sr ca and δ18o in a fast growing diploria strigosa coral evaluation of a new climate archive for the tropical atlantic this study provides the first monthly resolved 41 year record of geochemical variations 18o and sr ca in a fast growing diploria strigosa brain coral from guadeloupe caribbean sea linear regression yields a significant correlation of coral sr ca 18o with instrumental sea surface temperature sst on both monthly and mean annual scales e g r 0 59 for correlation between simple ocean data assimilation soda sst and sr ca and r 0 66 for 18o mean annual scale p 0 0001 the generated coral sr ca 18o sst calibration equations are consistent with each other and with published equations using other coral species from different regions moreover a high correlation of coral sr ca and 18o with local air temperature on a mean annual scale r 0 78 for sr ca r 0 73 for 18o p 0 0001 demonstrates the applicability of geochemical proxies measured from diploria strigosa corals as reliable recorders for interannual temperature variability both coral proxies are highly correlated with annual and seasonal mean time series of major sst indices in the northern tropical atlantic e g r 0 71 for correlation between the index of north tropical atlantic sst anomaly and sr ca and r 0 70 for 18o mean annual scale p 0 001 furthermore the coral proxies capture the impact of the el nino southern oscillation on the northern tropical atlantic during boreal spring thus fast growing diploria strigosa corals are a promising new archive for the atlantic ocean

a multiproxy approach to reconstructing sea surface conditions using coral skeleton geochemistry 1 we use elemental ratio mg ca sr ca u ca and ba ca and oxygen isotope data from a porites lutea coral head collected from offshore amedee island new caledonia 22 29 s 166 28 e to assess the degree to which changes in these geochemical variables reflect variations in sea surface conditions we have assessed the robustness of each geochemical proxy by comparing 25 years 1992 1968 of monthly geochemical variations with a local record of sea surface temperature sst and with the appropriate 1 by 1 grid box from a global gridded sst data set we conclude from our comparison that the most consistent proxies of monthly sst variations at this site are 18o r2 0 84 p 0001 and sr ca r2 0 84 p 0001 the fidelity of the coral based sr ca sst proxy was assessed via calibration verification exercises at new caledonia and rarotonga the paleoclimate accuracy of the coral sr ca sst technique is judged to be robust and the precision of the technique is estimated to be 0 3 0 5 2 based on the calibration verification exercise in contrast monthly variations in mg ca and u ca ratios are only moderately correlated with monthly sst variations r2 0 55 p 0001 for mg ca and r2 0 47 p 0001 the strength of the correlation between sst and mg ca and u ca varies as a function of time suggesting that variations in these ratios are not a simple function of sst variations this variability in goodness of fit between u ca sst and mg ca sst may ultimately limit the use of these ratios as coral paleothermometers averaging or stacking individual proxy sst records sr ca mg ca and u ca to generate a composite proxy sst record does not necessarily improve the proxy record if the signal to noise ratio in each proxy is highly variable for example stacking of sr ca mg ca u ca records at new caledonia produces a proxy sst time series that has greater standard error than the individual sr ca sst time series cf ordinary least squares standard error of 1 16 c versus 0 86 c ba ca variations have little correlation with sst sr ca mg ca or u ca variations at new caledonia in conclusion variations in oxygen isotopic composition of seawater calculated by removing the sr ca based temperature component of the 18o signal agree reasonably well with observed variations in sea surface salinity especially at the interannual timescale

geochemistry and skeletal structure of diploria strigosa implications for coral based climate reconstruction abstract geochemical tracers incorporated into the skeleton of reef building corals are ideal proxies for reconstructing environmental parameters of ambient seawater such as temperature and salinity at subseasonal resolution however validation concerns of these environmental proxies due to the complex skeleton of some tropical atlantic corals have hindered such coral based environmental reconstructions in this region compared to the tropical pacific in order to identify complications associated with the complex skeletal architecture of the massive brain coral diploria strigosa we performed microsampling experiments along and across individual skeletal elements we demonstrate that the mesoscale heterogeneity of sr ca 18o and 13c is a systematic feature of d strigosa and is linked to different vital effects between skeletal elements the thecal wall is significantly depleted in sr 18o and 13c compared to the adjacent septa and columella and differences between apparent temperature signatures of several degrees are greater for sr ca suggesting that this temperature proxy is more sensitive to skeletal mixing than 18o parallel subseasonal microsampling experiments performed along individual skeletal elements of a single corallite of a d strigosa coral which grew at a rate of 0 65 cm year allow for investigating potential biases associated with its complex skeletal mesoarchitecture highest correlation between sr ca and 18o from skeletal material retrieved from the centre of the thecal wall suggests that microdrilling the theca provides the best environmental signal compared to adjacent microsampling profiles moreover based on monthly mean climatology the temperature dependence of sr ca for this profile is comparable to previous calibrations published from faster growing d strigosa based on these results we conclude that accurate microsampling along the centre of the thecal wall of d strigosa is a prerequisite for generating robust climate reconstructions from its skeleton

reconstructing twentieth century sea surface temperature variability in the southwest pacific a replication study using multiple coral sr ca records from new caledonia 1 coral based climate reconstructions typically have not used multiple cores from a region to capture and replicate a climate signal largely because of concerns of coral conservation analytical expense and time constraints coral sr ca reproducibility through the twentieth century was investigated using three intracolony and three intercolony coral records from the reefs offshore of amedee island new caledonia different sampling resolutions were examined in coral sr ca fortnightly and monthly and 18o fortnightly monthly and seasonally as well as similar scale subsampling of the daily in situ sea surface temperature sst record the mean coral sr ca 18o and sst values do not change as a function of sampling resolution the coral sr ca signal is highly reproducible the average absolute offset between coeval monthly sr ca determinations between any two coral time series is 0 035 0 026 mmol mol 1 0 65 c which is less than twice the analytical precision of the coral sr ca measurements the stack average of the monthly coral sr ca variations and monthly anomalies are significantly correlated with monthly in situ sst 1967 1992 r 0 96 and 0 64 respectively p 0 05 and n 302 and 1 grid monthly sst data product 1900 1999 r 0 95 and 0 56 respectively p 0 05 and n 1198 the coral sr ca sst reconstruction exhibits interannual and decadal timescale fluctuations that exceed those observed in the gridded sst record which may reflect true differences between sst at a shallow reef site and those averaged over a 1 grid box or inadequacies in the methodology used to create the gridded sst product when few observations are available a warming trend of 0 6 c is observed in the twentieth century coral sr ca sst record

a potential bias in coral reconstruction of sea surface temperature 1 isotopic measurements in corals are used to reconstruct past sea surface temperature these reconstructions are based on calibration regression analyses using paired measurements of modern isotopic composition and sea surface temperature it is shown that error in these measurements of sea surface temperature can lead to substantial bias in reconstruction provided the variance of the measurement error is known or can be estimated a simple correction can eliminate this bias

a reconstruction of sea surface temperature variability in the southeastern gulf of mexico from 1734 to 2008 c e using cross dated sr ca records from the coral siderastrea siderea this study uses skeletal variations in coral sr ca from three siderastrea siderea coral colonies within the dry tortugas national park in the southeastern gulf of mexico 24 42 n 82 48 w to reconstruct monthly sea surface temperature sst variations from 1734 to 2008 common era c e calibration and verification of the replicated coral sr ca sst reconstruction with local regional and historical temperature records reveals that this proxy temperature relationship is stable back to 1879 c e the coral sst reconstruction contains robust interannual 2 0 c and multidecadal variability 1 5 c for the past 274 years the latter of which does not covary with the atlantic multidecadal oscillation winter sst extremes are more variable than summer sst extremes 2 2 c versus 1 6 c 2 suggesting that loop current transport in the winter dominates variability on interannual and longer time scales summer sst maxima are increasing 1 0 c for 274 years mc 0 5 c 2 whereas winter sst minima contain no significant trend colder decades 1 5 c during the little ice age lia do not coincide with decades of sunspot minima the coral sst reconstruction contains similar variability to temperature reconstructions from the northern gulf of mexico planktic foraminifer mg ca and the caribbean sea coral sr ca suggesting areal reductions in the western hemisphere warm pool during the lia mean summer coral sst extremes post 1985 c e 29 9 c exceeds the long term summer average 29 2 c for 1734 2008 c e yet the warming trend after 1985 c e 0 04 c for 24 years mc 0 5 2 is not significant whereas caribbean coral sr ca studies contain a warming trend for this interval

