climate instability during the last interglacial period recorded in the grip ice core isotope and chemical analyses of the grip ice core from summit central greenland reveal that climate in greenland during the last interglacial period was characterized by a series of severe cold periods which began extremely rapidly and lasted from decades to centuries as the last interglacial seems to have been slightly warmer than the present one its unstable climate raises questions about the effects of future global warming

assessing the reliability of magnesium in foraminiferal calcite as a proxy for water mass temperatures though many studies on the mg contents in the calcitic tests of foraminifers exist the processes controlling its uptake are still a matter of debate laboratory cultures offer an excellent opportunity to reveal these mechanisms the mg concentrations within single chambers of the planktic foraminifer globigerinoides sacculifer brady maintained under controlled laboratory conditions were measured 1 at variable temperatures 19 5 29 5 c and constant salinity and 2 at variable salinity 22 45 and constant temperature the experimental results suggest that under natural conditions temperature is the leading mechanism controlling the mg ca ratio temperature and magnesium are related proportionally a temperature increase of ca 10 c gives rise to an increase of the magnesium concentrations of ca 130 drastic unnatural salinity changes dominate the effects of temperature a 110 change in the mg ca ratio was observed when salinity was elevated or reduced by more than ca 10 specimens which underwent gametogenesis reveal significantly higher mg concentrations than specimens that did not release gametes partition coefficients for mg in foraminiferal calcite are orders of magnitude lower than values from inorganically precipitated calcite when comparing observed mg ca ratios of foraminiferal tests with predicted mg ca ratios calculated according to empirical equations it becomes evident that foraminiferal tests are undersaturated with respect to mg for the water temperature they have experienced apparently foraminifers are capable of controlling their mg concentration the physiological processes presumably responsible for such depressed mg ca ratios appear to be temperature controlled as deduced from the close relationship of the observed mg ca ratios and water temperature this study demonstrates that variations in temperature and salinity are definitely reflected in the mg content of foraminiferal tests magnesium may thus serve as a paleo proxy for past surface water temperatures as long as postdepositional changes and salinity variations are of subordinate importance or can be excluded

volcanic conduit controls on effusive explosive transitions and the 2010 eruption of merapi volcano indonesia abstract individual volcanoes can produce both effusive and explosive eruptions a transition between these two eruption styles dramatically changes the hazards and can occur either between distinct eruption events or within one eruption episode the causes of these transitions are difficult to determine due to the number of system parameters that can influence whether or not magma fragments in a runaway process we apply a numerical model of magma ascent in a volcanic conduit to isolate and test the effects of key parameters related to magma rheology and system geometry we find that for a given volcanic system parameters that control magma viscosity such as initial water mass fraction initial crystal volume fraction and temperature have the greatest influence on whether or not magma fragments during ascent and erupts explosively we also define a critical condition for the full set of initial parameters under which a transition in eruption style from effusive to explosive or the reverse is more likely to occur under these conditions small heterogeneities in the water or crystal content of the magma or small perturbations to the conduit pressure gradient due to magma chamber overpressure or dome growth or collapse can disrupt the magmatic conditions and cause a transition in eruption style the 2010 vei 4 eruption of merapi volcano included both effusive and explosive phases and was larger by an order of magnitude than its eruptions during the previous century we constrain our model for the merapi system using published literature values and show that between the previous eruption in 2006 and the 2010 eruption the shallow magmatic system at merapi reached critical conditions due to the ascent from depth of a large hotter more volatile rich magma under these critical conditions and according to our model results small changes in the volatile content of the magma small dome collapses subtle changes in degassing rate or the addition of co2 to the magma through decarbonation of the bedrock are all feasible mechanisms for triggering rapid transitions between effusive and explosive activity during the 2010 eruption period

magmatic processes revealed by textural and compositional trends in merapi dome lavas syn eruptive degassing of volcanoes may lead to syn eruptive crystallization of groundmass phases we have investigated this process using textural and compositional analysis of dome material from merapi volcano central java indonesia samples included dome lavas from the 1986 88 1992 93 1994 and 1995 effusive periods as well as pyroclastic material deposited by the november 1994 dome collapse with total crystallinities commonly in excess of 70 phenocrysts 1 microlites the liquids present in merapi andesites are highly evolved rhyolitic at the time of eruption feldspar microlites in dome rocks consist of plagioclase cores ab63an29or8 surrounded by alkali feldspar rims ab53an5or42 compositional pairs which are not in equilibrium a change in the phase relations of the ternary feldspar system caused by degassing best explains the observed transition in feldspar composition a small proportion of highly vesicular airfall tephra grains from the 1994 collapse have less evolved glass compositions than typical dome material and contain rimless plagioclase microlites suggesting that the 1994 collapse event incorporated less degassed partially liquid magma in addition to fully solidified dome rock as decompression drives volatile exsolution rates of degassing and resultant microlite crystallization may be governed by magma ascent rate microlite crystallinity is nearly identical among the 1995 dome samples an indication that similar microlite growth conditions ph2 o and temperature were achieved throughout this extrusive period however microlite number density varied by more than a factor of four in these samples and generally increased with distance from the vent low vent ward microlite number densities and greater microlite concentrations down flow probably reflect progressively decreasing rates of undercooling at the time of crystal nucleation during extrusion of the 1995 dome comparison between dome extrusion episodes indicates a correlation between lava effusion rate and microlite number density suggesting that extrusion slowed during 1995 crystal textures and compositions in the 1992 93 and 1994 domes share the range exhibited by the 1995 dome suggesting that transitions in crystallization conditions i e rates of undercooling determined by effusion rate are cyclic q 2000 elsevier science b v all rights reserved

a study of cleaning procedures used for foraminiferal mg ca paleothermometry the various cleaning steps required for preparation of foraminiferal samples for mg ca and sr ca analysis are evaluated for their relative importance and effects on measured elemental ratios it is shown that the removal of silicate contamination is the most important step for the measurement of mg ca ratios in an example bulk sample mg ca decreases from 10 5 to 2 5 mmol mol 1 during clay removal oxidation of organic material causes a lowering of sample mg ca in the order of 10 or approximately 1 c when converted to temperature use of dilute acid leaching to remove adsorbed contaminants causes partial dissolution of the sample carbonate and a corresponding decrease in mg ca reductive treatment also causes dissolution of the sample and a decrease in the mg ca ratio of up to 10 15 sample preparation for sr ca analysis does not require the same degree of rigor as is necessary for mg ca work the within run reproducibility of the method described here for g ruber in a core top sample from the arabian sea was 1 8 mean sample ratio was 4 72 mmol mol 1 when converted to temperature this becomes 28 0 2 c the equivalent result for sr ca was 0 5 mean ratio 1 44 mmol mol 1

eemian and early weichselian environments in southern sweden a multi proxy study of till covered organic deposits from the smaland peneplain based on their luminescence and infinite radiocarbon ages organic deposits beneath till at two sites on the smaland peneplain southern sweden nybygget and stora gaddevik are concluded to have formed before the middle weichselian applied palaeoecological methods include analyses of pollen diatoms charcoal fragments macroscopic remains of vascular plants and mosses and insect remains pollen stratigraphical correlations with previously studied interglacial interstadial sites in southern sweden denmark and northern germany suggest that the peat at nybygget dates from the brorup interstadial or the final stage of the eemian interglacial whereas the lake sediments at stora gaddevik probably were emplaced during the middle eemian we conclude that the peat was formed in a wetland characterized by both wood swamp and open mire vegetation and surrounded by semi open woodlands dominated by pine birch and hazel the middle eemian sequence at the stora gaddevik site provides evidence of a moderately nutrient rich to nutrient rich lake environment with relatively diverse aquatic vegetation regional vegetation as reconstructed using the reveals model was spruce woodland mixed with pine alder and birch but also included more open environments with hazel oak grasslands and sedge dominated wetlands water shield brasenia schreberi now extinct in europe was identified in the eemian lake deposits from both pollen and macroscopic remains

surface and subsurface seawater temperature reconstruction using mg ca microanalysis of planktonic foraminifera globigerinoides ruber globigerinoides sacculifer and pulleniatina obliquiloculata laser ablation inductively coupled plasma mass spectrometry microanalyses of mg ca across individual final chambers of three planktonic foraminifera species globigerinoides ruber g sacculifer and pulleniatina obliquiloculata reveal significant interspecies differences in test mg concentrations whereas these three species have similar mg ca values at low sea surface temperatures similar to 22 degrees c they diverge markedly at high sea surface temperatures similar to 29 degrees c explanations for these differences in species mg ca values based on detailed comparison of species intratest mg ca distributions suggest that compositional variability within tests cannot account for the observed deviation of species mg ca values in warm water equatorial regions multiple regression modeling and delta o 18 analysis of globigerinoides sacculifer tests indicate that interspecies differences in mg ca values result from different depth habitats the average mg ca values of g ruber final chambers reflect the temperature of the surface mixed layer 0 25 m whereas those of g sacculifer and pulleniatina obliquiloculata correlate best with subsurface temperatures at 50 75 m and 100 125 m water depths respectively mg ca calibration to the temperatures at these depths reveals a similar temperature control on mg test composition in all species combining our results with mg ca values from published culturing experiments we derive a generalized equation for the effect of temperature and seawater salinity on foraminiferal mg ca we also show that the mg ca composition of specific calcite layers within foraminiferal tests including the low mg ca layers of globigerinoides ruber and g sacculifer and the cortex layer of pulleniatina obliquiloculata correlates with seawater temperature and can be used as an additional proxy for seawater temperature

the last interglacial glacial cycle in ne fennoscandia a nearly continuous record from sokli finnish lapland abstract boreholes from the sokli basin in finnish lapland have recovered a unique sequence of diamicts interlayered with fine grained sediments that are rich in fossils the diamicts are interpreted as till beds deposited by the fennoscandian ice sheet the fine grained intercalations seem to represent a series of warm stages that include one interglacial and three interstadials the interglacial is characterized by a mixed taiga pollen assemblage and corresponds to a distinct diatom gyttja bed the interstadials show progressively colder floras from open birch forest to arctic forest limit to shrub tundra their sediments comprise gyttja interlayered with wood and sand interstadial 1 sands grading into sandy gyttja interstadial 2 and sands overlain by laminated silt and clay interstadial 3 the interstadial 2 and 3 deposits are underlain by diamict and are interpreted as deglaciation sequences silts with a tundra pollen assemblage separate the interglacial and interstadial 1 deposits luminescence dating evidence indicates that the interglacial bed most probably represents the nw european mainland eemian interglacial marine isotope stage mis 5e the interstadial 1 2 and 3 deposits are tentatively correlated with the early weichselian brorup and odderade interstadials and an interstadial of middle weichselian age respectively mis 5c 5a and 3 respectively the correlation implies that the easternmost part of the ice divide zone of the fennoscandian continental ice sheet was deglaciated during part of mis 3

pleistocene chronostratigraphy in estonia southeastern sector of the scandinavian glaciation abstract pleistocene chronostratigraphy in estonia is based on 29 studied sites sections the dating of which covers a span from approximately 200 ka bp to the pleistocene holocene chronostratigraphic boundary and a local varved clay chronology for eastern estonia which enables tentative correlation of lateglacial lg events to finnish and swedish varve chronologies analysis of existing and unpublished data was used to review the current pleistocene chronostratigraphy and particularly the history of weichselian cold stage in estonia osl ages from fluvial deposits that included the korvekula holsteinian or rongu eemian continental interglacial deposits revealed that the pre weichselian interglacial deposits were glacially dislocated during the weichselian available osl tl and 14 c dates and new 14 c ams ages of mammoth bones indicate ice free conditions between 105 and 68 ka bp and a comparatively mild middle weichselian between 43 and 22 ka bp the lg chronology indicates in general rapid average 110 m yr deglaciation of the territory between ca 14 7 and 12 7 ka bp the duration of the late weichselian glaciation in estonia ranged between 7 3 and 9 3 ka

