magma sediment mingling in an ordovician rift basin the plouezec plourivo half graben armorican massif france the plouezec plourivo basin ppb armorican massif is an ordovician half graben filled with red bed deposits lying on a cadomian metamorphic basement peperites crop out along its northeast coastal sector in connection with diverse magmatic and hydrothermal products combining field structural observations and geochemical analyses of magmatic rocks leads us to propose a model of emplacement of peperites in an extensional setting the ppb peperites result from mingling between magma and initially wet sediment the main corresponding facies consist of rounded magmatic bodies corrugated lava sediment contacts and a remarkable thin sheet of fluidized sediment extending over about 100 m parallel and c 10 cm above the base of a porphyritic lava flow a few ppb peperites formed under a dominant brittle regime are autoclastic breccias at the base of a lava flow and polymict breccias including both fluidal and blocky volcanic clasts sediment fluidization formation of vapor films magma sediment density contrasts and non explosive fragmentation are the main mechanisms invoked to generate the ppb peperites the c 100 m extended sediment derived sheet lying near the base of a lava flow likely formed by diapiric rise of fluidized sediment through molten lava we show that silicic contamination accompanied these peperitic processes

application of fluid rock reaction studies to in situ recovery from oil sand deposits alberta canada ii mineral transformations during an experimental statistical study of water bitumen shale reactions abstract solution mineral equilibria were calculated for the aqueous phase and x ray diffractograms obtained for the solids from the factorial experiment reported in part i of this series of papers in which a shale from the lower cretaceous mcmurray formation in the athabasca oil sand deposit of alberta in the presence or absence of bitumen was subjected to hydrothermal treatment with aqueous fluids of varying ph and salinity at two different temperatures for periods up to 92 hours data representing the departures from equilibrium and normalized x ray diffraction peak intensities were studied by statistical analysis of variance in addition to the dissolution of quartz montmorillonite was formed probably through a transitional illite montmorillonite interstratined layer structure with the reaction being favored by high ph of the aqueous phase the dissolution of siderite is significantly affected by time salinity and the interactions between ph and salinity time and salinity and ph temperature and time despite the restrictions imposed by a laboratory investigation the results demonstrate that mineral dissolution and transformation will be extensive during in situ recovery operations in oil sand deposits

sea level change along the italian coast during the holocene and projections for the future published and new sea level data are used to provide projections of sea level change in italy for the year 2100 by adding new isostatic and tectonic component to the ipcc and rahmstorf projections comparison of the observations from more than 130 sites with different geomorphological and archaeological sea level markers with the predicted sea level curves provides estimates of the vertical tectonic contribution to the relative sea level change the results are based on the most recent anu model for the ice sheets of both hemispheres including an alpine deglaciation model on the basis of the eustatic tectonic and isostatic components to the sea level change projections are provided for marine inundation scenarios for the italian coastal plains for the year 2100 that today are at elevations close to current sea level

geoscience rediscovers phoenicia s buried harbors after centuries of archaeological debate the harbors of phoenicia9s two most important city states tyre and sidon have been rediscovered and including new geoarcheological results reveal how where and when they evolved after their bronze age foundations the early ports lie beneath their present urban centers and we have indentified four harbor phases 1 during the bronze age tyre and sidon were characterized by semi open marine coves that served as protoharbors 2 biostratigraphic and lithostratigraphic data indicate the presence of early artificial basins after the first millennium b c 3 the harbors reached their apogees during the greco roman and byzantine periods 4 silting up and coastal progradation led to burial of the medieval basins lost until now

changes of relative sea level during the past 5000 years in the ancient harbor of marseilles southern france in the ancient harbor of marseilles marine fauna fixed upon archaeological structures as well as bio sedimentary units document a 1 5 m steady rise in relative sea level during the past 5000 years followed by a near stable level at present datum from about 1500 years ad to the last century this trend is similar to the one previously documented along the rocky coasts of the same region field observations inside and outside the harbor confirm that no sea level stand higher than the present ever occurred during the studied period in contradiction with the numerical model of peltier but in agreement with the glacio hydro isostatic models of lambeck and johnston and lambeck and bard q 2001 elsevier science b v all rights reserved

a new view of italian seismicity using 20 years of instrumental recordings in this paper we show the seismicity of the past 20 years that occurred in italy and surrounding regions hypocentral locations have been obtained by using p and s wave arrival times from the ingv national and several regional permanent seismic networks more than 48 000 events selected from an original data set of about 99 780 are used to reconstruct the most complete seismic picture of the italian region so far the seismicity distribution allows inference on seismotectonics of this complex region of subduction versus continental collision our results clearly reveal the geometry of the adria and the ionian subduction and a continuous normal fault belt in the upper crust following the apennines mountain range the depth of the seismogenic layer is computed from the cut off of seismicity at depth and shows large variations along and across the seismic active regions earthquakes are generated by the different velocity of slab retreat and the subsequent asthenospheric upwelling d 2004 elsevier b v all rights reserved

late quaternary slip rates on the acireale piedimonte normal faults and tectonic origin of mt etna sicily abstract mt etna is located along the east coast of sicily near the boundary between the continental crust of the hyblean plateau and the mesozoic oceanic crust of the ionian basin the main active faults near mt etna cut the base of its eastern flank forming a 30 km long system of nne and nnw trending ene chelon fault segments the acireale piedimonte system showing dip slip and oblique right lateral motion most segments are associated with shallow depth seismicity and all have late pleistocene to holocene vertical slip rates ranging between 1 and 2 mm yr typical of major active normal faults worldwide eruptive fissures arranged in nne to ne trending zones cut the highest slopes of the volcano on the footwall of the normal fault system structural analysis suggests that current motions along both the active faults and eruptive fissures are kinematically compatible and simply linked with ongoing wnw ese directed regional extension such extension characterizes at a greater scale the active tectonics of southern italy where all large shallow historical earthquakes have remained confined within a narrow normal fault belt or rift zone stretching from the northern calabrian arc to southeastern sicily the southernmost west dipping faults of that rift zone in calabria aspromonte cut across the calabro peloritan thrust belt to join the mostly east dipping acireale piedimonte faults along the western boundary of ionian oceanic lithosphere which continues southwards as the malta escarpment we thus relate magmatism at etna to dilational strain on the footwall of an east facing crustal scale normal fault at the bend where the siculo calabrian rift zone veers 60 eastwards as it begins to cross the calabrian arc leaving the east facing margin of the ionian sea to catch up with the west facing margin of the tyrrhenian sea farther north

volcano sedimentary characteristics in the abu treifiya basin cairo suez district egypt example of dynamics and fluidization over sedimentary and volcaniclastic beds by emplacement of syn volcanic basaltic rocks abstract this paper describes the neogene lava sediment mingling from the abu treifiya basin cairo suez district egypt the lava sediment interactions as peperites have been identified for the first time at the study area and can be used as paleoenvironmental indicators the identification of peperite reflects contemporaneous time relationship between volcanism and sedimentation and this finding is of primary importance to address the evolutional reconstruction of the abu treifiya basin characterization of the facies architecture and textural framework of peperites was carried out through detailed description and interpretation of their outcrops the peperites and sedimentary rocks are up to 350 m thick and form a distinct stratigraphic framework of diverse lithology that is widespread over several kilometers at the study area lateral and vertical facies of the peperites vary from sediment intercalated with the extrusive intrusive basaltic rocks forming peperitic breccias to lava sediment contacts at a large to small scales respectively peperites encompass five main facies types ascribed to i carbonate sediments hosted fluidal and blocky peperites ii lava flow hosted blocky peperites iii volcaniclastics hosted fluidal and blocky peperites iv sandstone siltstone rocks hosted blocky peperites and iv debris flows hosted blocky peperites soft sediment deformation structures vesiculated sediments sediments filled vesicles and fractures in lava flows indicate that lava flows mingled with unconsolidated wet sediments all the peperites in this study could be described as blocky or fluidal but mixtures of different clast shapes occur regardless of the host sediment the presence of fluidal and blocky juvenile clasts elucidates different eruptive styles reflecting a ductile and brittle fragmentation the gradual variation from fluidal to blocky peperite texture producing the vertical grading is affected by influencing factors e g the viscosity magma temperature confining pressure sediment fluidization and vapor film at the magma sediment interactions peperites in the study area record deposition within a shallow marine and fluvio lacustrine environment accumulated in a rift related basin developed during pre to syn rift phase respectively the facies transitions peperites in this area resulted from the explosive and sediment depositional processes which were mingled separately by volcanism under contrast geological conditions the development of such contrast in the depositional sequences reflects variation in the accommodation to sediment supply in the same accumulation space inside the depocenters during the rifting of the abu treifiya basin hydrothermal mineralizations comprising quartz and carbonate are restricted to peperites and lava flows

