7 7 and from 13 6 to 5 7 respectively and they differed among taxa 13 c values were similar for neolithic 13 c 8 1 2 3 copper age 13 c 8 4 0 6 and modern 13 c 8 4 0 5 herbivorous cernuella specimens alternatively fossil shells of the herbivorous ferussacia folliculum 13 c 9 9 1 2 and the omnivorous rumina decollata 13 c 11 1 2 showed substantially lower 13 c values than modern specimens which may suggest lower water stress during the early to mid holocene than today the 18 o values from modern specimens ranged from 1 1 to 0 6 while the 18 o values from fossil specimens ranged from 6 7 to 0 and they differed among species cernuella exhibited shell 18 o values that increased from the neolithic 18 o 2 3 1 8 and copper age 18 o 1 7 0 6 to the present 18 o 0 3 0 5 the 18 o values of fossil shells of f folliculum 18 o 3 7 1 0 and r decollata 18 o 4 0 1 6 were also lower than modern shells calculations of a published snail flux balance mixing model for 18 o values indicate that early to mid holocene shells precipitated during times when relative humidity was greater than today the se iberian peninsula was noticeably wetter 7200 cal bp and experienced drier conditions thereafter the results are consistent with other regional paleoclimatic proxies and reinforce the potential use of land snail shells as paleoenvironmental archives

stable isotope composition of late glacial land snail shells from grotta del romito southern italy palaeoclimatic implications abstract stable isotope composition of living and fossil land snail shells was determined at grotta del romito southern italy with the aim to reconstruct environmental and climatic variation in the area during late upper palaeolithic the investigated succession comprised 15 different excavated layers spanning between ca 13 000 and 14 500 yr cal bp the oxygen isotope composition of snail shells indicates a marked decrease at the layer d8 suggesting a climatic deterioration consistent with the gi 1d climatic event older dryas this climate deterioration may have been related to a substantial decrease of mean annual temperature with associated changes in the regional atmospheric circulation however the environmental conditions at the time of shell s growth in the other intervals sampled suggest condition comparable to the present day the carbon isotope composition of fossil snail shells is in agreement with other records which indicate a general increase of the 13 c values of organic matter during pleniglacial to late glacial caused by substantially lower atmospheric co 2 concentration at that time

joint inversion of broadband teleseismic and interferometric synthetic aperture radar insar data for the slip history of the mw 7 7 nazca ridge peru earthquake of 12 november 1996 1 the slip distribution of the 12 november 1996 mw 7 7 peru earthquake is determined using broadband teleseismic waveforms a differential sar interferogram interferometric synthetic aperture radar insar and a fault parametrization allowing slip and rupture velocity to vary along the rupture plane both data sets are inverted jointly to limit the trade off between the space and time aspects of the rupture the earthquake fault plane is located at the subduction interface it strikes parallel to the trench and dips 30 ne by inverting synthetic data we show how the insar and teleseismic data are complementary and how the joint inversion produces a gain in the spatial and temporal resolution of the slip model even with a sar interferogram that covers only part of the coseismic deformation the rupture of the 1996 peru event initiated on the southern flank of the subducted nazca ridge and propagated unilaterally toward the southeast along strike for more than 100 km at a depth between 20 and 40 km the area of maximum slip 6 7 m is located 50 km southeast of the hypocenter the total seismic moment is 4 4 1020 n m our joint inversion the source time function is approximately 60 s long and presents three major pulses of moment release the dominant one which occurred between 30 and 45 s does not correspond to the area of largest slip but to the rupture of a wide zone located about 100 km away from the hypocenter where slip reaches only 2 3 m computed coseismic coastal uplift correlates well with the location of raised marine terraces and with the topography of the coastal cordillera suggesting that these features may be related to the repetition of 1996 type events at the interface between the nazca ridge and the south american plate

paleoenvironment of the folsom archaeological site new mexico usa approximately 10 500 14c yr b p as inferred from the stable isotope composition of fossil land snail shells abstract well preserved aragonitic land snail shells vallonia from late pleistocene eolian sediment in the folsom archaeological site in new mexico exhibit an overall decrease of 18opdb from maximum values of 2 7 more positive than modern to younger samples with lower average values of about 3 6 within the modern range the age of the samples approximately 10 500 14c yr b p suggests that the decrease in 18o may manifest climatic changes associated with the younger dryas some combination of increased relative humidity and cooler temperatures with decreased 18o of precipitation during the times of snail activity can explain the decrease in shell 18o a well known paleoindian bison kill occurred at the folsom site during this inferred environmental transition average 13c values of the aragonite shells of the fossil vallonia range from 7 3 to 6 0 among different archaeological levels and are not as negative as modern values this suggests that the proportion of c4 vegetation at the folsom site approximately 10 500 14c yr b p was greater than at present a result which is consistent with other evidence for higher proportions of c4 plants in the region at that time

fault slip in the 1997 manyi tibet earthquake from linear elastic modelling of insar displacements summary the mw 7 6 1997 manyi earthquake occurred in an area of central northern tibet where sparse vegetation coverage and a lack of human habitation provide excellent conditions for interferometric synthetic aperture radar insar studies we use coseismic pairs of radar images acquired by the esa ers 2 satellite to construct interferograms of the surface displacement field due to the earthquake the location and extent of the coseismic fault rupture are mapped using a combination of optical satellite imagery high resolution digital topography interferometric correlation and azimuth offset measurements in so doing we are able to relate prominent geomorphic features in the fault zone to bends in the fault using elastic dislocation models consistent with this mapped fault trace we then test a range of fault geometries and slip conditions to find the combination which best explains the insar displacements our favoured model contains a reversal in fault dip approximately halfway along its length occurring at the location of a restraining bend slip on this model fault is heterogeneous with two areas of peak slip of 7 m or greater and components of dip slip displacement which vary significantly along strike the success of this model in fitting the data implies that an observed asymmetry in the coseismic interferograms can be explained in terms of the local fault geometry rather than by using non linear elastic rheologies as suggested by earlier authors

