self excitation process due to local seismic amplification responsible for the reactivation of the salcito landslide italy on 31 october 2002 1 an integrated numerical and geophysical approach was used to investigate the role of local seismic amplification in the reactivation of the salcito landslide italy after the molise earthquake of 31 october 2002 numerical stress strain analysis with flac 5 0 fdm software performed in dynamic configuration showed that the 1 hz frequency was consistent with landslide instability conditions the fourier spectrum of the triggering earthquake showed two main peaks occurring at 1 and 2 hz respectively which could be related to local effects the analysis of h v spectral ratios of ambient noise records obtained in the landslide area evidenced amplification effects in the 1 3 hz range on the basis of an engineering geology model numerical modeling of both 1 d and 2 d seismic wave propagation was conducted using linear and nonlinear solutions the simulation outputs showed 1 a 1 hz amplification ascribable to 2 d effects due to a landslide mass lying within a basin like geological structure 2 a double peak amplification at about 2 and 3 hz respectively ascribable to 1 d resonance of the landslide mass and 3 1 d plus lateral wave effects within the landslide mass in the 2 5 3 5 hz frequency range these findings suggest that local amplification of ground motion by the salcito landslide mass may generate a self excitation process responsible for its reactivation

a parametric numerical study of the interaction between seismic waves and landslides for the evaluation of the susceptibility to seismically induced displacements this study presents the results of a numerical analysis investigating the influence of the interaction between seismic waves and slopes on seismically induced displacements of existing landslides three step like slope geometries with dip angles varying from 10 degrees to 45 degrees and two landslide mechanisms were considered 54 multi frequential dynamic equivalent signals were applied to the models and were derived according to the lema des approach based on the accelerometric records of the european strong motion and cosmos databases the simulations were performed using a finite difference approach that assumed different viscous rheologies and considered different values for both the dynamic properties and the mechanical parameters the interaction between seismic waves and landslides was analyzed using frequency ratios defined for characteristic periods associated with the landslide dimensions i e thickness and length and the seismic input a regression analysis was also performed to derive correlations between seismically induced displacements and the frequency ratios the values of the arias intensity and the critical accelerations the obtained results reveal that a the seismically induced displacements increase with the seismic amplification induced by the landslide mass b the coupling of a 2d interaction between seismic waves and slope with the 1d resonance of the landslide mass which is strictly related to the high impedance contrasts between the landslide mass and the substratum significantly affects the seismically induced displacements and c the seismically induced displacements increase more intensely with increasing slope angle for a rototranslational mechanism with respect to a translational one moreover the seismically induced displacements that can be expected from the here obtained results can significantly differ from those computed by the sliding block stability analyses based on newmark s method

seabed bubble flux estimation by calibrated video survey for a large blowout seep in the north sea abstract a new approach to estimating seabed bubble emissions was applied to a rov video survey of the 22 4b blowout crater in the uk north sea video was analyzed to identify and classify bubble plumes and other seabed features plume occurrence then was gridded into quadrats and the total number of plumes in the crater s active portion estimated almost all of the seepage in the 40 45 m crater was localized within a 20 by 18 m ellipse all five major plumes in this ellipse were measured by direct capture with mean emission of 1 34 l s 1 at 12 bar range 0 54 3 5 l s 1 the primary source of variability 71 was temporal demonstrated by repeat measurements of a single vent overall temporal variability was consistent with highly fluid migration through a thick near seabed coarse grained sediment bed underlying the 22 4b crater seabed occurrence data were converted to flux based on direct capture measurements survey video and laboratory experiments where video was collected of bubble plumes of known flow for comparison with field video the derived best estimate total seabed emission flux was 90 l s 1 with an estimated uncertainty of 50 within a scenario uncertainty range of 50 142 l s 1 this is equivalent to 100 million l dy 1 at standard temperature and pressure or an annualized 25 kton however long term monitoring data showing large temporal variability suggests extrapolation to an annual basis is inappropriate

reassessment of probabilistic seismic hazard in the marmara region abstract in 1999 the eastern coastline of the marmara region turkey witnessed increased seismic activity on the north anatolian fault naf system with two damaging earthquakes m 7 4 kocaeli and m 7 2 duzce that occurred almost three months apart these events have reduced stress on the western segment of the naf where it continues under the marmara sea the undersea fault segments have been recently explored using bathymetric and reflection surveys these recent findings helped scientists to understand the seismotectonic environment of the marmara basin which has remained a perplexing tectonic domain on the basis of collected new data seismic hazard of the marmara region is reassessed using a probabilistic approach two different earthquake source models 1 the smoothed gridded seismicity model and 2 fault model and alternate magnitude frequency relations gutenberg richter and characteristic were used with local and imported ground motion prediction equations regional exposure is computed and quantified on a set of hazard maps that provide peak horizontal ground acceleration pga and spectral acceleration at 0 2 and 1 0 sec on uniform firm rock site condition 760 m sec average shear wave velocity in the upper 30 m these acceleration levels were computed for ground motions having 2 and 10 probabilities of exceedance in 50 yr corresponding to return periods of about 2475 and 475 yr respectively the maximum pga computed at rock site is 1 5 g along the fault segments of the naf zone extending into the marmara sea the new maps generally show 10 to 15 increase for pga 0 2 and 1 0 sec spectral acceleration values across much of marmara compared to previous regional hazard maps hazard curves and smooth design spectra for three site conditions rock soil and soft soil are provided for the istanbul metropolitan area as possible tools in future risk estimates