emplacement of lobate sheet flows with hyaloclastites onto soft sediment the erquy neoproterozoic lava pile armorican massif france abstract the neoproterozoic volcano sedimentary succession of the heussaye headland erquy belongs to the cadomian block located in the north east of the armorican massif france the volcanism dated at approximately 608 7 ma zircon u pb data occurred in a back arc basin this site exhibits a noteworthy verticalized pile of moderately metamorphosed greenschist facies basaltic andesite flows of arc back arc tholeiite affinity alternating with metasedimentary layers sandstones and siltstones a large range of volcanic facies characteristic of an underwater soft substrate environment can be continuously studied for over than 200 m parallel to the flow edges they include pillow lavas lava lobes fluidal peperites and sediment matrix hyaloclastites the presence of parallel lava lobes in a sector where one lava flow is capped by a variably thick hyaloclastite carapace together with the occurrence of asymmetric turbiditic folds in interbedded metasedimentary layers suggests the existence of an easterly facing gentle paleoslope the sudden thinning of this hyaloclastite carapace in two spots located approximately 60 m from each other is attributed to the synvolcanic activity of two conjugate normal paleofaults this hypothesis is supported by the observation of a hyaloclastite accumulation in one of the two spots close to a strike slip fault which may have been extensional at the time of the volcanism water entered the lava flow along the faults resulting in an interstitial network of hyaloclastites by quench fragmentation in the upper part of the hanging wall block all these observations are consistent with a model of lava emplacement along a subaqueous slope resulting from synmagmatic extensional faulting in a marginal basin context

new insights on the relative sea level change during holocene along the coasts of tunisia and western libya from archaeological and geomorphological markers new data of sea level changes for the mediterranean region along the coasts of northern africa are presented data are inferred from archaeological sites of punic roman age located along the coast of tunisia between tunis and jerba island and along the western coast of libya between sabratha and leptis magna data are based on precise measures of presently submerged archaeological markers that are good indicators of past sea level elevation nineteen selected archaeological sites were studied in tunisia and four in libya all aged between 2 0 and 1 5 ka bp the functional elevations of significant archaeological markers were measured with respect to the sea level at the time of measurements applying corrections for tide and atmospheric pressure values the functional elevations of specific architectural parts of the sites were interpreted related to sea level at the time of their construction providing data on the relative changes between land and sea observations were compared against sea level change predictions derived from the glacio hydro isostatic model associated with the last glacial cycle the results indicate that local relative sea level change along the coast of tunisia and libya has increased 0 2 0 5 m since the last 2 ka besides minor vertical tectonic movements of the land the observed changes are produced by eustatic and glacio hydro isostatic variations acting in the mediterranean basin since the end of the last glacial maximum

early permian volcano sedimentary successions beishan nw china peperites demonstrate an evolving rift basin abstract the lower permian volcano sedimentary zhesi group has been investigated in the hongliuhe and liuyuan areas in beishan china which is significant for the reconstruction of late paleozoic evolution in the southern part of the central asian orogenic belt a variety of volcanic facies were distinguished in the upper zhesi group pillow basalt with interstitial limestone thin interbedded limestone and basalt closely packed pillows pillow fragmented hyaloclastite breccia and peperite laser 40 ar 39 ar whole rock dating of the basalt yielding an age of 277 11 ma as well as early permian brachiopod fossils in the limestone interbedded with the basalt indicate that basalt was erupted in the early permian the identification of the peperite and other facies originating from magma sediment mingling reveals that the basaltic lava flows were derived from autochthonous basaltic magmatism and formed as part of the lower permian succession the peperite also indicates that these subaqueous basaltic lava flows are not dismembered ophiolitic components but formed in an autochthonous extensional setting in the early permian the clastic rocks in the lower zhesi group underlying the basaltic flows and peperites in the hongliuhe and liuyuan areas show a general fining upwards sequence indicating that they were deposited in a progressively deepening basin overlying the devonian hongliuhe suture zone subaqueous volcanism in a rift basin or basins accompanied by coeval deposition of carbonate sediment and mud built up the peperite bearing volcanogenic sedimentary successions from among the various tectonic hypotheses for the beishan region this study demonstrates that by early permian the region was developing post collisional rift basins

interactions between andesitic magma and poorly consolidated sediments examples in the neogene shirahama group south izu japan abstract the upper miocene lower pliocene shirahama group of south izu japan is a sequence of volcanielastic shallow sea sediments and subaqueous lava flows it is gently warped with indistinct preferred orientation and is cross cut by many andesitic intrusive bodies which range in size from less than a meter to several hundred meters the intrusive bodies exhibit various shapes and weak preferred orientation and often have hyaloclastic and peperitic textures along their peripheries hydrothermally altered and chaotically disturbed zones of host rocks also occur along the contacts the areas where the intrusive bodies are abundant are almost coincident with the areas where the more inclined beds and synsedimentary faults are developed the intrusive bodies dragged the surrounding beds with or without synsedimentary faults some intrusions occurred along the faults conjugate sets of the faults indicate that they were produced under unstable stress conditions these relationships between the beds and the intrusive bodies are assumed to have originated mostly by interaction between hot magma and poorly consolidated wet sediments at a shallow depth beneath the sea floor when the intrusions took place the stress conditions in the beds were irregular and unstable judging from the shapes and orientation of the intrusive bodies and also from the deformation characteristics of the enclosing beds some of the intrusive bodies are probably feeder dikes which supplied lave to the shirahama group

petrology and geochemistry of submarine volcanism in the sicily channel rift abstract submarine magmatism in the sicily channel rift began in the early pliocene and lasted until almost 200 yr ago we present here petrological and geochemical data on volcanic rocks dredged from graham and nameless banks and pantelleria seamounts in the pelagian sector of the sicily channel rift petrological evidence suggests that the ascent of magmas to the surface was relatively rapid probably through channels superimposed over the major tectonic discontinuities of the rift major and trace element data indicate an ocean island basalt affinity for graham and nameless bank alkaline lavas and a depleted tholeiitic signature for one pantelleria seamount which had a shallower mantle source sr nd pb isotopic compositions suggest a heterogeneous mantle source involving both focus zone fozo and high himu components lead isotopic compositions are slightly less radiogenic in the tholeiitic basalt and more radiogenic closer to himu in the alkaline lavas we hypothesize that a decompressional me

peperites and associated pillow lavas subjacent to the oman ophiolite abstract peperites are breccias consisting of a mix of cooled magma and sediment they result from the intrusion of molten rock into water saturated sediments we report an occurrence of peperite in the oman united arab emirates uae border region of khattm al shiklah and characterize samples that have been collected from 6 locations east of al ain uae at jabal um bak jabal hamra and jabal dai in oman geochemical analysis indicates that the magmas represented in these samples are related in addition field relations of the pillow lavas surrounded by limestone with deformed bedding and peperite boundaries between the pillows and the limestone are consistent with the pillow lavas forming directly within carbonate sediments it is likely that the ambient pressure was great enough and cooling of the magma rapid enough to prevent large explosions the fact that the magma also formed pillows is evidence of this the rapid quenching of the magma by water saturated fine unconsolidated sediments likely produced conditions similar to those attending pillow lava formation directly into water

modeling long term ground deformation due to the cooling of a magma chamber case of basiluzzo island aeolian islands italy 1 we estimate the long term vertical deformation of basiluzzo island located in the volcanic arc of the aeolian islands italy by inferring the subsidence of a roman age submerged wharf dated 2000 50 years ago we model the crustal deformation that produced this displacement as a cooling magma chamber emplaced during the formation of the island this is the first attempt to model crustal deformation using the subsidence of a submerged archaeological structure nowadays the top of the wharf which can be considered an unconventional leveling benchmark is located near punta levante at an average depth of 3 20 0 10 m below actual sea level and it is still in good conservation its present location is due to combined effect of sea level rise and volcanic and tectonic activity that occurred since it was built taking into account the architectural features of the wharf and that the mean sea level rise of the mediterranean sea has been estimated as 0 45 m during the last 2000 years flemming and webb 1986 we estimate a total subsidence of 3 75 0 10 m at a rate of about 1 87 mm yr 1 anzidei et al 2002 we propose a possible mechanism for the long term subsidence which occurred on a timescale of thousands of years by considering the earth s crust as a maxwell body we assume that the magmatic source is located directly beneath basiluzzo dome and underwent progressive solidification and subsequent volume reduction since its emplacement 50 000 years ago