structural analysis of the 1997 mw 7 5 manyi earthquake and the kinematics of the manyi fault central tibetan plateau abstract on 8th november 1997 the mw 7 5 manyi earthquake ruptured the left lateral strike slip manyi fault in the central tibetan plateau despite its large magnitude a comprehensive geological study on the co seismic surface rupture has not yet been reported so far here we reported on our new results of the co seismic surface ruptures and left lateral offsets caused by the earthquake based on detailed interpretation of recently acquired high resolution worldview and spot 5 images we recognized a primary 185 km long surface rupture that trends n80 e in consistence with previous results along the poorly developed segment at the eastern end of the manyi fault a new rupture is also identified which trends n57 e and extends 17 km the co seismic surface rupture zone exhibits many distinct features such as stepovers extensional cracks ponds restraining and releasing bends in relation to fault geometrical complexities by visual analysis of the displaced geomorphic features using satellite imagery we measured 198 co seismic offsets along the 200 km fault trace the results show a 3 7 m average offset and a maximum offset of up to 7 5 m near the epicenter area the newly found 17 km long rupture is interpreted to be linked to the main fault during the event if the manyi fault continues this northeastward propagation for additional 100 km it will separate the bayanhar block into two sub blocks such a new hypothetical block model will influence assessment of seismic potential near the block boundaries and estimate of deformation of the bayanhar block and the central tibetan plateau

implications of the apparent 14c age of cultured achatina fulica and the spatial features of 14c ages among modern land snail shells in china abstract it has long been known that many terrestrial snail shells are subject to the so called limestone effect however the magnitude and impact of this effect on the 13c values of snail shells and soft body tissue 13cshell and 13cbody are still unknown in this study achatina fulica snails were hatched and cultured under controlled conditions and supplied with 14c free calcium carbonate and lettuce a c3 plant as a calcium source and food supply respectively the snail shells and soft body tissues were sampled monthly for 5 months and 13c and radiocarbon dating analyses were conducted to trace carbon source variations at different growth stages our results show that the apparent 14c age of the shells and the corresponding 13cshell values increased progressively from the 1st to 3rd months and subsequently decreased during the 4th and 5th months the results demonstrate for the first time that carbonate ingestion has a straightforward influence on the 14c ages and 13c values of shells and that the limestone effect changes over the lifetime of snails moreover the apparent 14c ages of snails sampled in the field are older than modern ages when taken from the northern carbonate region and relatively young or the same as modern ages when collected from ferralic soils this further supports our findings from cultured snails and suggests that snail shells are good archives for radiocarbon dating purposes in southern china although the 13c values of the soft body tissues of cultured snails vary synchronously with those of the shell this seemingly common phenomenon cannot be easily explained by carbonate ingestion as the snail bodies are of more recent origin than the shells atmospheric co2 may be another candidate explaining the synchronicity between 13cshell and 13cbody as well as the f 14c variations of snail bodies however it is still unclear how snails differentially incorporate carbon from different sources e g carbonate and atmospheric co2 at different growth stages since carbon from different sources is combined in the bicarbonate pool in the hemolymph before being used by snails

frictional properties on the san andreas fault near parkfield california inferred from models of afterslip following the 2004 earthquake the abundance of geodetic and seismic data recording postseismic deformation following the 2004 parkfield earthquake provides an unprecedented opportunity to resolve frictional properties on the parkfield section of the san andreas fault the parkfield segment is a transition between the locked section to the southeast that last ruptured in the 1857 fort tejon earthquake and the creeping section to the northwest we develop three dimensional rate and state dependent friction models of afterslip following the 2004 earthquake to investigate the frictional behavior of the fault it is assumed that the coseismic rupture occurred on an area of the fault surrounded by aseismic creep that accelerated after the earthquake we estimate the distribution of coseismic slip afterslip and rate state frictional parameters by inverting a two step slip model in the model we 1 estimate the coseismic slip distribution from 1 hz global positioning system gps data and 2 use the corresponding coseismic shear stress change on the fault as input into a numerical afterslip model governed by rate state friction we find the rate state frictional parameter a b an indicator of frictional stability is in the range 10 4 10 3 at 50 mpa normal stress which is near the transition from potentially unstable negative a b to nominally stable positive a b friction the estimate of a b values falls within a wide range of experimental values reported for serpentinite which crops out along the san andreas fault zone the critical slip distance d c which characterizes the distance over which strength breaks down during a slip event is in the range 0 01 0 1 m consistent with seismic estimates and a fault gouge thickness of 1 10 m the afterslip model reproduces most features observed in the gps time series data including high surface velocities in the first few months after the earthquake and lower rates at later times as well as the cumulative postseismic displacement the model tends to underpredict the displacement data at later times suggesting that perhaps the modeled afterslip period ends too quickly or an unmodeled deformation process dominates the signal at later times

shallow intraplate seismicity related to the illapel 2015 mw 8 4 earthquake implications from the seismic source abstract the september 16 2015 mw 8 4 illapel chile earthquake is the first large event occurring in north central chile after the 1943 earthquake filling a known seismic gap in the region the earthquake took place in a complex tectonic region nearby an area where transition from erosive to accretionary margin occurs due to the collision of juan fernandez ridge jfr along the chilean margin we inverted the kinematic rupture process of the 2015 mw 8 4 illapel earthquake from the joint inversion of teleseismic body waves and near field data the relative weighting between datasets and the weighting of spatial temporal constraints are objectively estimated by applying the akaike s bayesian information criterion the coseismic slip model yields a total seismic moment of 4 92 1021 nm occurred over 120 s the rupture shows both downdip and updip propagation with slip extending along the thrust interface from 50 km depth to shallow near trench depths

coseismic slip distribution of the 2003 mw 6 6 san simeon earthquake california determined from gps measurements and seismic waveform data 1 we combine geodetic and seismic data sets to constrain the coseismic slip distribution of the mw6 6 san simeon earthquake which occurred in the central california coast ranges on december 22 2003 we use continuous and survey mode gps observations along with seismic waveform data from the california integrated seismic network cisn we invert both data sets for the distribution of finite fault slip in a layered earth model the inversion results indicate that the rupture extends to the southeast of the epicenter for approximately 25 30 km and occurred in a relatively shallow depth range between 1 to 10 km the average and peak slip are 0 61 m and 2 37 m respectively the scalar seismic moment is 7 85e18 nm and the static stress drop 1 7 mpa this thrust earthquake is characterized by its shallow along strike extended slip