diagenesis and geochemistry of porites corals from papua new guinea implications for paleoclimate reconstruction coral proxy records of sea surface temperature sst and hydrological balance have become important tools in the field of tropical paleoclimatology however coral aragonite is subject to post depositional diagenetic alteration in both the marine and vadose environments to understand the impact of diagenesis on coral climate proxies two mid holocene porites corals from raised reefs on muschu island papua new guinea were analysed for sr ca 18 o and 13 c along transects from 100 aragonite to 100 calcite thin section analysis showed a characteristic vadose zone diagenetic sequence beginning with leaching of primary aragonite and fine calcite overgrowths transitional to calcite void filling and neomorphic fabric selective replacement of the coral skeleton average calcite sr ca and 18 o values were lower than those for coral aragonite decreasing from 0 0088 to 0 0021 and 5 2 to 8 1 respectively the relatively low sr ca of the secondary calcite reflects the sr ca of dissolving phases and the large difference between aragonite and calcite sr ca partition coefficients the decrease in 18 o of calcite relative to coral aragonite is a function of the 18 o of precipitation carbon isotope ratios in secondary calcite are variable though generally lower relative to aragonite ranging from 2 5 to 10 4 the variability of 13 c in secondary calcite reflects the amount of soil co 2 contributing 13 c depleted carbon to the precipitating fluids diagenesis has a greater impact on sr ca than on 18 o the calcite compositions reported here convert to sst anomalies of 115 c and 14 c respectively based on calcite sr ca compositions in this study and in the literature the sensitivity of coral sr ca sst to vadose zone calcite diagenesis is 1 1 to 1 5 c per percent calcite in contrast the rate of change in coral 18 o sst is relatively small 0 2 to 0 2 c per percent calcite we show that large shifts in 18 o reported for mid holocene and last interglacial corals with warmer than present sr ca ssts cannot be caused by calcite diagenesis low level calcite diagenesis can be detected through x ray diffraction techniques thin section analysis and high spatial resolution sampling of the coral skeleton and thus should not impede the production of accurate coral paleoclimate reconstructions copyright 2003 elsevier science ltd

automatic detection of long period events at campi flegrei caldera italy 1 we propose a novel approach to analyze continuous seismic signal and separate the sources from background noise a specific application to the seismicity recorded at campi flegrei caldera during the 2006 ground uplift is presented the fundamental objective is to improve the standard procedures of picking the emergent onset arrivals of the seismic signals often buried in the high level ambient noise in order to obtain an appropriate catalogue for monitoring the activity of this densely populated volcanic area this is particularly useful in order to estimate the release of the seismic energy and to put constraints on the source dynamics an independent component analysis based approach for the blind source separation of convolutive mixtures is adopted to obtain a clear separation of long period events from the ambient noise the approach presents good performance and it is suitable for real time implementation in seismic monitoring its application to the continuous seismic signal recorded at campi flegrei has allowed the extraction of high quality waveforms considerably improving the detection of low energy events

interlaboratory study for coral sr ca and other element ca ratio measurements the sr ca ratio of coral aragonite is used to reconstruct past sea surface temperature sst twenty one laboratories took part in an interlaboratory study of coral sr ca measurements results show interlaboratory bias can be significant and in the extreme case could result in a range in sst estimates of 7 c however most of the data fall within a narrower range and the porites coral reference material jcp 1 is now characterized well enough to have a certified sr ca value of 8 838 mmol mol with an expanded uncertainty of 0 089 mmol mol following international association of geoanalysts iag guidelines this uncertainty at the 95 confidence level equates to 1 5 c for sst estimates using porites so is approaching fitness for purpose the comparable median within laboratory error is 0 5 c this difference in uncertainties illustrates the interlaboratory bias component that should be reduced through the use of reference materials like the jcp 1 there are many potential sources contributing to biases in comparative methods but traces of sr in ca standards and uncertainties in reference solution composition can account for half of the combined uncertainty consensus values that fulfil the requirements to be certified values were also obtained for mg ca in jcp 1 and for sr ca and mg ca ratios in the jct 1 giant clam reference material reference values with variable fitness for purpose have also been obtained for li ca b ca ba ca and u ca in both reference materials in future studies reporting coral element ca data should also report the average value obtained for a reference material such as the jcp 1

north atlantic climate variability since ad 1350 recorded in δ18o and skeletal density of bermuda corals the reconstruction of the climatic history during the past several hundred years requires a sufficient geographical coverage of combined climate proxy series especially in order to identify causal connections between the atmosphere and the ocean inclusion of marine records into composite climate time series is of fundamental importance we present two skeletal 18o chronologies of coral skeletons of diploria labyrinthiformis from bermuda fore reef sites covering periods in the nineteenth and twentieth centuries and compare them with instrumental temperature data both time series are demonstrated to display sea surface temperature sst variability on inter annual to decadal time scales on the basis of a specific modern 18o vs instrumental sst calibration we reconstruct a time series of sst anomalies between ad 1350 and 1630 covering periods during the little ice age the application of the coral 18o vs temperature relationship leads to estimates of past sst variability which are comparable to the magnitude of modern variations parallel to 18o chronologies we present time series of skeletal bulk density coral 18o and skeletal density reveal a strong similarity during little ice age confirming the reliability of both proxy climate indicators the past coral records presented in this study share features with a previously published climate proxy record from bermuda and a composite time series of reconstructed northern hemisphere summer temperatures the coral proxy data presented here represent a valuable contribution to elucidate northern atlantic subtropical climate variation during the past several centuries

a coral sr ca calibration and replication study of two massive corals from the gulf of mexico abstract this study examined the variations in the ratio of strontium to calcium sr ca for two atlantic corals montastraea faveolata and siderastrea siderea from the dry tortugas national park centered on 24 7 n 82 8 w in the gulf of mexico cores from coral colonies in close proximity 10s of meters and with the same environmental conditions i e depth and water chemistry were micro sampled with approximately monthly resolution and the resulting sr ca variations were calibrated with local sea surface temperature sst records replication tests for coral sr ca variations found high agreement between intra colony variations and between individual colonies of s siderea a single m faveolata colony was sampled regression analysis of monthly variations in coral sr ca and local sst revealed significant correlation on monthly and inter annual timescales verification of the calibration on different timescales found coral sr ca sst reconstructions in s siderea were more accurate than those from m faveolata especially on inter annual timescales sr ca sst calibration equations for the two species are significantly different cf sr ca 0 042 sst 10 070 s siderea sr ca 0 027 sst 9 893 m faveolata mean linear extension for m faveolata is approximately twice that of s siderea 4 63 4 31 and 8 31 mm year 1 a1 f1 and b3 respectively however seasonal sr ca variability in m faveolata is less than s siderea 0 323 0 353 and 0 254 mmol mol 1 a1 f1 and b3 respectively the reduced slope for m faveolata is attributed to physical sampling issues associated with complex time skeletal structure of m faveolata i e a sampling effect and not a growth effect since the faster growing m faveolata has the reduced sr ca variability

geochemistry based coral palaeoclimate studies and the potential of non traditional non massive porites corals recent developments and future progression understanding the natural variability of the earth s climate system and accurately identifying potential anthropogenic influences requires long term geographically distributed records of key climate indicators such as temperature and precipitation that extend prior to the last 400 years of the holocene reef corals provide an excellent source of high resolution climate records and importantly represent the tropical marine environment where palaeoclimate data are urgently required recent decades have seen significant improvement in our understanding of coral biomineralisation the associated uptake of geochemical proxies and methods of identifying and understanding the effects of both early and late post depositional diagenetic alteration these processes all have significant implications for interpreting geochemical proxies relevant to palaeoclimatic reconstructions this paper reviews the current state of the art in terms of coral based palaeoclimate reconstructions and highlights a key remaining problem the majority of coral based palaeoclimate research has been derived from massive colonies of porites however massive porites are not globally abundant and may not provide material of a particular age of interest in those regions where they are present therefore there is great potential for alternate coral genera to act as complimentary climate archives while it remains critical to consider five key factors vital effects differential growth morphologies geochemical heterogeneity in the skeletal ultrastructure transfer equation selection and diagenetic screening of skeletal material in order to allow the highest level of accuracy in coral palaeoclimate reconstructions it is also important to develop alternate taxa for palaeoclimate studies in regions where porites colonies are absent or rare currently as many as nine genera other than porites have proven at least limited utility in palaeothermometry most of which are found in the atlantic caribbean region where massive porites do not exist even branching taxa such as acropora have significant potential to preserve environmental archives increasing this capability will greatly expand the number of potential geochemical archives available for longer term temporal records of palaeoclimate

diploastrea heliopora sr ca and δ18o records from northeast luzon philippines an assessment of interspecies coral proxy calibrations and climate controls of sea surface temperature and salinity

the source scanning algorithm mapping the distribution of seismic sources in time and space summary we introduce a new method which we call the source scanning algorithm ssa for imaging the distribution of seismic sources in both time and space using trial locations and origin times the method calculates the brightness function by summing the absolute amplitudes observed at all stations at their respective predicted arrival times the spatial and temporal distribution of sources is then identified by a systematic search throughout the model space and time for the maximum brightness the greatest advantages of this method are that 1 it exploits waveform information both arrival times and relative amplitudes without the need to calculate highfrequency synthetic seismograms and 2 it requires neither pre assembled phase picking data nor any a priori assumptions about the source geometry a series of tests using synthetic data have shown that this method is robust and can faithfully recover the input source configuration to within 1 grid interval finally we demonstrate the value of the algorithm by locating a typical tremor event with emergent waveforms that occurred during the recent episodic tremor and slip ets sequence in the northern cascadia subduction zone

assessing coral sr ca sst calibration techniques using the species diploria strigosa the coral species diploria strigosa is a promising archive for paleoclimate reconstruction in the tropical atlantic but limited work has been accomplished thus far to quantify the relationship between strontium to calcium ratios and sea surface temperatures in this species in this study we collected three modern d strigosa coral colonies from anegada british virgin islands to refine the use of this species as a paleoclimate archive three regression techniques including ordinary least squares reduced major axis and weighted least squares were used to assess how assumptions implicit in these regression methods influence the calibration our analysis demonstrated that regression slopes were strongly impacted by the assumptions about data uncertainty we recommend using the unbiased weighted least squares regression technique for calibrating the sr ca paleothermometer especially when precise local sea surface temperature data are unavailable combining our sr ca data with previously published data from this species results in a multi site multi colony temperature sensitivity of 0 046 0 001 mmol mol c for mean centered monthly data 0 059 0 001 mmol mol c for monthly anomalies and 0 063 0 004 for annual anomalies we suggest these relationships are the best available characterization of the temperature dependence of sr ca in d strigosa and can be utilized in future paleoclimate reconstructions

