WorldWideScience

Sample records for volcanically influenced period

  1. Geopulsation, Volcanism and Astronomical Periods

    Institute of Scientific and Technical Information of China (English)

    Yang Xuexiang; Chen Dianyou; Yang Xiaoying; Yang Shuchen

    2000-01-01

    Volcanism is mainly controlled by the intermittent release of energy in the earth. As far as the differential rotation of the earth's inner core is concerned, the Galactic Year may change the gravitational constant G, the solar radiative quantity and the moving speed of the solar system and affect the exchange of angular momentum between core and mantle as well as the energy exchange between crust and mantle. As a result, this leads to eruptions of superplumes and magma, and controls the energy flow from core - mantle boundary (CMB) to crust. When the earth' s speed decreases, it will release a huge amount of energy. They are the reason of the correspondence of the volcanic cycles one by one with the astronomical periods one by one. According to the astronomical periods, volcanic eruptions may possibly be predicted in the future.

  2. The influence of volcanic activity on suspended sediment yield of rivers (Kamchatka, Russia)

    Science.gov (United States)

    Kuksina, Ludmila

    2014-05-01

    Kamchatka is specific region of suspended sediment yield formation. This fact is particularly connected with active volcanism in the territory. The influence of volcanism on suspended sediment yield characteristics was studied in various time scales - into-diurnal, seasonal and long-term ones. The study of spatial variability of these characteristics reveals the maximum values characterize river basins in zones of strong impact of volcanic eruptions, especially, rivers draining slopes and flanks of active volcanoes. Into-diurnal fluctuations were studied for rivers in volcanic areas. They are characterized by synchronous changes of water flow and turbidity. It's determined by weak erosion-preventive capacity of friable volcanic deposits and big slopes of channels (2.5 - 6.0 %). The maximum of water flow and turbidity is observed at the period between 12 and 6 pm. The air temperature reaches its maximum by that time, and consequently, the intensity of snow melting is also maximum one. The maximum of turbidity advances diurnal maximum of water flow a little, and it's connected with the features of flood wave moving and consecutive maximums of slopes, turbidity, velocity, water flow, and capacity of stream during flush. Into-diurnal fluctuations are determined by complicated and little-studied processes of mass transfer between stream and channel deposits. These processes are connected with into-diurnal changes of stream capacity and water transfer between channel and underflow. As the result water regime is pulsating. Rivers under the influence of volcanic eruptions transport the main amount of sediments during floods which usually occur in summer-autumn period (in the absence of extreme floods in winter-spring period during volcanic eruptions). Combination of maximum snow supply, significant precipitation in warm part of the year and weak erosion-preventive capacity of friable volcanic deposits on volcanoes slopes is the reason of the most intense erosion in this

  3. Volcanism and Tectonic Evolution in the North Qilian Mountains during Ordovician Period

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The Ordovician marine volcanic rocks in the north Qilian mountains are discussed in this paper. According to geology, petrotectonic assemblage and geochemistry, a new model about plate tectonic evolution of the north Qilian mountains is set up. The Ordovician marine volcanic rocks in the north Qilian mountains which characterized by the geological features of tectonic melange of continent to continent collision underwent complicated tectonic movement, and can be classified into three main kinds of petrotectonic assemblages. During Ordovician period, north Qilian area was a polyisland ocean which consisted of three ocean basins separated by the middle microcontinental blocks.

  4. Volcanic eruption volume flux estimations from very long period infrasound signals

    Science.gov (United States)

    Yamada, Taishi; Aoyama, Hiroshi; Nishimura, Takeshi; Iguchi, Masato; Hendrasto, Muhamad

    2017-01-01

    We examine very long period infrasonic signals accompanying volcanic eruptions near active vents at Lokon-Empung volcano in Indonesia, Aso, Kuchinoerabujima, and Kirishima volcanoes in Japan. The excitation of the very long period pulse is associated with an explosion, the emerging of an eruption column, and a pyroclastic density current. We model the excitation of the infrasound pulse, assuming a monopole source, to quantify the volume flux and cumulative volume of erupting material. The infrasound-derived volume flux and cumulative volume can be less than half of the video-derived results. A largely positive correlation can be seen between the infrasound-derived volume flux and the maximum eruption column height. Therefore, our result suggests that the analysis of very long period volcanic infrasound pulses can be helpful in estimating the maximum eruption column height.

  5. The Influence of Volcanic Aerosols on Planetary Habitability

    Science.gov (United States)

    Chen, Howard; Horton, Daniel Ethan

    2017-01-01

    On rocky planetary bodies such as Proxima Centuri b, the detection of sulphate aerosols may indicate volcanism and tectonic activity; ingredients hypothesized to be necessary for planetary habitability. However, due to the effect of atmospheric aerosols on a planet’s energy balance, coupled with eruption constituent and frequency uncertainties, the potential impact of volcanic activity on planetary habitability remains unresolved. Here, we employ multi-column climate models in conjunction with a parameter space approach to test the effect of volcanic aerosols on planetary climate with various climate sensitivities. Preliminary results indicate that volcanic activity could provide a means of extending the inner edge of the habitable zone (IHZ), depending on eruption constituents and frequency. Previous work using transit spectra simulations have demonstrated the possibility of detecting transient aerosols of volcanic origin. Our work investigates the range of habitability implications detection of such aerosols would imply.