transitions between explosive and effusive eruptions of silicic magmas water rich silicic magmas may erupt explosively giving rise to massive columns of fragmented ash1 5 or effusively as viscous bubbly lavas to form lava domes6 8 complex cycles of explosive and effusive eruptions are often observed8 12 although these two eruption mechanisms have been modelled independently1 8 the conditions under which a volcano exhibits a particular style of eruption are not known and the transitions between eruption styles are poorly understood by modelling the ascent of magma along a permeable conduit we show here that for small magma chamber overpressures the style of eruption explosive or effusive is dependent on the magma flow rate we also identify a critical overpressure above which only explosive eruptions occur complex eruption sequences follow naturally for example if a shallow magmatic system is supplied with magma at an intermediate flow rate the eruption will be slow and effusive until the chamber over pressure becomes too large an explosive eruption then relieves the overpressure and an effusive eruption style resumes we suggest that monitoring of temporal variations in chamber overpressure for example by measuring ground deformation can be used to assess whether a passively effusing volcano has the potential to erupt explosively

present day temperatures in northern scandinavia during the last glaciation scandinavia is generally considered to have been covered extensively with ice throughout marine isotope stages mis 4 2 between 75 and 10 ka here we present evidence for ice free warm conditions in the central area of the scandinavian glaciations during mis 3 our multiproxy data obtained from a lacustrine sequence in northern fin land reveal not only significant response in the northeastern sector of the scandinavian ice sheet to warming during the early part of mis 3 but also indicate rapid climate warming to present day temperatures in this ice free period new climate model simulations for interstadial conditions in mis 3 confirm the high mean july temperatures northeast of the scandinavian ice sheet in response to the high insolation values and the presence of the ice sheet during mis 3

a multidisciplinary effort to assign realistic source parameters to models of volcanic ash cloud transport and dispersion during eruptions during volcanic eruptions volcanic ash transport and dispersion models vatds are used to forecast the location and movement of ash clouds over hours to days in order to define hazards to aircraft and to communities downwind those models use input parameters called eruption source parameters such as plume height h mass eruption rate duration d and the mass fraction m63 of erupted debris finer than about 4 or 63 m which can remain in the cloud for many hours or days observational constraints on the value of such parameters are frequently unavailable in the first minutes or hours after an eruption is detected moreover observed plume height may change during an eruption requiring rapid assignment of new parameters this paper reports on a group effort to improve the accuracy of source parameters used by vatds in the early hours of an eruption we do so by first compiling a list of eruptions for which these parameters are well constrained and then using these data to review and update previously studied parameter relationships we find that the existing scatter in plots of h versus yields an uncertainty within the 50 confidence interval of plus or minus a factor of four in eruption rate for a given plume height this scatter is not clearly attributable to biases in measurement techniques or to well recognized processes such as elutriation from pyroclastic flows sparse data on total grain size distribution suggest that the mass fraction of fine debris m63 could vary by nearly two orders of magnitude between small basaltic eruptions 0 01 and large silicic ones 0 5 we classify eleven eruption types four types each for different sizes of silicic and mafic eruptions submarine eruptions brief or vulcanian eruptions and eruptions that generate co ignimbrite or co pyroclastic flow plumes for each eruption type we assign source parameters we then assign a characteristic eruption type to each of the world s 1500 holocene volcanoes these eruption types and associated parameters can be used for ash cloud modeling in the event of an eruption when no observational constraints on these parameters are available

petrologic constraints on the decompression history of magma prior to vulcanian explosions at the soufriere hills volcano montserrat abstract a series of 88 vulcanian explosions occurred at the soufriere hills volcano montserrat between august and october 1997 conduit conditions conducive to creating these and other vulcanian explosions were explored via analysis of eruptive products and one dimensional numerical modeling of magma ascent through a cylindrical conduit the number densities and textures of plagioclase microlites were documented for twenty three samples from the events the natural samples all show very high number densities of microlites and 50 by number of microlites have areas 2 pre explosion conduit conditions and decompression history have been inferred from these data by comparison with experimental decompressions of similar groundmass compositions our comparisons suggest quench pressures 13 75 mpa each during ascent from chamber to surface values are consistent with field studies of the same events and statistical analysis of explosion time series data the microlite volume number density trend with depth reveals an apparent transition from growth dominated crystallization to nucleation dominated crystallization at pressures of 7 mpa and lower a concurrent sharp increase in bulk density marks the onset of significant open system degassing apparently due to a large increase in system permeability above 70 vesicularity this open system degassing results in a dense plug which eventually seals the conduit and forms conditions favorable to vulcanian explosions the corresponding inferred depth of overpressure at 250 700 m near the base of the dense plug is consistent with depth to center of pressure estimated from deformation measurements here we also illustrate that one dimensional models representing ascent of a degassing crystal rich magma are broadly consistent with conduit profiles constructed via our petrologic analysis the comparison between models and petrologic data suggests that the dense conduit plug forms as a result of high overpressure and open system degassing through conduit walls

oxygen isotopes and sea level from the time that detailed oxygen isotope records derived from foraminifera living in the constant temperature environment of the abyssal ocean became available there has been a discrepancy between the ice volume record that these records imply and that derived from the altitude of dated coral terraces around the world here we re examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system

southwest scandinavia 40 15 kyr bp palaeogeography and environmental change twelve palaeogeographical reconstructions illustrate environmental changes at the southwest rim of the scandinavian ice sheet 40 15 kyr bp synchronised land sea and glacier configurations are based on the lithostratigraphy of tills and intertill sediments dating is provided by optically stimulated luminescence and calibrated accelerator mass spectrometry radiocarbon an interstadial sequence ca 40 30 kyr bp with boreo arctic proglacial fjords and subarctic flora and occasional glaciation in the baltic was succeeded by a last glacial maximum sequence ca 3020 kyr bp with the closure of fjords and subsequent ice streams in glacial lake basins in kattegat and the baltic steadily flowing ice from sweden bordered the norwegian channel ice stream a deglaciation sequence ca 20 15 kyr bp indicates the transgression of arctic waters retreat of the swedish ice and advance of baltic ice streams succeeded by a return to interstadial conditions when ameliorated ice free conditions prevailed in maritime regions glaciers advanced through the baltic and when interstadial regimes dominated the baltic glaciers expanded off the norwegian coast the largest glacier extent was reached in the north sea around 29 kyr bp about 22 kyr bp in denmark and ca 18 kyr bp in the baltic our model provides new data for future numerical and qualitative landform based models copyright c 2003 john wiley sons ltd less

a late pleistocene marine clay succession at kriegers flak westernmost baltic southern scandinavia in the baltic sea south of skane county in southern sweden an over consolidated marine clay succession on the northeastern slope of kriegers flak was observed in shallow seismic data as a unit overlain by younger weichselian sediments two cores were taken from the clay succession the foraminifera present were predominantly of two species elphidium excavatum and elphidium albiumbilicatum reflecting deposition under arctic boreal conditions stable oxygen isotope analyses were performed on foraminiferal tests and the results show extremely light 18o values ranging between 11 and 12 the cause of these extreme values is uncertain but may result from the high influence of meltwater brackish conditions are also indicated by the tolerance for low salinity shown by the foraminifera radiocarbon dating shows an infinite age 40000 yr bp the pollen flora seems mainly to have been redeposited which makes interpretation difficult the sea may have entered the baltic basin during periods with high eustatic levels an isostatic downloading of the crust or a combination of both it is suggested that the deposition of the overconsolidated marine clay succession occurred in the late saalian early eemian or early weichselian 1998 john wiley sons ltd

a middle weichselian interstadial lake deposit on sejero denmark macrofossil studies and dating studies of lake sediments on sejero in southern kattegat indicate a treeless arctic environment with the dwarf shrub salix polaris herbs and wetland mosses the mean july temperature was around 8 to 10 c an ams radiocarbon age determination of a salix twig yielded an age of around 36 000 14c yr bp which is in accordance with previous conventional dating of bulk sediment samples copyright 2006 john wiley sons ltd

intrusive and extrusive growth of the mount st helens lava dome lava domes grow by a combination of endogenous intrusive and exogenous extrusive addition of magma either as single continuous events1 2 or through a series of relatively small pulses which together build a larger construct3 evaluating the hazards that attend growth of a dome requires an assessment of the processes controlling whether lava is added to its interior or surface because many of these dangers depend on how volatiles are admitted to or released from hot magma if the volatile pressure inside an inflating dome becomes high enough sudden exposure provided by flow front slumping can lead to explosive decompression and the generation of pyroclastic flows4 5 on the other hand lava erupted on the oversteepened surface of a dome may collapse fragment and mix with snow or ice to form pyroclastic flows surges and mudflows6 7 here we provide a quantitative assessment of the partitioning of magma into endogenous intrusions and exogenous lobes using high resolution digital topographic maps of the mount st helens dome derived from aerial photographs taken periodically between 1980 and 1986 endogenous exogenous and total volume production rates follow distinct trends which provide important clues about the nature of eruption mechanisms calculating endogenous and exogenous components for active domes like those recently formed at redoubt volcano may help quantify magma chamber processes and provide another tool for understanding the re equilibration of shallow magmatic systems

systematic change of foraminiferal mg ca ratios across a strong salinity gradient abstract the mg ca ratio of foraminiferal calcite is an important proxy for estimating past ocean temperatures used in conjunction with 18 o of foraminiferal calcite it allows deconvolution of temperature and ice volume signals to infer past ocean temperatures and salinities assuming the relationship between seawater 18 o and salinity is known such work assumes that temperature is the only or at least the dominant environmental controller of foraminiferal mg ca the semi enclosed mediterranean sea where salinity varies from 36 to 40 psu over a seasonal temperature range of between only 5 c to 8 c provides a relevant setting to test this assumption outside the laboratory in this study planktonic foraminifera o universa g siphonifera g bulloides and g ruber white and pink were picked from 11 box core tops spanning the mediterranean salinity gradient and analysed for their trace element concentrations mg ca ratios are higher for the associated calcification temperatures than in other regions where calibrations have been conducted and correlate poorly with calcification temperature mg ca ratios are particularly high for samples from the eastern mediterranean where salinity is unusually high correlations of mg ca with the calcification salinity are statistically significant with mg ca changing by 15 59 per psu suggesting that salinity may act as a control on mg ca ratios in addition to the dominant temperature control we show that contamination by non carbonate material and diagenetic high mg carbonate overgrowths cannot account for the observed trend of increasing mg ca with salinity a relationship between mg ca and salinity is also suggested by re analysis of calibrations from open ocean settings these new mediterranean results are from a region with unusually high salinity but suggest that the effects of salinity on the mg ca palaeothermometer should be considered even in open ocean settings particularly where large salinity changes occurred in the past