variation in peperite textures associated with differing host sediment properties peperites formed by mixing of magma and wet sediment are well exposed along punta china baja california mexico where two sills intrude a section of lava flows limestones and volcaniclastic rocks irregular lobes and dikes extend from the sills several meters into host sediments including highly comminuted flow top breccias lithic lapilli tuff breccias and shelly micrites whereas intrusive contacts with lava flows are sharp and planar where one sill intruded both coarse grained volcaniclastic rock and fine grained limestone textural differences between the hosts produced strikingly different styles of peperite blocky masses of the basaltic intrusions up to 1 m in size were dispersed for distances up to 3 m into host lithic lapilli tuff breccias the blocks consequently underwent in situ fragmentation as they were rapidly quenched the high degree of dispersion resulted from steam explosions as the magma enveloped pockets of water in the coarse grained permeable host elutriation of fine grained material from vertical pipes in tuff breccia above the lower sill provides evidence for meter scale fluidization of the host the contact zone between the basaltic magma and the shelly micrite host resembles a mixture of two viscous immiscible fluids fluidal peperite intrusion occurred behind a stable vapor film which entrained lime mud particles and carried them off grain by grain as magma advanced into the host thin section scale elutriation pipes formed microglobular peperite represents a frozen example of a fuel coolant interaction fci between basaltic magma and fluidized micrite host the intimate intermixing of magma and host at the submillimeter level is attributed to fluid instabilities developed along the magma vapor host interface such intimate intermixing of magma and water bearing fragmental debris is commonly a precursory step toward explosive hydrovolcanism

ground movements and sea level changes in urban areas 5000 years of geological and archaeological record from naples southern italy abstract the occasion offered by the construction of a new branch of naples subway and the related geotechnical and archaeological investigations allowed recognition that the city shoreline underwent remarkable changes during the late holocene highstand when coastal evolution was influenced by vertical ground movements in particular for three investigation sites the density and quality of data were such to permit for the first time the reconstruction of graphs of relative sea level change rslc which compared with curves of the coeval eustatic changes in the tyrrhenian sea were transformed into data about the late holocene history of local tectonics by averaging the data collected in all the different sites the obtained curve of the tectonics suggests that the coastal strip of naples underwent a subsidence rate of 1 3 mm a from about 5000 bp to the xii century ad followed by a 1 m uplift during the last eight centuries mean rate of 1 0 mm a the subsidence trend is consistent with the regional tectonics even if the mean rate was less that in other portions of the bay of naples graben probably because the study area lies among the parallel synthetic faults forming the nw margin of that depression magnaghi sebeto fault zone and not on the proper hanging wall block the prevailing subsiding trend was probably interrupted by minor episodes of uplift not only in the last eight centuries but also during the 3rd millennium bc likely in connection with periods in which the volcano tectonic phenomena of the phlegrean fields district superimposed on the descending movements caused by the msfz the three investigation sites share substantially the same tectonic behaviour in the long term but the details of their rslc records show also discrepancies in some centuries if not due to errors in dating and or in estimating palaeo elevations such discrepancies could be ascribed to episodes of fragmentary tectonic behaviour due probably to occasional reactivation of some e w trending minor lines of the magnaghi sebeto fault zone

coastal sea level rise in southern europe and the nonclimate contribution of vertical land motion 1 in this study we extend the advanced approach of combining tide gauge and satellite altimetry data with supplemental equations from adjacent tide gauge records of at least 30 years of common data to investigate the relative importance of the nonclimate contribution of vertical land movement to the observed rates of sea level change along the coasts of southern europe the sensitivity tests proved that the advanced approach is robust and accurate at the submillimeter per year level of around 0 4 mm yr 1 in estimating rates of vertical land movements it enabled identifying stations displaying large rates of vertical land movements that must be taken into account when predicting future sea level rise and appraising the exposure to its impacts on populations and assets the average rate of coastal climate related sea level rise in the mediterranean sea was consequently revisited to be of 1 7 mm yr 1 over the past century whereas the atlantic northern iberian coast revealed a significant high rate of sea level rise in excess of 3 4 mm yr 1 for the past 70 years future work should consider applying this powerful approach to other geographic contexts as a useful source of supplementary data for geodynamic studies

vertical gps ground motion rates in the euro mediterranean region new evidence of velocity gradients at different spatial scales along the nubia eurasia plate boundary we use 2 5 to 14 years long position time series from 800 continuous global positioning system gps stations to study vertical deformation rates in the euro mediterranean region we estimate and remove common mode errors in position time series using a principal component analysis obtaining a significant gain in the signal to noise ratio of the displacements data following the results of a maximum likelihood estimation analysis which gives a mean spectral index 0 7 we adopt a power law white noise stochastic model in estimating the final vertical rates and find 95 of the velocities within 2 mm yr with uncertainties from filtered time series 40 smaller than from the unfiltered ones we highlight the presence of statistically significant velocity gradients where the stations density is higher we find undulations of the vertical velocity field at different spatial scales both in tectonically active regions like eastern alps apennines and eastern mediterranean and in regions characterized by a low or negligible tectonic activity like central iberia and western alps a correlation between smooth vertical velocities and topographic features is apparent in many sectors of the study area glacial isostatic adjustment and weathering processes do not completely explain the measured rates and a combination of active tectonics and deep seated geodynamic processes must be invoked excluding areas where localized processes are likely or where subduction processes may be active mantle dynamics is the most likely process but regional mantle modeling is required for a better understanding

subaqueous volcanism in the etnean area evidence for hydromagmatic activity and regional uplift inferred from the castle rock of acicastello abstract the subalkaline rocks outcropping at the acicastello castle rock catania sicily and on its abrasion platforms are related to the oldest etnean volcanism 500 300 ka gillot p y kieffer g romano r 1994 the evolution of mount etna in the light of potassium argon dating acta vulcanol 5 81 87 here submarine lavas with pillows closely packed onto each other are associated with heterogeneous and poorly sorted volcaniclastic breccia levels with sub vertical sharp boundaries the present day attitude was previously interpreted as due to a local tilt di re m 1963 hyaloclastites and pillow lavas of acicastello mt etna bull volcanol 25 281 284 kieffer g 1985 evolution structurale et dynamique d un grand volcan polygenique stades d edification et activite actuelle de l etna sicile clermont ferrand iidoctorat etat tesi clermont ferrand ii or to the seaward sliding of the entire eastern etnean flank borgia a ferrari l pasquare g 1992 importance of gravitational spreading in the tectonic and volcanic evolution of mount etna nature 357 231 235 on the assumption of originally horizontal boundaries on the contrary our observations do not match the hypothesis of a significantly tilted succession and lead us to conclude that apart from the strong regional uplift the present castle rock exposure did not suffer any substantial change of its attitude

coastal uplift earthquakes and active faulting of rhodes island aegean arc modeling based on geodetic inversion the geodetic inversion technique was used to model the fault pattern responsible for the uplifted holocene notches along the ne rhodes island coast se edge of the hellenic aegean arc input in the modeling was the elevation of uplifted notches up to 6000 yr old which are interpreted to reflect remains of fossil shorelines to testify to a series of earthquakes producing both uplift and subsidence i e to elastic dislocations and to correspond to geodetic data senso lato these shorelines up to 3 8 m high were probably originally continuous along the whole of the 75 km long se rhodes coast possibly locally disturbed by minor normal faults and reflect the last phases of the uplift and tilting of the island as a rather rigid block since late pliocene their radiocarbon dating was further refined from archeological data testifying to an about 1 m subsidence associated with the 227 bc earthquake followed by 3 m seismic uplift inversion constrained by the hypothesis of a compressional fault offshore rhodes was based on standard uniform slip elastic dislocation analysis it proved to depend only weakly even on extreme glacio isostatic corrections and indicated that coastal uplift is dominated by a main compressional fault zone offshore sub parallel to the island coast with normal faults inland reflecting thin skin tectonics this fault pattern similar to that of western crete is confirmed by seismic reflection profiles indicating a major reverse close to the modeled fault and can explain 1 the occurrence of strong m 7 5 historical earthquakes producing tsunamis and destruction on an east mediterranean scale 2 the alternation of uplift and subsidence as a result of fault shift inside the same fault zone and 3 the long term uplift of the island as a rather conjugate effect of the formation of an about 4 5 km deep 5 myr old marine basin se of rhodes bounded to the nw by the modeled fault zone the seismic risk of rhodes higher in its ne part of the island and than what was previously believed is associated with strong m 7 5 earthquakes producing widespread destruction tsunamis coastal uplift and coastal subsidence