  6. Volcanic influence on centennial to millennial Holocene Greenland temperature change.

    Science.gov (United States)

    Kobashi, Takuro; Menviel, Laurie; Jeltsch-Thömmes, Aurich; Vinther, Bo M; Box, Jason E; Muscheler, Raimund; Nakaegawa, Toshiyuki; Pfister, Patrik L; Döring, Michael; Leuenberger, Markus; Wanner, Heinz; Ohmura, Atsumu

    2017-05-03

    Solar variability has been hypothesized to be a major driver of North Atlantic millennial-scale climate variations through the Holocene along with orbitally induced insolation change. However, another important climate driver, volcanic forcing has generally been underestimated prior to the past 2,500 years partly owing to the lack of proper proxy temperature records. Here, we reconstruct seasonally unbiased and physically constrained Greenland Summit temperatures over the Holocene using argon and nitrogen isotopes within trapped air in a Greenland ice core (GISP2). We show that a series of volcanic eruptions through the Holocene played an important role in driving centennial to millennial-scale temperature changes in Greenland. The reconstructed Greenland temperature exhibits significant millennial correlations with K(+) and Na(+) ions in the GISP2 ice core (proxies for atmospheric circulation patterns), and δ(18)O of Oman and Chinese Dongge cave stalagmites (proxies for monsoon activity), indicating that the reconstructed temperature contains hemispheric signals. Climate model simulations forced with the volcanic forcing further suggest that a series of large volcanic eruptions induced hemispheric-wide centennial to millennial-scale variability through ocean/sea-ice feedbacks. Therefore, we conclude that volcanic activity played a critical role in driving centennial to millennial-scale Holocene temperature variability in Greenland and likely beyond.

  7. Major optical depth perturbations to the stratosphere from volcanic eruptions: Steller extinction period, 1961-1978

    Science.gov (United States)

    Stothers, Richard B.

    2001-02-01

    A revised chronology of stratospheric aerosol extinction due to volcanic eruptions has been assembled for the period 1961-1978, which immediately precedes the era of dedicated satellite measurements. On the whole, the most accurate data consist of published observations of stellar extinction, supplemented in part by other kinds of observational data. The period covered encompasses the important eruptions of Agung (1963) and Fuego (1974), whose dust veils are discussed with respect to their transport, decay, and total mass. The effective (area-weighted mean) radii of the aerosols for both eruptions are found to be 0.3-0.4 μm. It is confirmed that, among known tropical eruptions, Agung's dust was unique for a low-latitude eruption in remaining almost entirely confined to the hemisphere of its production. A new table of homogeneous visual optical depth perturbations, listed by year and by hemisphere, is provided for the whole period 1881-1978, including the pyrheliometric period before 1961 that was investigated previously.

  8. Source Dynamics of Long-Period Seismicity in Volcanic and Hydrothermal Systems

    Science.gov (United States)

    Chouet, B. A.

    2006-12-01

    Long-period (LP) seismicity, including individual LP events and tremor, is widely observed in relation to magmatic and hydrothermal activities in volcanic areas and is recognized as a precursory phenomenon for eruptive activity. The waveform of the LP event is characterized by simple decaying harmonic oscillations except for a brief interval at the event onset. This characteristic event signature is commonly interpreted as oscillations of a fluid-filled resonator in response to a time-localized excitation. By the same token, tremor may be viewed as oscillations of the same resonator in response to a sustained excitation. Because the properties of the resonator system at the source of the LP event can be inferred from the complex frequencies of the decaying harmonic oscillations in the tail of the seismogram, these events are particularly important in the quantification of volcanic and hydrothermal processes. The damped oscillations in the LP coda are characterized by two parameters, T and Q, where T is the period of the dominant mode of oscillation, and Q is the quality factor of the oscillatory system representing the combined effects of radiation and intrinsic losses. Typical periods observed for LP events are in the range 0.2 - 2 s, while observed Q range from values near 1 to values larger than 100. Waveform inversions of LP signals carried out so far point to a crack geometry at the source of these events. Detailed investigations of the oscillating characteristics of LP sources based on the fluid-filled crack model suggest source dimensions ranging from tens to several hundred meters. Such studies further indicate that dusty gases and bubbly basalt are the most common types of fluids involved at the source of LP events in magmatic systems, while misty gases, steam and bubbly water commonly represent LP events of hydrothermal origin. Observations carried out in different volcanic settings point to a wide variety of LP excitation mechanisms. At Stromboli

  9. Susceptibility of volcanic ash-influenced soil in northern Idaho to mechanical compaction

    Science.gov (United States)

    Deborah S. Page-Dumroese

    1993-01-01

    Timber harvesting and mechanical site preparation can reduce site productivity if they excessively disturb or compact the soil. Volcanic ash-influenced soils with low undisturbed bulk densities and rock content are particularly susceptible. This study evaluates the effects of harvesting and site preparation on changes in the bulk density of ash-influenced forest soils...