constraints on unrest in the tolbachik volcanic zone in kamchatka prior the 2012 13 flank fissure eruption of plosky tolbachik volcano from local seismicity and gps data abstract a new fissure eruption began on 27 november 2012 on the southern slope of plosky tolbachik volcano which is located in central kamchatka russia and is part of the klyuchevskoy volcano group we analyzed the displacement of the earth surface and the seismicity during several months before the eruption onset according to seismic and gps data the eruption was preceded by about 4 5 months july november 2012 of synchronous crustal deformation and seismicity the seismic anomaly comprises low energy level seismicity mainly m 1 2 2 3 under plosky tolbachik volcano at a depth of less than 5 km in the 2 3 weeks immediately preceding the eruption the rate of seismicity and the amount of radiated seismic energy exceeded the long term average values 2000 2011 by more than 40 times the deformation anomaly was recorded by displacement of the gps points at distances from 20 to 60 km to the north of tolbachik the principal axis of the compressive strain was approximately directed towards the tolbachik eruption site the permanent gps network detected radial compression and tangential stretching the compressive strain reached about 10 7 prior to eruption onset the comparable duration of seismic and deformation anomalies 4 5 months before the eruption is consistent with a common origin connected to magma rising from depth and is interpreted as indicating that they were medium term precursors to the eruption data recorded during this unrest episode of the tolbachik volcanic zone will contribute to understanding of the reawakening of volcanic activity in this region and others worldwide with similar characteristics

location and mechanism of very long period tremor during the 2008 eruption of okmok volcano from interstation arrival times 1 we describe continuous very long period vlp tremor that occurred during the 2008 eruption of okmok volcano alaska due to its low frequency content in band from the 0 2 0 4 hz the wave field of the vlp tremor is relatively free of path effects from continuous recordings of the vlp tremor on 2 three component broadband and 3 single component short period instruments we devise a method to locate the epicenter of the tremor based on interstation arrival times computed with cross correlation we find the epicenter since the vertical and radial components of the vlp tremor wave field are dominated by rayleigh waves and the time shifts are related to lateral propagation over the 4 h period studied this procedure yields a location nnw of cone d close to the new cone built over the course of the eruption similar analysis using the transverse horizontal components from the 2 three component broadband instruments yields strong constraints on the source mechanism of the vlp tremor we observe an anomalous interstation arrival time due to the existence of a nodal plane in the love wave radiation pattern the orientation of a compensated linear vector dipole clvd source estimated from the transverse components closely aligns with the regional maximum horizontal stress direction the depth of the clvd source is constrained by matching the vertical components to the rayleigh wave radiation pattern at all five stations we find the vlp tremor source depth to be 2 km bsl positioned between the magma chamber at okmok 3 km bsl and the surface

dynamics of seismogenic volcanic extrusion at mount st helens in 2004 05 the 2004 05 eruption of mount st helens exhibited sustained near equilibrium behaviour characterized by relatively steady extrusion of a solid dacite plug and nearly periodic shallow earthquakes here we present a diverse data set to support our hypothesis that these earthquakes resulted from stick slip motion along the margins of the plug as it was forced incrementally upwards by ascending solidifying gas poor magma we formalize this hypothesis with a dynamical model that reveals a strong analogy between behaviour of the magma plug system and that of a variably damped oscillator modelled stick slip oscillations have properties that help constrain the balance of forces governing the earthquakes and eruption and they imply that magma pressure never deviated much from the steady equilibrium pressure we infer that the volcano was probably poised in a near eruptive equilibrium state long before the onset of the 2004 05 eruption

deep volcanic tremor and magma ascent mechanism under kilauea hawaii deep harmonic tremor originating at depths around 40 km under kilauea was studied using records accumulated since 1962 at the hawaii volcano observatory of the u s geological survey the deep source of the tremor was determined by onset times and confirmed by the relative amplitude across the island wide network of seismometers the period of tremor was conclusively shown to be determined by the source effect and not by the path or station site effect because the period would change considerably in time but maintained uniformity across the seismic net during the tremor episode the tremor appeared to be primarily composed of p waves we interpret the observed period and amplitude in terms of the stationary crack model of aki et al 1977 and find that the seismic moment rates for deep tremors are considerably larger than those for shallow tremors suggesting more vigorous transport for the former we propose a kinematic source model which may be more appropriate for deep tremor according to this model a measurable quantity called reduced displacement is directly proportional to the rate of magma flow a systematic search for deep tremor episodes was made for the period from 1962 through 1979 and the amplitude period and duration of the tremor were tabulated we then constructed a cumulative reduced displacement plot over the 18 year period the result shows a generally steady process which does not seem to be significantly affected by major eruptions and large earthquakes near the surface the total magma flow estimated from the reduced displacement is however one order of magnitude smaller than that estimated by swanson 1972 it may be that most channels transport magma aseismically and only those with strong barriers generate tremor

mid to late holocene changes in tropical atlantic temperature seasonality and interannual to multidecadal variability documented in southern caribbean corals proxy reconstructions of tropical atlantic sea surface temperature sst that extend beyond the period of instrumental observations have primarily focused on centennial to millennial variability rather than on seasonal to multidecadal variability here we present monthly resolved records of sr ca a proxy of sst from fossil annually banded diploria strigosa corals from bonaire southern caribbean sea the individual corals provide time windows of up to 68 years length and the total number of 295 years of record allows for assessing the natural range of seasonal to multidecadal sst variability in the western tropical atlantic during snapshots of the mid to late holocene comparable to modern climate the coral sr ca records reveal that mid to late holocene sst was characterised by clear seasonal cycles persistent quasi biennial and prominent interannual as well as inter to multidecadal scale variability however the magnitude of sst variations on these timescales has varied over the last 6 2 ka the coral records show increased seasonality during the mid holocene consistent with climatemodel simulations indicating that southern caribbean sst seasonality is induced by insolation changes on orbital timescales whereas internal dynamics of the climate system play an important role on shorter timescales interannual sst variability is linked to ocean atmosphere interactions of atlantic and pacific origin pronounced interannual variability in the western tropical atlantic is indicated by a 2 35 ka coral possibly related to a strengthening of the variability of the el nino southern oscillation throughout the holocene prominent inter to multidecadal sst variability is evident in the coral records and slightly more pronounced in the mid holocene we finally argue that our coral data provide a target for studying holocene climate variability on seasonal and interannual to multidecadal timescales when using further numerical models and high resolution proxy data

rapid 20th century warming in the caribbean and impact of remote forcing on climate in the northern tropical atlantic as recorded in a guadeloupe coral we have generated 104 year long 1895 1999 monthly 18o and sr ca time series from a fast growing diploria strigosa coral core drilled off guadeloupe island lesser antilles coral sr ca reliably records interannual to decadal surface air temperature sat variations in the region and shows a pronounced warming of approximately 1 5 c since 1950 with the strongest warming 1 2 c occurring since 1975 this warming is also evident in sat measured at guadeloupe which ends in 1951 thus our sr ca series extends the air temperature record by 56 years we find that the past few decades are the warmest years over the entire period of record the accelerated warming since 1950 is accompanied by a pronounced decrease in regional precipitation this dampens the warming signal indicated by coral 18o which is too low only 0 7 0 8 c since 1951 consistently 18osw estimated from the coral proxies also shows a strong decrease since 1950 our data suggest an inverse relationship between sat and precipitation i e warmer and drier for the latter half of the 20th century with the strongest trends since the mid 1970s this is consistent with recent observational and model data which report that while over the tropical oceans rainfall has increased due to an increase in sea surface temperatures precipitation over land regions is reduced a continuation of this warming and drying trend over caribbean land regions would have severe societal consequences especially in the context of anthropogenic warming the el nino southern oscillation enso and the north atlantic oscillation nao are the two major climate modes affecting large scale sst variability in the northern tropical atlantic both sr ca and 18o show a close relationship to enso and the nao a quantitative comparison between extremes in mean march may coral 18o and the nino3 and nao indices imply that climate variability in the northern tropical atlantic is mainly forced by tropical pacific and north atlantic variability spectral analysis suggests that the relative importance of enso and the nao is frequency dependent with enso dominating at interannual and the nao dominating at interdecadal time scales

rapid analysis of high precision sr ca ratios in corals and other marine carbonates a method for rapid determination of high precision sr ca ratios in scleractinian corals is presented using an inductively coupled plasma atomic emission spectrophotometer samples are corrected for instrument drift using a reference solution similar to the approach used for analysis of stable isotopes using gas source mass spectrometry further correction for variation of the sr ca ratio with ca concentration is accomplished using internal standards the precision once all corrections have been made is better than 0 1 relative standard deviation 1 for samples of similar ca concentration and better than 0 2 for samples with variable ca concentrations this method increases the sample throughput by approximately a factor of 20 relative to thermal ionization mass spectrometry and significantly reduces instrument and per sample costs comparison of sr ca data for a coral from the galapagos islands with an instrumental temperature record shows excellent agreement and demonstrates the potential for application of this technique to samples of modern and fossil scleractinian corals and other marine carbonates including foraminifera