the fracture behaviour of volcanic glass and relevance to quench fragmentation during formation of hyaloclastite and phreatomagmatism quench fragmentation is a non explosive process that occurs when molten magma is super cooled to glass upon contact with ambient water this occurs when coherent lavas are erupted subaqueously when they flow into water when magma intrudes into water saturated sediments and when magma and water interact explosively during phreatomagmatism quench fragmentation also occurs alongside explosive phreatomagmatic activity although products of quench fragmentation hyaloclastite sensu stricto have been discussed qualitatively in the volcanological literature compared to explosive fragmentation processes very little is known about the exact dynamics of quench fragmentation of magma and how this relates to the rheology and physical properties of volcanic glass based on literature from materials engineering we present a detailed review of the processes by which glass forms the properties of glass and the fracture mechanics that cause it to fragment non explosively we also consider how this can be applied to understanding the dynamics behind the volcanological processes of in situ glass fragmentation during quenching in wet environments and phreatomagmatism important parameters for the occurrence of quench fragmentation are the temperature difference between the magma and the ambient water and how much the ambient water is superheated above its leidenfrost temperature the geometry of the lava or magma intrusion the thermal conductivity and the thermal expansion are also of great importance the resistance of the magma against fragmentation can be increased with the presence of crystals provided the thermal expansion of the crystals does not greatly exceed that of the glass vesicles have the opposite effect unless the magma is highly vesicular this overview then provides a solid basis for further quantitative study of quench fragmentation and hyaloclastite formation

strain accumulation across the messina straits and kinematics of sicily and calabria from gps data and dislocation modeling article i nfo we use global positioning system gps velocities and dislocation modeling to investigate the rate and nature of interseismic strain accumulation in the area affected by the 1908 mw 7 1 messina earthquake southern italy within the framework of the complex central mediterranean microplate kinematics our data confirm a change in the velocity trends between sicily and calabria moving from nnw ward to ne ward with respect to eurasia and detail a fan like pattern across the messina straits where maximum extensional strain rates are 65 nanostrains yr extension normal to the coast of northern sicily is consistent with the presence of sw ne trending normal faults half space dislocation models of the gps velocities are used to infer the slip rates and geometric fault parameters of the fault zone that ruptured in the messina earthquake the inversion and the bootstrap analysis of model uncertainties finds optimal values of 3 5 2 0 1 3

endogenous growth of a miocene submarine dacite cryptodome rebun island hokkaido japan momo iwa rebun island hokkaido japan is a dacite cryptodome 200 300 m across and 190 m high the dome is inferred to have intruded wet poorly consolidated sediment in a shallow marine environment the internal structure of the dome is concentric with a massive core banded rim and narrow brecciated border all of which are composed of compositionally uniform feldspar phyric dacite boundaries between each of the zones are distinct but gradational the massive core consists of homogeneous coherent unfractured dacite and is characterized by radial columnar joints 60 200 cm across the banded rim encircles the massive core and is 40 m wide it is characterized by large scale flow banding parallel to the dome surface the flow banding comprises alternating partly crystalline and more glassy bands 80 150 cm thick the outermost brecciated border is up to 80 cm thick and consists of in situ breccia and blocky peperite the in situ breccia comprises polyhedral dacite clasts 5 20 cm across and a cogenetic granular matrix the blocky peperite consists of polyhedral dacite clasts 0 5 2 cm across separated by the host sediment mudstone the internal structures of the dome suggest endogenous growth involving a continuous magma supply during a single intrusive phase and simple expansion from the interior although much larger the internal structures of momo iwa closely resemble those of lobes in subaqueous felsic lobe hyaloclastite lavas

fish tanks of eastern crete greece as indicators of the roman sea level abstract the ancient fish tanks and fish traps of crete are relics of the roman domination of the island they were usually constructed near the major urban centers of that period the direct relationship of their various functional characteristics with past sea levels and the relatively accurate determination of their construction dates establish them as sensitive indicators of sea level change through space and time the fish tanks presented in detail in this study namely those of matala chersonissos mochlos and sitia and the fish trap in the gulf of zakros have all been reported recorded and or interpreted in regard to their operation by previous researchers in the absence of a comprehensive interdisciplinary approach to the issue uneven methodologies inaccurate data and wrong measurements have led to erroneous conclusions about sea level during their operation and about the size and direction of vertical tectonic movements in eastern crete during the upper holocene the present study is based on a new underwater survey in the course of which the architectural and functional features of the ancient constructions were reexamined precisely their depth from modern sea level was measured and their relationship with coastal landforms indicative of a past sea levels was investigated a review of their manner of operation and their modern submerged position allowed the definition of a roman mean sea level 1 24 m 0 09 m below the present one the submersion of the central and eastern parts of crete included in the same tectonic block with a total length of at least 150 km at an average tectonic rate of 0 65 mm year during the last 1900 100 years occurred as is shown by historical evidence during a paroxysmal tectonic event probably related to the strong earthquake of 1604

sea level change and vertical land movements since the last two millennia along the coasts of southwestern turkey and israel abstract this paper provides new relative sea level data inferred from coastal archaeological sites located along the turkish coasts of the gulf of fethye 8 sites and israel between akziv and caesarea 5 sites the structures selected are those that for effective functioning can be accurately related to sea level at the time of their construction thus their positions with respect to present sea level provide a measure of the relative sea level change since their time of construction useful information was obtained from the investigated sites spanning an age range of 2 3 1 6 ka bp the inferred changes in relative sea level for the two areas are distinctly different from a rise of 2 41 to 4 50 m in turkey and from 0 to 0 18 m in israel sea level change is the combination of several processes including vertical tectonics glacio hydro isostatic signals associated with the last glacial cycle and changes in ocean volume for the israel section the present elevations of the mis 5 5 tyrrhenian terraces occur at a few meters above present sea level and vertical tectonic displacements are small data from gps and tide gauge measurements also indicate that any recent vertical movements are small the mis 5 5 shorelines are absent from the investigated section of the turkish coast consistent with crustal subsidence associated with the hellenic arc the isostatic signals for the israel section of the coast are also small ranging from 0 11 mm yr to 0 14 mm yr depending on site and earth model and the observed eustatic average sea level change corrected for this contribution is a rise of 13 5 2 6 cm during the past 2 ka this is attributed to the time integrated contribution to sea level from a combination of thermal expansion and other increases in ocean volume the observed sea levels from the turkish sites in contrast indicate a much greater rise of up to 2 2 mm yr since 2 3 ka bp occurring in a wide area between knidos and kekova the isostatic signal here is also one of a rising sea level of up to 1 mm yr and site and earth model dependent and the corrected tectonic rate of land subsidence is 1 48 mm yr this is the primary cause of dramatic relative sea level rise for this part of the coast

textural evidence of peperites inside pillow lavas at acicastello castle rock mt etna sicily globular and microglobular peperites with mingled sediment in millimetric to decimetric domains are described from inside pillow lavas at acicastello castle rock mt etna sicily for the first time the peperites now comprise basalt and minor remnants of fine grained detrital material with smectite and zeolite crystallised during late hydrothermal activity we propose that peperites formed when the magma ascending towards the surface intruded and intermixed with the unconsolidated wet pleistocene bluish marly clays of the substrate subsequently they were transported by the uprising magma from the source region towards the surface where they are preserved in pillow lavas