  10. Influence of mesostasis in volcanic rocks on the alkali-aggregate reaction

    KAUST Repository

    Tiecher, Francieli

    2012-11-01

    Mesostasis material present in the interstices of volcanic rocks is the main cause of the alkali-aggregate reaction (AAR) in concretes made with these rock aggregates. Mesostasis often is referred to as volcanic glass, because it has amorphous features when analyzed by optical microscopy. However, this study demonstrates that mesostasis in the interstitials of volcanic rocks most often consists of micro to cryptocrystalline mineral phases of quartz, feldspars, and clays. Mesostasis has been identified as having different characteristics, and, thus, this new characterization calls for a re-evaluation of their influence on the reactivity of the volcanic rocks. The main purpose of this study is to correlate the characteristics of mesostasis with the AAR in mortar bars containing basalts and rhyolites. © 2012 Elsevier Ltd. All rights reserved.

  11. Borobudur, a basin under volcanic influence: 361,000 years BP to present

    Science.gov (United States)

    Gomez, C.; Janin, M.; Lavigne, F.; Gertisser, R.; Charbonnier, S.; Lahitte, P.; Hadmoko, S. R.; Fort, M.; Wassmer, P.; Degroot, V.; Murwanto, H.

    2010-10-01

    Borobudur basin is located in Central Java (Indonesia), 30 km to the North of Yogyakarta City. The basin is famous for its UNESCO world heritage temple and for one of the world's most active volcanoes, Merapi, located to the East of Borobudur basin. Merapi is one of the three andesitic volcanoes that surround the basin: Merapi, Merbabu and Sumbing volcanoes. Therefore, volcanic activity has strongly influenced the evolution of Borobudur basin. The object of this contribution is to present the evolution of Borobudur basin over the last 161,000 years in the light of volcanic influence. The methodology and tools developed for this research span over different areas of expertise, from geochemistry, geology and geomorphology to remote sensing, GIS and archeology. Results highlight the following points: Two major volcanic events deposited volcaniclastic materials up to tens of meters thick ~ 119,000 years BP and ~ 31,000 years BP. in the Southern part of the Borobudur basin. The second volcanic event could correspond to the collapse of the older Ancient Merapi ( Camus et al., 2000) or Proto-Merapi Stage ( Newhall et al., 2000). There is no trace in the Borobudur basin of a large debris avalanche debris avalanche inferred in the literature for Merapi Volcano was either too small to reach 20 km from the actual summit of Merapi; or, despite the orientation of the avalanche caldera rim on Merapi Volcano, the debris avalanche was deposited more towards the South, completely eroded or covered by younger deposits. There are several generations of paleolakes in the Borobudur basin. The latest one has shrunk until historical times, corroborating the theory of Newhall et al. (2000) and Murwanto et al. (2004) that Borobudur Temple was standing by a water body. Most of these paleolakes were impounded following volcanic events. Paleolakes most probably originated from the blockage of the hydrographic network by volcanic material. Borobudur temple was never buried under volcanic

  12. Attenuation of short period seismic waves at Etna as compared to other volcanic areas

    Science.gov (United States)

    Del Pezzo, E.; Gresta, S.; Patané, G.; Patané, D.; Scarcella, G.

    1987-11-01

    Coda Q for Etna volcano is frequency dependent and the Q frequency pattern and the numerical values ranging from about 100 at 1 Hz to about 300 at 18 Hz are similar to the values obtained for other volcanoes: Campi Flegrei, Aeolian Islands and Hawaii. Moreover the frequency pattern and the numerical values of coda quality factor, for most of the seismically active zones of Italy are very different from those of the volcanic zones. Several studies of the location of magma chambers show the presence of magma pockets beneath Lipari and Vulcano Islands of the Aeolian archipelago and an anomalous low velocity body beneath Etna. These evidences suggest that a possible interpretation of the characteristic frequency pattern of Q on volcanic areas is that the presence of magma can modify the scattering environment and consequently the coda Q estimates.

  13. Physical and Radiative Properties of Aerosol Particles in the Caribbean: Influence of African Dust and Soufriere Volcanic Ash

    Science.gov (United States)

    Villanueva-Birriel, C. M.; Mayol-Bracero, O. L.; Sheridan, P.; Ogren, J. A.