a method for the joint inversion of geodetic and seismic waveform data using abic application to the 1997 manyi tibet earthquake geodetic imaging data and seismicwaveformdata have complementary strengthswhen considering the modelling of earthquakes the former particularly modern space geodetic techniques such as interferometric synthetic aperture radar insar permit high spatial density of observation and thus fine resolution of the spatial pattern of fault slip the latter provide precise and accurate timing information and thus the ability to resolve how that fault slip varies over time in order to harness these complementary strengths we propose a method through which the two data types can be combined in a joint inverse model for the evolution of slip on a specified fault geometry we present here a derivation of akaike s bayesian information criterion abic for the joint inversion of multiple data sets that explicitly deals with the problem of objectively estimating the relative weighting between data sets as well as the optimal influence of model smoothness constraints in space and time we demonstrate our abic inversion scheme by inverting insar displacements and teleseismic waveform data for the 1997 manyi tibet earthquake we test using a simplified fault geometry three cases insar data inverted alone vertical component teleseismic broad band waveform data inverted alone and a joint inversion of both data sets the insar only model and seismic only model differ significantly in the distribution of slip on the fault plane that they predict the joint inversion model however has not only a similar distribution of slip and fit to the insar data in the insar only model suggesting that those data provide the stronger control on the pattern of slip but is also able to fit the seismic data at a minimal degradation of fit when compared with the seismic only model the rupture history of the preferred joint inversion model indicates bilateral rupture for the first 20 s of the earthquake followed by a further 25 s of westward unilateral rupture afterwards with slip peaking at 7m in the upper 6 km of the fault this joint inversion approach is thus shown to be a viable method for the study of large shallow continental earthquakes and may be of particular benefit in cases where near field seismic observations are not available the authors 2014 published by oxford university press on behalf of the royal astronomical society

stable isotope ecology of land snails from a high latitude site near fairbanks interior alaska usa abstract land snails have been investigated isotopically in tropical islands and mid latitude continental settings while high latitude locales where snails grow only during the summer have been overlooked this study presents the first isotopic baseline of live snails from fairbanks alaska 64 51 n a proxy calibration necessary prior to paleoenvironmental inferences using fossils 13c values of the shell 10 4 0 4 and the body 25 5 1 0 indicate that snails consumed fresh and decayed c3 plants and fungi a flux balance mixing model suggests that specimens differed in metabolic rates which may complicate paleovegetation inferences shell 18o values 10 8 0 4 were 4 higher than local summer rain 18o if calcification occurred during summer a flux balance mixing model suggests that snails grew at temperatures of 13 c rainwater 18o values of 15 and relative humidity of 93 results from fairbanks were compared to shells from san salvador bahamas at 24 51 n average annual 18o values of shells and rainwater samples from the bahamas were both 10 18o enriched with respect to seasonal summer alaskan samples at a coarse latitudinal scale shell 18o values overwhelmingly record the signature of the rainfall during snail active periods while tropical snails record annual average environmental information high latitude specimens only trace summer season climatic data

pleistocene holocene environmental change in the canary archipelago as inferred from the stable isotope composition of land snail shells abstract the isotopic composition of land snail shells was analyzed to investigate environmental changes in the eastern canary islands 28 29 n over the last 50 ka shell 13c values range from 8 9 to 3 8 at various times during the glacial interval 15 to 50 ka moving average shell 13c values were 3 higher than today suggesting a larger proportion of c4 plants at those periods shell 18o values range from 1 9 to 4 5 with moving average 18o values exhibiting a noisy but long term increase from 0 1 at 50 ka to 1 6 1 8 during the lgm 15 22 ka subsequently the moving average 18o values range from 0 0 at 12 ka to 0 9 at present calculations using a published snail flux balance model for 18o constrained by regional temperatures and ocean 18o values suggest that relative humidity at the times of snail activity fluctuated but exhibited a long term decline over the last 50 ka eventually resulting in the current semiarid conditions of the eastern canary islands consistent with the aridification process in the nearby sahara thus low latitude oceanic island land snail shells may be isotopic archives of glacial to interglacial and tropical subtropical environmental change

broadband source modeling of the november 8 1997 tibet mw 7 5 earthquake and its tectonic implications we studied the source process of a large ms 7 9 intraplate earthquake that occurred on november 8 1997 at 1002 ut in a remote region of northern tibet we used four distinct methods to investigate the broadband source process and thereby better understand the tectonic implications of this event we relocated aftershocks using a master event technique and found that the distribution of aftershocks covers a region of 200 km in lateral extent we also employed a surface wave spectral inversion technique to estimate the mainshock moment depth centroid location and centroid time and utilized an empirical green s function technique to extract rupture directivity information and a detailed source time function from observed seismograms we also inverted body waves to estimate the moment release along the fault and the source time function the 1997 earthquake ruptured a strike slip fault that appears to be an extension or splay of the kun lun fault system this fault is one of the most seismically active strike slip faults within the tibetan plateau and has had events with surface wave magnitudes of 6 1 7 4 and 7 9 in this region since 1973 the rupture released most of the energy within the first 20 s and propagated bilaterally initially with the later rupture propagating westward for 20 30 s the absence of large aftershocks suggests that the earthquake efficiently released the stored strain comparing mainshock to the largest aftershock energy ratios for this event and other large strike slip events shows that faulting within the plateau has the characteristics of weak faults e g fracture zone faulting

joint inversion of insar gps teleseismic and strong motion data for the spatial and temporal distribution of earthquake slip application to the 1999 izmit mainshock the space time distribution of slip of the 17 august 1999 izmit earthquake is investigated by inverting synthetic aperture radar sar interferometry and global positioning system gps data together with teleseismic broadband and near field strong motion records surface offsets are used as an added constraint special emphasis is given to analysis of the resolution of the different data sets we use a four segment finite fault model and a nonlinear inversion scheme allowing slip to vary in amplitude direction and duration as well as variable rupture velocity from the inversion of synthetic data we find that the best spatial resolution can be expected in the upper half of the fault model above 12 km where coverage of the interferometric sar data is good western half of the rupture and near the gps and strong motion stations teleseismic data are found to have a lower resolution that is more evenly distributed over the fault model the joint inversion of all the data sets has an increased resolving power compared with the separate inversions and gives a more robust description of the space and time distribution of slip our study shows the importance of resolution tests in evaluating the reliability of earthquake kinematic models and it confirms that an excellent fit of a single kind of data does not necessarily imply a good retrieval of the kinematic properties of an earthquake the izmit rupture which is almost pure right lateral strike slip faulting is dominated by the bilateral breaking of a central asperity located between 29 7 e about 10 km west of the city of golcuk and 30 4 e eastern margin of sapanka lake with slip reaching 6 8 m in the depth range 6 12 km the western termination of the rupture is found near the city of yalova but large slip ends around 29 7 e about 10 km east of hersek delta a second area of large slip is required by all the data sets further east toward the city of duzce between 30 7 e and 31 1 e karadere and duzce faults this eastern slip zone which is separated from the main central asperity by an area of greatly reduced slip is less well constrained by the data however a strong motion station near the city of duzce helps to locate a high slip patch near 31 1 e in the depth range 6 12 km the total seismic moment resulting from the joint inversion is 2 4 1027 dyne cm most of the energy release occurred in a short time less than 15 sec corresponding to the bilateral breaking of the central asperity rupture propagation is relatively uniform and fast toward the west with a rupture velocity close to 3 5 km sec propagation of large slip toward the east is initially slower but it accelerates during a short time interval about 10 sec after rupture nucleation eastward progression then slows down to less than 2 km sec after 15 sec and rupture almost vanishes in amplitude ca 20 sec after initiation rupture propagation then proceeds on the easternmost karadere and duzce fault segments east of 30 7 e from 22 to ca 50 sec supershear rupture propagation is not required for modeling the waveforms considered in this study the hypocenter of the duzce earthquake which occurred 3 months later 12 november 1999 m w 7 2 is located in the immediate vicinity of the easternmost slip patch of the izmit earthquake manuscript received 28 july 2000