tectonic and volcanic evolution of panarea aeolian islands italy abstract based on new geophysical volcanological structural and radiometric data a morphological structural reconstruction of the submarine part of the panarea volcanic edifice is provided and a model for the evolution of the entire complex is proposed panarea is a small part of a much larger submarine edifice whose overall shape is one of a truncated cone with an eastern protrusion the base of the cone is about 1500 m below sea level it has a diameter of about 23 km and an area of 460 km2 several lobes are present on the steep eastern slopes of the cone and the wide submarine top is of a morphology which is more complex than previously thought the evolution of the panarea volcanic complex occurred in three stages 1 1 development of a central volcano in the western sector of the complex the island of panarea represents the top of this volcano 2 2 eastward shifting of volcanic activity producing development of the lobed eastern sector of the complex 3 3 extensive caldera collapse of the central part of the complex and emplacement within the collapsed area of domes and lava bodies of various affinities some of which are basaltic ne sw oriented structures seem to have had a fundamental role during the development of the panarea volcanic complex these structures have been active until recent times and are of regional significance indeed the evolution of nearby stromboli has been controlled by the ne sw trending structures panarea and stromboli also display similar magnetic anomaly trends geochemical affinities and temporal relationships in volcanism

late quaternary deformation history of the volcanic edifice of panarea aeolian arc italy a series of raised palaeoshorelines is documented along the emergent coastal slopes of panarea and surrounding islets at elevations of 115 palaeoshoreline ia and 100 m a s l ib 62 5 m ii 35 m iii 12 m iv 10 12 va and 5 m vb according to stratigraphic constraints and cross cutting relationships these palaeoshorelines are correlated with discrete high sea level stillstands during marine oxygen isotope stages mis 5e 5c 5a and 3 coastal elevation changes suggest the occurrence of a long term sustained uplift trend of the volcanic edifice since the last interglacial last 124 ka the uplift rates are not constant but display a progressive deceleration from maximum values of 1 5 1 58 m ka in the period between 124 and 100 ka down to the lowest values of 0 66 0 69 m ka which tend to be constant starting from 81 ka bp the long term deformation pattern of panarea suggests that a transitory volcano related component of uplift interplayed with the regional tectonic component affecting the sub volcanic basement which has undergone a persistent and widespread uplift since the mid pleistocene the volcano related component of uplift prevailing between 124 and 100 81 ka is interpreted as the result of visco elastic deformation mechanisms which characterize the progressive re equilibration of the shallow magmatic system following the incoming quiescence of the volcanic edifice the long term uplift values at panarea are higher than in the main portion of the western central aeolian arc where a mean uplift rate of 0 34 m ka was estimated since the last interglacial last 124 ka such a pattern of deformation on a regional scale may be a response to active deformation processes connected with the southeastward rollback of the subducting ionian slab which is still active only in correspondence with the eastern sector of the aeolian arc including panarea in the short term a localized submergence trend has been documented at the nearby islet of basiluzzo for the last 2 000 years likely connected to neo tectonic movements along main ne sw trending faults

a miocene basanite peperitic dyke at stanley northwestern tasmania australia abstract a miocene basanite dyke at stanley northwestern tasmania australia displays well preserved peperite texture the dyke is 2 m wide and has intruded basaltic breccia host sediment one contact of the dyke is fluidally shaped and amoeboid apophyses 10 25 cm long extend into the host sediment whereas the other contact is characterized by blocky peperite texture comprising tabular to wedge shaped clasts up to 30 cm across separated by host sediment the clasts have internal spherical fractures and some show splinter texture vesicles are common in the clasts and those intersected by clast margins have been filled with sediment the interior of the dyke comprises close packed blocky peperite consisting of tabular wedge shaped and polyhedral clasts tens of centimetres across separated by host sediment these clasts show well developed jigsaw fit texture the textures and structures in the basanite dyke are inferred to have formed in two stages an earlier hotter apophysis forming stage and a later cooler angular clast forming stage both of which occurred during the intrusion of magma into wet poorly consolidated sediment in a shallow marine environment during the apophysis forming stage the magma had relatively low viscosity and progressively displaced wet sediment the wet sediment around the dyke was partly fluidized by vaporization of pore water the angular clast forming stage reflects a change in the rheological behaviour of the magma from ductile to brittle most likely in response to decreasing temperature the chilled parts of the dyke were subject to stress arising from cooling contraction and also from continued pulsatory movement of hotter still ductile magma in the interior of the dyke resulting in brittle fragmentation brittle fragmentation was accompanied by movement of host sediment into the newly created open spaces forming blocky peperite spherical fractures splinter texture and sediment filled vesicles formed during the angular clast forming stage because the host sediment is texturally identical either side of the dyke increasing magma viscosity as temperature decreased combined with pulsatory intrusion were evidently important in the production of the blocky peperite

new gps constraints on the africa eurasia plate boundary zone in southern italy 1 southern italy is a key area for understanding the tectonic processes in the africa eurasia collision zone we analyze new gps measurements carried out between 1994 and 2001 the results are presented in terms of time series trajectories and velocities of crustal motion as well as a geodetic strain rate field while central italy corsica sardinia and the tyrrhenian sea move like the eurasian plate the overall motion of the sicily rift zone region matches african plate motion unexpected are the north northwest directed motions of northeastern sicily and the eolian islands most striking on the deformation field are a north south oriented compression along the northern sicilian coast compression between apulia and northwestern greece as well as extension in the sicily rift zone and the interior of sicily

archaeological remains as sea level change markers a review abstract the mediterranean sea constitutes a unique basin from an historical and archaeological point of view as it has been a privileged way of communication for thousands of years for the people that dwelled on its shores their passage has left many traces on the seabeds in the areas where the ancient commercial routes passed and remains of structures where moorings havens or dwellings existed some of these structures nowadays submerged offer interesting indications aiding the reconstruction of the ancient coastlines this contribution aims to examine recent work in coastal geo archaeology targeting both 1 gathering and discussion of the data particularly those pertaining to the italian coasts and 2 commentary on the methodological debate and verification of the possibility of a protocol that may contain unequivocal referring elements to investigate the archaeological evidence currently underwater because of the relative sea level variations harbour infrastructures fishponds villae maritimae caves nymphaei private or public buildings or town quarters pre and protohistorical villages quarries caves etc a clear and more coherent methodological assumption may be needed the archaeological interpretation must initially establish the maritime and or harbour nature and vocation of the site determine its typology and specific usage analyze the elements of its building techniques that reveal themselves as meaningful markers of height or depth at the time of building and its functional elements the measure of the emerged part with respect to the average sea level and point out the time of construction its chronological range of usage frequentation the dynamics of its abandonment destruction obliteration the evaluation of both the height and functional depth to the mean sea level depends on the typology of the archaeological evidence its use and the local tide amplitudes the surface of a pier surely has a functional elevation different from that of a haulage area or a platea or a pavement

sea level in roman time in the central mediterranean and implications for recent change instrumental records indicate that ocean volumes during the 20th century have increased so as to raise eustatic sea level by f1 2 mm year and the few available records suggest that this is higher than for the previous century geological data indicate that ocean volumes have increased since the main phase of deglaciation about 7000 years ago but whether this continued into the recent past remains unclear yet this is important for establishing whether the recent rise is associated with global warming or is part of a longer duration non anthropogenic signal here we present results for sea level change in the central mediterranean basin for the roman period using new archaeological evidence these data provide a precise measure of local sea level of 1 35f0 07 m at 2000 years ago part of this change is the result of ongoing glacio hydro isostatic adjustment of the crust subsequent to the last deglaciation when corrected for this using geologically constrained model predictions the change in eustatic sea level since the roman period is 0 13f0 09 m a comparison with tide gauge records from nearby locations and with geologically constrained model predictions of the glacio isostatic contributions establishes that the onset of modern sea level rise occurred in recent time at f100f53 years before present d 2004 elsevier b v all rights reserved