    2007-12-01

    Atmospheric particles such as dust and volcanic ash have the potential of influencing the earth's radiative budget directly by scattering or absorbing solar radiation in the atmosphere and indirectly by affecting cloud condensation nuclei (CCN) concentrations and, therefore, cloud albedo. The radiatively-important properties of atmospheric particles are determined at the most fundamental level by their chemical composition and size distributions; therefore, the importance of studying the chemical, physical, and optical aerosol properties. Over the summer months, the island of Puerto Rico receives African dust incursions that reduce visibility and have an impact on public health, ecosystem, and climate. Visibility is also negatively affected when the island receives south-east winds and the Soufriere volcano (Montserrat Island) has been active. Here we present preliminary results of measurements performed during 2006 and 2007 at Cape San Juan, a ground-based station located at the northeastern tip of Puerto Rico. The cases investigated showed three possible types of air masses: clean (C), with African Dust (AD), and with volcanic ash (VA) from the Soufriere. We used a condensation particle counter to determine the particle number concentration, a sunphotometer (part of the AERONET) to determine volume size distributions and aerosol optical thickness (AOT), a 3-wavelength nephelometer to determine the scattering coefficients, and a 3-wavelength particle/soot absorption photometer (PSAP) for the absorption coefficients. The particle number concentrations were higher for AD and VA periods (up to about 700 cm-3 on average for both cases) in contrast to ~400 cm-3 for the C period. Volume size distributions showed bimodal distributions for the three cases with a greater influence of the coarse fraction for the C and VA periods and an increase in the fine particles for the AD period. The total scattering coefficient showed higher values for the AD (30 Mm-1) and the VA (26

  14. Tree-ring density variations during the 1450s period of strong volcanic forcing

    Science.gov (United States)

    Esper, Jan; Büntgen, Ulf; Hartl-Meier, Claudia; Oppenheimer, Clive; Schneider, Lea

    2017-04-01

    Ice core based reconstructions of the magnitude and timing of volcanic eruptions are used to force climate models and therefore are of critical importance for assessing the dynamics of the global climate system. The forcing timeseries of the past millennium are punctuated by a few very large volcanic events including a major eruption in the 1450s. This event was originally attributed to the Kuwae caldera in the South Pacific dated to the year 1452. Recent evidence from high-resolution ice core records, however, indicated a shift by six years (to 1458), a change that will fundamentally alter 15th century climate simulations and affect model/proxy comparisons. Here we compile a Northern Hemisphere network of 25 tree-ring maximum latewood density chronologies extending back over the past 650+ years and analyze the 1450s temperature deviations. Warm season temperature reconstructions from these data reveal the spatially most coherent and by far most severe cooling of the 15th century occurred in 1453. Cooling was overall stronger in the Eurasian high latitudes and northwestern North America, and less severe in central and southern Europe. These findings indicate that the original dating of a large eruption in 1452 was correct.

  15. Global correlation of volcanic centers on Venus with uplands and with extension: Influence of mantle convection and altitude

    Science.gov (United States)

    Crumpler, L. S.; Head, James W., III; Aubele, J. C.

    1992-01-01

    The observed distribution of volcanism on Venus and its associations with geologic and tectonic characteristics are examined for significant global-scale tectonic, mantle, and volcanic influences. We find that volcanic centers are correlated geologically with zones of extension, infrequent in lowland regions, and infrequent in regions with evidence for tectonic shortening. In addition, volcanic centers are significantly concentrated in a broad region at least 10,000 km in diameter between Beta, Alta, and Themis Regiones. This area is nearly hemispheric in scale and coincides spatially with the area of greatest concentration of extensional characteristics. Our analysis suggests that the observed distribution patterns of volcanic centers reflect the regional patterns of extension, the origin of the extension and volcanism are closely related, and the hemispheric scale of both patterns implies a deep-seated origin such as large-scale interior mantle dynamic patterns. However, altitude-dependent effects on both the formation and preservation of volcanic centers could also strongly influence the observed distribution pattern.

  16. Supplement of: The Influence of Volcanic Eruptions on the Climate of Tropical South America During the Last Millennium in an Isotope-Enabled General Circulation Model

    Science.gov (United States)

    Colose, Christopher; LeGrande, Allegra N.; Vuille, Mathias

    2016-01-01

    Currently, little is known on how volcanic eruptions impact large-scale climate phenomena such as South American paleo-intertropical Convergence Zone (ITCZ) position and summer monsoon behavior. In this paper, an analysis of observations and model simulations is employed to assess the influence of large volcanic eruptions on the climate of tropical South America. This problem is first considered for historically recent volcanic episodes for which more observations are available but where fewer events exist and the confounding effects of El NioSouthern Oscillation (ENSO) lead to inconclusive interpretation of the impact of volcanic eruptions at the continental scale. Therefore, we also examine a greater number of reconstructed volcanic events for the period 850CE to present that are incorporated into the NASA GISS ModelE2-R simulation of the last millennium.An advantage of this model is its ability to explicitly track water isotopologues throughout the hydrologic cycle and simulating the isotopic imprint following a large eruption. This effectively removes a degree of uncertainty associated with error-prone conversion of isotopic signals into climate variables, and allows for a direct comparison between GISS simulations and paleoclimate proxy records.Our analysis reveals that both precipitation and oxygen isotope variability respond with a distinct seasonal and spatial structure across tropical South America following an eruption. During austral winter, the heavy oxygen isotope in precipitation is enriched, likely due to reduced moisture convergence in the ITCZ domain and reduced rainfall over northern South America. During austral summer, however, more negative values of the precipitation isotopic composition are simulated over Amazonia, despite reductions in rainfall, suggesting that the isotopic response is not a simple function of the amount effect. During the South American monsoon season, the amplitude of the temperature response to volcanic forcing is larger