measurement of marine hydrocarbon seep flow through fractured rock and unconsolidated sediment abstract three turbine seep tents measured gas flux variations including an ejection at one tent several conceptual models of hydrocarbon migration were developed from the relationship between fluxes at the tents 1 a resistor capacitor network to model oil and gas flux in the seep system including an oil regulator model 2 a fracture oil deposition model where oil deposited on fracture walls progressively clogs and then blocks fractures also measured were bubble size distributions for minor and major vents that were narrow and broad respectively and varied with time due to oil flux very oily bubbles with different trajectories were observed

long term acoustic monitoring at north sea well site 22 4b highlights first study using long term passive acoustic monitoring of methane seeps at well blowout site 22 4b seep acoustic temporal variations correlated with ocean tides major acoustic transient event recorded on 8 december 2011 with high temporal resolution abstract marine seeps produce underwater sounds as a result of bubble formation and fragmentation upon emission from the seabed the frequency content and sound levels of these emissions are related to bubble size distribution and emission flux providing important information on methane release from the seafloor long term passive acoustic monitoring was used to continuously record seep sounds over a 7 month period within the blowout crater at the abandoned well site 22 4b in the central north sea also recorded were water column fluid velocities and near seafloor water conductivity temperature and pressure acoustic signatures were primarily from 1 to 10 khz key features were relatively broad spectral peaks at about 1 0 1 5 2 2 3 1 3 6 and 5 1 khz temporal variations in spectral levels were apparently associated with tides the recordings also documented a series of major episodic events including a large and persistent increase 10 db in overall sound levels and spectral broadening on 8 december 2011 the acoustic temporal pattern of this event was consistent with other recorded large transient events in the literature and the major event was correlated with dramatic changes in other measurements including increased water column fluid velocities increased pressure and decreased salinity indicating real changes in emission flux observed seabed morphology changes reported elsewhere in this special issue also likely were related to this event these data demonstrate the dynamic nature of marine seepage systems show the value of monitoring systems and provide direct supporting evidence for a violent formation mechanism of many widespread seep associated seabed features like pockmarks

strontium calcium ratios in modern porites corals from the great barrier reef as a proxy for sea surface temperature calibration of the thermometer and monitoring of enso high precision sr ca ratios are reported for porites corals from davies reef at 19 s on the midshelf of the great barrier reef australia skeletal growth parameters were also determined from coral slabs using x ray photographs and densitometry measurements a calibration of the sr ca thermometer has been obtained using in situ measured sea surface temperatures which gives sr ca 10 10 48 0 01 0 0615 0 0004 t wheret is in c this calibration applies to different species of porites and a large range of annual extension and calcification rates provided sampling follows a major growth axis biases of 1 2 c have been observed in the low density margins where growth is hampered by interfering fans of corallites the analytical and the long term reproducibility of sr ca derived temperatures are both better than 0 3 c 2 coral growth parameters such as the extension rate or density generally appear to respond to environmental changes such as rainfall but do not affect the sr ca partitioning between coralline aragonite and seawater no correlation has been found between calcification rate and sr ca variations consistent with sr ca being mainly controlled by temperature in the great barrier reef the interannual variability in sst is primarily related to the el nino southern oscillation phenomenon and is typically marked by a cold anomaly during the winter preceding the mature warm phase instrumental records show that the surface waters of the coral sea around 19 s have experienced a significant cooling associated with the el ninos of 1965 1972 and 1982 1983 which the porites corals record faithfully the coral derived temperatures for the period from 1965 to 1993 show an increase of 1 3 c which has occurred mainly since 1979 this warming is larger in magnitude but consistent with the trend for the southern hemisphere land and marine temperature records which shows an increase of around 0 4 c

characteristics and scaling of bubble plumes from marine hydrocarbon seepage in the coal oil point seep field 1 the fate of marine seep gases in the ocean and atmosphere is intimately connected with bubble and bubble plume processes which are strongly size and depth dependent size dependent flux distributions and vertical velocity functions vz r were measured with a video bubble measurement system in the santa barbara channel california several distinct plume types were identified for which size distributions were measured major minor intermediate and obstructed a further vent class is elastic which was observed but not quantified in addition any plume class could be oily minor plumes generally produced a lower emission flux q and showed narrow peaked that were well described as gaussian the radius of the dominant peak rp of minor plumes varied as q0 40 with correlation coefficient r2 0 84 in agreement with theoretical relationship of rp q0 4 for q above a critical flow rate oil contamination was found to affect rp and was not used in the fit a probability distribution rp for all gaussian bubble plumes was itself well described by a combination of gaussian functions which were different for different seep areas major plumes showed a broad distribution including very small and very large bubbles and were well described by a power law with exponent a which varied with q according to a 0 43 0 55 log q with r2 0 77 one obstructed vent was analyzed and shared characteristics with the minor bubble plumes mixed bubble plume size distributions showed characteristics of both major and minor plume classes i e were described by a combination of gaussian functions and power laws and were steeper higher a than major plumes for the same q oily plumes produced complex confused bubble size distributions upwelling velocities vup r were derived from vz r and increased as vup q0 66 r2 0 64 however consideration of the more intense plumes q 2 cm s 1 showed vup q0 35 in agreement with other published field measurements thus the weaker bubble plumes were observed during the acceleration phase