peperite a review of magma sediment mingling the study of peperite is important for understanding magma water interaction and explosive hydrovolcanic hazards this paper reviews the processes and products of peperite genesis peperite is common in arc related and other volcano sedimentary sequences where it can be voluminous and dispersed widely from the parent intrusions it also occurs in phreatomagmatic vent filling deposits and along contacts between sediment and intrusions lavas and hot volcaniclastic deposits in many environments peperite can often be described on the basis of juvenile clast morphology as blocky or fluidal but other shapes occur and mixtures of different clast shapes are also found magma is dominantly fragmented by quenching hydromagmatic explosions magma sediment density contrasts and mechanical stress as a consequence of inflation or movement of magma or lava magma fragmentation by fluid fluid shearing and surface tension effects is probably also important in fluidal peperite fluidisation of host sediment hydromagmatic explosions forceful intrusion of magma and sediment liquefaction and shear liquification are probably the most important mechanisms by which juvenile clasts and host sediment are mingled and dispersed factors which could influence fragmentation and mingling processes include magma host sediment and peperite rheologies magma injection velocity volatile content of magma total volumes of magma and sediment involved total volume of pore water heated presence or absence of shock waves confining pressure and the nature of local and regional stress fields sediment rheology may be affected by dewatering compaction cementation vesiculation fracturing fragmentation fluidisation liquefaction shear liquification and melting during magma intrusion and peperite formation the presence of peperite intraclasts within peperite and single juvenile clasts with both sub planar and fluidal margins imply that peperite formation can be a multi stage process that varies both spatially and temporally mingling of juvenile clast populations formed under different thermal and mechanical conditions complicates the interpretation of magma fragmentation and mingling mechanisms

a late ordovician phreatomagmatic complex in marine soft substrate environment the crozon volcanic system armorican massif france the mafic lavas and the diabases of crozon armorican massif france belong to an anorogenic ordovician volcanic complex emplaced on a rifted passive margin in north gondwana magma passed through syn volcanic soft sedimentary substrate which is today mostly composed of alternating sandstones and mudstones from llanvirn to ashgill in age field observations together with microscopic studies and geochemical analyses of magmatic rocks lead us to propose a model of volcano formation which combines hydromagmatic processes peperitic intrusions a shallow submarine tephra settling eruption fed turbidity currents and a pillow lava effusion the crozon outcrops can be used to reconstruct a complete cross section from the root of the volcanic complex to the lavas and breccias emplaced on the sea floor the sites expose i a hypabyssal breccia containing mud chunks and coarse grained diabase clasts with amoeboidal fine grained magmatic material ii bulbous peperitic sills and pillow like lobes bearing a great quantity of sediment derived enclaves of fluidal morphology iii volcaniclastic breccias containing near spherical magmatic clasts that resulted from the complete fragmentation of sills in the ductile regime iv a rhythmic peperitic breccia interpreted as the product of mingling between thin lava flows and soft calcareous sediment the crozon volcanic form resulting from explosive interaction with subsurface surface water was probably a subaqueous collapsed tuff cone this upper part of the system is synchronous with an ashgill carbonate sedimentation which overlies an ordovician siliciclastic succession deposited in shelf environments

late paleozoic peperites in west junggar china and how they constrain regional tectonic and palaeoenvironmental setting abstract late paleozoic peperites have been identified for the first time at the bottom of tailegula formation in west junggar china this finding is significant for the reconstruction of late paleozoic evolution in the junggar region the peperites form successions up to 500 m thick interbedded with basaltic lava and sedimentary rocks four types of peperites are described and interpreted as resulting from basaltic lava bulldozed into wet unconsolidated sediments at their basal contacts zircon la icp ms u pb dating of a tuff lens enclosed by lava showed that the peperites formed in the late devonian ca 364 ma the peperite bearing units probably formed at a water depth of less than 3 km and are generally undeformed occurring in continuous stratigraphic sections distributed regionally over a distance of 100 km on either side of the darbut and baijiantan ophiolitic belts in contrast to the highly deformed slices of ophiolite they demonstrate that the darbut and baijiantan ophiolitic belts should not be interpreted as significant plate boundaries and represent the underlying ocean crust uplifted along tectonic lineaments within a continuous shallow remnant ocean basin the peperites formed during the spreading phase of the remnant ocean basin and represent the final stages of creation of oceanic crust

crustal velocity and strain rate fields in italy and surrounding regions new results from the analysis of permanent and non permanent gps networks summary we present a new geodetic velocity solution for italy and the surrounding areas obtained from an analysis of continuous and survey mode global positioning system observations collected between 1991 and 2002 we have combined local regional and global networks into a common reference frame velocity solution providing a new detailed picture of the regional scale deformation field in the central mediterranean our velocity estimates are computed with respect to a new stable eurasian reference frame constraining the kinematics of the greater african eurasian plate boundary system in the study area we provide strain rate values for the main seismotectonic districts which are in good agreement with the seismic deformation inferred from earthquake focal mechanisms the southern tyrrhenian area calabria the apennines the southeastern alps the southern dinarides and the albanides display deformation rates at the order of 20 30 nanostrain yr 1 the corsica sardinia block moves according to eurasian plate motions and there is no indication that the opening of the tyrrhenian is still active the pelagian and sicilian domains are separated by a northwest southeast discontinuity the sicily channel rifted area and marginally significant relative motion between the pelagian plateau and the african plate is also observed the southern tyrrhenian is affected by north south compression and accommodates up to 50 per cent of the africa eurasia relative plate motion whereas the calabrian arc exhibits 2 mm yr 1 northwest southeast extension the observed deformation pattern suggests the presence of a major approximately north south tectonic discontinuity separating the sicilian and calabrian domains an extensional boundary observed along peninsular italy coincides with the distribution of seismogenic faults along the axis of the apennines this boundary separates a tyrrhenian and an adriatic domain with diverging velocities orientated north nnw ward and northeastward respectively the apennines are extending perpendicularly to the chain axis at rates of less than 3 mm yr 1 and only in the outer northern apennines indications of active shortening are observed insignificant deformation is observed in the western po plain and the western alps while the central and eastern alps display north south shortening the eastern adriatic domain is shortening perpendicular to the dinaric front with strain rates increasing from north to south the locus of collision between the aegean balkan system and the adriatic and ionian domains is marked by the kephalonia fault system which accommodates up to 20 1 mm yr 1 of right lateral motion the deformation pattern observed in the peri adriatic domain is well described by a counter clockwise rotation of the adriatic microplate around a pole located in the western alps

sea level change during the holocene in sardinia and in the northeastern adriatic central mediterranean sea from archaeological and geomorphological data abstract we provide new data on relative sea level change from the late holocene for two locations in the central mediterranean sardinia and ne adriatico they are based on precise measures of submerged archaeological and tide notch markers that are good indicators of past sea level elevation twelve submerged archaeological sites were studied six aged between 2 5 and 1 6 ka bp located along the sardinia coast and a further six dated 2 0 ka bp located along the ne adriatic coast italy slovenia and croatia for sardinia we also use beach rock and core data that can be related to holocene sea level the elevations of selected significant archaeological markers were measured with respect to the present sea level applying corrections for tide and atmospheric pressure values at the time of surveys the interpretation of the functional heights related to sea level at the time of their construction provides data on the relative changes between land and sea these data are compared with predictions derived from a new glacio hydro isostatic model associated with the last glacial cycle sardinia is tectonically relatively stable and we use the sea level data from this island to calibrate our models for eustatic and glacio hydro isostatic change the results are consistent with those from another tectonically stable site the versilia plain of italy the northeast adriatic italy slovenia and croatia is an area of subsidence and we use the calibrated model results to separate out the isostatic from the tectonic contributions this indicates that the adriatic coast from the gulf of trieste to the southern end of istria has tectonically subsided by 1 5 m since roman times

evidence of active subsidence at basiluzzo island aeolian islands southern italy inferred from a roman age wharf abstract the aeolian arc southern tyrrhenian sea italy is one of the most active volcanic areas of the mediterranean basin affected by volcanic hydrothermal and seismic activity ancient populations settled this region since historical times building coastal installations which currently are valuable archaeological indicators of relative sea level changes and vertical land movements in this study we show and discuss data on the relative sea level change estimated from a submerged wharf of roman age dated between 50 b c and 50 a d located at basiluzzo island this structure has been studied through marine surveys and archaeological interpretations and is presently located at a corrected depth of 4 10 0 2 m we explain this submergence by a cumulative effect of the relative sea level change caused by the regional glacio hydro isostatic signal active since the end of the last glacial maximum and the local volcano tectonic land subsidence finally a total subsidence rate of 2 05 0 1 mm yr 1 with a volcano tectonic contribution of 1 43 0 1 mm yr 1 for the last 2 ka bp is inferred from the comparison against the latest predicted sea level curve for the southern tyrrhenian sea suggesting new evaluations of the volcano tectonic hazard for this area of the aeolian islands