mis 3 mammoth remains from sweden implications for faunal history palaeoclimate and glaciation chronology the distribution of low arctic megafaunal remains in time and space from the area previously covered by the scandinavian ice sheet sis suggests the presence of breeding mammoth populations in the circum baltic region during the time interval from 44 to 26 ka ago the transport history of 30 mammoth teeth and bones from southern and north central sweden was estimated and the remains were subjected to osteological analyses and 14c dating oxygen isotope analyses of tooth enamel indicate a palaeoclimate considerably more homogenous than that experienced in sweden today showing moderate north south gradients in the d18o value of precipitation and temperature in general the results support the model of restricted ice sheet distribution during the second half of the middle weichselian the clear discrepancy in the inferred absence of glaciation in the central swedish uplands and the baltic basin as evidenced by the swedish mammoth data versus the danish osl based glaciation chronology in the period from 40 to 30 ka ago is discussed in the light of radiocarbon calibration and glacial dynamics r 2007 published by elsevier ltd less

a multi disciplinary macrofossil study of middle weichselian sediments at kobbelgard mon denmark abstract multi proxy studies of radiocarbon and luminescence dated middle weichselian sediments and allochthonous plant and animal macrofossils from kobbelgaard mon point to a lacustrine environment with shallow mesotrophic fresh water the lake was surrounded by mires rich in mosses and carex while the vegetation on the uplands was tree less and herb dominated but with scattered shrubs the climate was considerably colder than at the present day with average july temperatures around 11 c about 6 c below those for the region today probably normal for the later part of the middle weichselian the sediments contain the first remains of lemmings dicrostonyx torquatus and lemmus lemmus found in denmark

overview of the 2006 eruption of mt merapi abstract in the last part of the 20th century and the beginning of the 21st century mt merapi in central java indonesia erupted about every 2 5 years most of the eruptions were low in explosivity with vei 3 or less eruptions usually involve the formation of a lava dome either in the beginning or in the end of the eruptive episode for the 2006 eruption the precursory signal was first observed in the middle of the year 2005 with a decrease in edm slope distances to points on the rim an increase of seismicity and a possible increase of so 2 emissions those early events marked the beginning of a more continuous period of inflation which led to the eruption in total the pre eruption displacement of the southern rim reached at least 2 4 m toward the measuring station in kaliurang kal from late april until june 2006 a lava dome grew on the summit with a volume that gradually increased until it reached about 4 1 million m 3 in 38 days the total of erupted magma was about 5 3 million m 3 dense rock equivalent dre the dome subsequently collapsed in three steps from june 4 to june 14 leaving an open scar on its southeast side in this paper we detail the changes of dome morphology that were monitored by taking successive photographs from similar positions the eruption in 2006 marked a significant change in summit morphology from west southwestward opening during the 20th century to the currently southeast orientation also an mw 6 4 earthquake occurred on 26 may midway through the eruption which adds interesting questions about the relationship of the eruption and the earthquake edm data from 2006 and previous eruptions show that the summit remains inflated after each eruption i e no significant deflation occurs following eruptions the lack of post eruption deflation suggests that magma remains in the shallow parts of the edifice after the eruption as a result the complex of summit lava domes and their intrusive roots grow with time and merapi s rim and summit become progressively more unstable and prone to collapse

precursory inflation of shallow magma reservoirs at west sunda volcanoes detected by insar 1 we use 2006 2009 alos interferometric synthetic aperture radar data over the entire west sunda arc indonesia home of 13 of the world s active volcanoes to derive arc wide time dependent ground deformation data we present unambiguous evidence of inflation at six volcanoes three of which erupted after the observation period we show that these volcanoes have shallow magma reservoirs at 1 3 km depth below the average regional elevation a global comparison of reservoir depths at arc volcanoes suggests that volcanoes in extensional and strike slip settings west sunda can develop shallow reservoirs whereas volcanoes in compressional settings may lack them thus magma ascend through the upper crust could be influenced by intra arc tectonic settings

on the fidelity of shell derived δ18oseawater estimates article i nfo 18 oseawater a robustproxyforsurfacesalinity we assessthe fidelity of shell derived 18 oseawater estimates for the surface dwelling foraminifer globigerinoides ruber white using an atlantic meridional coretop transect spanning basin scale temperature and salinity gradients shell derived and observed 18 oseawater values are well correlated r 2 0 77 but a large systematic bias is observed shell mg ca ratios are significantly elevated above values expected from observed and isotopic calcification temperatures in the saline subtropical gyres of both hemispheres this temperature independent shell mg ca ratio variability termed excess mg ca i s highly correlated with surface salinity r 2 0 77 and the observed salinity dependence 27 4 is much higher than indicated by culture studies 6 2 our coretop data are used to develop new atlantic basin temperature and salinity calibration equations that are accurate 1 1 c and 0 20 respectively precise r 2 0 82 and 0 81 respectively and verifiable using previously published data these results are valid for the relatively high salinities of the subtropical atlantic 35 5 37 3 we discover that inclusion of other published data from lower salinity regions b35 indicates little or no excess mg ca taken together these results point to a strongly non linear positive salinity effect on shell mg ca ratios that significantly affects the accuracy of sst and 18

new spatial mg ca temperature calibrations for three arctic benthic foraminifera and reconstruction of north iceland shelf temperature for the past 4000 years 1 we have developed cold end mg ca temperature calibrations for three common arctic benthic foraminifera islandiella norcrossi helenae melonis barleeanus and cassidulina neoteretis and compare the three calibrations in a late holocene downcore record 0 4000 cal yr b p the calibration and downcore trends for the three arctic species extend the observation that mg incorporation into benthic foraminifera is species specific for the calibration we use a set of ctd casts bottom water 18oseawater measurements and surface grab samples collected from the iceland margin cruise b997 and the greenland margin cruise bs1191 water depth of sites used ranges from 165 to 656 m while spatial bottom temperature ranges from 0 to 7 c mg ca values ranged from 1 02 to 1 47 for i norcrossi helenae 0 64 to 2 21 for m barleeanus and 0 93 to 1 38 mmol mol for c neoteretis we calibrated mg ca content against isotopic calcification temperature calculated using t 16 9 4 0 18ocalcite corrected for vital effect 18oseawater exponential calibrations for the three species are as follows i norcrossi helenae mg ca 1 051 0 03 exp 0 060 0 011 t m barleeanus mg ca 0 658 0 07 exp 0 137 0 020 t and c neoteretis mg ca 0 864 0 07 exp 0 082 0 020 t on the basis of mg ca in these benthic species the downcore record from core md99 2269 is reconstructed bottom temperature values are interpreted to reflect variable inflow of atlantic and arctic water to the north iceland shelf during the last 4000 cal yr b p all three reconstructions show a decline by 0 1 c per century from circa 1500 0 cal yr b p which coincides with an increase in arctic benthic foraminifera abundances and a rise in sea ice proxies in the same core intriguingly c neoteretis diverges periodically to higher average temperature atlantic water conditions than shown by m barleeanus or i norcrossi helenae which both show arctic water temperature circa 1500 4000 cal yr b p

fault associated seabed mounds carbonate knolls off western ireland and north west australia abstract groups of seabed mounds suspected to be modern carbonate knolls or bioherms have been located on reflection seismic data in the porcupine basin off western ireland and in the vulcan sub basin off north west australia the size of these mounds is impressive often being over 1 km across and over 100 m high in the porcupine basin they occur in water depths of 650 1000 m whereas in the vulcan sub basin they occur in water depths of 200 350 m shallow seabed coring in the porcupine basin has provided data on the age lithological composition and hydrocarbon concentrations in the upper 3 m layer of sediment both on and off the mounds in both basins the mounds occur close to faults which may provide conduits for upward migrating hydrocarbons the seepage of hydrocarbons is suspected to have caused local eutrophication or fertilization by providing nutrients to bacteria which in turn are part of the food chain for higher organisms the dominant organism in the porcupine basin examples appears to be the deep water coral lophelia sp whereas in the vulcan sub basin the mounds appear to be halimeda dominated

palaeoenvironments in the southern baltic sea basin during marine isotope stage 3 a multi proxy reconstruction abstract sediment cores from kriegers flak in the southwestern baltic sea provide a unique possibility to study the middle weichselian history of the baltic basin three weichselian interstadial units have been identified and are attributed to marine isotope stage 3 mis 3 60 25 ka the oldest unit a is characterized by a deglaciation sequence gradually turning into brackish water clay the low diversity benthic foraminiferal fauna stable oxygen isotope values and mg ca ratios indicate low temperature and salinity for unit a a hiatus separates unit a from the overlying unit b which was deposited in wetlands and shallow lakes between 42 and 36 cal ka bp macrofossil and pollen analyses indicate deposition of unit b in an area dominated by a tree less open tundra environment possibly with some birch and pine in sheltered positions the uppermost unit c is characterized by clay deposition including redeposition of material from older sediments unit b optically stimulated luminescence osl ages indicate deposition of unit c between 26 and 28 5 ka radiocarbon ages of 39 and 40 cal ka bp for unit c are considered to be too old the following depositional model is suggested i isostatic depression of the region after an advance of the scandinavian ice sheet sis most likely the ristinge ice advance previously dated to c 55 50 ka enabled an inflow of marine waters into the baltic basin during the deposition of unit a ii isostatic rebound caused a regression at kriegers flak and a hiatus between units a and b iii wetlands and smaller lakes formed in the uplifted area between 42 and 36 cal ka bp unit b iv deposition of glaciolacustrine clays at kriegers flak demonstrates that a growing sis dammed kattegat and the baltic basin c 28 5 to 26 ka the new evidence from kriegers flak provides a solid framework for future mis 3 palaeoenvironmental reconstructions in the circum baltic area

historical eruptions of merapi volcano central java indonesia 1768 1998 abstract information on merapi eruptive activity is scattered and much is remotely located a concise and well documented summary of this activity has been long needed to assist researchers and hazard mitigation efforts and the aim of this paper is to synthesize information from the mid 1700s to the present a descriptive chronology is given with an abbreviated chronology in a table that summarizes events by year assigns preliminary volcanic explosivity index vei ratings and hartmann classifications and provides key references the history of volcano monitoring is also outlined the study reveals that a major difference in eruption style exists between the twentieth and nineteenth centuries although the periodicity between larger events seems about the same during the twentieth century activity has comprised mainly the effusive growth of viscous lava domes and lava tongues with occasional gravitational collapses of parts of oversteepened domes to produce the nuees ardentes commonly defined as merapi type in the 1800s however explosive eruptions of relatively large size occurred to vei 4 and some associated fountain collapse nuees ardentes were larger and farther reaching than any produced in the twentieth century these events may also be regarded as typical eruptions for merapi the nineteenth century activity is consistent with the long term pattern of one relatively large event every one or two centuries based on the long term eruptive record deduced by others from volcanic stratigraphy it is uncertain whether or not a recurrence time model continues to apply to merapi but if so merapi could soon be due for another large event and its occurrence with only modest or inadequately appreciated precursors could lead to a disaster unprecedented in merapi s history because the area around the volcano is now much more densely populated