mg ca sr ca and u ca ratios of a porites coral from sanya bay hainan island south china sea and their relationships to sea surface temperature high resolution mg ca sr ca and u ca ratios are reported in the skeleton of porites sp collected from sanya bay on the south coast of the hainan island china using inductively coupled plasma mass spectrometry combined with isotope dilution technique icp ms id the coralline mg ca ratios covary with sea surface temperatures sst for the 10 year interval giving the relationship between mg ca and sst as t degrees c 14 13 0 31 8 846 0 068 x 10 3 mg ca with the mean square weighted deviation mswd of 9 7 using this equation we are able to reconstruct sst record with a precision better than 0 5 degrees c several sr ca and u ca ratios show poor linear relationships with the measured sst this study indicates that the growth rates of the coral do not significantly affect coralline mg ca sr ca and u ca ratios however the high meteoric precipitation in this area which may cause a heavy run off from the island may change seawater sr ca and u ca ratios and ruin the relationships between coralline sr ca or u ca ratios and sst this implies that in coastal areas like hainan coralline mg ca ratios are valid for reconstructing the sst records but sr ca and u ca ratios may be suspected c 2000 elsevier science b v all rights reserved

a probable earthquake scenario near istanbul determined from dynamic simulations abstract we perform numerical simulations of dynamic rupture processes along the north anatolian fault in the sea of marmara which poses a high risk to the nearby city of istanbul several fault geometry models nucleation points and initial stress states are tested the likelihood of each earthquake scenario is evaluated and a probabilistic assessment of the ground motion estimation is proposed the simulation results suggest that the fault geometrical configuration is not favorable for producing an earthquake of magnitude 6 7 as no scenario is found on the contrary the probability of occurrence of an earthquake of magnitude greater than 7 is high most of these large events are characterized by epicenters located in the central or eastern parts of the sea of marmara however the possibility of a western initiated rupture propagating eastward the worst scenario for the istanbul region cannot be ruled out many simulations led to supershear ruptures as observed for the nearby 1999 izmit earthquake and this significantly influences ground motion prediction in the region

a coral oxygen isotope record from the northern red sea documenting nao enso and north pacific teleconnections on middle east climate variability since the year 1750 a 245 year coral oxygen isotope record from the northern red sea ras umm sidd egypt 28 n in bimonthly resolution is presented the mean annual coral 18o signal apparently reflects varying proportions of both sea surface temperature and 18oseawater variability in conjunction with instrumental observations of climate the coral record suggests for interannual and longer timescales that colder periods are accompanied by more arid conditions in the northern red sea but increased rainfall in the southeastern mediterranean whereas warmer periods are accompanied by decreased rainfall in the latter and less arid conditions in the northern red sea a 70 year oscillation of probably north atlantic origin dominates the coral time series interannual to interdecadal variability is correlated with instrumental indices of the north atlantic oscillation nao the el nino southern oscillation enso and north pacific climate variability the results suggest that these modes contributed consistently to middle east climate variability since at least 1750 preferentially at a period of 5 7 years

evidences of landslide earthquake triggering due to self excitation process the basin like setting of stiff bedrock combined with pre existing landslide masses can contribute to seismic amplifications in a wide frequency range 0 10 hz and induce a self excitation process responsible for earthquake triggered landsliding here the self excitation process is proposed to justify the far field seismic trigger of the cerda landslide sicily italy which was reactivated by the 6th september 2002 palermo earthquake ms 5 4 about 50 km far from the epicentre the landslide caused damage to farm houses roads and aqueducts close to the village of cerda and involved about 40 106 m3 of clay shales the first ground cracks due to the landslide movement formed about 30 min after the main shock a stress strain dynamic numerical modelling performed by fdm code flac 5 0 supports the notion that the combination of local geological setting and earthquake frequency content played a fundamental role in the landslide reactivation since accelerometric records of the triggering event are not available dynamic equivalent inputs have been used for the numerical modelling these inputs can be regarded as representative for the local ground shaking having a pga value up to 0 2 m s2 which is the maximum expected in 475 years according to the italian seismic hazard maps a 2d numerical modelling of the seismic wave propagation in the cerda landslide area was also performed it pointed out amplification effects due to both the structural setting of the stiff bedrock at about 1 hz and the pre existing landslide mass in the range 3 6 hz the frequency peaks of the resulting amplification functions a f fit well the h v spectral ratios from ambient noise and the h h spectral ratios to a reference station from earthquake records obtained by in situ velocimetric measurements moreover the fourier spectra of earthquake accelerometric records whose source and magnitude are consistent with the triggering event show a main peak at about 1 hz this frequency value well fits the one amplified by the geological setting of the bedrock in correspondence with the landslide area which is constituted of marly limestones and characterised by a basin like geometry

directivity of slope dynamic response to seismic shaking 1 a four year long accelerometric monitoring of a landslide prone slope area in italy provided evidence of amplifications with systematic directional differences in shaking energy by a factor of 2 3 apparently correlated with the directions of local topographic features the examination of regional scale data revealed similar site response directivity phenomena also on some steep rock slopes not affected by amplification the spectral properties of the site responses were investigated using hvsr analysis and a new approach based on the multiplication of spectra from several events the results suggest that such phenomena are caused by a directional redistribution of spectral energy controlled by a combination of interrelated topographic and geologic factors acting in similar directions

pseudostatic coefficient for use in simplified seismic slope stability evaluation pseudostatic slope stability procedures are commonly used in engineering practice however the selection of the seismic coefficient employed in the analysis is often based on precedence without due consideration of the amount of seismic displacement that constitutes satisfactory performance for each particular project and without incorporating the vastly different seismic exposure for sites around the world in this note a rational basis for selecting the seismic coefficient is presented the proposed procedure requires that the engineer establishes the project specific allowable level of seismic displacement the seismic response characteristics of the slope are represented by the fundamental period of the potential sliding mass and the site dependent seismic demand is characterized by the 5 damped elastic design spectral acceleration at the degraded period of the potential sliding mass the level of uncertainty in the estimates of the seismic demand and displacement can be handled through the use of different percentile estimates of these values with the proposed equations the engineer can properly incorporate the amount of seismic displacement judged to be allowable and the seismic hazard at the site in the selection of the seismic coefficient