rupture process of the 2004 parkfield earthquake from near fault seismic waveform and geodetic records 1 the 28 september 2004 parkfield earthquake arguably the best recorded earthquake ever allows for detailed investigation of finite source models and their resolution we have developed finite source models using gps and interferometric synthetic aperture radar geodetic data and seismic strong motion waveform data f 0 5 hz both independently and combined the preferred model shows that the rupture is predominantly unilateral to the nw with a small component to the se slip is concentrated into two primary patches one near the hypocenter and the other between 10 and 23 km to the nw within a narrow depth range 5 13 km the scalar seismic moment is 1 3 1018 n m mw 6 0 the overall rupture length is 23 km the peak slip is 0 45 m and the rupture velocity is 2 6 km s the average static stress drop obtained from the spatially distributed slip model is 2 3 mpa and peak values are 10 mpa a detailed sensitivity and resolution analysis shows that the recovered slip the average rupture velocity risetime and slip velocity are well resolved

imaging coseismic rupture in far field by slip patches summary since the end of the 1970s teleseismic waves are used routinely to infer the first order characteristics of the event location depth duration focal mechanism but finding the second order kinematic parameters spatial distribution of slip rupture velocity and more basically the discrimination between the fault plane and the other nodal plane of distant events remains a difficult task classically these events are studied by two different methods either they are seen as a succession of subevents each of which is considered as a point source or like in near field as extended sources where the kinematic parameters are retrieved on a grid the first approach is not physically satisfactory and can lead to erroneous interpretations of the

spatial and temporal distribution of slip for the 1992 landers california earthquake we have determined a source rupture model for the 1992 landers earthquake m w 7 2 compatible with multiple data sets spanning a frequency range from zero to 0 5 hz geodetic survey displacements near field and regional strong motions broadband teleseismic waveforms and surface offset measurements have been used explicitly to constrain both the spatial and temporal slip variations along the model fault surface our fault parameterization involves a variable slip multiple segment finite fault model which treats the diverse data sets in a self consistent manner allowing them to be inverted both independently and in unison the high quality data available for the landers earthquake provide an unprecedented opportunity for direct comparison of rupture models determined from independent data sets that sample both a wide frequency range and a diverse spatial station orientation with respect to the earthquake slip and radiation pattern in all models consistent features include the following 1 similar overall dislocation patterns and amplitudes with seismic moments of 7 to 8 10 26 dyne cm seismic potency of 2 3 to 2 7 km 3 2 very heterogeneous unilateral strike slip distributed over a fault length of 65 km and over a width of at least 15 km though slip is limited to shallower regions in some areas 3 a total rupture duration of 24 sec and an average rupture velocity of 2 7 km sec and 4 substantial variations of slip with depth relative to measured surface offsets the extended rupture length and duration of the landers earthquake also allowed imaging of the propagating rupture front with better resolution than for those of prior shorter duration strike slip events our imaging allows visualization of the rupture evolution including local differences in slip durations and variations in rupture velocity rupture velocity decreases markedly at shallow depths as well as near regions of slip transfer from one fault segment to the next as rupture propagates northwestward along the multiply segmented fault length the rupture front slows as it reaches the northern limit of the johnson valley landers faults where slip is transferred to the southern homestead valley fault an abrupt acceleration is apparent following the transfer this process is repeated and is more pronounced as slip is again passed from the northern homestead valley fault to the emerson fault although the largest surface offsets were observed at the northern end of the rupture our modeling indicates that substantial rupture was also relatively shallow less than 10 km in this region

early middle holocene land snail shell stable isotope record from grotta di latronico 3 southern italy this paper compares stable isotope d 18 o and d 13 c records of early middle holocene land snail shells from the archaeological deposits of grotta di latronico 3 ltr3 southern italy with modern shell isotopic data no substantial interspecific variability was observed in shell d 18 o d 18 os of modern specimens pomatias elegans cornu aspersum eobania vermiculata helix ligata and marmorana fuscolabiata in contrast interspecific shell d 13 c d 13 cs variability was significant probably due to different feeding behaviour among species the d 18 os values of living land snails suggest that species hibernate for a long period during colder months so that the signal of 18 o depleted winter rainfall in their d 18 os is lost this suggests that d 18 os and d 13 cs values of pomatias elegans from this archaeological succession provide valuable clues for seasonal spring autumn climatic con ditions during the early middle holocene the d 18 os values of fossil specimens are significantly lower than in modern shells and in agreement with other palaeoclimatic records suggesting a substantial increase of precipitation and or persistent changes in air mass source trajectories over this region between ca 8 8 cal ka bp and 6 2 6 7 ka ago the d 13 cs trend suggests a transition from a slightly 13 c enriched to a 13 c depleted diet between early and middle holocene compared to present conditions we postulate that this d 13 cs trend might reflect changes in the c3 vegetation community potentially combined with other environmental factors such as regional moisture increase and the progressive decrease of atmospheric co2 concentration copyright 2010 john wiley sons ltd