mount st helens and santiaguito lava domes the effect of short term eruption rate on surface texture and degassing processes in order to assess the effect of eruption rate on the surface morphology and degassing mechanisms of silicic lava flows we studied surface characteristics and obtained water content and hydrogen isotopic values of samples from flows at the mount st helens and santiaguito lava domes we compared the surface textures and inferred degassing processes to short term extrusion rates and found that when domes are small and eruption rates are high lava will not completely degas in transit to the surface allowing additional volatile loss through surface vesiculation which results in the formation of a scoriaceous carapace when domes exceed a critical size and or their cooled crusts reach a critical strength emergence of new magma is impeded short term eruption rates decline and more thorough degassing can take place leading to smooth textured flows lacking scoria development at mount st helens this transition occurred during the dome s third year when it grew from 31 8 to 53 2 106 m3 santiaguito attained a comparable state after 2 3 years of growth and for most of its 70 year history has produced non vesicular lava degassing patterns that combine closed open and kinetic processes can be distinguished using isotope data obtained from samples whose positions on a flow and emplacement histories are well constrained evidence for these patterns is most clearly preserved in lavas erupted during early rapid stages of dome growth petrologists and volcanologists seeking to infer magma chamber conditions from the volatile contents of extruded lavas thus need to sample flows early in their emplacement while paying attention to surface texture position relative to the vent and flow front and time of emergence

merapi 2010 eruption chronology and extrusion rates monitored with satellite radar and used in eruption forecasting abstract despite dense cloud cover satellite borne commercial synthetic aperture radar sar enabled frequent monitoring of merapi volcano s 2010 eruption near real time interpretation of images derived from the amplitude of the sar signals and timely delivery of these interpretations to those responsible for warnings allowed satellite remote sensing for the first time to play an equal role with in situ seismic geodetic and gas monitoring in guiding life saving decisions during a major volcanic crisis our remotely sensed data provide an observational chronology for the main phase of the 2010 eruption which lasted 12 days 26 october 7 november 2010 unlike the prolonged low rate and relatively low explosivity dome forming and collapse eruptions of recent decades at merapi the eruption began with an explosive eruption that produced a new summit crater on 26 october and was accompanied by an ash column and pyroclastic flows that extended 8 km down the flanks this initial explosive event was followed by smaller explosive eruptions on 29 october 1 november then by a period of rapid dome growth on 1 4 november which produced a summit lava dome with a volume of 5 10 6 m 3 a paroxysmal vei 4 magmatic eruption with ash column to 17 km altitude destroyed this dome greatly enlarged the new summit crater and produced extensive pyroclastic flows to 16 km radial distance in the gendol drainage and surges during the night of 4 5 november the paroxysmal eruption was followed by a period of jetting of gas and tephra and by a second short period 12 h of rapid dome growth on 6 november the eruption ended with low level ash and steam emissions that buried the 6 november dome with tephra and continued at low levels until seismicity decreased to background levels by about 23 november our near real time commercial sar documented the explosive events on 26 october and 4 5 november and high rates of dome growth 25 m 3 s 1 an event tree analysis for the previous 2006 merapi eruption indicated that for lava dome extrusion rates 1 2 m 3 s 1 the probability of a large 1872 scale eruption was 10 consequently the order of magnitude greater rates in 2010 along with the explosive start of the eruption on 26 october the large volume of lava accumulating at the summit by 4 november and the rapid and large increases in seismic energy release deformation and gas emissions were the basis for warnings of an unusually large eruption by the indonesian geological agency s center for volcanology and geologic hazard mitigation cvghm and their volcano research and technology development center bpptk in yogyakarta warnings that saved thousands of lives

10 000 years of explosive eruptions of merapi volcano central java archaeological and modern implications abstract stratigraphy and radiocarbon dating of pyroclastic deposits at merapi volcano central java reveals 10 000 years of explosive eruptions highlights include 1 construction of an old merapi stratovolcano to the height of the present cone or slightly higher our oldest age for an explosive eruption is 9630 60 14 c y b p construction of old merapi certainly began earlier 2 collapse s of old merapi that left a somma rim high on its eastern slope and sent one or more debris avalanche s down its southern and western flanks impoundment of kali progo to form an early lake borobudur at 3400 14 c y b p hints at a possible early collapse of merapi the latest somma forming collapse occurred 1900 14 c y b p the current cone new merapi began to grow soon thereafter 3 several large and many small buddhist and hindu temples were constructed in central java between 732 and 900 a d roughly 1400 1000 14 c y b p explosive merapi eruptions occurred before during and after temple construction some temples were destroyed and or buried soon after their construction and we suspect that this destruction contributed to an abrupt shift of power and organized society to east java in 928 a d other temples sites though were occupied by caretakers for several centuries longer 4 a partial collapse of new merapi occurred 14 c y b p eruptions 700 800 14 c y b p 12 14th century a d deposited ash on the floors of still occupied candi sambisari and candi kedulan we speculate but cannot prove that these eruptions were triggered by the same partial collapse of new merapi and that the eruptions in turn ended caretaker occupation at candi sambisari and candi kedulan a new or raised lake borobudur also existed during part or all of the 12 14th centuries probably impounded by deposits from merapi 5 relatively benign lava dome extrusion and dome collapse pyroclastic flows have dominated activity of the 20th century but explosive eruptions much larger than any of this century have occurred many times during merapi s history most recently during the 19th century are the relatively small eruptions of the 20th century a new style of open vent less hazardous activity that will persist for the foreseeable future or alternatively are they merely low level background activity that could be interrupted upon relatively short notice by much larger explosive eruptions the geologic record suggests the latter which would place several hundred thousand people at risk we know of no reliable method to forecast when an explosive eruption will interrupt the present interval of low level activity this conclusion has important implications for hazard evaluation

controls on shell mg ca and sr ca in cultured planktonic foraminiferan globigerinoides ruber white mg ca and sr ca ratios were determined on a single species of planktonic foraminiferan globigerinoides ruber white collected from the gulf of eilat and cultured in seawater at five different salinities 32 to 44 five temperatures 18 to 30 c and four ph values 7 9 to 8 4 the mg ca temperature calibration of cultured g ruber with an exponential slope of 8 3 c agrees well with previously published calibrations from core tops and sediment traps however the dependence of mg ca on salinity with an exponential slope of 5 3 psu is also significant and should be included in the calibration equation with this purpose we calculated a calibration equation for g ruber dependent on both temperature and salinity within the 95 confidence limits mg ca mmol mol exp 0 06 0 02 s psu 0 08 0 02 t c 2 8 1 0 r2 0 95 the influence of ph on mg ca ratios is negligible at ambient seawater ph 8 1 to 8 3 however we observe a dominating ph control on shell mg ca when the ph of seawater is lower than 8 0 sr ca in g ruber shows a significant positive correlation with average growth rate presumably part of the variability in shell sr ca in the geological record is linked to changes in growth rates of foraminifera as a response to changing environmental conditions

pre eruptive reheating during magma mixing at quizapu volcano and the implications for the explosiveness of silicic arc volcanoes effusive explosive transitions are observed in volcanoes erupting water rich magmas that lack mineralogical evidence of degassing suggesting that gas loss occurred rapidly and ascent was fast despite the high viscosity of rhyodacitic to rhyolitic melts here we show that pre eruptive heating of water rich silicic magma by mixing with hot recharge in subvolcanic chambers controls the effusive explosive transition volcan quizapu chile emitted a 5 km3 mingled dacite andesite lava flow in a d 1846 1847 that was 130 c hotter than the 5 km3 of the same dacite that lead to a plinian eruption in a d 1932 we explain the suppression of explosive fragmentation in the 1846 1847 lavas by enhanced syneruptive magma degassing as a consequence of late reheating following mixing with andesite recharge higher magma temperatures led to the transitioning into effusive eruptive behavior by significantly accelerating volatile diffusion and lowering melt viscosity which facilitated bubble nucleation growth and coalescence while also inhibiting brittle fragmentation thus recharge by mafic magmas in subvolcanic magma chambers may reduce the risk of explosive eruptions in cases where heat can be efficiently transferred to cold volatile rich silicic magmas

earthquake induced variations in extrusion rate a numerical modeling approach to the 2006 eruption of merapi volcano indonesia abstract extrusion rates during lava dome building eruptions are variable and eruption sequences at these volcanoes generally have multiple phases merapi volcano java indonesia exemplifies this common style of activity merapi is one of indonesia s most active volcanoes and during the 20th and early 21st centuries effusive activity has been characterized by long periods of very slow

middle weichselian palaeolacustrine basin in the venta river valley and vicinity northwest lithuania exemplified by the purviai outcrop abstract investigations of the middle weichselian sequences in the baltic region are of great importance for determination of the extent of the middle weichselian glaciation especially during mis 4 and palaeogeography of mis 3 an extensive area of distribution of palaeolacustrine sediments sand clay silt with humus and interlayers of peat ca 80 km 2 occurring under the relief forming upper weichselian till was determined in the vicinity of venta northwest lithuania in the course of geological mapping the investigations of the purviai outcrop in the venta river valley included pollen analysis lithology determination of mollusca and radiocarbon dating the sequence of the purviai outcrop reflects the presence of nonglacial palaeoenvironments before the late weichselian ice advance two intervals containing pollen and spores lpaz i and lpaz ii were identified and interpreted as two separate climatostratigraphic events lpaz i showing severe conditions cryomer and lpaz ii showing slight climatic improvement thermomer during the deposition of the lpaz i the main composition of the local vegetation included cyperaceae and artemisia the pollen record of lpaz 1 shows cold wet severe periglacial conditions with an open landscape and sedge communities during the formation of lpaz ii the surrounding territory was covered by park tundra with birch pine and some admixture of scattered spruce dwarf birch and juniper two radiocarbon dates from the sediments containing pollen and spores were obtained 33 540 370 calbp and 33 800 460 calbp the cryomer i lpaz and the thermomer ii lpaz of the purviai outcrop are tentatively correlated respectively with the nemunas 2d cryomer and the mickunai 3 thermomer in south east lithuania where these units form a middle weichselian interstadial complex tentatively the purviai units are correlated with the denekamp interstadial complex the presence of the venta palaeolacustrine basin implies that north lithuania was ice free 33 ka bp

mg ca paleothermometry in high salinity environments planktonic foraminiferal mg ca ratios have become a fundamental temperature proxy in past climate reconstructions however in the highly evaporative seas of the tropics and subtropics anomalously high planktonic foraminiferal mg ca ratios arise possibly linked to high salinities the extent to which salinity affects mg uptake into foraminiferal calcite remains disputed some studies suggest only minor salinity effects whereas others suggest a dominant role here we present new data from the highly saline 40 red sea which separate pure foraminiferal calcite from other phases the results show that high mg ca ratios 7 to 13 mmol mol found by conventional analysis of planktonic foraminifera from a red sea sediment core are not caused by increased mg uptake into foraminiferal calcite in a high salinity setting e g beyond those predicted by culturing studies but instead result from secondary high mg calcite overgrowths the overgrowths likely formed near the sediment seawater interface from caco3 supersaturated interstitial seawater

transitions between explosive and effusive phases during the cataclysmic 2010 eruption of merapi volcano java indonesia transitions between explosive and effusive activity are commonly observed during dome forming eruptions and may be linked to factors such as magma influx ascent rate and degassing however the interplay between these factors is complex and the resulting eruptive behaviour often unpredictable this paper focuses on the driving forces behind the explosive and effusive activity during the well documented 2010 eruption of merapi the volcano s largest eruption since 1872 time controlled samples were collected from the 2010 deposits linked to eruption stage and style of activity these include scoria and pumice from the initial explosions dense and scoriaceous dome samples formed via effusive activity as well as scoria and pumice samples deposited during subplinian column collapse quantitative textural analysis of groundmass feldspar microlites including measurements of areal number density mean microlite size crystal aspect ratio groundmass crystallinity and crystal size distribution analysis reveal that shallow pre and syn eruptive magmatic processes acted to govern the changing behaviour during the eruption high an up to 80 mol an microlites from early erupted samples reveal that the eruption was likely preceded by an influx of hotter or more mafic magma transitions between explosive and effusive activity in 2010 were driven primarily by the dynamics of magma ascent in the conduit with degassing and crystallisation acting via feedback mechanisms resulting in cycles of effusive and explosive activity explosivity during the 2010 eruption was enhanced by the presence of a plug of cooled magma within the shallow magma plumbing system which acted to hinder degassing leading to overpressure prior to initial explosive activity