geophysical investigation and dynamic modelling of unstable slopes case study of kainama kyrgyzstan summary the presence of massive quaternary loess units at the eastern border of the fergana basin kyrgyzstan central asia makes this area particularly prone to the development of catastrophic loess earthflows causing damages and injuries almost every year efficient disaster management requires a good understanding of the main causes of these mass movements that is increased groundwater pressure and seismic shaking this paper focuses on the kainama earthflow mainly composed of loess which occurred in 2004 april its high velocity and the long run out zone caused the destruction of 12 houses and the death of 33 people in summer 2005 a field survey consisting of geophysical and seismological measurements was carried out along the adjacent slope by combination and geostatistical analysis of these data a reliable 3 d model of the geometry and properties of the subsurface layers as shown in the first part of the paper was created the analysis of the seismological data allowed us to point out a correlation between the thickness of the loess cover and the measured resonance frequencies and associated amplification potential the second part of this paper is focused on the study of the seismic response of the slope by numerical simulations using a 2 d finite difference code named flac modelling of the seismic amplification potential along the slope confirmed the results obtained from the seismological survey strong amplifications at the crest and bottom of the slope where there is a thick loess cover and almost no amplification in the middle part of the slope furthermore dynamic slope stability analyses were conducted to assess the influence of local amplifications and increased groundwater pressures on the slope failure the results of the dynamic modelling although preliminary show that a combination of seismic and hydrologic origin pore pressure build up during the seismic shaking is the most probable scenario responsible for the 2004 failure

application of a characteristic periods based cpb approach to estimate earthquake induced displacements of landslides through dynamic numerical modelling the authors would like to thank the european union erdf for financial support via the monitorizacion sismica de deslizamientos criterios de reactivacion y alerta temprana project of the programa operativo feder de andalucia 2007 2013

delta o 18 sr ca and mg ca records of porites lutea corals from leizhou peninsula northern south china sea and their applicability as paleoclimatic indicators combined seasonal to monthly resolution coral skeletal delta 18 o sr ca and mg ca records are reported for one modem and two late holocene porites lutea corals from a fringing reef at leizhou peninsula the northern coast of the south china sea scs all the profiles for the period 1989 2000 reveal annual cycles well correlated with instrumental sea surface temperatures sst and display broad peaks in summer and narrow troughs in winter reflecting seasonal growth rate variations calibration against instrumental sst yields the following equations delta 18 o 0 174 0 010 xsst degrees c 1 02 0 27 mswd 5 8 sr ca mmol mol 0 0424 0 0031 xsst degrees c 9 836 0 082 mswd 8 6 and mg ca mmol mol 0 110 0 009 xsst degrees c 1 32 0 23 mswd 55 the scatter in the mg ca sst relationship is much larger than analytical uncertainties can account for suggesting the presence of sst unrelated components in the mg ca variation calculated sr ca sst values for two later holocene porites lutea samples u series ages similar to 541 bc and similar to 487 ad respectively from the same reef suggest that sst in the scs at similar to 541 bc was nearly as warm as in the 1990s the warmest decade of the last century but at similar to 487 ad it was significantly cooler this observation is consistent with climatic data reported in chinese historic documents confirming that the sr ca sst relationship is a reliable thermometer removing the sst component in the delta 18 o variation based on calculated sr ca sst values the residual delta 18 o reflects the deviation of the holocene seawater delta 18 o from the modem value which is also a measure of the holocene sea surface salinity sss or the summer monsoon moisture level in mainland china such residual delta 18 o was close to zero at similar to 541 bc and 0 3 parts per thousand at similar to 487 ad suggesting that it was as wet as in the 1990s at similar to 541 bc but significantly drier at similar to 487 ad in mainland china which are also consistent with independent historic records calculated mg ca sst values for the two late holocene corals are significantly lower than the sr ca sst values and are also in conflict with chinese historic records suggesting that coral mg ca is not reliable proxy for sst at comparable sr ca ranges fossil corals always display negative mg ca offsets if compared with the modem coral of the same site we interpret this observation as due to preferential loss of mg during meteoric dissolution of cryptic mg calcite bearing microbialites in the exposed fossil corals microbialites mgo up to 17 sr only 100 300 ppm are ubiquitous during reef building processes and their presence in only a trace amount will have a significant impact on coral mg ca ratios without detectable influence on coral sr ca ratios c 2004 elsevier b v all rights reserved

the interaction of seismic waves with step like slopes and its influence on landslide movements abstract the interaction of seismic waves with slopes is a major factor influencing landslide movements that involve slope stability local site seismic amplification and topographic effects affecting ground motion the results of a numerical study of landslide movements induced by the interaction of seismic waves with step like slopes are presented here to investigate this input slope interaction a dynamic analysis was performed using the finite difference stress strain numerical code flac 6 0 under visco plastic conditions the dynamic signals were selected to be representative of different peak ground accelerations pgas arias intensities and frequency contents and they were used in a parametric study of different step like slopes with different geometrical configurations in terms of dip height and thickness of geological strata the derived outputs were processed for a seismic amplification analysis and to evaluate the induced stress strain effects in terms of progressive failure and resulting displacements the obtained results i describe a fundamental role of topography in amplifying or de amplifying the seismic ground motion ii demonstrate that the progressive failure of unsheared slopes influences the seismic amplification iii show that the strain effects on unsheared slopes in terms of progressive failure are more intense with increasing arias intensity and slope dip iv prove that amplification or de amplification processes can justify the values of displacements involving pre existing landslide masses which are significantly different with respect to those expected on the basis of sliding block approaches i e newmark s and flexible sliding block methods v highlight that in the geological setting considered here the seismically induced displacements arising from the reactivation of pre existing landslide masses can be significantly underestimated by sliding block approaches in the case of low angle slopes characterised by high k values i e the ratios between the critical pseudostatic threshold ky of the landslide and pgas of the applied seismic input