high precision and high resolution carbonate 230th dating by mc icp ms with sem protocols abstract to facilitate the measurement of u th isotopic compositions suitable for high precision and high resolution 230th dating of coral and speleothem carbonates secondary electron multiplier sem protocol techniques for multicollector inductively coupled plasma mass spectrometry mc icp ms have been developed the instrumental sensitivities are 1 2 with a precision of 1 2 2 for abundance determination of 50 200 fg 234u 1 4 ng 238u or 230th this method features chemistry refinements improvements to procedural and instrumental blanks spectral inference reductions and careful consideration of non linear sem behavior measurement consistency of this mc icp ms combined with previous mass spectrometric results on u th standards and a variety of carbonates demonstrates the validity of the sem protocol method for fossil corals a routine u th isotopic determination at permil level precision requires only 10 50 mg of carbonate as little as 200 mg of young coral with an age of less than 20 yr can be dated with a precision of 0 3 0 8 yr about 20 200 mg speleothem samples with sub ppm to ppm u are required to earn a 5 precision on ages from 5 to 100 kyr requirement of small sample size 10 100s mg carbonate can permit high temporal resolution to date speleothems with slow growth rates i e 1 10 mm kyr this high precision 230th chronology is critical to accurately establish age models date events and splice geochemical proxy time series records from multiple samples in the fields of paleoclimatology and paleoceanography the u th isotopic determination techniques described here can also be applied to different environmental samples such as waters rocks and sediments

feeding volcanoes of the kluchevskoy group from the results of local earthquake tomography 1 we present a seismic model of the area beneath the kluchevskoy volcano group kamchatka russia based on the tomographic inversion of more than 66000 p and s arrival times from more than 5000 local earthquakes that occurred in 2004 and that were recorded by 17 permanent stations below a depth of 25 km beneath the kluchevskoy volcano we observed a very strong anomaly in the vp vs ratio that reached as high as 2 2 this is a probable indicator of the presence of partially molten material with a composition corresponding to deeper mantle layers the upper part of this anomaly at a depth of 25 30 km coincides with a cluster of strong seismicity that can be explained by strong mechanical stresses in the lowermost crust due to magma ascension water release and or phase transitions in the crust we observed regular seismicity clusters that link the mantle anomaly with the kluchevskoy volcano and most likely indicate the paths of magma migration between depths of 8 and 13 km we see several patterns of high vp vs ratios interpreted as intermediate depth magma storages directly below the kluchevskoy volcano we observed a shallow body of high vp vs which probably represents the activated magma chamber just beneath the volcano cone which erupted in the beginning of 2005 the existence of three levels of magma storage based on results of local earthquake tomography may explain the variety of the lava composition and eruption regimes in different volcanoes of the kluchevskoy group

locating sources of volcanic tremor and emergent events by seismic triangulation application to arenal volcano costa rica 1 we address the issue of locating the sources of volcanic tremor and emergent events with a method requiring a limited amount of equipment a network of several triangular seismic antennas made of vertical sensors is used the slowness vectors are estimated at each array on a sliding window by inverting the time delays between the sensors calculated with the cross spectral method a probabilistic approach is adopted whereby each measure and its error are represented by a probability density function pdf a weighted summation of the pdfs is carried out in which the stable directions of propagation are enhanced the effects of the structural heterogeneities are taken into account by introducing an additional error associated to a robust hyperbolic secant sech type pdf the resulting pdfs of the back azimuth are combined to calculate a pdf of the source location the maximum likelihood of this pdf is taken as an estimate of the source position and its spread is characterized by a covariance analysis data from an experiment carried out at arenal volcano costa rica with four arrays are analyzed the precision and robustness of the method are tested by exploring the influence of the array configuration and other parameters the mean standard deviation on the position of the sources is 600 m for the tremor and 400 m for the explosions and long period lp events several tremors explosions and lp events are analyzed and their sources located the seismogenic zone is located in a 600 m radius area centered on the active crater

complex polarization analysis of particle motion knowledge of particle motion polarization aids in identifying phases on three component seismograms the scheme of montalbetti and kanasewich 1970 is extended to analytic three component seismograms where the imaginary part of the signal is the hilbert transform of the real part this scheme has only one free parameter the length of the time window over which the polarization parameters are estimated so it can be applied in a routine way to three component data the azimuth and dip of the direction of maximum polarization and the degree of elliptical polarization as a function of time for the seismograms are obtained polarization analysis of strong motion data from the 1971 san fernando earthquake aids in the discrimination between wave types which is important for the understanding of the complicated earthquake induced shaking observed in basins most arrivals are incident on the receivers in the direction of the back azimuth to the epicenter which suggests that despite the complicated motions two dimensional finite difference methods are sufficient to understand the effect on seismic waves of the los angeles and san fernando basins vidale and helmberger 1986b

a monochromatic earthquake suggesting deep seated magmatic activity beneath the izu ooshima volcano japan after a quiescence of 12 years the izu ooshima volcano located about 30 km east of the izu peninsula in central japan erupted on november 15 1986 on august 27 1985 about 1 year before the eruption a peculiar earthquake of magnitude 2 7 took place near the moho boundary just beneath the izu ooshima volcano where seismic activity is otherwise absent analysis of digital data obtained by the telemetered seismic network of the national research center for disaster prevention reveals the following distinctive features of the seismic waves 1 the main part of the wave train is composed of s waves and a small p phase precedes it 2 the spectral density has a sharp peak at 1 0 hz which is independent of the epicentral distance azimuth and time indicating a monochromatic spectrum at the source 3 ground motion for the initial part of the s wave is polarized in the n s direction at almost all the stations the amplitude ratios of s to p waves and the polarization pattern of s waves suggest that a traction force caused by magma flow is a more probable source than a double couple mechanism free oscillation of the magma reservoir or opening of a tensile crack we propose a traction force model for this earthquake in which magma flow through a conduit produces unidirectional viscous force on the conduit walls the observations imply a n s force direction and a maximum force of about 2 8 1010 n the pressure difference between the ends of the conduit is estimated as 6 1 107 pa 610 bar under the assumption of conduit dimensions of 2 km 1 km the monochromatic nature of the source spectrum is difficult to account for by the free oscillation of a magma reservoir we tentatively suggest the intermittent opening of a barrier in the conduit as a plausible mechanism of the periodic oscillation

last interglacial temperature seasonality reconstructed from tropical atlantic corals abstract reconstructions of last interglacial lig mis 5e 127 117 ka climate offer insights into the natural response and variability of the climate system during a period partially analogous to future climate change scenarios we present well preserved fossil corals diploria strigosa recovered from the southern caribbean island of bonaire caribbean netherlands these have been precisely dated by the 230 th u method to between 130 and 120 ka ago annual banding of the coral skeleton enabled construction of time windows of monthly resolved strontium calcium sr ca temperature proxy records in conjunction with a previously published 118 ka coral record our eight records of up to 37 years in length cover a total of 105 years within the lig period from these sea surface temperature sst seasonality and variability in the tropical north atlantic ocean is reconstructed we detect similar to modern sst seasonality of 2 9 c during the early 130 ka and the late lig 120 118 ka however within the mid lig a significantly higher than modern sst seasonality of 4 9 c at 126 ka and 4 1 c at 124 ka is observed these findings are supported by climate model simulations and are consistent with the evolving amplitude of orbitally induced changes in seasonality of insolation throughout the lig irrespective of wider climatic instabilities that characterised this period the climate model simulations suggest that the sst seasonality changes documented in our lig coral sr ca records are representative of larger regions within the tropical north atlantic these simulations also suggest that the reconstructed sst seasonality increase during the mid lig is caused primarily by summer warming a 124 ka old coral documents for the first time evidence of decadal sst variability in the tropical north atlantic during the lig akin to that observed in modern instrumental records

paleoclimate proxy perspective on caribbean climate since the year 1751 evidence of cooler temperatures and multidecadal variability 1 annually resolved coral 18o and sr ca records from southwestern puerto rico are used to investigate caribbean climate variability between 1751 and 2004 c e mean surface ocean temperatures in this region have increased steadily by about 2 c since the year 1751 with sr ca data indicating 2 1 0 8 c and 18o data indicating 2 7 0 5 c coral geochemical records from across the tropics demonstrate that regional variability is important for understanding climate variations at centennial time scales a strong multidecadal salinity signal in the oxygen isotope data correlates with observed multidecadal temperature variations in the northern hemisphere instrumental wind and precipitation data indicate that the most recent coral isotopic variations are caused by expansion and contraction of the steep regional salinity gradient forced by trade wind anomalies through meridional ekman transport the timing of the fluctuations suggests that the multidecadal scale wind and surface circulation anomalies might play a role in atlantic temperature variability and meridional overturning circulation but further work is needed to confirm this suggestion