marginal marine environments of the skagerrak and kattegat a baseline study of living stained benthic foraminiferal ecology this is the first detailed investigation of the distribution and ecology of living stained shallow water 0 6 m foraminifera along the skagerrak kattegat coast eastern north sea a total of 25 species 13 agglutinated 12 calcareous are common in the 169 sediment surface samples which were collected from 27 geographic areas the sediment grain size and total organic carbon toc content are strongly variable and the salinity and temperature ranges were 10 31 and 9 30 c respectively at the time of sampling july to october but temperatures down to freezing occur during the winter the species are divided into six environmental categories of which the first five comprise euryhaline and the sixth essentially stenohaline taxa 1 species associated only with marsh plants 2 species basically but not entirely associated with marsh plants 3 species basically but not entirely restricted to non marsh areas 4 species solely recorded in non marsh intertidal to subtidal environments 5 species restricted to subtidal areas 6 species basically living in the most open marine areas in this region marshes have a patchy distribution and they are small and compressed due to low tidal ranges 80 mud ammoscalaria runiana is common only in coarse grained sediments 20 mud with low toc 0 7 there are no marked biogeographic boundaries within the skagerrak kattegat area but 10 of the 25 commonly occurring species have not been reported from the adjacent baltic sea probably partly due to the brackish character of the water there the southern limits of distribution of the northern species elphidium albiumbilicatum ammotium cassis and ophthalmina kilianensis are in the kattegat baltic sea

magma eruption rates of merapi volcano central java indonesia during one century 1890 1992 the magma eruption rates of merapi volcano form 1890 to 1992 are re examined chronologically for this volcano movements of extruded lavas and domes as well as their extrusions are important because they control the modes of the subsequent activities and cause nuees ardentes and lahars the monthly eruption rates varied widely but the cumulative volume of lavas has increased linearly and is expressed as 0 1x106 m3 month the magma production rate of this volcano may have been constant for these 100 years recurrent excessive effusion of lavas is tentatively interpreted by assuming a magma reservoir the averaged eruption rate is small in comparison with other volcanoes such as nyramuragia kilauea and vesuvio however it is remarkable that the activity has been continuous for these 100 years and the total amount of lava discharged during this period reached more than 108 m3 a simple model for the formation of the 1992 lava dome is presented the viscosity of the lavas is probably between 106 and 107 p and the length of the magma conduit is probably less than 10 km

stability of volcanic conduits during explosive eruptions abstract geological evidences of volcanic conduit widening are common in most pyroclastic deposits e g presence of lithic fragments from different depths suggesting a continuous modification of the conduit geometry during volcanic eruptions however the controlling factors of the mechanisms driving conduit enlargement e g erosion local collapse are still partially unclear as well as the influence of conduit geometry on the eruptive dynamics although numerical models have been systematically employed to study volcanic conduits their mechanical stability and the eruptive dynamics related to non cylindrical conduits have been poorly addressed we present here a 1d steady state model which includes the main processes experimented by ascending magmas i e crystallization rheological changes fragmentation drag forces outgassing and degassing and the application of two mechanical stability criteria mohr coulomb and mogi coulomb in order to study the collapse conditions of volcanic conduits during a representative explosive rhyolitic eruption it emerges that mechanical stability of volcanic conduits is mainly controlled by its radial dimension and a minimum radius for reaching stable conditions can be computed as a function of water content and inlet overpressure additionally for a set of input parameters thought typical of explosive rhyolitic volcanism we estimated a minimum magma flux for developing a mechanically stable conduit 7 10 7 3 10 8 kg s results are consistent with the unsteady character usually observed in sub plinian eruptions opposite to mainly stationary plinian eruptions commonly characterized by higher magma discharge rates we suggest that cylindrical conduits represent a mechanically stable configuration only for large radii because the instability conditions are not uniform along the conduit the widening processes probably lead to conduit geometries with depth varying width consequently as our model is able to consider volcanic conduits with depth dependent radius two plausible and previously untested geometries have been studied evidencing major and complex modifications in some eruptive parameters particularly exit pressure and mass discharge rate and suggesting that the geometry acquired by the conduit as it is widened influences the eruptive dynamics

harmonic ionospheric oscillation by the 2010 eruption of the merapi volcano indonesia and the relevance of its amplitude to the mass eruption rate abstract using continuous data from ground based global satellite navigation system gnss receivers in java and sumatra indonesia we studied the response of ionospheric total ionospheric electron content tec to the 2010 nov 5 eruption of the merapi volcano in central java we then compared the results with the case of the 2014 feb 13 eruption of the kelud volcano eastern java the tec showed a quasi periodic oscillation of a frequency 4 mhz with average amplitudes of 0 9 and 1 8 relative to background values lasting for 20 and 120 min for the merapi and kelud eruptions respectively by comparing the two cases together with the 2015 april eruption of the calbuco volcano chile we found the relative tec oscillation amplitude may scale with the mass eruption rate this suggests that the product of such tec oscillation amplitude and the duration provides a new measure for the total volume of the volcanic deposits

drumlinised glaciofluvial and glaciolacustrine sediments on the smaland peneplain south sweden new information on the growth and decay history of the fennoscandian ice sheets during mis 3 abstract dug trenches in sediment cored drumlins on the smaland peneplain southern sweden occurring intermixed with rock cored drumlins revealed sedimentary successions and facies suggesting that the core sediments were primarily deposited proglacially both in glaciolacustrine settings as delta front and more distal deeper water sediments and as glaciofluvial braidplain sediments from the relationship between the drumlin sorted sediment cores and their surficial drape by a till carapace it is concluded that erosion was the main drumlin forming process here reshaping the original sediment morphology into streamlined landforms after which a more or less thick traction till was deposited over the eroded and or deformed ice bed interface drumlin formation probably took place during the last deglaciation over the area the drumlin core sediments in 14 excavated trenches were dated by optically stimulated luminescence osl most retrieved ages fall into two distinct groups both within marine isotope stage 3 c 60 30 ka when plotted as mean osl ages for each site all but two sites fall either into an older age group c 48 56 ka seven sites or into a younger age group c 28 38 ka five sites these age intervals correlate well with the suggested time spans for the ristinge and klintholm ice advances in denmark by ice flowing from the baltic basin westwards terminating in fan shaped patterns these interstadial ice advances in the southwestern sector of the fennoscandian ice sheet give rise to enigmatic questions on the physics and mechanics of ice sheet build up and decay especially as palaeoenvironmental data for northern fennoscandia suggest widespread ice free conditions within roughly the same time fame as the recorded ice advances in the south

benthic foraminiferal mg ca paleothermometry a revised core top calibration core top samples from different ocean basins have been analyzed to refine our current understanding of the sensitivity of benthic foraminiferal calcite magnesium calcium mg ca to bottom water temperatures bwt benthic foraminifera collected from hawaii little bahama bank sea of okhotsk gulf of california ne atlantic ceara rise sierra leone rise the ontong java plateau and the southern ocean covering a temperature range of 0 8 to 18 c were used to revise the cibicidoides mg ca temperature calibration the mg ca bwt relationship of three common cibicidoides species is described by an exponential equation mg ca 0 867 0 049 exp 0 109 0 007 bwt stated errors are 95 ci the temperature sensitivity is very similar to a previously published calibration however the revised calibration has a significantly different preexponential constant resulting in different predicted absolute temperatures we attribute this difference in the preexponential constant to an analytical issue of accuracy some genera notably uvigerina show apparently lower temperature sensitivity than others suggesting that the use of constant offsets to account for vital effects in mg ca may not be appropriate downcore mg ca reproducibility as determined on replicate foraminiferal samples is typically better than 0 1 mmol mol 1 2 s e thus considering the errors associated with the cibicidoides calibration and the downcore reproducibility bwt may be estimated to within 1 c application of the revised core top mg ca bwt data to cenozoic foraminiferal mg ca suggests that seawater mg ca was not more than 35 lower than today in the ice free ocean at 50 ma

textural and mineral chemistry constraints on evolution of merapi volcano indonesia abstract we analyze and compare the textures of merapi lavas basalts and basaltic andesites ranging in age from proto merapi through modern activity with the goal of gaining insights on the temporal evolution of merapi s magmatic system analysis of textural parameters such as phenocryst and microphenocryst crystallinity coupled with crystal size distribution theory provides information about the storage and transport of magmas we combine textural analyses with geochemical investigations for a comprehensive comparison of erupted lavas over time the chemical analyses identify crystal growth processes in magma chambers and underline differences between sample groups our work suggests the occurrence of two distinct histories presumably associated with at least two generally distinct types of rheological behaviors and storage transport systems these behaviors are associated with different plagioclase growth patterns with both groups influenced by late stage shallow decompression degassing induced microlite crystallization both groups contain amphibole crystals that indicate an early period of mid crustal to deep crustal storage of water rich magmas dome lavas from the 20th century eruptive activity indicate quasi steady state nucleation and growth evolution interspersed with episodes of reheating and textural coarsening suggesting residence in magma storage at multiple depths both 10 km and

viscosity of high crystal content melts dependence on solid fraction 1 the rheological properties of suspensions containing high solid fractions are investigated attention is focused on viscosity of silicate and magmatic melt systems a general empirical equation which describes the relative viscosity of suspensions as a function of suspended solid fraction is proposed in the limit of very dilute solid concentrations it reduces to the einstein equation the proposed relationship is satisfactorily applied to reproduce available experimental data relative to silicate melts moreover the extrapolation of the model to very high concentrations is compared with experimental observations on partially melted granite

yampi shelf browse basin north west shelf australia a test bed for constraining hydrocarbon migration and seepage rates using combinations of 2d and 3d seismic data and multiple independent remote sensing technologies abstract the yampi shelf on australia s north west shelf is highly prospective with two discrete hydrocarbon sources producing dry gas and oil to reduce exploration uncertainty relating to gas flushing and poor top seal capacity a study was undertaken to characterise hydrocarbon migration in the area it used a combination of seismic amplitude and structural data integrated with shipboard water column geochemical sniffer wasi data satellite synthetic aperture radar or sar data and aircraft acquired airborne laser fluorosensor alf data data were acquired synchronously and in staged programs to allow both direct comparison and time series analysis of results massive natural dry gas and oil seepage was detected though the relative abilities of wasi sar and alf to detect and characterise this seepage were markedly different the spatial distribution concentration and relative composition of the detected seepage were controlled principally by the regional seal s thickness and capacity rather than by the inherent composition and flux of the migrating hydrocarbons wasi preferentially identified gas seepage often in basin ward locations because the high relative permeability of gas favoured its early leakage even through thick seals sar preferentially identified oil seepage which was episodic and largely restricted to the basin margin at the regional zero edge of seal reflecting the low relative permeability of oil even through thin seals it leaked late alf principally detected low level oil seepage from charged traps and was hence most useful for trap ranking the ability of these remote sensing tools as well as that of seismic data itself to detect hydrocarbons appears critically dependant upon interplays between the relative sensitivity of the assorted tools to detect various hydrocarbon phases and the capacity of the top seal itself the study has demonstrated that the interactions between geology and hydrocarbon charge are predictable and that understanding these interactions is crucial for the reliable interpretation of remote sensing data