intercomparison of coral oxygen isotope data and historical sea surface temperature sst potential for coral based sst field reconstructions we examine the extent to which the large scale features of the sea surface temperature sst anomaly field are represented by a sparse observational network of coral oxygen isotope 18o time series regression of annually averaged 18o data against gridded estimates of local sst anomaly within the period 1856 1990 confirm the literature regression of 18o anomaly on sst anomaly for indo pacific corals however while interannual sst variability is generally well represented by individual coral time series observed decadal and secular variability does not always display a linear relationship to local sst anomaly instead many records appear to better recover nonlocal large scale phenomena which in turn are related to either the coral local sst or sst covariant changes in seawater 18o we employ empirical orthogonal function eof analysis to identify common patterns of variability in the coral data we find two significant patterns which are interpretable as the oceanographic signature of the el nino southern oscillation enso and as a near global warming in which the eastern equatorial pacific cools a third pattern weakly resembles the pacific decadal oscillation these modes are seen more clearly in a singular vector decomposition svd of the covariance between the coral data and the dominant patterns of large scale historical sst variability the results are consistent with those found in eof and svd analyses of sst data from the coral locations as additional coral based proxy estimates become available they will improve the resolution of the patterns recovered these results suggest that a sparse network of coral data may be used to reconstruct interannual secular and decadal sst variability for preinstrumental periods albeit with large uncertainty

passive acoustic records of seafloor methane bubble streams on the oregon continental margin abstract we present acoustic records of methane bubble streams recorded 10 km southwest of heceta bank on the oregon continental margin using an autonomous hydrophone the hydrophone was deployed at 1228 m water depth via a remotely operated vehicle rov during the e v nautilus expedition na072 in june 2016 bubble sound is produced by detachment of the gas bubble from the end of a tube or conduit which causes the bubble to oscillate producing a sound signal despite persistent ship propeller and rov noise the acoustic signature of the overall bubble seep site can be seen in the hydrophone record as a broadband 1 0 45 khz series of short duration 10 20 ms oscillatory signals that occur in clusters lasting 2 3 s the frequency of an individual bubble s oscillation is proportional to the bubble s radius estimates here of bubble radii are consistent with bubble sizes observed in rov still images acoustic signal loss models imply bubble sounds might be recorded over an area of seafloor from 300 3 2 104 m2 this study represents a first step in attempting to identify and quantify deep ocean bubble stream sounds using passive acoustic techniques

the acoustic signature of marine seep bubbles observations of seabed bubbles 62m depth at a natural marine hydrocarbon seep by passive acoustic and optical approaches are compared the acoustic and optical methods observed a bimodal distribution with peaks at 1500 and 1750hz and 2200 and 2800 m radius respectively radii were 20 lower than predicted by the minnaert formula frequency shifts were observed for bubbles emitted within a few milliseconds and were attributed to coupling between nearby bubbles surfactants also may have played a role

simplified procedure for estimating earthquake induced deviatoric slope displacements a simplified semiempirical predictive relationship for estimating permanent displacements due to earthquake induced deviatoric deformations is presented it utilizes a nonlinear fully coupled stick slip sliding block model to capture the dynamic performance of an earth dam natural slope compacted earth fill or municipal solid waste landfill the primary source of uncertainty in assessing the likely performance of an earth waste system during an earthquake is the input ground motion hence a comprehensive database containing 688 recorded ground motions is used to compute seismic displacements a seismic displacement model is developed that captures the primary influence of the system s yield coefficient ky its initial fundamental period ts and the ground motion s spectral acceleration at a degraded period equal to 1 5 ts the model separates the probability of zero displacement i e 1 cm occurring from the distribution of nonzero displacement so that very low values of calculated

composite mechanism of the buyukcekmece turkey landslide as conditioning factor for earthquake induced mobility abstract earthquake induced displacements of landslides are significantly conditioned by their 1d and 2d interactions with seismic waves as currently proven by several studies nevertheless the role of a more complex geological setting responsible for a heterogeneous composition of the landslide mass can significantly influence these phenomena the heterogeneity can also depend on multiple phases of the landslide activity responsible for dislodging the whole landslide mass into submasses each one delimited by secondary scarps and characterized by individual mobility hence in the framework of the european project marsite marmara supersite new directions in seismic hazard assessment through focused earth observation in the marmara supersite the buyukcekmece landslide located approximately 30 km w of istanbul turkey was considered as a case study this landslide involves a large mass of approximately 140 million cubic metres composed of silty clays tuffs and sands ascribable to cenozoic geological formations the landslide is characterized by multiple phases of activity with a composite rototranslational mechanism which created seven submasses delimited by secondary scarps the scheme of water circulation in the landslide slope based on piezometer data as well as on a geological survey accounts for two flow nets the first shallower flow net is located in superficial sandy deposits outcropping in the dislodged landslide submasses the second deeper flow net is located in the main sliding surface a slope stability analysis following a global limit equilibrium approach provided a distribution of the pseudostatic coefficient vs pore water pressure the results show that the stability of the landslide submasses increases moving downslope and reactivations are expected in the case of earthquakes with a return period between 475 and 2475 yr according to the local seismic hazard dynamic numerical modelling was also performed using the stress strain finite difference code flac 7 0 to derive the distributions of horizontal displacements vs characteristic period ratios defined as the period due to depth ts and total length tl of the landslide mass over the earthquake characteristic period tm the obtained results indicate that an effective characteristic period of the landslide tl related to the length of a single counter slope tilted submass can provide a more correct explanation for the effect of seismic wave interactions on earthquake induced displacements this result indicates that the earthquake induced mobility of the buyukcekmece landslide is strongly conditioned by its composite rototranslational mechanisms in general these results indicate that landslide evolution can induce a change over time for the characteristic periods related to the dimensions of the dislodged landslide portions and then modify its interactions with seismic waves