explosion craters associated with shallow submarine gas venting off panarea island italy explosions of hot water steam and gas are common periodic events of subaerial geothermal systems these highly destructive events may cause loss of life and substantial damage to infrastructure especially in densely populated areas and where geothermal systems are actively exploited for energy we report on the occurrence of a large number of explosion craters associated with the offshore venting of gas and thermal waters at the volcanic island of panarea italy demonstrating that violent explosions similar to those observed on land also are common in the shallow submarine environment with diameters ranging from 5 to over 100 m the observed circular seafloor depressions record a history of major gas explosions caused by frequent perturbation of the submarine geothermal system over the past 10 000 years estimates of the total gas flux indicate that the panarea geothermal system released over 70 mt of co2 over this period of time suggesting that co2 venting at submerged arc volcanoes contributes significantly to the global atmospheric budget of this greenhouse gas the findings at panarea highlight that shallow submarine gas explosions represent a previously unrecognized volcanic hazard around populated volcanic islands that needs to be taken into account in the development of risk management strategies

fluidization of wet sediments during the emplacement and cooling of various igneous bodies during the emplacement and cooling of igneous bodies fluidization of wet sediment by water vapour may occur by heating or by pressure relief during the opening of fractures momentary fluidization causes sediment reconstitution and local transport continuous fluidization can result in substantial sediment displacement theoretical considerations show that fluidization due to heating is not likely to occur at depths where pressure is much greater than 312 bars studies of the emplacement of sills of andesite ayrshire fluid rhyolite ramsey island and viscous rhyolite moelwyn hills recognize a wide range of phenomena attributable to wet sediment fluidization and in places modify existing interpretations the transgressive bases of the subaqueously welded ash flow tuffs of the capel curig volcanic formation are consistent with emplacement attended by fluidization of the subjacent sediment evidently fluidization is a means by which large volumes of wet sediment can be replaced by igneous material with minimal disturbance of the remaining host also fluidization can result in exceptionally complex contact relationships between sedimentary host and intrusive rocks and can cause fractures formed during cooling to be thoroughly pervaded by sediment fluidization is commonly associated with the formation of peperites

magma water interactions in subaqueous and emergent basaltic in the subaqueous growth and emergence of a basaltic volcano clasts are formed by one or a combination of 1 explosive release of magmatic volatiles 2 explosive expansion and collapse of steam formed at magma water contact surfaces 3 explosive expansion of steam following enclosure of water in magma or entrapment of water close to magma and 4 cooling contraction these processes named respectivelymagmatic explosivity contact surface steam explosivity bulk interaction steam explosivity andcooling contraction granulation can be enhanced by mutual interaction and feedback the first three explosive processes are limited at certain water depths hydrostatic pressures and become increasingly vigorous at shallower levels the depth of onset of magmatic explosivity depends largely on juvenile volatile content it is up to 200 m for tholeiitic magmas and up to 1 km for alkalic magmas at the depth where formation of clastic deposits becomes predominant over effusion of lavas magmatic explosivity is subordinate to steam explosivity as a clast forming process the upward transition to accumulation of dominantly clastic deposits is not simply related to the onset of substantial exsolution of magmatic volatiles and can occur without it contact surface explosivity commonly requires initiation by a vigorous impact between magma and water and although no certain depth limit is known likelihood of such explosivity decreases rapidly with depth clast generation by bulk interaction explosivity appears to be restricted to depths much shallower than that of the critical pressure of water which in sea water is at about 3 km cooling contraction granulation can occur in any depth of water but at shallow levels may be replaced by contact surface explosivity during continuous eruption under water tephra can be ejected and deposited within a cupola of steam such that rapid quenching does not occur emergent volcanoes are characterized by distinctive steam explosive activity that results primarily from a bulk interaction between rapidly ascending magma and a highly mobile slurry of clastic material water and steam the water gets into the vent by flooding across or through the top of the tephra pile and violent explosions cease when this access is sealed the eruptions during emergence of surtsey and capelinhos typify the distinctive explosive activity the style and controls of which are different from those of maar volcanoes

analysis of satellite and in situ ground deformation data integrated by the sistem approach the april 3 2010 earthquake along the pernicana fault mt etna italy case study abstract etna is known worldwide as one of the most studied and monitored active volcanoes flank instability along the eastern and southern portions of mt etna has been observed and measured thanks to geodetic networks and insar data analysis the spreading area is bordered to the north by the east west pernicana fault system pfs whose dynamics is often linked with the eruptive activity as recently observed during the 2002 2003 eruption a seismic sequence occurred from april 2 3 2010 along the pfs with very shallow a few hundred meters mainshocks of magnitude 4 3 and 3 6 explosions and ash emissions at the summit craters followed this swarm culminating a few days later april 7 8 despite their small magnitude the earthquakes caused damage and significant surface fracturing along the pfs in order to investigate and measure the deformations in the near field of the earthquakes the sistem integration approach has been exploited the sistem enabled integrating geodetic in situ ground deformation measurements gps and leveling with satellite interferometric measurements envisat and alos in order to obtain high resolution 3d displacement maps allowing to overcome the limitations of each technique and take advantage of the particular features of each of them the integrated ground deformation field evidenced that the medium behave elastically we inverted the sistem results using an optimization algorithm based on the genetic algorithm ga in order to model the kinematics of the pfs associated to seismic swarm the results are in good agreement with the field evidence and improved the knowledge on the kinematics of the pfs and mt etna s unstable flank

late quaternary relative sea level changes and vertical movements at lipari aeolian islands indicators of former sea levels are recognised on the emergent portion of lipari aeolian islands they correlate with three raised shorelines located at elevations of 43 45 m above present sea level i 23 27 m ii and about 12 m iii according to stratigraphical constraints these shorelines correlate with the sea level highstands corresponding to marine oxygen isotope substages 5e 124 ka 5c 100 ka and 5a 81 ka respectively the correlation of the shoreline i with substage 5e is supported by a u th age 119 6 ka obtained from corals chronological and height data relevant to the fossil shorelines indicate that lipari was affected by uplift with an average rate of 0 34 mm yr 1 during the past 125 ka this uplift rate accords with the average uplift rates obtained during the same time period from the nearby islands of filicudi 0 31 mm yr 1 and salina 0 36 mm yr 1 combined these data suggest a similar uplift trend related to regional tectonic processes in contrast to the long term uplift a localised submergence trend documented especially for the last century affects the eastern coast of lipari this subsidence is related to neo and or volcano tectonic processes copyright 2002 john wiley sons ltd

pumiceous peperite in a submarine volcanic succession at mount chalmers queensland australia pumiceous peperite comprising irregularly shaped apophyses of feldspar phyric rhyolitic tube pumice and siltstone occurs within well bedded volcaniclastic sandstone and siltstone facies of the early permian berserker beds at mount chalmers australia the tube pumice structure is preserved where sericite or silica have replaced the glass of vesicle walls and vesicles have been infilled by silica in some instances the peperite occurs gradationally above or below intervals of coherent feldspar phyric rhyolite that are also predominantly pumiceous the siltstone in the pumiceous peperite is texturally homogeneous locally vesicular and contains shards and crystals derived from disintegration of the pumiceous rhyolite pumiceous rhyolite and peperite occur at various positions in the stratigraphy and may represent interconnected intrusive digits or lobes intrusion of the lobes was accommodated by expansion of the pore water and possible fluidisation of the host sediment resulting in local destruction of bedding the lobes developed chilled margins at contacts with wet sediment and inflated in response to vesiculation and the supply of new magma cooling of the lobes was possibly accompanied by development of microfractures in the glassy vesicle walls rupture of the chilled margin and propagation of fractures into the interior could have temporarily and locally depressurised the lobes resulting in failure disintegration and mixing with the adjacent wet and or steam rich sediment hot pumiceous rhyolite in lobe interiors may have interacted directly with the wet sediment and been dismembered by quench fragmentation and or steam explosions bubbles of magmatic gas and or steam were trapped in the sediment that mixed with the pumiceous rhyolite the development of pumiceous texture in the sills was favoured by emplacement beneath a thin cover of wet sediment in a relatively shallow submarine shelf setting in which the confining pressure was sufficiently low to permit vesiculation this setting was also important in limiting the extent of degassing of the pumiceous rhyolite during cooling