osl dating of middle weichselian age shallow basin sediments in western latvia eastern baltic abstract this paper presents the results of the first attempt to date the quaternary sediments of western latvia in the southeast baltic region using luminescence the analyses have been carried out on sandy sediments of the jurkalne formation that are located between upper and lower scandinavian sourced tills previous publications on the origin of the quaternary sediments in the region are reviewed and it is found that there are a wide range of explanations for their processes of formation and their age of formation it is concluded that although the sandy sediments were deposited in freshwater environment although they contain both marine and freshwater fauna and flora a property that is explained by derivation and glaciotectonic deformation and mixing the samples used for dating were collected from surface exposures and boreholes and yield results that range in age from 52 10 ka bp to 26 4 1 ka bp as a result of this study it is suggested that the dated sediments were deposited in a freshwater basin during mis 3 and are overlain by a till deposited by scandinavian ice during the late weichselian mis 2 lgm the underlying till is attributed to a middle weichselian glaciation and tentative suggestions are presented for the age of other deposits that underlie the dated sediment

extrusion cycles during dome building eruptions abstract we identify and quantify controls on the timescales and magnitudes of cyclic periodic volcanic eruptions using the numerical model domeflow de michieli vitturi et al 2010 which was developed by the authors for magma systems of intermediate composition domeflow treats the magma mixture as a liquid continuum with dispersed gas bubbles and crystals in thermodynamic equilibrium with the melt and assumes a modified poiseuille form of the viscous term for fully developed laminar flow in a conduit of cylindrical cross section during ascent magma pressure decreases and water vapor exsolves and partially degasses from the melt as the melt simultaneously crystallizes causing changes in mixture density and viscosity two mechanisms previously proposed to cause periodic eruption behavior have been implemented in the model and their corresponding timescales explored the first applies a stick slip model in which motion of a shallow solid plug is resisted by static dynamic friction as described in iverson et al 2006 for a constant magma supply rate at depth this mechanism yields cyclic extrusion with timescales of seconds to tens of seconds with values generally depending on assumed friction coefficients the second mechanism does not consider friction but treats the plug as a high viscosity newtonian fluid during viscous resistance pressure beneath the degassed plug can increase sufficiently to overcome dome overburden plug weight and viscous forces and ultimately drive the plug from the conduit in this second model cycle periods are on the order of hours and decrease with increasing magma supply rate until a threshold is reached at which point periodicity disappears and extrusion rate becomes steady vanishingly short periods magma volatile content for fixed chamber pressure has little effect on cycle timescales but increasing volatile content increases mass flow rate and cycle magnitude as defined by the difference between maximum and minimum extrusion rates increasing mass flow rate also increases the magnitude of predicted deformation cycles both models have been applied to dome building eruptions using conditions appropriate for the soufriere hills volcano montserrat results suggest that the modeled stick slip mechanism cannot explain the cycles of extrusion and explosion well documented at montserrat timescales of hours however a subset of the simulations for the viscous plug model are consistent with the montserrat data and therefore demonstrate the feasibility of this second formulation

foraminiferal mg ca increase in the caribbean during the pliocene western atlantic warm pool formation salinity influence or diagenetic overprint we constructed a high resolution mg ca record on the planktonic foraminifer globigerinoides sacculifer in order to explore the change in sea surface temperature sst due to the shoaling of the isthmus of panama as well as the impact of secondary factors like diagenesis and large salinity fluctuations the study covers the latest miocene and the early pliocene 5 6 3 9 ma and was combined with 18o to isolate changes in sea surface salinity sss before 4 5 ma sstmg ca and sss show moderate fluctuations indicating a free exchange of surface ocean water masses between the pacific and the atlantic the increase in 18o after 4 5 ma represents increasing salinities in the caribbean due to the progressive closure of the panamanian gateway the increase in mg ca toward values of maximum 7 mmol mol suggests that secondary influences have played a significant role evidence of crystalline overgrowths on the foraminiferal tests in correlation with aragonite sr ca and productivity cyclicities indicates a diagenetic overprint on the foraminiferal tests laser ablation inductively coupled plasma mass spectrometry analyses however do not show significantly increased mg ca ratios in the crystalline overgrowths and neither do calculations based on pore water data conclusively result in significantly elevated mg ca ratios in the crystalline overgrowths alternatively the elevated mg ca ratios might have been caused by salinity as the 18o record of site 1000 has been interpreted to represent large fluctuations in sss and cultivating experiments have shown an increase in mg ca with increasing salinity we conclude that the mg ca record 4 5 ma can only reliably be considered for paleoceanographical purposes when the minimum values not showing any evidence of secondary influences are used resulting in a warming of central caribbean surface water masses after 4 5 ma of 2 c

an overview of the seismicity of merapi volcano java indonesia 1983 1994 abstract from 1982 to 1995 merapi volcano java indonesia experienced two main eruptive cycles from 1984 to 1986 and from 1992 to 1994 each cycle had a duration slightly larger than 2 years four major eruptive events occurred in 1984 1986 1992 and 1994 these eruptions were monitored by a telemetered seismic network we present an overview of the seismicity observed between 1983 and 1995 from seismological observations several types of characteristic events are recognised volcanotectonic earthquakes are standard microearthquakes either shallow an aseismic zone is situated between two seismic zones at a depth between 1 5 and 2 5 km below the summit we postulate that it is a small shallow magma reservoir where magma injected from below can be stored temporarily we try to relate seismic observations during both eruptive cycles to the initial injection of deep magma to the superficial magma system the first eruption in each case seems to involve magma enriched in gas that extrudes the content of the conduit and explodes the old dome a regular outflow of magma follows the initial explosion and gradually a dome is building up then it stops and a period of repose is observed later a second episode of dome growth occurs the height of the dome reaches a maximum corresponding to a state of lithostatic equilibrium the time delay of more than 2 years between the beginning and the end of a cycle may result from crystallisation in a volatile rich magma and from the building up of pressure in the superficial magma pocket some important events like the collapse of the dome on 22 november 1994 are not preceded by any seismic precursor when it reaches a large volume the dome is not stable and is likely to collapse by gravity for instance after the sudden influx of matter or gas or after a heavy rain on merapi tremors are observed but do not always precede a dangerous event

field observations and surface characteristics of pristine block and ash flow deposits from the 2006 eruption of merapi volcano java indonesia abstract a series of pristine block and ash flow deposits from the may june 2006 eruption of merapi represent an exceptional record of small volume pyroclastic flows generated by gravitational lava dome collapses over a period of about two months the deposits form nine overlapping lobes reaching 7 km from the summit in the gendol river valley on the volcano s southern flank which were produced by successive flows generated during and after the major dome collapse event on june 14 both single pulse post june 14 events and multiple pulse pyroclastic flows generated by sustained dome collapses on june 14 are recognised and three types of deposits spread over an area of 4 7 km are distinguished totalling 13 3 10 6 m 3 1 valley confined basal avalanche deposits 11 7 10 6 m 3 in the gendol river valley 2 overbank pyroclastic flow and associated surge deposits 1 4 10 6 m 3 where parts of the basal avalanche spread laterally onto interfluves and were subsequently channeled into the surrounding river valleys and 3 dilute ash cloud surge deposits 0 2 10 6 m 3 along valley margins variations in the distribution surface morphology and lithology of the deposits are related to the source materials involved in individual pyroclastic flow forming events and varying modes of transport and deposition of the different flows inferred flow velocities of the largest block and ash flows generated on june 14 vary from 43 8 13 5 m s for the basal avalanche and from 62 6 24 2 m s for the ash cloud surge the minimum temperatures range from 400 c for the basal avalanche to 165 c for the overlying ash cloud due to the potential of being re channeled into adjacent river valleys and flowing laterally away from the main river channel the overbank pyroclastic flows are considered the most hazardous part of the block and ash flow system the conditions that lead to their development during flow transport and deposition must be taken into account when assessing future pyroclastic flow hazards at merapi and similar volcanoes elsewhere

the geological evolution of merapi volcano central java indonesia merapi is an almost persistently active basalt to basaltic andesite volcanic complex in central java indonesia and often referred to as the type volcano for small volume pyroclastic flows generated by gravitational lava dome failures merapi type nuees ardentes stratigraphic field data published and new radiocarbon ages in conjunction with a new set of 40k 40ar and 40ar 39ar ages and whole rock geochemical data allow a reassessment of the geological and geochemical evolution of the volcanic complex an adapted version of the published geological map of merapi wirakusumah et al 1989 peta geologi gunungapi merapi jawa tengah geologic map of merapi volcano central java 1 50 000 is presented in which eight main volcano stratigraphic units are distinguished linked to three main evolutionary stages of the volcanic complex proto merapi old merapi and new merapi construction of the merapi volcanic complex began after 170 ka the two earliest proto merapi volcanic edifices gunung bibi 109 60 ka a small basaltic andesite volcanic structure on merapi s north east flank and gunung turgo and gunung plawangan 138 3 ka 135 3 ka two basaltic hills in the southern sector of the volcano predate the merapi cone sensu stricto old merapi started to grow at 30 ka building a stratovolcano of basaltic andesite lavas and intercalated pyroclastic rocks this older merapi edifice was destroyed by one or possibly several flank failures the latest of which occurred after 4 8 1 5 ka and marks the end of the old merapi stage the construction of the recent merapi cone new merapi began afterwards mostly basaltic andesite pyroclastic and epiclastic deposits of both old and new merapi 11 792 90 14c years bp cover the lower flanks of the edifice a shift from medium k to high k character of the eruptive products occurred at 1 900 14c years bp with all younger products having high k affinity the radiocarbon record points towards an almost continuous activity of merapi since this time with periods of high eruption frequency interrupted by shorter intervals of apparently lower eruption rates which is reflected in the geochemical composition of the eruptive products the holocene stratigraphic record reveals that fountain collapse pyroclastic flows are a common phenomenon at merapi the distribution and run out distances of these flows have frequently exceeded those of the classic merapi type nuees ardentes of the recent activity widespread pumiceous fallout deposits testify the occurrence of moderate to large subplinian eruptions vei 3 4 during the mid to late holocene vei 4 eruptions as identified in the stratigraphic record are an order of magnitude larger than any recorded historical eruption of merapi except for the 1872 ad and possibly the october november 2010 events both types of eruptive and volcanic phenomena require careful consideration in long term hazard assessment at merapi

woolly mammoth mammuthus primigenius blum and its environment in northern europe during the last glaciation abstract woolly mammoths were large herbivorous cold adapted mammals of the late pleistocene the diet and habitat requirements of the species set certain constraints on the palaeoenvironments it could occupy the relationship between the mammoth s shifting range and changing environments can be explored using independent data on ice sheet configuration temperature and vegetation provided the locality and age of the fossil remains can be validated here we present a comprehensive record of occurrence of the woolly mammoth in the circum baltic region of northern europe during the last glaciation based on a compilation of radiocarbon dated remains the record shows that the mammoth was widespread in northern and north eastern europe during marine isotope stage 3 mis 3 at 50 000 30 000 calibrated years ago 50 30 ka the presence of the species up to 65 n latitude supports the restriction of the scandinavian ice sheet sis during mis 3 the widest distribution range round 30 ka was followed by a decline that led to the disappearance of mammoths from the area during the maximum extent of the sis from 22 to 18 ka the woolly mammoth re colonized the baltic region and southern scandinavia after the onset of the late glacial deglaciation at 17 ka the late glacial record suggests a markedly fluctuating population changing its range in tune with the rapid environmental changes the last appearance of mammoth in our study region was in estonia during the younger dryas greenland stadial 1 gs1 at about 12 ka the two major periods of occurrence during mis 3 and the late glacial stadial suggest that mammoth had a wide tolerance of open to semi open tundra and steppe tundra habitats with intermediately cold climate whereas the 22 18 ka disappearance suggests a major southward and or eastward retreat in response to extremely cold glacial conditions near the sis margin the final regional extinction correlates with the re forestation during the rapid warming at the younger dryas holocene boundary