high resolution windows into early holocene climate srca coral records from the huon peninsula high precision measurements of srca ratios are reported for porites corals from the uplifted holocene coral terraces at huon peninsula papua new guinea the early holocene porites have u th mass spectrometric ages of 8920 60 yr and 7370 50 yr and 234u t values of 145 2 similar to modern seawater the srca coral records provide 5 6 year high resolution near weekly time windows into early holocene sea surface temperatures seasonal temperature fluctuations are generally in the range of 1 c with occasional excursions of 2 c which may indicate the more frequent recurrence of very strong enso el nino southern oscillation events mean annual srca temperatures of 24 2 1 1 c and 22 9 0 8 c have been obtained which are 2 3 c cooler than that exhibited by a modern porites these results indicate that during the early holocene the equatorial western pacific ocean was at least several degrees cooler than present day temperatures this is consistent with late glacial coral records from the caribbean that indicate lower 6 c sea surface temperatures for the equatorial oceans the huon peninsula corals also indicate that ssts were several degrees cooler than those in the caribbean during the early holocene thus although the northern hemisphere summer radiation maximum occurred at 10 ka there appears to have been a significant lag in the response of the equatorial western pacific ocean to this warming cooler early holocene sea surface temperatures in the western pacific may have been due to changing patterns of ocean atmosphere circulation resulting from the exposure of large areas of continental shelf in the southeast asia region a consequence of lower glacial sea levels it is likely that ocean temperatures in the huon peninsula were influenced by the opening at 7 ka of the torres strait that now separates new guinea from the australian mainland

nonlinear coupled seismic sliding analysis of earth structures earthquake induced sliding displacements of earth structures are generally evaluated using simplified sliding block analyses that do not accurately model the seismic response of the sliding mass nor the seismic forces along the slide plane the decoupled approximation introduced to capture each of these effects separately is generally believed to be conservative however recent studies using linear viscoelastic sliding mass models have revealed instances where the decoupled approximation is unconservative in this paper a coupled analytical model that captures simultaneously the fully nonlinear response of the sliding mass necessary for intense motions and the nonlinear stick slip sliding response along the slide plane is presented the proposed sliding model is validated against shaking table experiments of deformable soil columns sliding down an inclined plane the effect of sliding on the response of earth structures is evaluated and comparisons are made between sliding displacements calculated us

advances and problems in understanding the seismic response of potentially unstable slopes abstract the influence of site effects on landslide triggering during earthquakes has been inferred in several studies but its evaluation is made difficult by the complexity of factors controlling the dynamic response of potentially unstable slopes and also by the lack of local ground motion instrumental observations this work explores this problem and reports new findings based on an ongoing long term accelerometric monitoring conducted on a landslide prone test area in the apennine mountains italy where the presence of site effects enhancing seismic susceptibility of local slopes has been invoked on the basis of historic accounts of landsliding triggered at large epicentral distance the recordings relative to low to moderate magnitude earthquakes showed significant amplifications affecting hillslope portions covered by thick 5 m colluvia and pronounced amplification maxima oriented along the local maximum slope direction on a recent deep seated landslide while the amplifications seem most likely linked to high impedance contrast between surface materials and underlying substratum the causes of directivity are less clear the case of the monitored test site together with evidence of site response directivity identified on other hillslopes suggest that the directivity phenomena can result from a combination of topographic lithological and structural factors that act together to re distribute shaking energy focusing it on site specific directions thus it is difficult to single out the critical factors controlling such phenomena and no general criterion for the identification of sites affected by directivity is proposed here nevertheless the presence and orientation of site response directivity can be revealed through reconnaissance techniques by using recordings of seismic weak motion and or ambient microtremors and calculating azimuthal variation of shaking energy and horizontal to vertical ground motion spectral ratios a comparison with the recordings obtained during the recent m w 6 3 earthquake that hit the abruzzo region in april 2009 demonstrated that analysis relying on data from low energy events can furnish valid indications for slope behaviour also under stronger shaking provided the data are well differentiated in terms of distance azimuth and source characteristics furthermore the comparative analysis of the abruzzo earthquake recordings at a landslide and reference sites showed that directivity properties of strong shaking had been correctly anticipated using earlier weak motion observations however under the complex slope conditions the identification of resonance frequencies from horizontal to vertical spectral ratios estimated from weak motion accelerometric recordings does not seem reliable and better results have been obtained by velocimetric microtremor recordings