  17. The influence of volcanic eruptions on the climate of tropical South America during the last millennium in an isotope-enabled general circulation model

    Science.gov (United States)

    Colose, Christopher M.; LeGrande, Allegra N.; Vuille, Mathias

    2016-04-01

    Currently, little is known on how volcanic eruptions impact large-scale climate phenomena such as South American paleo-Intertropical Convergence Zone (ITCZ) position and summer monsoon behavior. In this paper, an analysis of observations and model simulations is employed to assess the influence of large volcanic eruptions on the climate of tropical South America. This problem is first considered for historically recent volcanic episodes for which more observations are available but where fewer events exist and the confounding effects of El Niño-Southern Oscillation (ENSO) lead to inconclusive interpretation of the impact of volcanic eruptions at the continental scale. Therefore, we also examine a greater number of reconstructed volcanic events for the period 850 CE to present that are incorporated into the NASA GISS ModelE2-R simulation of the last millennium. An advantage of this model is its ability to explicitly track water isotopologues throughout the hydrologic cycle and simulating the isotopic imprint following a large eruption. This effectively removes a degree of uncertainty associated with error-prone conversion of isotopic signals into climate variables, and allows for a direct comparison between GISS simulations and paleoclimate proxy records. Our analysis reveals that both precipitation and oxygen isotope variability respond with a distinct seasonal and spatial structure across tropical South America following an eruption. During austral winter, the heavy oxygen isotope in precipitation is enriched, likely due to reduced moisture convergence in the ITCZ domain and reduced rainfall over northern South America. During austral summer, however, more negative values of the precipitation isotopic composition are simulated over Amazonia, despite reductions in rainfall, suggesting that the isotopic response is not a simple function of the "amount effect". During the South American monsoon season, the amplitude of the temperature response to volcanic forcing is

  18. Periodicities in sediment temperature time-series at a marine shallow water hydrothermal vent in Milos Island (Aegean Volcanic arc, Eastern Mediterranean)

    Science.gov (United States)

    Aliani, Stefano; Meloni, Roberto; Dando, Paul R.

    2004-05-01

    Time-series data sets of total bottom pressure (tidal plus atmospheric), seawater temperature and sediment temperature from a marine shallow hydrothermal vent (Milos, Hellenic Volcanic Arc, Aegean Sea) were studied to determine factors influencing periodicity at the vents. Bottom pressure and vent temperature were mainly opposite in phase, with the main fluctuations of vent temperature occurring at tidal frequencies. Although the fluctuations in atmospheric pressure were of the same order as those due to tidal pressure, the contribution of atmospheric pressure was considerably weaker at diurnal frequencies. Some sudden discontinuities in sediment temperature were recorded, at least one of these may have been caused by seismic events. Seawater temperature changes were not reflected in the sediment temperature record. Transient loadings, such as tidal loadings, barometric pressure and earth tides, may affect the pore pressure in sediments, influencing fluid expulsion and sediment temperature as a consequence. Most of the contribution to the fluctuations in sediment temperature depends on tidal loadings. Gravitational forces, in the form of earth tides, can also be involved and barometric pressure is probably responsible for long period temperature oscillations.

  19. Thermal Waters in Maguarichi, Chihuahua, Mexico: Influence on Volcanic Rocks Alteration

    Science.gov (United States)

    Mascote, C. R.; Espejel-Garcia, V. V.; Villalobos-Aragon, A.

    2013-05-01

    Piedras de Lumbre, Maguarichi, is located 294 km. to the SW of Chihuahua city, in northern Mexico, in the Sierra Madre Occidental (SMO). The study area is composed of a set of igneous volcanic rocks affected by hydrothermal flows, which apparently run along a fault. Outcrops of hot springs, going out with high pressure, are active all over the year and have no seasonal flow changes. The hydrothermal flows, approximately 20, that reach the surface area at Piedras de Lumbre, are altering the volcanic rocks that surround the hot springs. The study area is highly altered, and evidenced by a variety range of colors in the rock surfaces. The rock samples collected at the region show a crystal growth due to the influence of the salts from the thermal water. The rocks closest to the water openings have a change in its mineralogy, with the mafic minerals, present in andesites, been replaced by carbonates and sulfates, leaving only the clear mineral pseudomorphs. On the crust of the rocks a white layer of material (salts), product of the thermal waters has precipitated. The alteration is perceived only about 5 m. or less around the hot springs. The water, which has high contents of arsenic and sulfates has exerted a strong alteration in rhyolitic and andesitic rocks.