regional stress field in the area of stromboli italy insights into structural data and crustal tectonic earthquakes abstract crustal tectonic seismicity on stromboli is here discussed along with the regional tectonic and geodynamic context of the aeolian archipelago italy the aim of this paper is to contribute to the reduction of the crucial gap in information concerning the tectonic activity originating at the volcano stromboli in the last decade it is indeed well known that strombolian eruptions related to the persistent state of activity on this volcano allow a fast collection of seismic data which are mainly represented by explosion quakes and tremor however only some sporadic information concerns tectonic earthquakes due to their low occurrence rate a catalog of 150 crustal tectonic earthquakes recorded at stromboli from 1985 to 1996 is presented here the analyses of the seismograms were carried out on the basis of the records of the station str located in the southwestern part of the island the magnitude considered ranged from 1 5 to 3 7 hypocentral location indicates foci at less than 12 km although for the majority of the earthquakes which are not recorded at the seismic stations deployed on the other islands of the aeolian archipelago a shallower within a few kilometers depth can be hypothesized the strain release associated with the 150 tectonic earthquakes of our catalog was also evaluated the low levels of occurrence and seismic energy release reached throughout the ca twelve years analyzed here confirm the minor role played by processes of brittle failure of rocks this aspect of seismic activity is nevertheless important as it can provide a contribution to the knowledge of the dynamics of this volcano the focal mechanisms available integrated with data from the literature show the t axes oriented about ne sw and nw se these findings are consistent with the deformative and tectonic characteristics of this volcanic edifice and of the aeolian archipelago which shows the same two directions of extension this is in agreement with subduction which is very old or which passively evolves towards the final stages and is controlled by the transform activity of the aeolian tindari giardini fault system

local and downstream relationships between labrador sea water volume and north atlantic meridional overturning circulation variability abstractwhile it has generally been understood that the production of labrador sea water lsw impacts the atlantic meridional overturning circulation moc this relationship has not been explored

the 2002 2003 submarine gas eruption at panarea volcano aeolian islands italy volcanology of the seafloor and implications for the hazard scenario abstract a submarine gas eruption started in november 2002 offshore of panarea volcano aeolian islands italy the intensity of the gas emission and the considerable anomalies of the geochemical and geophysical parameters have alarmed the volcanological community and the italian civil protection agency on the possibility that this activity may represent a volcanic unrest at panarea volcano we used a high resolution marine digital terrain model mdtm with 0 5 m accuracy and detailed underwater surveys by scuba diving to study the exhalation centres and the geological morphological and structural features of the seafloor and to clarify the relationships between gas vents distribution submarine volcanological structures and the recent deformation of this area the underwater surveys revealed an exhalative field characterised by 21 main active gas vents and craters from metres to tens of metres in diameter and a pervasive exhalation from the seafloor hundreds of fossil craters associated with gas pipes and hydrothermal alteration are also present on the seafoor craters pipes and conduits are not associated with juvenile deposits and relate to a long standing history of gas exhalation and eruptions we present the first geological sketch map of the seafloor surrounding the exhalative area and establish the role of ne and nw trending fractures as the main pathways for the gas exhalation

tectonic volcanic and hydrothermal features of a submarine portion of the aeolian arc tyrrhenian sea abstract multibeam side scan sonar remotely operated vehicle and bottom sampling data have been acquired over a sector of the aeolian arc to assess its volcano tectonic characteristics and hydrothermal mineralization potential in this paper we report a description of the areas where major tectonic volcanic and hydrothermal activity has been observed there areas are the basiluzzo area the secca dei pesci area the southwestern panarea platform the secca del capo highs the offshore area between salina and lipari and the eastern slope of vulcano the study region lies at the junction of two major e w and ne sw trending tectonic lineaments through which the extensional faulting of the calabrian and sicilian margins leading to the formation of the tyrrhenian back arc sea took place the recent tectonics of the study area dominated by ne sw and e w trending extensional structures appears to be still controlled by the processes which have originated the tyrrhenian back arc opening many newly discovered recent volcanic features have been observed e g 1 three pairs of volcanic cones aligned along ne sw tectonic lineaments in the offshore between salina and lipari 2 a field of fresh tube and pillow lavas in the eastern offshore of vulcano 3 outcrops of fresh volcanic rocks in the panarea platform in particular around basiluzzo islet suggesting recent volcanic activity two types of hydrothermal mineralization were sampled i e sediment hosted sulphide deposits and fe rich crusts and sediments the polymetallic sulphide deposits were sampled in a depression south of basiluzzo islet for which area a kuroko type hydrothermal system reaching high temperature black ore deposition is suggested in the other sectors of the study area however a lower temperature hydrothermal circulation is thought to have originated the fe rich tetsusekiei type samples

evidence of vertical tectonic uplift at briatico calabria italy inferred from roman age maritime archaeological indicators abstract calabria is one of the most complex geological regions of the mediterranean basin which experienced large earthquakes and uplift and is still undergoing active tectonics along its coasts are located archaeological sites that can be used as powerful indicators of the relative vertical movements between land and sea since their construction this paper presents and discusses data on the relative sea level change as estimated from maritime archaeological indicators of the last 2 0 ka bp existing along the tyrrhenian coast of briatico these sites still show the remnants of a roman age fish tank and a submerged breakwater about 320 m long the palaeo sea level has been obtained measuring the functional elevation of the significant archaeological markers their elevation was compared against the latest predicted sea level curve for the holocene along the tyrrhenian coast of calabria as this coastal area is affected by significant and continuous vertical tectonic uplift during pleistocene the data show the counterbalance between coastal uplift and relative sea level change caused by the glacio hydro isostasy acting since the construction of these archaeological sites the sum of these movements determined an about null relative sea level change for this location these data are in contrast with other part of the tectonically stable areas of the mediterranean and provide evidence that crustal uplift continued in the last 1806 50 y at a rate of 0 65 mm y

processes of magma wet sediment interaction in a large scale jurassic andesitic peperite complex northern sierra nevada california the middle jurassic tuttle lake formation in the northern sierra nevada california comprises a thick volcaniclastic sequence deposited in a submarine island arc setting and penetrated by numerous related hypabyssal intrusions a composite andesite diorite intrusive complex 4 5 km long and 1 5 km thick was emplaced while the host tuttle lake sediments were still wet and unconsolidated large parts of the intrusive complex consist of peperite formed where andesitic magma intruded and intermixed with tuff lapilli tuff and tuff breccia the southern half of the complex consists of augite phyric andesite containing peperite in numerous small isolated pockets and in more extensive laterally continuous zones the peperites comprise three main types recognized previously in other peperite studies fluidal peperite consists of small 30 cm closely spaced at least partly interconnected globular to amoeboid andesite bodies enclosed by tuff this peperite type developed during intrusion of magma into fine grained wet sediment along unstable interfaces and fluidization of the sediment facilitated development of complex intrusive geometries blocky peperite and mixed blocky and fluidal peperite formed where magma intruded coarser sediment and underwent variable degrees of brittle fragmentation by quenching and dynamic stressing of rigid margins possibly aided by small steam explosions the northern half of the intrusive complex consists predominantly of a different type of peperite in which decimetre scale plagioclase phyric andesite clasts with ellipsoidal elongate or angular polyhedral shapes are closely packed to widely dispersed within disrupted host sediment textural features suggest the andesite clasts were derived from conduits through which magma was flowing and preserved remnants of the conduits are represented by elongate sinuous bodies up to 30 m or more in length disruption and dispersal of the andesite clasts are inferred to have occurred at least partly by steam explosions that ripped apart a network of interconnected feeder conduits penetrating the host sediments closely packed peperite is present adjacent to mappable intrusions of coherent andesite and along the margin of a large mass of coarse grained diorite these coherent intrusions are considered to be major feeders for this part of the complex examples of magma wet sediment interaction similar in scale to the extensive peperites described here occur elsewhere in ancient island arc strata in the northern sierra nevada based on these and other published examples large scale peperites probably are more common than generally realized and are likely to be important in settings where thick sediment sequences accumulate during active volcanism careful mapping in well exposed terrains may be required to recognize large scale peperite complexes of this type

tectonic features of the lipari vulcano complex aeolian archipelago italy from 10 years 1996 2006 of gps data this research has benefited from funding provided by the italian presidenza del consiglio dei ministri dipartimento della protezione civile dpc