a snapshot of climate variability at tahiti at 9 5 ka using a fossil coral from iodp expedition 310 1 the integrated ocean drilling program iodp expedition 310 recovered drill cores from the drowned reefs around the island of tahiti 17 40 s 149 30 w many of which contained samples of massive corals from the genus porites herein we report on one well preserved fossil coral sample a 13 6 cm long porites sp dated by uranium series techniques at 9523 33 years monthly 18o and sr ca determinations reveal nine clear and robust annual cycles coral 18o and sr ca determinations estimate a mean temperature of 24 3 c 3 2 c colder than modern for tahiti at 9 5 ka however this estimate is viewed with caution since potential sources of cold bias in coral geochemistry remain to be resolved the interannual variability in coral 18o is similar between the 9 5 ka coral record and a modern record from nearby moorea the seasonal cycle in coral sr ca is approximately the same or greater in the 9 5 ka coral record than in modern coral records from tahiti paired analysis of coral 18o and sr ca indicates cold wet warm dry interannual anomalies opposite from those observed in the modern instrumental record

body and surface wave reconstruction from seismic noise correlations between arrays at piton de la fournaise volcano body wave reconstruction from ambient seismic noise correlations is an important step toward improving volcano imaging and monitoring here we extract body and surface waves that propagate in piton de la fournaise volcano on la reunion island using ambient noise cross correlation and array processing techniques ambient noise was continuously recorded at three dense arrays each comprising 49 geophones to identify and enhance the green s function from the ambient noise correlation we apply a double beamforming dbf technique between the array pairs the dbf allows us to separate surface and body waves direct and reflected waves and multipathing waves based on their azimuths and slownesses we successfully extract body waves between all the combinations of arrays including the wave that propagates through the active magmatic system of the volcano additionally we identify the effects of uneven noise source distribution and interpret the surface wave reflections

reproducibility of geochemical and climatic signals in the atlantic coral montastraea faveolata 1 monthly resolved 41 year long stable isotopic and elemental ratio time series were generated from two separate heads of montastraea faveolata from looe key florida to assess the fidelity of using geochemical variations in montastraea the dominant reef building coral of the atlantic to reconstruct sea surface environmental conditions at this site the stable isotope time series of the two corals replicate well mean values of 18o and 13c are indistinguishable between cores compare 0 70 versus 0 68 for 13c and 3 90 versus 3 94 for 18o mean values from the sr ca time series differ by 0 037 mmol mol which is outside of analytical error and indicates that nonenvironmental factors are influencing the coral sr ca records at looe key we have generated significant 18o sea surface temperature sst r 0 84 and sr ca sst r 0 86 calibration equations at looe key however these equations are different from previously published equations for montastraea variations in growth parameters or kinetic effects are not sufficient to explain either the observed differences in the mean offset between sr ca time series or the disagreement between previous calibrations and our calculated 18o sst and sr ca sst relationships calibration differences are most likely due to variations in seawater chemistry in the continentally influenced waters at looe key additional geochemical replication studies of montastraea are needed and should include multiple coral heads from open ocean localities complemented whenever possible by seawater chemistry determinations

record of little ice age sea surface temperatures at bermuda using a growth dependent calibration of coral sr ca 1 strontium to calcium ratios sr ca are reported for a massive brain coral diploria labyrinthiformis collected from the south shore of bermuda and are strongly correlated with both sea surface temperature sst and mean annual skeletal growth rate high sr ca ratios correspond with cold ssts and slow skeletal growth rate and vice versa we provide a quantitative calibration of sr ca to extension rate and sst along the axis of maximum growth and derive a growth dependent sr ca sst calibration equation to reconstruct western subtropical north atlantic ssts for the past 223 years when the influence of growth rate is excluded from the calibration sr ca ratios yield ssts that are too cold during cool anomalies and too warm during warm anomalies toward the end of the little ice age 1850 sst changes derived using a calibration that is not growth dependent are exaggerated by a factor of 2 relative to those from the growth corrected model that yields ssts 1 5 c cooler than today our results indicate that incorporation of growth rate effects into coral sr ca calibrations may improve the accuracy of ssts derived from living and fossil corals

sea surface temperature variability in the 16th century at bermuda inferred from coral records abstract records of skeletal 18 o in monthly and sr ca ratios in half yearly resolution were obtained from a bermuda coral diploria labyrinthiformis for the time period 1520 1603 15 yr ad within the little ice age annual and decadal averages of both sea surface temperature proxies indicate temperature variabilities of 0 5 c standard deviation and 0 3 c respectively both numbers are close to recent instrumental observations approximately 30 of the interannual time series variance of 18 o is concentrated in broad bands centered at periods of 30 16 and 7 8 yr the last two reflecting the influence of the north atlantic oscillation although this large scale climate signal is present in the record there is no correlation with other contemporaneous northern hemisphere proxy data resulting from spatial differences in climate variability

a multicoral calibration method to approximate a universal equation relating sr ca and growth rate to sea surface temperature 1 combining strontium to calcium ratios sr ca with mean annual growth rates in bermuda diploria labyrinthiformis brain corals is shown to improve sea surface temperature sst calibrations relative to instrumental data growth corrected sr ca sst calibrations based on single coral colonies over the same calibration interval however are found to be poorly suited for application to data from different coral colonies this raises concerns about the accuracy of sst reconstructions from fossil coral measurements that involve extrapolation beyond the range of values seen during the calibration period here we pursue a novel approach to this problem by incorporating data from multiple coral colonies into a single growth corrected sr ca sst calibration equation effectively expanding the range of modern values constraining the model the use of a multiple colony calibration model for reconstructing sst yields greater precision and accuracy relative to instrumental data than single colony models providing greater confidence for applications to fossil coral samples

imaging the dynamics of magma propagation using radiated seismic intensity 1 at shallow depth beneath the earth s surface magma propagates through strongly heterogeneous volcanic material inversion of buoyancy and or solidification have strong impacts on the dynamics of propagation without any change of magma supply in this paper we study the spatial and time evolution of magma intrusions using induced seismicity we propose a new method based on ratio analysis of estimates of radiated seismic intensities recorded at different stations during seismic swarms by applying this method to the january 2010 piton de la fournaise volcano eruption we image complex dike propagation dynamics which strongly differ from a model of constant velocity dike propagation we provide a new method to image in real time the dynamics of dike propagation and to infer the position of eruptive fissures

array analysis of the seismic wavefield of long period events and volcanic tremor at arenal volcano costa rica we use wavefield decomposition methods time domain crosscorrelation and frequency domain music to analyze seismic data recorded by a dense small aperture array located 2 km west of arenal volcano costa rica and operated during 2 5 days the recorded wavefield is dominated by harmonic tremor and includes also spasmodic tremor and long period lp events we find that the initial stages of lp events are characterized by three different wave arrivals these arrivals propagate with similar back azimuths pointing to the volcano summit 80 n and increasing apparent slownesses of 0 4 1 1 and 1 7 s km spasmodic tremors can not be regarded as coherent signals on the contrary harmonic tremors are highly coherent characterized by the stability of the apparent slowness vector estimates apparent slownesses lay in the range 1 2 s km back azimuths point in the general direction of the volcano but with a large variability 40 120 n nevertheless there are long term variations and evidences of multiple simultaneous components in the harmonic tremor wavefield these observations suggest that lp events and tremor are generated in a shallow source area near the volcano summit although they do not share exactly the same source region or source processes the tremor source is located in the shallowest part of the plumbing system beneath the lava crust this dynamic region is subject to complex fluctuations of the physical conditions degassing events at different locations of this region might generate variable seismic radiation patterns the effects of topography and heterogeneous shallow structure of the volcano may amplify these variations and produce the wide directional span observed for volcanic tremor on the other hand the lp source seems to be more repeatable lp events are likely triggered by fragmentation of the fluid flow in a slightly deeper portion of the volcanic conduits

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

body wave imaging of earth s mantle discontinuities from ambient seismic noise ambient seismic noise correlations are widely used for high resolution surface wave imaging of earth s lithosphere similar observations of the seismic body waves that propagate through the interior of earth would provide a window into the deep earth we report the observation of the mantle transition zone through noise correlations of p waves as they are reflected by the discontinuities associated with the top 410 kliometers km and the bottom 660 km of this zone our data demonstrate that high resolution mapping of the mantle transition zone is possible without using earthquake sources

magma migration at the onset of the 2012 13 tolbachik eruption revealed by seismic amplitude ratio analysis abstract in contrast of the 1975 76 tolbachik eruption the 2012 13 tolbachik eruption was not preceded by any striking change in seismic activity by processing the klyuchevskoy volcano group seismic data with the seismic amplitude ratio analysis sara method we gain insights into the dynamics of magma movement prior to this important eruption a clear seismic migration within the seismic swarm started 20 hours before the reported eruption onset 05 15 utc 26 november 2012 this migration proceeded in different phases and ended when eruptive tremor corresponding to lava flows was recorded at 11 00 utc 27 november 2012 in order to get a first order approximation of the magma location we compare the calculated seismic intensity ratios with the theoretical ones as expected the observations suggest that the seismicity migrated toward the eruption location however we explain the pre eruptive observed ratios by a vertical migration under the northern slope of plosky tolbachik volcano followed by a lateral migration toward the eruptive vents another migration is also captured by this technique and coincides with a seismic swarm that started 16 20 km to the south of plosky tolbachik at 20 31 utc on november 28 and lasted for more than 2 days this seismic swarm is very similar to the seismicity preceding the 1975 76 tolbachik eruption and can be considered as a possible aborted eruption