  20. Short-period volcanic gas precursors to phreatic eruptions: Insights from Poás Volcano, Costa Rica

    Science.gov (United States)

    de Moor, Maarten; Aiuppa, Alessandro; Pacheco, Javier; Avard, Geoffroy; Kern, Christoph; Liuzzo, Marco; Martinez, Maria; Giudice, Gaetano; Fischer, Tobias P.

    2016-01-01

    Volcanic eruptions involving interaction with water are amongst the most violent and unpredictable geologic phenomena on Earth. Phreatic eruptions are exceptionally difficult to forecast by traditional geophysical techniques. Here we report on short-term precursory variations in gas emissions related to phreatic blasts at Poás volcano, Costa Rica, as measured with an in situ multiple gas analyzer that was deployed at the edge of the erupting lake. Gas emitted from this hyper-acid crater lake approaches magmatic values of SO2/CO2 1–6 days prior to eruption. The SO2 flux derived from magmatic degassing through the lake is measureable by differential optical absorption spectrometry (sporadic campaign measurements), which allows us to constrain lake gas output and input for the major gas species during eruptive and non-eruptive periods. We can further calculate power supply to the hydrothermal system using volatile mass balance and thermodynamics, which indicates that the magmatic heat flux into the shallow hydrothermal system increases from ∼27 MW during quiescence to ∼59 MW during periods of phreatic events. These transient pulses of gas and heat from the deeper magmatic system generate both phreatic eruptions and the observed short-term changes in gas composition, because at high gas flux scrubbing of sulfur by the hydrothermal system is both kinetically and thermodynamically inhibited whereas CO2gas is always essentially inert in hyperacid conditions. Thus, the SO2/CO2 of lake emissions approaches magmatic values as gas and power supply to the sub-limnic hydrothermal system increase, vaporizing fluids and priming the hydrothermal system for eruption. Our results suggest that high-frequency real-time gas monitoring could provide useful short-term eruptive precursors at volcanoes prone to phreatic explosions.

  1. Time-varying autoregressive model for spectral analysis of microseismic experiments and long-period volcanic events

    Science.gov (United States)

    Tary, J. B.; Herrera, R. H.; van der Baan, M.

    2014-01-01

    Recent studies show that the frequency content of continuous passive recordings contains useful information for the study of hydraulic fracturing experiments as well as longstanding applications in volcano and global seismology. The short-time Fourier transform (STFT) is usually used to obtain the time-frequency representation of a seismic trace. Yet, this transform has two main disadvantages, namely its fixed time-frequency resolution and spectral leakage. Here, we describe two methods based on autoregressive (AR) models: the short-time autoregressive method (ST-AR) and the Kalman smoother (KS). These two methods allow for the AR coefficients to vary over time in order to follow time-varying frequency contents. The outcome of AR methods depends mainly on the number of AR coefficients. We use a robust approach to estimate the optimum order of the AR methods that best matches the spectral comparison between Fourier and AR spectra. Comparing the outcomes of the three methods on a synthetic signal, a long-period volcanic event, and microseismic data, we show that the STFT and both AR methods are able to track fast changes in frequency content. The STFT provides reasonable results even for noisy data using a simple and effective algorithm. The coefficients of the AR filter are defined at all time in the case of the KS. However, its better time resolution is slightly offset by a lower frequency resolution and its computational complexity. The ST-AR has a high spectral resolution and the lowest sensitivity to background noises, facilitating the identification of the various frequency components. The estimated AR coefficients can also be used to extract parts of the signal. The study of long-term phenomena, such as resonance frequencies, or transient events, such as long-period events, could help to gain further insight on reservoir deformation during hydraulic fracturing experiments as well as global or volcano seismological signals.

  2. Influences of the 2010 Eyjafjallajökull volcanic plume on air quality in the northern Alpine region

    Directory of Open Access Journals (Sweden)

    K. Schäfer

    2011-03-01

    sulphur dioxide under high solar irradiance. It became evident that during the course of several days, the Eyjafjallajökull volcanic emissions influenced the near-surface atmosphere and thus the ambient air quality. Following knowledge about health effects of air pollutants and volcanic plume compounds, it is assumed that the volcanic plume contributed to the overall exposure of the population and therefore may have had minor effects on the exacerbation of respiratory and cardiovascular symptoms.