oxygen and carbon stable isotopes of modern land snail shells as environmental indicators from a low latitude oceanic island abstract land snails provide a unique opportunity to study terrestrial paleoenvironments because their shells which are generally highly abundant and well preserved in the fossil record contain a temporal record of environmental change in the form of isotope codes to evaluate the utility of this approach for a low latitude oceanic setting 207 modern shells of 18 species of land snail were analyzed for their oxygen and carbon isotope composition along a north and south facing altitudinal gradient 10 2160 m a s l in tenerife island 28 n of the canary archipelago shells collected at each locality showed a relatively large range in isotope composition which was greater along the south facing transect drier and hotter suggesting that the variance in shell isotope values may be related to water stress although pooled isotope values did not generally show strong relationships with environmental variables i e altitude temperature and precipitation mean isotope values were strongly associated with some climatic factors when grouped by site the mean 18o value of the shell 18oshell by site displayed a negative correlation with elevation which is consistent with the positive relationship observed between temperature and the 18o value of rain 18orain calculated 18o values of the snail body water 18obody derived from observed temperatures and 18oshell values using the equation of grossman and ku grossman e l and ku t l 1986 oxygen and carbon isotope fractionation in biogenic aragonite chem geol isotope geosci sec 59 59 74 displayed a trend with respect to altitude that was similar to measured and hypothetical 18o values for local rain water the calculated 18obody values from the shell declined 0 17 vsmow per 100 m which is consistent with the altitude effect observed for tropical rains in western africa and it correlated negatively with rainfall amount accordingly lower 18oshell values indicate lower temperatures lower 18orain values and possibly higher rainfall totals a positive correlation between the mean 13c values of shells 13cshell and plants by site suggests that shells potentially record information about the surrounding vegetation the 13cshell values varied between 15 7 and 0 6 vpdb indicating that snails consumed c3 and c4 cam plants where more negative 13cshell values probably reflects the preferential consumption of c3 plants which are favored under wetter conditions individuals with more positive 13cshell values consumed a larger percentage of c4 plants other potential factors such as carbonate ingestion or atmospheric co2 contribution were unlikely that were more common at lower elevations of the hotter and drier south facing transect the relatively wide range of shell isotope values within a single site requires the analysis of numerous shells for meaningful paleoclimatic studies although small differences were observed in isotope composition among snail species collected at a single sampling site they were not significant suggesting that isotope signatures extracted from multi taxa snail data sets may be used to infer environmental conditions over a broad range of habitats

carbon and oxygen isotope composition of shell carbonate of desert land snails abstract variation in 13 c 12 c and 18 o 16 o ratios in the shell carbonate of several species of land snails was studied along a climatic gradient in semi arid to arid areas in the southern levant 13 c was found to be enriched in snails from communities having plants with a c 4 photosynthetic pathway depleted 13 c values were found in areas with high mean annual rainfall apparently due to higher input of metabolic co 2 as a result of greater snail activity shell carbonate 18 o values show a weak relation to the 18 o values of rainwater the shell 18 o values are enriched by 2 8 relative to isotopic equilibrium with environmental waters enrichment is suggested to result from metabolic effects on body water with lower activity producing greater enrichment but evaporation could also be a factor consistent differences in both 13 c and 18 o were found among species and may relate to the time when shell deposition occurs as with most paleoenvironmental indicators the application of shell isotopes is complicated by the multiplicity of controls of isotopic composition

a non linear geodetic data inversion using abic for slip distribution on a fault with an unknown dip angle summary we have developed a method of geodetic data inversion for slip distribution on a fault with an unknown dip angle a common strategy for obtaining slip distribution in previous studies is to first determine the fault geometry by minimizing the square misfit under the assumption of a uniform slip on a rectangular fault and then apply the usual linear inversion technique to estimate a slip distribution on the determined fault it is not guaranteed however that the fault determined under the assumption of a uniform slip gives the best fault geometry for a spatially variable slip distribution the inverse problem is non linear for cases with unknown fault geometries but the non linearity of the problems is actually weak when we can assume the fault surface to be a flat plane in particular when a clear trace of coseismic faults is observed on the earth s surface only the dip angle is an unknown parameter to determine the fault geometry then we regarded the dip angle as an hyperparameter that prescribed the structure of parametric models and obtained the best estimate of the dip angle using akaike s bayesian information criterion abic with the best estimate of the dip angle we can obtain the slip distribution on the fault based on the maximum likelihood principle we applied the method to the insar data of the 1995 dinar turkey earthquake and obtained a much lower dip angle than the previous analyses

stable isotope ecology δ18o δ13c δ15n of modern land snails along an altitudinal gradient in southern appalachian mountains usa abstract the first isotopic baseline is established for the snail neohelix from the big santeetlah creek watershed appalachian mountains shell 18o 3 6 to 0 4 declined with altitude 0 06 per 100 m and correlated with measured rain 18o a flux balance model suggests that relative humidity increased from 0 89 at 710 m to 0 91 at 1620 m in agreement with higher precipitation at higher altitudes coherent relationships between shell precipitation and humidity suggest that this taxon should be a valid paleoprecipitation archive in north america the respective 13c and 15n values of body 28 3 to 23 2 0 4 to 4 9 and shell organics 28 2 to 24 0 0 0 to 3 4 did not exhibit a trend with altitude and were uncorrelated with potential food resources a stable isotope mixing model suggests that neohelix primarily consume fungi 48 and lichen 17 with minimal ingestion of c3 plants the relative contributions of different food items however varied in an unpredictable fashion along the altitudinal gradient this study illustrates that even though snail foraging ecology from woodlands is complex and more variable than anticipated combining several isotope systems permits dietary inferences more easily than field observations alone

a late pleistocene refugium in mediterranean north africa palaeoenvironmental reconstruction from stable isotope analyses of land snail shells haua fteah libya abstract the late pleistocene to holocene archaeological record of north africa is key to understanding the emergence of anatomically modern humans into west asia and europe and the broadening of subsistence strategies in the shift from hunter gatherer to pastoral agricultural lifeways some contend that these developments were modulated by major shifts in climate and environment evaluation of this hypothesis requires the pairing of local and regional climate records with well dated archaeological sequences the haua fteah archaeological site in the gebel akhdar region of libya provides a key site to test this hypothesis as the cave contains one of the longest and most complete sequences of human occupation in north africa as well as abundant material for palaeoenvironmental reconstruction this study uses stable isotope analyses 18o and 13c of the terrestrial mollusc helix melanostoma to construct a palaeoenvironmental framework for interpreting north african human environment interactions from the upper palaeolithic to the neolithic 30 000 to 5000 years ago the land snail stable isotope records from haua fteah suggests that cool arid conditions in the cave peaked during marine isotope stage mis 2 this stage was however only marginally drier than previous and subsequent stages and coincided with an increase in occupation density in the cave this suggests that the gebel akhdar may have served as an environmental refugium from the more extreme aridity in the surrounding sahara and arid coastal plains for late stone age lsa populations in north africa conditions became progressively wetter towards the holocene however generally wetter conditions were interrupted by two arid episodes at c 8 0 ka and 7 3 ka that appear to coincide with regional changes reflected elsewhere in the mediterranean basin