identification and analysis of dihydro ar curcumene enantiomers and related compounds in petroleum isodihydro ar curcumene 1 1 5 dimethylhexyl 3 methylbenzene has been identified in petroleum using gc ms techniques by comparing its retention time and mass spectrum with the same parameters from a reference compound it co occurs in crude oil with dihydro ar curcumene and is suggested to originate from this compound via a sedimentary rearrangement process enantiomers of both compounds have also been shown to occur in crude oils using chiral gc ms techniques the elution order of the enantiomers has been established using reference compounds of known configuration

a high resolution calibration of sr ca thermometry using the caribbean coral montastraea annularis 1 a relationship has been established between the sr ca ratio in the skeleton of the scleractinian coral montastraea annularis and sea surface water temperature in south florida in order to obtain this correlation specimens of montastraea annularis were transplanted to a site at a local reef where every two to three months throughout a 2 year period the corals were stained with alizarin red s and where water temperature which annually ranges between 20 and 30 c was continually monitored at the end of the experimental period the coral skeleton was sampled at a rate of 50 samples per year each sample corresponding to only around 20 g of calcium carbonate for the 2 5 year period the sr ca ratio exhibited excellent correlation in the first year r2 0 83 sr ca mmol mol 10 11 0 0452 sst c but a rather poorer correlation in the second year r2 0 68 sr ca mmol mol 10 09 0 0406 sst c averaging the data into monthly values for year 1 we determined a relationship of sr ca mmol mol 10 165 0 0471 sst c on the basis of the excellent correlation between temperature and sr ca we feel that this relationship is the most accurate discrepancies in the second year are suggested to arise from slight sampling errors relative to the stain lines

validation of coral temperature calibrations geochemical analyses of coral skeletons are increasingly used to estimate past sea surface temperatures ssts in this paper we suggest that the standard method of calibrating geochemical time series against a usually short local time series requires modification in order to draw large scale inferences about climate from coral proxy data it is also necessary to 1 calibrate against larger fields such as the local gridded data sets and 2 validate results against an independent data set e g early 20th century this approach has been applied in a pilot study to a coral record from new caledonia despite a high 18o correlation r 0 88 with the in situ and gridded sst data sets estimated early 20th century temperatures are more than 1 5 c colder than observed if the standard seasonal calibration is used regression against mean annual temperatures which has a different slope relation yields better estimates of early 20th century ssts however testing of a sr ca record from new caledonia yields better agreement with early 20th century ssts routine validation exercises for other coral sites are necessary to clarify the robustness of geochemical coral proxies as estimators of past environmental change

seismic and infrasonic evidences for an impulsive source of the shallow volcanic tremor at mt etna italy during a seismo acoustic experiment we recorded volcanic tremor around the summit craters of mt etna volcano tremor shows amplitude modulation which disappear 900 m from the crater area the infrasonic wavefield is coherent even at distances of 750 m time delay between infrasonic transient is stable around 1 3 s and is consistent with the position of the source in the voragine crater amplitude modulation of tremor is well correlated 0 72 with infrasound amplitude with a time lag of 0 37 s coherent with a shallow position of the source amplitude of volcanic tremor decays over increasing distances according to geometrical spreading of body waves tremor wavefield shows a linear polarization following the same time occourrence as the infrasonic pulses polarization azimuth indicates that wavefield rectilinearity is mostly due to p waves we infer that most of the volcanic tremor we recorded at mt etna is generated by superimposition of small impulsive sources acting at 1 2 s rate caused by pressure instability during magma degassing

seasonal changes in sea surface temperature and salinity during the little ice age in the caribbean sea deduced from mg ca and 18o 16o ratios in corals abstract the oxygen isotopic composition 18 o of coral skeletons reflects a combination of sea surface temperature sst and the 18 o of seawater which is related to sea surface salinity sss in contrast the magnesium calcium mg ca ratio of a coral skeleton reflects sst independent of salinity by using the relationships among coral mg ca ratios coral 18 o seawater 18 o and sst it is possible to determine past sst and sss uniquely such determinations were made and calibrated using the mg ca ratio and the 18 o of the modern part of a 3 m long coral core montastrea faveolata collected from the southwest coast of puerto rico in the caribbean sea where both sst and sss changes seasonally and the seawater 18 o measured at the coral site our results yielded three relationships coral mg ca sst 18 o coral 18 o water sst and 18 o water sss with these calibration equations seasonal changes in sst and sss during the little ice age lia in the caribbean sea were reconstructed the 18 o and mg ca ratio of the coral skeleton between 1699 and 1703 suggests that the sst during the lia was approximately 2 c cooler than present with the sss showing greater seasonal changes as well these results are in good agreement with climate based reconstruction from corals based on oxygen isotopes although the possibility of some uncertainty remain in our estimation including long term decadal scale trends in climate

interpreting sea surface temperature from strontium calcium ratios in montastrea corals link with growth rate and implications for proxy reconstructions 1 we analyzed strontium calcium ratios sr ca in four colonies of the atlantic coral genus montastrea with growth rates ranging from 2 3 to 12 6 mm a 1 derived sr ca sea surface temperature sst calibrations exhibit significant differences among the four colonies that cannot be explained by variations in sst or seawater sr ca for a single coral sr ca ratio of 8 8 mmol mol 1 the four calibrations predict ssts ranging from 24 0 to 30 9 c we find that differences in the sr ca sst relationships are correlated systematically with the average annual extension rate ext of each colony such that sr ca mmol mol 1 11 82 0 13 0 058 0 004 ext mm a 1 0 092 0 005 sst c this observation is consistent with previous reports of a link between coral sr ca and growth rate verification of our growth dependent sr ca sst calibration using a coral excluded from the calibration reconstructs the mean and seasonal amplitude of the actual recorded sst to within 0 3 c applying a traditional nongrowth dependent sr ca sst calibration derived from a modern montastrea to the sr ca ratios of a conspecific coral that grew during the early little ice age lia 400 years b p suggests that caribbean ssts were 5 c cooler than today conversely application of our growth dependent sr ca sst calibration to sr ca ratios derived from the lia coral indicates that ssts during the 5 year period analyzed were within error 1 4 c of modern values

diagenesis in pleistocene 80 to 500 ka corals from the ironshore formation implications for paleoclimate reconstruction abstract fossil corals provide a unique opportunity for paleoclimate research because they can be dated and they incorporate climate controlled seawater proxies into their aragonitic skeletons during growth coral skeletons however can only produce reliable environmental information if they have not been diagenetically altered an issue that becomes increasingly probable as the age of the corals increase although commonly used analytical techniques such as thin section scanning electron microscopy and x ray diffraction can highlight obvious mineralogical changes subtle changes in the trace element and isotopic composition of the skeletons may not be evident this premise is assessed by examining orbicella annularis and montastrea cavernosa corals from the pleistocene ironshore formation units a f on grand cayman 80 500 ka to determine the diagenetic effects on both physical and chemical properties of corals in the ironshore formation the corals in units a and c were altered in a semi open diagenetic system by seawater diluted by meteoric water which resulted in chemical diagenesis that changed the elemental and isotopic composition of the corals even though their aragonitic skeletons show no obvious signs of change in contrast the limestones in unit b have been pervasively recrystallized in an open diagenetic system by meteoric waters that caused both chemical and physical changes the corals in units d to f however underwent minimal diagenesis and show no evidence of alteration for altered corals from the ironshore formation elevated mg ca and low sr ca ratios provide evidence of subtle chemical diagenetic changes even in corals that have retained their primary aragonitic skeleton thus corals that are formed of 95 wt aragonite show no evidence of cementation and have mg ca ratios 8 0 mmol mol 1 18o values 5 7 and 13c values 3 0 are ideal candidates for paleoclimate reconstruction adoption of these criteria shows that the corals from units d to f can be used to calculate sea surface temperatures sst whereas those from units a to c cannot be used for this purpose the calculated sst and the corresponding temperature profiles derived from the corals in units d to f are consistent with global sst reconstructions during the pleistocene unit d corals record an overall increase in sst which is consistent with elevated temperatures associated with marine isotope stage mis 5e whereas units e and f record overall cooling which is consistent with the end of the peak interglacials of mis 5c and 5a respectively

array tracking of the volcanic tremor source at deception island antarctica we have found experimental evidence which shows that the volcanic tremor recorded at deception island south shetland islands antarctica is a superposition in time of overlapping hybrid events we studied data from a small aperture seismic array data analysis for tremor and hybrids included 1 spectral analysis 2 apparent slowness and back azimuth determination by using the zero lag cross correlation method and 3 polarization analysis both types of events share these common features a two dominant spectral bands at frequencies 1 3 hz the most energetic and 4 8 hz b several coherent phases with the same back azimuth to the source and apparent slowness along the whole signal c in the high frequency band the apparent slowness is very low around 0 17 s km indicating the propagation of body waves d in the low frequency band the apparent slowness is high around 1 6 s km consistent with the presence of surface waves and e clear p wave onset followed by a complex pattern of rayleigh waves therefore both types of events are strongly related because they share the same source region the same wave propagation properties and the same wave composition moreover several arrivals that resemble a single hybrid event have been found along the tremor signals due to these reasons we hypothesize that volcanic tremor of deception island is a superposition of hybrid type events the source of both types could be the interaction between thaw water and hot materials in a shallow aquifer