the impact of salinity on the mg ca and sr ca ratio in the benthic foraminifera ammonia tepida results from culture experiments abstract over the last decade sea surface temperature sst reconstructed from the mg ca ratio of foraminiferal calcite has increasingly been used in combination with the 18o signal measured on the same material to calculate the 18ow a proxy for sea surface salinity sss a number of studies however have shown that the mg ca ratio is also sensitive to other parameters such as ph or co 3 2 and salinity to increase the reliability of foraminiferal mg ca ratios as temperature proxies these effects should be quantified in isolation individuals of the benthic foraminifera ammonia tepida were cultured at three different salinities 20 33 and 40 psu and two temperatures 10 15 c the mg ca and sr ca ratios of newly formed calcite were analyzed by laser ablation icp ms and demonstrate that the mg concentration in a tepida is overall relatively low mean value per experimental condition between 0 5 and 1 3 mmol mol when compared to other foraminiferal species sr being similar to other foraminiferal species the mg and sr incorporation are both enhanced with increasing temperatures however the temperature dependency for sr disappears when the distribution factor dsr is plotted as a function of calcite saturation state this suggests that a kinetic process related to is responsible for the observed dependency of sr incorporation on sea water temperature the inferred relative increase in dmg per unit salinity is 2 8 at 10 c and 3 3 at 15 c for the salinity interval 20 40 psu this implies that a salinity increase of 2 psu results in enhanced mg incorporation equivalent to 1 c temperature increase the dsr increase per unit salinity is 0 8 at 10 c and 1 3 at 15 c for the salinity interval 20 40 psu

interpretation of ground surface changes prior to the 2010 large eruption of merapi volcano using alos palsar aster tir and gas emission data abstract understanding precursory signals is essential to forecast eruptions hazards and mitigate risks satellite observations have been shown to increasingly contribute to this goal we use differential inteferometric synthetic aperture radar d insar and sar backscattering intensity data from alos palsar to define a time series of ground surface displacements for the 2006 2010 inter eruptive period at merapi volcano we correlate trends in the displacement data to trends for summit temperature determined using data from the aster sensor and to gas emission data we show that processing of the satellite data must be performed carefully before meaningful interpretations can be drawn for example after careful removal of the topographic effect on phase delays we detect only subtle inter eruptive episodes of cyclic deformation in the d insar and sar backscattering data these small mostly sub centimeter displacements contrast with meter scale pre eruptive displacements along an electronic distance measurement edm line on the south flank of the volcano we suggest that this difference is a consequence of localized movement within the summit area a result that has important implications for understanding merapi s structure for monitoring network design and for eruption forecasting although small merapi s inter eruptive deformation cycles are also seen in thermal data from aster and gas emissions accordingly we interpret these cycles as the result of successive movement of individual magma batches migrating upward from deeper to shallower storage systems located along a ne dipping conduit in view of magma migration prior to eruptions these cycles may also serve as a precursory signal for large eruptions at merapi such as the one that took place in early november 2010

a simple explanation for the space based calculation of lava eruption rates abstract knowing how lava effusion rates vary during basaltic eruptions can be of great significance when trying to provide preliminary forecasts regarding how far lava will flow however problems exist in accurately determining effusion rates using conventional field based techniques to ameliorate this problem harris et al j geophys res 102 1997 7985 8003 bull volcanol 59 1997 49 64 j volcanol geotherm res 102 2000 237 269 developed a method for determining effusion rates using infrared satellite data and showed how the method could be used to provide realistic estimates of effusion rates repeatedly during several eruptions at kilauea hawai i krafla iceland etna and stromboli italy harris et al j geophys res 102 1997 7985 8003 bull volcanol 59 1997 49 64 indicate that their method allows instantaneous lava effusion rates to be determined thermodynamically by equating the amount of heat lost by an active lava flow derived from the satellite data to the amount of heat liberated by the cooling mass of lava the purpose of this paper is to provide a simpler alternative explanation we find that rather than being used to calculate heat loss harris et al j geophys res 102 1997 7985 8003 bull volcanol 59 1997 49 64 j volcanol geotherm res 102 2000 237 269 actually use the satellite data to estimate the area of active lava present within the satellite s field of view at the movement of data acquisition thus changes in the effusion rates they present can only be proportional to changes in this area the active flow areas were then multiplied by a constant the value of which is obtained from a crude approximation of the lava flows heat balance crucially the absolute value of this term falls within the range of an empirically derived parameter that was found by pieri and baloga j volcanol geotherm res 30 1986 29 45 to explain strong linear correlations between eruption rate i e the time averaged effusion rate and lava flow area for 34 historic hawaiian flows as a result we find that the method of harris et al j geophys res 102 1997 7985 8003 does not yield instantaneous effusion rates but instead provides a valid and useful way to estimate average effusion rates i e the eruption rate from measurements of flow area

emplacement temperatures of the november 22 1994 nuee ardente deposits merapi volcano java abstract a study of emplacement temperatures was carried out for the largest of the 22 november 1994 nuee ardente deposits at merapi volcano based mainly on the response of plastic and woody materials subjected to the hot pyroclastic current and the deposits and to some extent on eyewitness observations the study emphasizes the turgo kaliurang area in the distal part of the area affected by the nuee ardente where nearly 100 casualties occurred the term nuee ardente as used here includes channeled block and ash flows and associated ash clouds of surge and fallout origins the emplacement temperature of the 8 m thick channeled block and ash deposit was relatively high 550 c based mainly on eyewitness reports of visual thermal radiance emplacement temperatures for ash cloud deposits a few cm thick were deduced from polymer objects collected at turgo and kaliurang most polymers do not display a sharp melting range but polyethylene terephthalate used in water bottles melts between 245 and 265 c and parts of the bottles that had been deformed during fabrication molding turn a milky color at 200 c the experimental evidence suggests that deposits in the turgo area briefly achieved a maximum temperature near 300 c whereas those near kaliurang were

a review of the history of the baltic sea 13 0 8 0 ka bp abstract the dynamic history of the baltic sea during the millennia following the last deglaciation has been one of the main topics for many generations of quaternary geologists around the baltic sea based on the present state of knowledge and certain hypotheses a model for the development during the baltic ice lake yoldia sea and ancylus lake stages are presented the oresund strait was the threshold of the initial stage of the baltic ice lake and was eroded down to bedrock as a result of the isostatic uplift the emerging threshold forced the baltic ice lake to rise above sea level at ca 12 0 ka bp this gradual up damming ended at ca 11 2 ka bp when the large glacial lake was lowered 5 10m by possible subglacial drainage at mt billingen a glacial readvance during the younger dryas ended a ca 400 year long land bridge between sweden and the continent by blocking the former drainage route once again the baltic ice lake had to rise above sea level to be drained over the oresund strait at ca 10 5 ka bp a gradual ice recession began and 200 years later when the receding ice sheet could not withhold the up dammed water masses the final drainage of the baltic ice lake occurred which rapidly lowered the water level within the baltic basin with ca 25 m and ended the baltic ice lake stage the next stage the yoldia sea was characterized by a complex pattern of relative sea level changes with large differences within the baltic basin a very restricted baltic sea in the south and thus an extensive landbridge at ca 9 9 ka bp a short 100 200 years saline ingression is seen in the baltic sediment records from stockholm in the north to the southernmost parts of the yoldia sea the gradually shallower strait in south central sweden the narke strait ended the saline influence 300 400 years later the two remaining outlets west of lake vanern gota alv and otteid steinselva had become too shallow to swallow the outflowing yoldia sea waters at this stage the baltic lake vanern level could thus not fall in pace with the relative sea level fall outside the outlet areas this was the isolation of lake vanern and the baltic from the sea and the beginning of the ancylus lake since the water depth of the larger gota alv outlet had to be more or less maintained the ancylus lake level had to rise in pace with the uplift of the outlet region this caused a significant and rapid transgression 10 30 m in ca 300 years in the southern baltic which flooded large areas with recently immigrated pine forests since the oresund strait during the yoldia sea stage had been uplifted more than southerly areas the ancylus transgression ended with a new drainage pathway at ca 9 2 ka bp through the darss sill area in the southern baltic and northwards through the store belt strait this so called dana river had cut off the former large land bridge the quaternary deposits of this new threshold were eroded and a fairly rapid regression set in at ca 9 0 ka bp the dana river had eroded down to the sea level which isolated lake vanern from the ancylus lake and created a land bridge between southern sweden and northwards ca 800 years later when the sea level rose above the oresund threshold marine water could enter the baltic and at ca 8 0 ka bp brackish water characterized the southern baltic this marks the end of the ancylus lake

effects of gas escape and crystallization on the complexity of conduit flow dynamics during lava dome eruptions 1 we investigated the coupled effects of gas escape and crystallization on the dynamics of lava dome eruptions using a one dimensional conduit flow model the relationship between chamber pressure pch and mass flow rate q for steady conduit flow commonly has a regime of negative differential resistance i e dpch dq 0 5 feedback 1 is the main mechanism that forms negative differential resistance in this case the transition from lava dome to explosive eruption occurs when the magma supply rate exceeds a fixed critical value for low phenocryst content magma volume fraction 0 5 feedback 2 plays a key role so that the transition is controlled by the permeability of the surrounding rocks the critical magma supply rate remarkably decreases with decreasing permeability transition due to feedback 2 is associated with a change in the chemical composition of volcanic gas a drastic increase in magma porosity from nearly 0 to greater than 0 8 and overpressure at a shallower level which can be detected from geochemical and geophysical field observations

an absolute chronology for the raised beach and associated deposits at sewerby east yorkshire england the raised beach sediments revealed in the cliffs at sewerby east yorkshire are widely regarded as ipswichian in age previously reported evidence for this dating is reviewed and new results from a range of luminescence dating techniques applied to the blown sand deposit overlying the raised beach are reported these provide the first absolute date for the sewerby site of 120 84 11 82 ka which places the blown sand at the boundary between oxygen isotope stages ois 5e and 5d as the underlying raised beach is little older than the blown sand it probably formed during ois stage 5e as suggested by the faunal evidence