dynamics of the gas flux from shallow gas hydrate deposits interaction between oily hydrate bubbles and the oceanic environment decomposition of methane hydrates on the continental margins is a potentially significant source of atmospheric methane but the input depends upon the poorly understood fate of the hydrocarbon bubbles rising from the sea floor during a field trip to the gulf of mexico three different seepages were imaged and analyzed three different imaging techniques were tried side front and back illumination of which back illumination produced the best results the images were analyzed and the size dependent bubble distribution mass flux and rise speeds determined the total observed gas flux was 62 3 10 3 mol s 1 primarily methane of which a single vent produced seven times the next largest vent of this major vent 50 of the bubble mass was contained in the largest bubbles r 5500 m the vertical velocities demonstrated that these bubbles were heavily contaminated with oil which was also corroborated by bubble shape and oscillation observations

a high resolution sr ca and δ18o coral record from the great barrier reef australia and the 1982 1983 el nino abstract a high resolution near weekly sr ca and oxygen isotopic record is presented for a coral from the pandora reef in the great barrier reef gbr of australia during the period 1978 to 1984 the records are well correlated except for periods of high rainfall when river runoff has significantly modified the 18o value of seawater using the sr ca temperature calibration of de villiers et al 1994 the sr ca records exhibit seasonally controlled cyclical sst sea surface temperature variations of from 21 to 28 c during the very strong el nino of 1982 1983 the sr ca systematics indicate a sharp drop in the winter sst to 18 5 c this represents a temperature anomaly of 3 c which is approximately twice that given by the 18o variations suggesting an 2 amplification of the anomaly by the sr ca system possibly due to the increasing dominance of inorganically controlled aragoniteseawater fractionation the oxygen isotopic systematics show the combined effects of both temperature and changing seawater 18o values the latter reflecting the influx of 18o depleted runoff during periods of high rainfall due to the extremely low 10 3 sr and ca contents of river run off relative to seawater it is possible to use the sr ca thermometer to calculate temperatures independent of major floods and hence deconvolve the combined effects in the oxygen isotopic record of variable temperature and the 18o value of seawater using this approach it is possible to quantitatively reproduce the volume of runoff from the burdekin river during the periods of major flooding that occurred in early 1979 and 1981 the results of this study demonstrate that the combined use of high resolution sr ca and 18o systematics in scleractinian corals is a powerful tool for providing quantitative constraints on past climate

calibration of stable oxygen isotope signatures in galapagos corals a 2 year 1993 1994 study was conducted in the galapagos islands ecuador to determine the relationship between 18o in skeletal carbonate and sea surface temperature sst in three species of reef building corals pavona clavus pavona gigantea and porites lobata coral samples were grown at 3 10 and 3 m depth at bartolome island champion iisland and urvina bay isabela island respectively hourly measurements of sst and sea surface salinity sss were taken at each site immediately adjacent to colonies which were stained biannually to establish the chronology of growth in addition surface waters were sampled periodically bimonthly to monthly at each site to determine variation in 18o seawater results indicate the mean annual ssts were similar between sites varying from 22 9 c at champion to 23 8 c at urvina bay comparisons of monthly sst averages between instrumental and remote sensing satellite 1 1 grid data show a high correspondence r2 ranging from 0 84 to 0 94 indicating that remote sensing data are useful for interpreting the 18o record in corals when instrumental data are lacking here 18ocoral analyses of eight specimens show that coralline aragonite is a reliable indicator of sst in galapagos in general higher resolution coral sampling year resolved more of the monthly variation in sst up to 97 at a sampling resolution of 1 4 samples per millimeter of linear skeletal growth comparisions of the 18ocoral signal among and between species at the same site showed consistent seasonal patterns of variation closely tracking sst in addition comparisons between sites were highly concordant with some differences reflecting local variation in sst seasonal patterns however were essentially the same over the entire region thus we conclude that the 18ocoral signal from coral skeletons in galapagos can be used to interpret regional changes in sst variation

tracking an oil slick from multiple natural sources coal oil point california oil slicks on the ocean surface emitted from natural marine hydrocarbon seeps offshore from coal oil point in the santa barbara channel california were tracked and sampled over a 2 h period the objectives were to characterize the seep oil and to track its composition over time using a new sampling device a catamaran drum sampler catdrums the sampler was designed and developed at ucsb chromatograms showed that oil originating from an informally named very active seep area shane seep primarily evolved during the first hour due to mixing with oil originating from a convergence zone slick surrounding shane seep

comprehensive analysis of the local seismic response in the complex buyukcekmece landslide area turkey by engineering geological and numerical modelling multi risk management requires a strong comprehension of possible effects induced by natural hazardous events in this regard landslides triggering due to earthquakes results from complex interactions between seismic waves and slopes multidisciplinary approaches can significantly contribute to better understand such interactions the large buyukcekmece landslide about 1500 m wide and 1830 m long located in turkey avcilar peninsula about 15 km northward from the north anatolian fault zone nafz was selected as case study in the framework of the european project marsite marmara supersite new directions in seismic hazard assessment through focused earth observation in the marmara supersite the avcilar area was recently affected by the 17th august 1999 mw 7 4 kocaeli and by the 12th november mw 7 2 duzce earthquakes the buyukcekmece landslide involves upper oligocene to lower miocene deposits consisting of silty clays tuffs and sands no earthquake induced re activations are testified so far but the landslide area was interested by a very intense urbanization during the last decade a detailed engineering geological model for the local seismic response of the buyukcekmece landslide slope was constructed based on geophysical measurements data from a multisensor in hole monitoring system and stress strain numerical modelling several tens of earthquakes were recorded from october 2014 to may 2015 in the landslide site by considering in hole and surface data the reliability of the local seismic response obtained by numerical modelling respect to the empirically derived one was checked in terms of both site to reference spectral ratios and transfer function between surface and downhole sites inside the landslide mass the 2d numerical amplification functions confirm that the local seismic response is a consequence of the complex geological setting of the landslide slope while no relevant amplification effects can be referred to topographic features based on these results the interaction between seismic waves and the buyukcekmece landslide slope cannot be neglected to evaluate the possibility of future landslide re activations