a late pleistocene steller sea lion eumetopias jubatus from courtenay british columbia its death associated biota and paleoenvironment a partial juvenile steller sea lion eumetopias jubatus skeleton from nearshore marine sands at courtenay vancouver island british columbia has been radiocarbon dated to 12 570 70 bp this date is supported by both stratigraphic and regional sea level emergence data and is similar to radiocarbon dates on a steller sea lion humerus from bowen island just north of vancouver the juvenile apparently died from a blow to the braincase most likely caused by a steller sea lion bull the courtenay specimen is significant since very few pleistocene otariid fossils are complete enough to be assigned to modern taxa associated mollusk remains indicate that the marine paleoclimate of the fossil locality was considerably colder than now close to that along the northern reaches of cook inlet and prince william sound alaska pollen and plant macrofossils collected from the courtenay site clearly demonstrate the presence of lodgepole pine pinus contorta forests nearby during this early late glacial interval fish remains mainly pacific cod and walleye pollock with some salmon from this site probably reflect selection by adult sea lions at a rookery resume un squelette partiel d une otarie juvenile de steller eumetopias jubatus provenant de sables marins cotiers a courtenay sur l ile de vancouver daterait de 12 570 70 ans avant le present selon une datation au radiocarbone cette datation est corroboree a la fois par des donnees stratigraphiques et d emergence regionale du niveau de la mer elle est aussi similaire aux datations au radiocarbone de l humerus d une otarie de steller provenant de l ile de bowen tout juste au nord de vancouver le juvenile est apparemment mort d un coup au neurocr ne probablement de la part d une otarie de steller m le le specimen de courtenay est important car tres peu de fossiles d otariides du pleistocene sont assez complets pour etre assignes aux taxons modernes les restes de mollusques associes indiquent que le paleoclimat marin de la localite fossilifere etait considerablement plus froid que presentement se rapprochant de celui des troncons nord de cook inlet et du golfe de prince william en alaska des macrofossiles de plantes et de pollens recueillis au site courtenay demontrent clairement la presence de forets de pin tordu pinus contorta a proximite au cours de cet intervalle tardi glaciaire precoce les restes de poissons surtout de morue du pacifique et de goberge de l alaska avec un peu de saumon de ce site sont probablement le reflet d une selection par les otaries adultes d une roquerie

holocene 4 5 1 7 cal kyr bp paleoenvironmental conditions in central argentina inferred from entire shell and intra shell stable isotope composition of terrestrial gastropods the isotopic fingerprint of terrestrial gastropods has been increasingly used as a credible natural paleoenvironmental archive most published work has used this proxy at tropical and temperate latitudes of the northern hemisphere and focused on entire shell analysis the present study provides entire shell and intra shell isotopic profiles to infer average and seasonal late holocene environmental conditions in central argentina 30 s shells of plagiodontes daedaleus gastropoda odontostomidae were retrieved from the alero deodoro roca sector b site one of the few archaeological sites in central argentina rich in shells collected by pre hispanic hunter gatherer groups ancient entire shells exhibited values that were 2 5 higher in 13c and 1 8 higher in 18o than modern individuals pointing to higher abundance of c4 plants and overall drier conditions lower relative humidity and or higher rain 18o during 4 5 1 7 cal kyr bp than today in agreement with published regional proxies intra shel

stable carbon and oxygen isotopic variations in modern rabdotus land snail shells in the southern great plains usa and their relation to environment abstract variations of stable isotopic ratios of carbon 13c 12c and oxygen 18o 16o were investigated in modern shells of two species of rabdotus land snails r dealbatus and r alternatus in the southern great plains geographic variation in relation to climate and vegetation microgeographic variation variability among individuals and detailed records of seasonal variations within individual shells were studied stable carbon isotopic ratios in shell carbonate are primarily a function of the isotopic composition of the diet of the snails as represented by the isotopic composition of shell organic matter this in turn reflects the presence or absence of cam crassulacean acid metabolism or c4 plants vegetation density may have a small effect on the carbon isotope ratios microgeographic variation samples within 25 to 300 m is greater than that seen across different climatic regions and points to very local control of isotopic variations predominantly related to vegetation seasonal variations as assessed through serial analysis of individual shells up to 35 samples per shell may provide a means for distinguishing between isotopic influences of perennial cam vs annual c4 plants carbon isotopic variations in time series of shells from a site provide a means of reconstructing temporal changes in environment and climate oxygen isotopic values of shell carbonate are uniform across the region and also show no significant microgeographic variation the oxygen isotopic composition appears to be mainly a function of the rainwater isotopic composition with no direct influence of rainfall amount or evaporative effects the 18o values are only 2 enriched relative to estimated equilibrium with rainwater variability is low sd of 0 8 among sites so the isotopic composition of fossil rabdotus shells can provide a precise record of changes in the isotopic composition of rain over time

environmental significance of 13c 12c and 18o 16o ratios of modern land snail shells from the southern great plains of north america c 12 c and 18 o 16 o ratios of aragonite shells of modern land snails from the southern great plains of north america were measured for samples from twelve localities in a narrow east west corridor that extended from the flint hills in north central oklahoma to the foothills of the sangre de cristo mountains in northern new mexico usa across the study area shell y 18 o values pdb scale ranged from 4 1x to 1 2x while y 13 c values ranged from 13 2x to 0 0x y 18 o values of the shell aragonite were predicted with a published steady state evaporative flux balance model the predicted values differed with one exception by less than 1x from locality averages of measured y 18 o values this similarity suggests that relative humidity at the time of snail activity is an important control on the y 18 o values of the aragonite and emphasizes the seasonal nature of the climatic information preserved in the shells correlated y 13 c values of coexisting vallonia and gastrocopta suggest similar feeding habits and imply that these genera can provide information on variations in southern great plains plant ecology although there is considerable scatter multispecies transect average y 13 c values of the modern aragonite shells are related to variations in the type of photosynthesis i e c3 c 4 in the local plant communities the results of this study emphasize the desirability of obtaining isotope ratios representing averages of many shells in a locale to reduce possible biases associated with local variations among individuals species etc and thus better represent the bneighborhoodq scale temporal and or spatial environmental variations of interest in studies of modern and ancient systems d 2004 university of washington all rights reserved