rapid sea level fall and deep ocean temperature change since the last interglacial period we have dated huon peninsula papua new guinea and barbados corals that formed at times since the last interglacial period applying both 230 th and 231 pa dating techniques as a test of age accuracy we show that marine isotope stage mis 5e ended prior to 113 1 8 0 7 kyr when sea level was 319 m during mis 5b sea level was 357 m at 92 6 8 0 5 kyr having dropped about 40 m in approximately 10 kyr during the mis 5c 5b transition sea level then rose more than 40 m during the mis 5b 5a transition also in about 10 kyr mis 5a lasted until at least 76 2 8 0 4 kyr at a level of 324 m at that time combined with earlier data that places mis 4 sea level at 381 m at 70 8 kyr our late mis 5a data indicate that sea level fell almost 60 m in less than 6 kyr 10 6 m kyr during the mis 5 4 transition the magnitude of the drop is half that of the glacial interglacial amplitude and approximatelyequivalent to the volume of the present dayantarctic ice sheet during this interval the minimum average rate of net continental ice accumulation was 18 cm yr likely facilitated by efficient moisture transport from lower latitudes at three specific times 60 6 8 0 3 50 8 8 0 3 and 36 8 0 2 kyr during mis 3 sea level was between 385 and 374 m sea level then dropped to 3107 m at 23 7 8 0 1 kyr early in mis 2 before dropping further to last glacial maximum lgm values and then rising to present values during the last deglaciation times of rapid sea level drop correspond to times of high winter insolation at low northern latitudes and high winter latitudinal gradients in northern hemisphere insolation supporting the idea that these factors mayhave resulted in high water vapor pressure in moisture sources and efficient moisture transport to high latitude glaciers therebycontributing to glacial buildup we combined our sea level results with deep sea n 18 o records as a means of estimating the temperature and ice volume components in the marine n 18 o record this analysis confirms large deep ocean temperature shifts following mis 5e and during termination i deep ocean temperatures changed bymuch smaller amounts between mis 5c and 2 maximum temperature shift in the deep pacific is about 2 whereas the shift at a site in the atlantic is 4 under glacial conditions temperatures at both sites are near the freezing point the shift in the atlantic is likelycaused bya combination of changing proportions of northern and southern source waters as well as changing temperature at the sites where these deep waters form

millennial scale variability during the last glacial the ice core record the oxygen isotope records from greenland ice cores show a very strong reproducible pattern of alternation between warm greenland interstadials gi and cold greenland stadials gs at millennial scale during the last glacial period here we summarise what is known about this variability from ice core records the typical cycle has a sawtooth pattern with a very rapid warming event occurring in a few decades a slow cooling trend and then a final fast cooling 25 such events have been numbered in the last glacial the recent gicc05 age scale provides the best available age scale that can be directly applied to this stratigraphy and we summarise the timing of the warming events and the length and strength of each event the greenland stratigraphy can be transferred to other records if we make assumptions about the contemporaneous nature of rapid events in different archives other parameters such as the snow accumulation rate and the concentration of terrestrial dust and sea salt recorded in the greenland cores also show a strong contrasting pattern between gi and gs methane concentrations are generally high during gi and lower during gs with the increase from gs to gi occurring within a century antarctic ice cores show a different pattern each gi has an antarctic counterpart but antarctica appears to warm while greenland is in a gs and cool during gi these changes are consistent with a mechanism involving ocean heat transport but the rapid nature of warmings poses a challenge for modellers while the rapid methane changes pose questions about the pattern of land biosphere emissions during the glacial that are also relevant for understanding glacial interglacial methane variability

insights into volcanic conduit flow from an open source numerical model 1 numerical models that calculate the fluid dynamics of explosive volcanic eruptions have been used with increasing frequency to understand volcanic processes and evaluate volcanic hazards yet those who develop such models rarely make them publicly available so that they can be verified used and possibly improved by other scientists in this paper i present a visual interactive open source numerical model that calculates steady state flow of magma and gas in vertical eruptive conduits and contains user friendly utilities for quickly determining physical thermodynamic and transport properties of silicate melts h2o gases and melt gas crystal mixtures the model represents an advance over previously published conduit models by incorporating a non arrhenian viscosity relation for hydrous silicate melts a relation between viscosity and volume fraction of gas that depends on capillary number and adiabatic temperature changes in the mixture using established thermodynamic relations for melts and h2o gas respectively volcanologists who have not had access to conduit models have frequently approximated conduit flow using an analytical equation for incompressible laminar newtonian pipe flow which predicts that the mass flux is proportional to the fourth power of conduit radius and inversely proportional to mixture viscosity the model presented here which is not much more difficult to use than a back of the envelope calculation shows that the pipe flow approximation significantly overestimates the sensitivity of mass flux to both conduit radius and mixture viscosity results from the model also show that viscous heating in the lower conduit which is not considered in most other models may increase the mass flux of large silicic eruptions by several percent and decrease the viscosity of the mixture at the fragmentation depth by a few tens of percent

evaluation of the impact of the 2010 pyroclastic density currents at merapi volcano from high resolution satellite imagery field investigations and numerical simulations the 2010 pyroclastic density currents pdc at merapi have presented a rare opportunity to collect a uniquely detailed dataset of the source extent lateral variations and impact of various pdc deposits on a densely populated area using traditional volcanological field based methods and a multi temporal dataset of high resolution satellite imagery a total of 23 pdc events have been recognized including 5 main channeled flows 15 overbank flows derived from overspill and re channelization of the main pdcs into adjacent tributaries and two main surge events the 2010 pdc deposits covered an area of 22 3 km2 unequally distributed between valley filling 6 9 overbank 22 4 and surge and associated fallout deposits 71 7 their total estimated non dre volume is 36 3 106 m3 with 50 2 of this volume accounting for valley filling deposits 39 3 for overbank deposits and 10 5 for surge and associated fallout deposits more than 70 of the total volume was deposited during the third eruptive phase 4 5 november and only 16 6 11 5 and 0 9 during the first 26 29 october second 30 october 3 november and fourth phase 6 23 november respectively the internal architecture and lithofacies variations of the 2010 pdc deposits were investigated using data collected from 30 stratigraphic sections measured after one rainy season of erosion the results show that complex local scale variations in flow dynamics and deposit architectures are apparent and that the major factors controlling the propagation of the main flows and their potential hazards for overbanking were driven by 1 the rapid emplacement of several voluminous pdcs associated with the steady infilling of the receiving landscape after the two first phases of the eruption 2 longitudinal changes in channel capacity following increased sinuosity in the valley and decreased containment space and 3 the effects of varying source mechanisms gravitational dome collapse vertical or lateral dome explosions and column collapse and source materials involved during individual pdc forming events integration of these data into numerical simulations of the channeled and overbank pdcs of the third eruptive phase 4 5 november using two well established geophysical mass flow models titan2d and volcflow allow us to evaluate the ability of these models to reproduce the main features of the natural deposits and some of the flow overbanking processes observed in the field using such a multi technique approach the dataset obtained in this study not only characterizes the pdcs and related hazards at merapi but will allow comparisons with similar events at other volcanoes around the globe

temperature evolution during magma ascent in basaltic effusive eruptions a numerical application to stromboli volcano the dynamics of magma ascent are controlled by the complex interdependent processes of crystallisation rheological evolution gas exsolution outgassing non ideal gas expansion and temperature evolution temperature changes within the conduit in particular play a key role on ascent dynamics since temperature strongly controls the crystallisation process which in turn has an impact on viscosity and thus on magma ascent rate the cooling produced by gas expansion is opposed by the heat produced by crystallisation and therefore the temperature profile within the conduit is quite complex this complexity means that unravelling the dynamics controlling magma ascent requires a numerical model unfortunately comprehensive integrated models with full thermodynamic treatment of multiple phases and rheological evolution are challenging to produce due to the numerical challenges involved until now models have tended to focus on aspects of the problem without a holistic approach in which petrological thermodynamic rheological and degassing processes and their interactions were all explicitly addressed and quantified here we present a new multiphase steady state model for magma ascent in which the main physical and chemical processes such as crystallisation degassing outgassing rheological evolution and temperature variations are quantitatively calculated basaltic magma s crystallisation and flow are sensitive to initial temperature and volatile content and therefore we investigate temperature variations during magma ascent in a basaltic system with a range of volatile contents as a test case we use one of the most well studied recent basaltic effusive eruptions the 2007 eruption of stromboli italy assuming equilibrium crystallisation and exsolution we compare the solutions obtained both with and without an isothermal constraint finding that temperature variations within the conduit have a significant influence on the ascent dynamics and therefore cannot be ignored when modelling basaltic volcanism furthermore we find good agreement between model results and volcanological observations when the non isothermal condition is assumed we investigate through a sensitivity analysis the role of magma chamber temperature on mass flow rate and crystal content we find that a temperature variation of 30 k at the base of the conduit has a bigger effect on mass discharge rate than an increase of 1 wt in water content finally we find that whilst variations in initial co2 concentration can affect the temperature pressure and viscosity profiles along the conduit they do not alter the macroscopic behaviour of the system c 2015 elsevier b v all rights reserved

paroxysmal dome explosion during the merapi 2010 eruption processes and facies relationships of associated high energy pyroclastic density currents an 11 minute sequence of laterally directed explosions and retrogressive collapses on 5 november 2010 at merapi indonesia destroyed a rapidly growing dome and generated high energy pyroclastic density currents pdcs spreading over 22 km2 with a runout of 8 4 km while contemporaneous co genetic valley confined pdcs reached 15 5 km this event formed stage 4 of the multi stage 2010 eruption the most intense eruptive episode at merapi since 1872 the deposits and the widespread devastating impact of associated high energy pdcs on trees and buildings show striking similarities with those from historical volcanic blasts montagne pelee martinique bezymianny russia mount st helens usa soufriere hills montserrat we provide data from stratigraphic and sedimentologic analyses of 62 sections of the first unequivocal blast like deposits in merapi s recent history we used high resolution satellite imagery to map eruptive units and flow direction from the pattern of extensive tree blowdown the stratigraphy of stage 4 consists of three depositional units u0 u1 u2 that we correlate to the second third and fourth explosions of the seismic record both u1 and u2 show a bi partite layer stratigraphy consisting each of a lower l1 layer and an upper l2 layer the lower l1 layer is typically very coarse grained fines poor poorly sorted and massive and was deposited by the erosive waxing flow head the overlying l2 layer is much finer grained fines rich moderately to well sorted with laminar to wavy stratification l2 was deposited from the waning upper part and wake of the pdc field observations indicate that pdc height reached 330 m with an internal velocity of 100 m s 1 within 3 km from the source the summit s geometry and the terrain morphology formed by a major transversal ridge and a funneling deep canyon strongly focused pdc mass towards a major constriction thereby limiting the loss of kinetic energy this favored elevated pdc velocities and high particle concentration promoted overspilling of pdcs across high ridges into other river valleys and generated significant dynamic pressures to distances of 6 km that caused total destruction of buildings and the forest the merapi 2010 eruption highlights that explosive and gravitational disintegration of a rapidly growing dome can generate devastating high energy high velocity pdcs this constitutes a credible high impact scenario for future multi stage eruptions at merapi and at other volcanoes that pose particular monitoring crisis response and risk reduction challenges

reconciliation of late quaternary sea levels derived from coral terraces at huon peninsula with deep sea oxygen isotope records a major discrepancy between the late quaternary sea level changes derived from raised coral reef terraces at the huon peninsula in papua new guinea and from oxygen isotopes in deep sea cores is resolved the two methods agree closely from 120 ka to 80 ka and from 20 ka to 0 ka ka 1000 yr before present but between 70 and 30 ka the isotopic sea levels are 20 40 m lower than the huon peninsula sea levels derived in earlier studies new high precision u series age measurements and revised stratigraphic data for huon peninsula terraces aged between 30 and 70 ka now give similar sea levels to those based on deep sea oxygen isotope data planktonic and benthic 18o data using the sea level and deep sea isotopic data oxygen isotope ratios are calculated for the northern continental ice sheets through the last glacial cycle and are consistent with results from greenland ice cores the record of ice volume changes through the last glacial cycle now appears to be reasonably complete