volcanic tremor location during the 2004 mount etna lava effusion 1 a lava emission started at mt etna italy on 7 september 2004 neither earthquake seismicity heralded or accompanied the opening of the fracture field from which the lava poured out nor volcanic tremor changed in amplitude and frequency content at the onset of the effusive activity to highlight long term changes we propose a method for the location of the tremor source based on a 3d grid search using the amplitude decay of the seismic signal from january to november 2004 we find the centroid of the tremor source within a zone close to and partially overlapped with the summit craters pre effusive phase which extended up to 2 km south of them effusive phase the depths are of between 1698 and 2387 m a s l we hypothesize the lava effusion stemmed from a degassed magma body although we find evidence of temporary magma overpressure conditions such as those documented on 25 september

on the variations of flow rate in non explosive lava eruptions abstract a physical model is developed to determine factors which influence the dynamics of non explosive lava eruptions in the model magma rises in a laminar regime from an overpressured chamber surrounded by elastic rock and erupts at the surface where the accumulation of lava may alter the vent pressure in a flow rate versus volume diagram an eruption follows a path which is sensitive to relative changes in flow variables such as viscosity conduit dimensions and thickness of lava over the vent the path does not depend on the unknown elastic properties of the country rock or the chamber dimensions with appropriate volcanological data an observed flow rate versus volume path can be interpreted the approach is applied to three well documented eruptions in each case the eruption rate was partially influenced by decreasing chamber pressure the 1988 1990 eruption of lonquimay chile exhibits an early phase of conduit shrinkage which lasted about 100 days probably due to magma solidification against country rock the 1979 eruption of la soufriere de saint vincent west indies was initially affected by lava dome growth and later passed through a phase possibly caused by constriction of the conduit the 1943 1952 eruption of paricutin mexico was affected by changes of lava level in the cinder cone and magma properties in these three eruptions the pre eruptive chamber overpressures were similar 10 20 mpa even though the erupted volumes differed by as much as two orders of magnitude

fidelity of the sr ca proxy in recording ocean temperature in the western atlantic coral siderastrea siderea massive corals provide a useful archive of environmental variability but careful testing of geochemical proxies in corals is necessary to validate the relationship between each proxy and environmental parameter throughout the full range of conditions experienced by the recording organisms here we use samples from a coral growth study to test the hypothesis that sr ca in the coral siderastrea siderea accurately records sea surface temperature sst in the subtropics florida usa along 350 km of reef tract we test calcification rate measured via buoyant weight and linear extension le rate estimated with alizarin red s staining as predictors of variance in the sr ca records of 39 individual s siderea corals grown at four outer reef locations next to in situ temperature loggers during two year long periods we found that corals with calcification rates 1 7 mg cm 2 d 1 or 1 7 mm yr 1 le returned spuriously high sr ca values leading to a cold bias in sr ca based sst estimates the threshold type response curves suggest that extension rate can be used as a quality control indicator during sample and drill path selection when using long cores for sst paleoreconstruction for our corals that passed this quality control step the sr ca sst proxy performed well in estimating mean annual temperature across three sites spanning 350 km of the florida reef tract however there was some evidence that extreme temperature stress in 2010 cold snap and 2011 sst above coral bleaching threshold may have caused the corals not to record the temperature extremes known stress events could be avoided during modern calibrations of paleoproxies

the lack of equipartitioning in global body wave coda correlation of the coda of large earthquakes can be used to retrieve body waves at teleseismic distances this retrieval depends on waves propagating with equal energy in all directions equipartitioning we carry out a beamforming analysis of body waves at periods of 10 and 40 s recorded at usarray and show that the late coda up to 10 h after the okhotsk earthquake is dominated by waves propagating in the great circle direction late coda waves are not equipartitioned this implies for seismic interferometry that teleseismic body waves can only be extracted from the coda when the earthquake and the receivers are located on a great circle this happens automatically when the employed stations are antipodal or when the autocorrelation of waves is used the use of long period ambient seismic noise relies on the distribution of sources because scattering only marginally randomizes directions this provides insight into recent observations of core phases extracted from seismic interferometry

depth migration of seismovolcanic tremor sources below the klyuchevskoy volcanic group kamchatka determined from a network based analysis we present a method for automatic location of dominant sources of seismovolcanic tremor in 3 d based on the spatial coherence of the continuously recorded wavefield at a seismic network we analyze 4 5 years of records from the seismic network at the klyuchevskoy volcanic group in kamchatka russia when four volcanoes experienced tremor episodes after enhancing the tremor signal with spectral whitening we compute the daily cross correlation functions related to the dominant tremor sources from the first eigenvector of the spectral covariance matrix and infer their daily positions in 3 d we apply our technique to the tremors beneath shiveluch klyuchevskoy tolbachik and kizimen volcanoes and observe the yearlong preeruptive volcanic tremor beneath klyuchevskoy from deep to shallow parts of the plumbing system this observation of deep volcanic tremor sources demonstrates that the cross correlation based method is a very powerful tool for volcano monitoring

the temperature relationship in coralline aragonite influence of variability in and skeletal growth parameters this paper provides an evaluation of two of the most likely pitfalls of sr ca thermometry i e the effect of biogenic cycling of sr vs ca in the surface ocean and the effect of variable extension rate on sr incorporation in coralline aragonite the authors also report calibration of the sr ca temperature relationship for three coral species porites lobata pocillopora eydouxi and pavona clavus collected for the hawaiian and galapagos islands analyses of seawater samples show significant spatial and depth variability in the sr ca ratio the uncertainty introduced by this effect is estimated to be 0 2 degrees c for corals located in tropical oligotrophic waters and potentially larger for corals located in upwelling areas sr ca along two different growth axes of a galapagos pavona clavus with annual extension rates of approximately 6 and 12 mm y respectively indicate an offset of 1 2 degrees c with higher sr ca values associated with slower extension rates the offset observed between the two growth axes may be the result of variations in extension and or calcification rate these results are important in determining past sea surface temperatures for reconstruction of paleoclimates

characterization of the 2008 kasatochi and okmok eruptions using remote infrasound arrays 1 the 2008 plinian eruptions of kasatochi and okmok volcanoes were recorded by six remote international monitoring system infrasound arrays high amplitude infrasound at these stations combined with remote sensing permits insight into important volcanic source parameters such as origin times durations and source characteristics infrasound from the 7 8 august kasatochi eruption consists of three well defined eruption pulses with the first two steam rich and the last ash rich pulse 2 is the most energetic and impulsive okmok produced over 9 h of continuous infrasound on 12 13 july acoustic propagation modeling for the okmok eruption and first kasatochi pulse predict thermospheric ducting and origin times consistent with seismic and satellite observations however theoretical acoustic origin times of pulses 2 3 are predicted to occur 15 min earlier than the seismic stratospheric ducting for these later pulses provides more consistent origin times although both volcanoes ejected ash into the stratosphere 15 km kasatochi produced higher amplitude infrasound than okmok previous studies have shown sustained infrasound with frequencies 2000 km and does not seem to be appreciably affected by changes in ash content between the eruption pulses

improved extended reconstruction of sst 1854 1997 abstract an improved sst reconstruction for the 1854 1997 period is developed compared to the version 1 analysis in the western tropical pacific the tropical atlantic and indian oceans more variance is resolved in the new analysis this improved analysis also uses sea ice concentrations to improve the high latitude sst analysis and a modified historical bias correction for the 1939 41 period in addition the new analysis includes an improved error estimate analysis uncertainty is largest in the nineteenth century and during the two world wars due to sparse sampling the near global average sst in the new analysis is consistent with the version 1 reconstruction the 95 confidence uncertainty for the near global average is 0 4 c or more in the nineteenth century near 0 2 c for the first half of the twentieth century and 0 1 c or less after 1950

permanent tremor of masaya volcano nicaragua wave field analysis and source location the masaya volcano nicaragua is a basaltic caldera in a subduction zone the permanent source of the volcanic tremor was located inside santiago crater at the lava lake s position and 400 m below the ne rim and therefore corresponds to superficial magma activity we used two tripartite arrays 90 m side one semicircular array r 120 m in 1992 and two semicircular arrays r 60 m and a 2500 m long linear array radiating out from the source and on the flank of the crater in 1993 we used both a cross spectrum method and a correlation method to determine the wave delay time between the reference station and the other stations of an array and to quantify the wave field using the delays therefore by intersecting the back azimuth wave directions from the arrays we could pinpoint the source additionally the correlation coefficients obtained as functions of frequency for the three components of motion confirm the inferred position of the source of tremor the tremor s wave field is composed of comparable quantities of dispersed rayleigh and love surface waves whose phase velocities lie in the ranges 730 1240 m s at 2 hz and 330 550 m s at 6 hz the dispersive phase velocities were inverted to obtain crustal structures with a minimal number of layers the resulting velocity models are similar for the northern and southern parts of the volcano after geometrical spreading corrections q2hz 14 and q3hz 31 were determined along the northern linear array the typical low velocities and low q corresponding to the cone structure and are similar to those of other basaltic volcanoes like puu oo hawaii and klyuchevskoy kamchatka