corals at their latitudinal limits laser ablation trace element systematics in porites from shirigai bay japan the rapid analytical technique of laser ablation inductively coupled plasma mass spectrometry la icp ms was used to measure the trace elements b mg sr ba and u in a high latitude coral colony porites lobata taken from shirigai bay japan 32 n a wide range of sea surface temperatures ssts 14 5 28 c and upwelling events influenced this coral cold winter ssts caused a decrease and or cessation of skeletal extension measurements of u ca and sr ca indicate an approximately linear response to ssts above 18 c and a non linear response below 18 c mg ca and b ca measurements both showed annual cycles broadly consistent with sst variations but also exhibited intra annual fluctuations not associated with temperature suggesting that the incorporation of mg and b into the coral skeleton was not simply regulated by temperature it is shown that ba ca ratios provide a proxy for wind induced seasonal upwelling this is inferred from the strong correlations between the strength of zonal winds 1 month prior to the sst minimum and the ba ca maximum secondary upwelling events occurred during the summers of 1982 1987 1991 and 1992 these summers were cooler than average and were associated with el nino southern oscillation events

site effects modelling applied to the slope affected by the suusamyr earthquake kyrgyzstan 1992 abstract in 1992 a large magnitude earthquake ms 7 3 hit the northern part of the kyrgyz tien shan range where it triggered rockslides and many debris slides or flows one of these mass movements occurred on the chet korumdy ridge located in the suusamyr basin it consists of a multi rotational debris slump in its upper part that turned into a debris flow in its lower part involving arenitic material overlying silty clays it has a volume of about 0 5 to 1 10 6 m 3 a maximum thickness of 40 m and a run out of 200 m the field observations and measurements carried out on this slope suggest that local amplification effects could have contributed to the initiation of the seismic failure to test this hypothesis in the lack of instrumental evidence of local ground motion recordings we conducted a sensitivity study of site effects based on a numerical analysis in the visco elastic domain with a two dimensional finite difference code varying the topography and the geology of the investigated slope topographic site effects are found to be less important than geological site effects which are controlled by the contrast of impedance between the surface materials and the bedrock the geometry of the low velocity surface layer has also an influence on site effects which is often difficult to be distinguished from pure topographic effects considering all modelling results we conclude that site amplifications alone cannot have triggered the suusamyr landslide during the 1992 earthquake the static slope stability analyses done in previous studies revealed that the suusamyr failure neither can have a purely static origin even if the water table is very high within the arenite layer only a minor failure develops in the lower part of the slope therefore we believe that the triggering of the suusamyr landslide is a consequence of pore pressure build up in areas characterized by significant ground motion amplifications

seismic hazard in istanbul following the 17 august 1999 izmit and 12 november 1999 duzce earthquakes two recent destructive earthquakes that occurred along the western part of the north anatolian fault zone nafz the 17 august 1999 m w 7 4 izmit and 12 november 1999 duzce m w 7 2 earthquakes have caused major concern about future earthquake occurrences and their possible consequences in the istanbul area probabilistic seismic hazard analyses are performed for the larger istanbul area including the gulf of izmit and the marmara sea region hazard computations were done assuming different combinations of four attenuation relations and three alternative source models the three models used are 1 standard poissonian earthquake occurrence with area sources 2 renewal model assuming characteristic earthquakes with area and fault sources and 3 renewal model assuming characteristic earthquakes with refined area and fault sources results are presented in twelve different maps of peak ground acceleration pga with a 10 chance of exceedance in 50 yr among the earthquake recurrence models the results assuming model 3 yield the highest pga values reaching greater than 0 3 g at the western end of the gulf of izmit in general pga values decrease toward north and are reduced down to less than 0 2 g in central istanbul in the bosphorous area the four attenuation relations examined display significant variations and their effects become especially critical for distances less than 50 km in addition spectral hazard levels corresponding to 475 yr return period are computed and presented as uniform hazard response spectra for 5 damping two sites are selected one in hard rock and the other in soft sediments in general these results correlate well with the turkish seismic design code tsdc recommendations for the two site conditions the estimates of the future earthquake hazard potential of the istanbul area are sensitive to our present day understanding of the behavior of the fault segments in the marmara sea region

gaia s breath global methane exhalations abstract methane ch 4 is the most abundant organic compound in the earth s atmosphere where it acts as a greenhouse gas and thus has implications for global climate change the current atmospheric ch 4 budget however does not take into account geologically sourced ch 4 seepage geological sources of ch 4 include natural macro and micro seeps mud volcanoes and other miscellaneous sources such as gas hydrates magmatic volcanoes geothermal regions and mid ocean ridges macro seeps contribute 25 tg teragrams ch 4 yr to the atmosphere whereas micro seepage contributes perhaps 7 tg ch 4 yr mud volcanoes emit 5 tg ch 4 yr and miscellaneous sources emit 8 tg ch 4 yr to the atmosphere thus the total contribution to the atmosphere from geological sources is estimated to be 45 tg ch 4 yr which is significant to the atmospheric organic carbon cycle and should be included in any global inventory of atmospheric ch 4 we argue that the atmospheric ch 4 global inventory of the interplanetary panel on climate change must be adjusted in order to incorporate geologically sourced ch 4 from naturally occurring seepage