  3. Characteristics of volcanic gas correlated to the eruption activity; Case study in the Merapi Volcano, periods of 1990-1994

    Directory of Open Access Journals (Sweden)

    Priatna Priatna

    2014-06-01

    Full Text Available http://dx.doi.org/10.17014/ijog.vol2no4.20074Volcanic gases, collected from Gendol and Woro solfatara fields, the summit of Merapi Volcano during 1990-1994, show an increase in chemical composition of H , CO, CO , SO , and HCl prior to the volcanic events, on the contrary to the drastic decreasing water vapour. The carbon/sulfur ratio of the volcanic gases lies between 1.5 and 5.7 which means that they were derived from the fresh magma. The Apparent Equilibrium Temperature (AET which is calculated from chemical compositions of volcanic gases using reaction of SO +3H = H S+2H O showed an increasing value prior to the volcanic events. The Merapi activities lasted during August 1990 to November 1994 showed a significant increase in ratio SO /H S prior to the November 1994 pyroclastic flow. The isotopic composition of volcanic gas condensates indicates that water vapour in Gendol is directly derived from the fresh magma. On the other hand, the contamination and cooling by the subsurface water occurred around the Woro field at a shallow part. 

  4. Spatial and temporal variations of diffuse CO_{2} degassing at the N-S volcanic rift-zone of Tenerife (Canary Islands, Spain) during 2002-2015 period

    Science.gov (United States)

    Alonso, Mar; Ingman, Dylan; Alexander, Scott; Barrancos, José; Rodríguez, Fátima; Melián, Gladys; Pérez, Nemesio M.

    2016-04-01

    Tenerife is the largest of the Canary Islands and, together with Gran Canaria Island, is the only one with a central volcanic complex that started to grow at about 3.5 Ma. Nowadays the central complex is formed by Las Cañadas caldera, a volcanic depression measuring 16×9 km that resulted from multiple vertical collapses and was partially filled by post-caldera volcanic products. Up to 297 mafic monogenetic cones have been recognized on Tenerife, and they represent the most common eruptive activity occurring on the island during the last 1 Ma (Dóniz et al., 2008). Most of the monogenetic cones are aligned following a triple junction-shaped rift system, as result of inflation produced by the concentration of emission vents and dykes in bands at 120o to one another as a result of minimum stress fracturing of the crust by a mantle upwelling. The main structural characteristic of the southern volcanic rift (N-S) of the island is an apparent absence of a distinct ridge, and a fan shaped distribution of monogenetic cones. Four main volcanic successions in the southern volcanic rift zone of Tenerife, temporally separated by longer periods (˜70 - 250 ka) without volcanic activity, have been identified (Kröchert and Buchner, 2008). Since there are currently no visible gas emissions at the N-S rift, diffuse degassing surveys have become an important geochemical tool for the surveillance of this volcanic system. We report here the last results of diffuse CO2 efflux survey at the N-S rift of Tenerife, performed using the accumulation chamber method in the summer period of 2015. The objectives of the surveys were: (i) to constrain the total CO2 output from the studied area and (ii) to evaluate occasional CO2 efflux surveys as a volcanic surveillance tool for the N-S rift of Tenerife. Soil CO2 efflux values ranged from non-detectable up to 31.7 g m-2 d-1. A spatial distribution map, constructed following the sequential Gaussian simulation (sGs) procedure, did not show an

  5. Influence of perturbations on period-doubling bifurcation

    DEFF Research Database (Denmark)

    Svensmark, Henrik; Samuelsen, Mogens Rugholm

    1987-01-01

    The influence of noise and resonant perturbation on a dynamical system in the vicinity of a period-doubling bifurcation is investigated. It is found that the qualitative dynamics can be revealed by simple considerations of the Poincaré map. These considerations lead to a shift of the bifurcation...

  6. Influence Of Volcanic Scoria On Mechanical Strength, Chemical Resistance And Drying Shrinkage Of Mortars

    Directory of Open Access Journals (Sweden)

    Al-Swaidani A.

    2014-09-01

    Full Text Available In the study, three types of cement have been prepared; one CEM I type (the control sample and two blended cements: CEM II/A-P and CEM II/B-P (EN 197-1, each of them with three replacement levels of volcanic scoria: (10 %, 15 %, 20 % wt. and (25 %, 30 %, 35 % wt., respectively. Strength development of mortars has been investigated at 2, 7, 28 and 90 days curing. Evaluation of chemical resistance of mortars containing scoria-based cements has been investigated through exposure to 5 % sulphate and 5 % sulphuric acid solutions in accordance with ASTM C1012 & ASTM 267, respectively. Drying shrinkage has been evaluated in accordance with ASTM C596. Test results showed that at early ages, the mortars containing CEM II/B-P binders had strengths much lower than that of the control mortar. However, at 90 days curing, the strengths were comparable to the control mortar. In addition, the increase of scoria significantly improved the sulphate resistance of mortars. Further, an increase in scoria addition improved the sulphuric acid resistance of mortar, especially at the early days of exposure. The results of drying shrinkage revealed that the CEM II/B-P mortar bars exhibited a greater contraction when compared to the control mortar, especially at early ages. However, drying shrinkage of mortars was not influenced much at longer times.