improving regional seismic event location in china in an effort to improve our ability to locate seismic events in china using only regional data we have developed empirical propagation path corrections and applied such corrections using traditional location routines thus far we have concentrated on corrections to observed p arrival times for crustal events using travel time observations available from the usgs earthquake data reports the international seismic centre bulletin the preliminary international data center reviewed event bulletin and our own travel time picks from regional data location ground truth for events used in this study ranges from 25 km for well located teleseimic events down to 2 km for nuclear explosions located using satellite imagery we also use eight events for which depth is constrained using several waveform methods we relocate events using the evloc algorithm from a region encompassing much of china latitude 20 55 n longitude 65 115 e we observe that travel time residuals exhibit a distance dependent bias using iaspei91 as our base model to remedy this bias we have developed a new 1 d model for china which removes a significant portion of the distance bias for individual stations having sufficient p wave residual data we produce a map of the regional travel time residuals from all well located teleseismic events residuals are used only if they are smaller than 10 s in absolute value and if the seismic event is located with accuracy better than 25 km from the residual data correction surfaces are constructed using modified bayesian kriging modified bayesian kriging offers us the advantage of providing well behaved interpolants and their errors but requires that we have adequate error estimates associated with the travel time residuals from which they are constructed for our p wave residual error estimate we use the sum of measurement and modeling errors where measurement error is based on signal to noise ratios when available and on the published catalog estimate otherwise our modeling error originates from the variance of travel time residuals for our 1 d china model we calculate propagation path correction surfaces for 74 stations in and around china including six stations from the international monitoring system the statistical significance of each correction surface is evaluated using a cross validation technique we show relocation results for nuclear tests from the balapan and lop nor test sites and for earthquakes located using interferometric synthetic aperture radar these examples show that the use of propagation path correction surfaces in regional relocations eliminates distance bias in the residual curves and significantly improves the accuracy and precision of seismic event locations

stable isotope composition of middle to late holocene land snail shells from the marroquies archeological site jaen southern spain paleoenvironmental implications abstract the marroquies archeological site located in the metropolitan area of jaen 37 46 southern spain contains land snail shells which have been preserved jointly with other human and zooarcheological remains new radiocarbon analyses carried out on pristine domestic animal and human bones confirmed that these remains belong to the copper age interval 4470 3880 cal bp n 8 land snail entire shells of two species one herbivorous and one omnivorous were analyzed for 13 c 12 c and 18 o 16 o ratios to estimate the paleoenvironmental conditions prevailing during the middle to late holocene in the southernmost part of europe the 13 c values of fossil shells ranged from 13 8 to 8 1 n 15 whereas modern specimens ranged from 10 8 to 8 6 n 20 the fact that ancient and modern shells generally exhibited similar 13 c values suggests that the 13 c values of the vegetation have remained relatively stable during 4470 3880 cal bp and the present snail species did not differ in 13 c values despite their differing dietary habits the 18 o values of fossil shells ranged from 4 9 to 1 2 n 15 whereas modern specimens ranged from 2 8 to 0 9 n 20 fossil shells were on average 2 lower in 18 o values than modern shells calculations from a snail evaporative steady state flux balance model suggest that shells at 4470 3880 cal bp precipitated under appreciably higher relative humidity conditions than today whereas rain 18 o values and air temperatures at the soil air interface during snail active period were possibly similar although samples from this study represent a time period in which the well documented late holocene aridification trend in southern spain already started snails suggest conditions at 4470 3880 cal bp were yet noticeably wetter than at present this study shows that land snail shells preserved in holocene archeological sites offer valuable paleoenvironmental information in their isotope codes

younger dryas early holocene transition in the south eastern iberian peninsula insights from land snail shell middens the land snail sphincterochila candidissima from archeological records in villena se spain was studied isotopically to estimate the younger dryas yd early holocene transition in the western mediterranean live collected individuals exhibited body 21 8 1 6 and shell 5 8 1 4 d 13 c values typical of a c3 plant diet probably combined with carbonate ingestion calculations of a carbon flux balance mixing model suggest that living specimens experienced similar metabolic rates with comparable ratio of input and output fluxes of bicarbonate from the snail hemolymph all fossil shells showed comparable d 13 c values among each other but values were 2 higher than living specimens this may be explained by higher water stress at the yd holocene transition or by the suess effect shell d 18 o values averaged 1 3 0 8 for living individuals 0 5 0 8 for holocene 8 4 10 2 cal ka bp specimens and 0 4 0 6 for yd 12 0 12 4 cal ka bp snails an oxygen flux balance mixing model suggests that yd shells precipitated during relative humidity rh values of 79 82 after which rh increased gradually reaching maximum values of 87 88 at 8 4 8 6 cal ka bp and from there rh eventually declined to present values of 82 comparisons with other snail data suggest that the xerophilous sphincterochila records different environmental signatures fro other contemporaneous taxa copyright 2013 john wiley sons ltd

geodetic data inversion using a bayesian information criterion for spatial distribution of fault slip summary we developed a new inversion method to reconstruct static images of seismic sources from geodetic data using akaike s bayesian information criterion abic coseismic surface displacements are generally related with a slip distribution on a fault surface by linear integral equations parametric expansion of the fault slip distribution by a finite number of known basis functions yields a set of observation equations expressed in a simple vector form incorporating prior constraints on the smoothness of slip distribution with the observation equations we construct a bayesian model with unknown hyperparameters the optimal values of the hyperparameters which control the structure of the bayesian model are objectively determined from observed data by using abic once the values of hyperparameters are determined we can use the maximum likelihood method to find the optimal distribution of fault slip we examined the validity of this method through a numerical experiment using theoretical data with random noise we analysed geodetic data associated with the 1946 nankaido earthquake ms 8 2 by using this method the result shows that the fault slip distribution of this earthquake has two main peaks of 4 and 6 m located off kii peninsula and muroto promontory these two high slip areas are clearly separated by a low slip zone extending along kii strait such a slip distribution corresponds with the fact that the rupture process of this earthquake in the western part is notably different from that in the eastern part