shallow degassing events as a trigger for very long period seismicity at kīlauea volcano hawai i the first eruptive activity at k lauea volcano s summit in 25 years began in march 2008 with the opening of a 35 m wide vent in halema uma u crater the new activity has produced prominent very long period vlp signals corresponding with two new behaviors episodic tremor bursts and small explosive events both of which represent degassing events from the top of the lava column previous work has shown that vlp seismicity has long been present at k lauea s summit and is sourced approximately 1 km below halema uma u by integrating video observations infrasound and seismic data we show that the onset of the large vlp signals occurs within several seconds of the onset of the degassing events this timing indicates that the vlp is caused by forces sourced at or very near the lava free surface due to degassing transmitted down the magma column and coupling to the surrounding rock at 1 km depth

long period earthquakes in the long valley caldera region eastern california most earthquakes occurring near long valley caldera since the onset of recurring swarm activity in 1980 have the broad band signature typical of tectonic or volcano tectonic earthquakes with impulsive high frequency p and s waves with the mammoth mountain earthquake swarm in mid 1989 we began detecting occasional events with a marked deficiency in energy above 5 hz a feature typical of long period lp volcanic earthquakes these events occur beneath the southwest flank of mammoth mountain at focal depths ranging from 10 to 28 km distinctly deeper than the 2 to 10 km depth range for tectonic earthquakes in the area the lp events occur at intervals ranging from weeks to months individual occurrences typically consist of several events within 2 to 5 minutes where the largest event has never been first magnitudes range from 0 5 to 1 8 the mid crustal focal depths of the lp events are similar to occurrences at a number of areas with holocene volcanism in japan and the western united states they may indicate the movement of magmatic fluids but do not necessarily indicate an imminent volcanic eruption

variation of initial 230th 232th and limits of high precision u th dating of shallow water corals one hundred eighty u th data including 23 isochrons on 24 pristine modern and holocene corals and 33 seawater samples were analyzed using sector field mass spectrometry to understand the variability of initial 230th 232th 230th 232th0 this dataset allows us to further assess the accuracy and precision of coral 230th dating method by applying quality control including careful sampling and subsampling protocols and the use of contamination free storage and workbench spaces the resulting low procedural blanks give an equivalent uncertainty in age of only 0 2 0 3 yr for 1 2 g of coral sample using site specific 230th 232th0 values or isochron techniques our study demonstrates that corals with an age less than 100 yrs can be 230th dated with precisions of 1 yr six living subtidal coral samples were collected from two continental shelf sites nanwan off southern taiwan in the western pacific and son tra off central vietnam in the south china sea one coral core was drilled from an open ocean site santo island vanuatu in the western tropical pacific and modern and fossil intertidal coral slabs 17 in total were cut from six sites around the islands of simeulue lago north pagai and south pagai of sumatra in the eastern indian ocean the results indicate that the main source of thorium is the dissolved phase of seawater with variation of 230th 232th0 depending on local hydrology with intense input of terrestrial material low 230th 232th0 atomic ratios of 4 9 10 6 and 3 2 10 6 with a 10 variation are observed in nanwan and son tra respectively at the santo site we find a value of 5 6 10 6 at 4 horizons and one high value of 24 10 6 in a sample from ad 1974 6 0 5 likely due to the upwelling of cold water during a la nina event between ad 1973 and 1976 the natural dynamics of 230th 232th0 recorded in the intertidal corals at sites in the sumatran islands are complicated so that this value varies significantly from 3 0 to 9 4 10 6 three of the 141 modern coral 230th ages differ from their true ages by 23 to 4 indicating the presence of detrital material with anomalous 230th 232th values duplicate measurement of coeval subsamples is therefore recommended to verify the age accuracy this improved high precision coral 230th dating method raises the prospects of refining the age models for band counted and tracer tuned chronologies and of advancing coral paleoclimate research

deep structure of the northeastern japan arc and its relationship to seismic and volcanic activity evidence for possible deep seated magmatic activity beneath northeastern japan can be obtained from seismic observations tomographic inversions of p wave velocity data show low velocity zones distributed in the crust and upper mantle beneath active volcanoes in or around these zones anomalously low frequency micro earthquakes perhaps caused by magmatic activity are found at depths of 25 40 km distinct s wave reflectors corresponding to the upper surfaces of magma bodies are found at depths of 10 18 km large crustal earthquakes also occur around the low velocity zones these observations reveal the distribution of magma reservoirs at depths and elucidate its relation with shallow seismicity beneath volcanic arcs

the effect of skeletal mass accumulation in porites on coral sr ca and δ18o paleothermometry 1 paleotemperature estimates based on coral sr ca have not been widely accepted because the reconstructed glacial holocene shift in tropical sea surface temperature 4 6 c is larger than that indicated by foraminiferal mg ca 2 4 c we show that corals over estimate changes in sea surface temperature sst because their records are attenuated during skeletogenesis within the living tissue layer to quantify this process we microprofiled skeletal mass accumulation within the tissue layer of porites from australasian coral reefs and laboratory culturing experiments the results show that the sensitivity of the sr ca and 18o thermometers in porites will be suppressed variable and dependent on the relationship between skeletal growth rate and mass accumulation within the tissue layer our findings help explain why 18o sst sensitivities for porites range from 0 08 c to 0 22 c and are always less than the value of 0 23 c established for biogenic aragonite based on this observation we recalibrated the coral sr ca thermometer to determine a revised sensitivity of 0 084 mmol mol c after rescaling most of the published sr ca sst estimates for the indo pacific region for the last 14 000 years 7 c to 2 c relative to modern fall within the 95 confidence envelope of the foraminiferal mg ca sst records we conclude that two types of calibration scales are required for coral paleothermometry an attenuated porites specific thermometer sensitivity for studies of seasonal to interannual change in sst and importantly the rescaled 0 084 mmol mol c sr ca sensitivity for studies of 20th century trends and millennial scale changes in mean sst the calibration scaling concept will apply to the development of transfer functions for all geochemical tracers in corals

sr ca sea surface temperature calibration in the coral porites lutea from subtropical northern south china sea strontium to calcium sr ca ratios in annual bands of porites corals are commonly used as past sea surface temperature proxy in tropical oceans whereas studies that refer to sr ca sst calibration in high latitude corals are rather rare in general here we present a 50 year 1961 2010 near fortnightly sr ca record in two porites lutea corals living near the northern limit of reef building corals in the subtropical northern south china sea where winter temperatures are extreme for hermatypic corals the sr ca time series shows a clear annual cyclicity with marked sharp narrow winter peaks comparison with an instrumental sst record since 1961 indicates that this sr ca record is chiefly modulated by sst two different methods are discussed for calibrating sr ca with sst the correlation between interpolated sr ca and sst is significant but the coefficient is relatively low mainly attributed to extreme cold winter ssts similar to 16 degrees c which cause a significant decrease or even cessation of coral skeletal extension another modified method using only annual low sr ca values which could clearly be matched with the same features in the instrumental sst record is more reliable the modified regression equation does not encompass ssts below 24 degrees c the fidelity of the coral based sr ca sst calibration was assessed and the precision of the method is estimated to be 031 0 62 degrees c based on the calibration verification exercise the modified method is suggested in marginal coral areas with extreme intra annual sst variation e g from 13 to 30 degrees c c 2013 elsevier b v all rights reserved

array measurements and modeling of sources of shallow volcanic tremor at kilauea volcano hawaii we show that resonances in near surface layers path effects or a combination of near surface resonances and source resonances source effects could be responsible for the sharp spectral peaks found in the records of gas piston activity and volcanic tremor recorded near puu oo crater on kilauea volcano hawaii two types of sources are found to be compatible with observations and can not be distinguished using our data in one model impulsive explosion point sources are embedded in the puu oo structure in the other model impulsive point sources of pressure excite the resonances of a fluid filled crack embedded in that structure both models require shallow sources z 100 m and display a strong dependence of the radiated spectrum on source depth over a depth range comparable to the overall thickness of the surficial layers based on these results it may be possible to track changes in source depth through temporal changes in observed spectra a potentially useful tool for monitoring volcanic activity at this site we estimate the depth and spatial extent of volcanic tremor and gas piston activity using two dense arrays with respective apertures of 800 and 120 m located near puu oo measurements of slowness ray parameter and azimuth as a function of time clearly indicate that the sources of volcanic tremor and gas piston activity are located beneath or in close proximity to the puu oo crater at depths shallower than approximately 1 km based on slowness and particle motion analyses we find that the records of volcanic tremor and gas piston events at puu oo consist of a complex combination of body and surface waves

sr ca u ca and δ18o records in recent massive corals from bermuda relationships with sea surface temperature abstract high resolution records of sr ca u ca ratios and 18o have been obtained in two recent colonies of massive corals diploria labyrinthiformis from bermuda the three geochemical proxies display regular seasonal variations and are well correlated with each other however some important discrepancies are observed between the two colonies the average seasonal variations of the three geochemical proxies are lower by almost 50 in one of the profiles where the seasonal oscillation also displays a strong asymmetry with narrower summer maxima different calculations are discussed for calibrating sr ca and 18o with sea surface temperatures sst we show that the method using only temperature minima and maxima is slightly more accurate and is also more reliable our results from bermuda corals confirm that the temperature dependency of sr ca u ca and 18o is species dependent as previously shown by others and that vital effects are clearly involved in the geochemical incorporation of trace elements in the coral skeleton finally a simple model involving seasonal variation of the growth rate and a kinetic fractionation related to growth rate is presented to explain the differences between the two bermuda colonies it is shown that these factors may prevent corals from recording the complete temperature seasonality and could be the cause for the discrepancies observed between profiles resulting in significant biases of the sst reconstructions