geodetic data inversion using abic to estimate slip history during one earthquake cycle with viscoelastic slip response functions summary we developed a new method of geodetic data inversion to estimate slip history at a plate interface by using akaike s bayesian information criterion abic in this method we considered the effects of viscoelastic stress relaxation in the asthenosphere which cannot be neglected to estimate slip history at a plate interface during one earthquake cycle we also introduced a proper formulation to incorporate two sorts of partially dependent prior information into observed data by bayes rule by applying the new inversion method to levelling data for 1893 1983 in shikoku southwestern japan we reconstructed the pattern of space time variation in slip motion during one earthquake cycle including the 1946 nankai earthquake at the interface between the eurasian and the philippine sea plates the result shows that a steady slip motion at a plate convergence rate 40 mm yr 1 proceeds in the shallow and the deep regions through the entire earthquake cycle in the intermediate depth range 10 30 km on the other hand an instantaneous slip of approximately 4 m occurs at the time of the nankai earthquake after that this portion keeps in stationary contact until the occurrence of the next nankai earthquake if we neglect the effects of viscoelastic stress relaxation the inversion analysis gives geophysically unrealistic results

coseismic deformation from the 1999 mw 7 1 hector mine california earthquake as inferred from insar and gps observations we use interferometric synthetic aperture radar insar and global positioning system gps observations to investigate static deformation due to the 1999 m w 7 1 hector mine earthquake that occurred in the eastern california shear zone interferometric decorrelation phase and azimuth offset measurements indicate regions of surface and near surface slip which we use to constrain the geometry of surface rupture the inferred geometry is spatially complex with multiple strands the southern third of the rupture zone consists of three subparallel segments extending about 20 km in length in a n45 w direction the central segment is the simplest with a single strand crossing the bullion mountains and a strike of n10 w the northern third of the rupture zone is characterized by multiple splays with directions subparallel to strikes in the southern and central the average strike for the entire rupture is about n30 w the interferograms indicate significant along strike variations in strain which are consistent with variations in the ground based slip measurements using a variable resolution data sampling routine to reduce the computational burden we invert the insar and gps data for the fault geometry and distribution of slip we compare results from assuming an elastic half space and a layered elastic space results from these two elastic models are similar although the layered space model predicts more slip at depth than does the half space model the layered model predicts a maximum coseismic slip of more than 5 m at a depth of 3 to 6 km contrary to preliminary reports the northern part of the hector mine rupture accommodates the maximum slip our model predictions for the surface fault offset and total seismic moment agree with both field mapping results and recent seismic models the inferred shallow slip deficit is enigmatic and may suggest that distributed inelastic yielding occurred in the uppermost few kilometers of the crust during or soon after the earthquake

source rupture process of the tecoman colima mexico earthquake of 22 january 2003 determined by joint inversion of teleseismic body wave and near source data the spatial and temporal slip distribution of the tecoman colima mexico earthquake is estimated from near source strong motion and teleseismic body wave data to perform a stable inversion we applied smoothing constraints and determined their optimal relative weights on the observed data using an optimized akaike s bayesian information criterion abic the source parameters are as follows strike dip slip 300 20 93 seismic moment m 2 3 1020 n m source duration 30 sec along strike distance 35 km along dip distance 70 km we found that the rupture process can be divided into three stages the rupture nucleated near the hypocenter stage i then it broke the first asperity centering about 15 km southwest from the epicenter stage ii and the rupture propagated to the northeast and the second asperity was broken stage iii we also estimated the shear stress change due to the rupture process of the mainshock on and around the major fault zone it appears that one cluster of aftershocks for the first 5 days which took place in and adjacent to the zones of stress increased due to the fault rupture during the mainshock but overall correlation between the aftershock location and the stress pattern is not clear manuscript received 14 may 2003

rupture process of the april 24 2017 mw 6 9 valparaiso earthquake from the joint inversion of teleseismic body waves and near field data abstract the central chilean margin 32 33 s is characterized by the subduction of the juan fernandez ridge jfr beneath the continental south american plate the jfr corresponds to a hotspot track composed by seamounts typically 3 3 5 km high above the surrounding seafloor with a ridge trench collision zone underlying the prominent valparaiso forearc basin vfb this region has been affected by several large and mega earthquakes where the last event corresponds to a complex seismic sequence that took place at the southern edge of vfb in april 2017 the spatio temporal distribution of the seismic events is characterized by a predominant southeast migration of the seismicity an mw 6 9 earthquake triggered two days after the sequence started and occurred at the northern end of the rupture area of the 1985 mw 8 0 valparaiso earthquake we compute the kinematic rupture process of the 2017 mw 6 9 valparaiso earthquake from the joint inversion of teleseismic body waves and near field data the akaike s bayesian information criterion was used to objectively estimate both the relative weighting between datasets and the weighting of spatial and temporal constraints used as a priori information the coseismic slip is distributed over an area of dimensions 35 10 km2 with a maximum slip of 1 5 m the rupture propagated unilaterally downdip the source duration from the moment rate solution is 20 s with a total seismic moment of 3 05 1019 nm mw 6 9 the analysis of the seismicity shows that most of the events occurred along the plate interface foreshock clustered northern from the mainshock epicenter and the aftershocks occurred to the southeast at a deeper location the inverted regional moment tensors show similar faulting mechanism than the mainshock the seismic sequence started two days before the mainshock and lasted for about two weeks and a migration pattern of the seismicity was observed the rupture of the 2017 mw 6 9 earthquake nucleated where the san antonio seamount belonging to the jfr is subducting and propagated downwards along a zone that presents high interseismic coupling the complex seismic sequence might be explained by an aseismic slip transient in the zone and the influence of the downdip migration of fluids from the accretionary prism along the subduction channel the erosive and tunneling effect left by the sudden slip of the subducting seamount might provide the cavity for downdip migration of fluids and subsequent swarm seismicity

source process of the chi chi earthquake a joint inversion of strong motion data and global positioning system data with a multifault model the chi chi taiwan earthquake of 21 september 1999 was a large thrust earthquake that caused disastrous damage the surface fracture trace runs along the chelungpu fault which strikes n5 e along most of the faulting area but turns to the northeast while approaching its northern end it finally presents a horsetaillike faulting system and bends to an east northeast direction at the northern end both strong motion and global positioning system gps data recorded large displace ments in the northern part in this study we use a multifault model to simulate the observed large strong motion and gps data the results of the joint inversion reveal that in the southern part slip occurred mainly in the shallow portion reaching a maximum about 20 m on the ene fault where the rupture propagated to the deep part of the fault there was obviously slip vector rotation from south to north such that the slip on the branched fault plane was almost purely reverse faulting the seismic moment a total of 2 7 10 20 n m was released in less than 40 sec during the mainshock aftershocks occurred mainly in areas where little or no slip occurred slip vector rotation can be explained by the complexity of regional tectonic stress changes in tectonic stress at the northern end of the fault inhibited the northward propagation of the rupture and favored the rupturing of the ene fault