  7. The Santorini Volcanic Complex: A detailed multi-parameter seismological approach with emphasis on the 2011-2012 unrest period

    Science.gov (United States)

    Papadimitriou, P.; Kapetanidis, V.; Karakonstantis, A.; Kaviris, G.; Voulgaris, N.; Makropoulos, K.

    2015-04-01

    The present study is focused on the examination of the state of the recently activated Santorini Volcanic Complex (SVC) area, located in the Southern Aegean Sea. The seismic activity was investigated in detail and different methodologies have been applied to examine whether the SVC area approached an eruptive phase during the 2011-2012 seismic crisis period. The detailed spatiotemporal analysis for the broader study area revealed two different seismic patterns: low seismic activity until 2010, mainly concentrated within the Anydros basin and close to the submarine volcano, Columbo, and activation during 2011 and 2012 of two previously quiescent regions. The first is the Santorini Caldera, which had been active for more than one year, and the second is the area south of Christiana Islands, which was activated in January 2012 with the occurrence of two major events of magnitude 5.1 and 5.2, respectively, followed by a large number of aftershocks. In this study, manual analysis and relocation of the 2011-2012 seismic crisis in the SVC was performed, in order to obtain a high-resolution image of the activated structures. The seismicity within the Santorini Caldera, which is oriented approximately NE-SW, was rapidly diminished after the activation of the Christiana area. A large number of focal mechanisms were determined which mainly indicated strike-slip faulting inside the Caldera. Furthermore, the fault plane solutions of the major events in the area south of Christiana, derived by waveform modeling, also suggested similar type of faulting. This type differs from the normal faults observed in the Anydros basin. However, the stress field in all cases is consistently oriented in a NW-SE direction. Since the Santorini Volcano was seismically activated for the first time after the 1950 eruption, changes of the physical properties of the medium were examined using different approaches to assess the state of the volcano. The shear-wave splitting analysis revealed the

  8. The influence of volcanic eruptions on growth of central European trees in NE Germany during the last Millennium

    Science.gov (United States)

    Pieper, H.; Heinrich, I.; Heussner, K. U.; Helle, G.

    2011-12-01

    Large volcanic eruptions have strong impacts on the global climate, lowering the global temperature and increasing the diffuse light fraction for one to several years after the eruptions. It has been argued that due to scattering by volcanic sulfur aerosol the more diffuse light fraction can be used more efficiently by forests. However, other observations suggest a growth decrease because of the cooler conditions following large eruption. Trees growing to the north of the temperate zone are mainly temperature-limited and therefore a reduction in ring width after large volcanic eruptions seems inevitable. Since tree growth in the temperate zone is less limited by temperature than by other climate parameters such as precipitation, it was hypothesized that tree growth may not suffer from lower temperatures so much but profit from increased diffuse light and reduced water stress. Therefore, a database of long tree-ring chronologies originating from several sites in NE-Germany was used to test whether tree growth suffered or profited from the globally changed conditions after large eruptions. The growth relationships were tested against 49 individual large volcanic eruptions from the last 1000 years. High-resolution ice core records of sulfate measurements calibrated against atmospheric observations after modern eruptions identified the timing and magnitude of the eruptions since 1000 CE. A more negative influence on tree growth was detected in two tree-ring width chronologies of oak and pine (Quercus robur L. and Pinus sylvestris L.) originating from three different sites (Greifswald, Eberswalde and Saxony) in eastern Germany for up to four years after large eruptions. Overall, the long tree-ring chronologies covering more or less the last millennium indicated a more negative relationship to volcanic eruptions. In comparison, the chronologies of Q. robur reveal a more negative response after large eruptions than those of P. sylvestris. Only in Greifswald both tree

  9. Influence of management practices on C stabilization pathways in agricultural volcanic ash soils (Canary Islands, Spain)

    Science.gov (United States)

    Hernandez, Zulimar; María Álvarez, Ana; Carral, Pilar; de Figueiredo, Tomas; Almendros, Gonzalo

    2014-05-01

    periodical inputs of manures. This includes accumulation of slightly transformed material in scenarios of high C mineralization rates, such are in vitrandic soils. ii) Accumulation of resilient organo-mineral complexes in non andic-soils with crystalline minerals and probable inputs of pyrogenic C in the past. Finally, iii) accumulation of aliphatic structures, such as carbohydrate- and N-rich macromolecules, leading to HAs with characteristics in common with those formed in aquatic environments. The formation of these HAs could be favoured by microbial activity in andic Anthrosols, and would define a specific type of soil C stabilization mechanism of aliphatic compounds encapsulated in nanoparticle-size soil pores, where persistent hydromorphic conditions were favoured by amorphous gels in volcanic ash soils. [1] Lal, R., 2004. Mitigation and Adaptation Strategies for Global Change 12, 303-322. [2] Stevenson, F.J., 1994. Humus Chemistry: Genesis, composition, reactions. 2nd ed. Wiley, New York. [3] Ellis, G.P., 1959. Advances in Carbohydrate Chemistry 14, 63-134. [4] Almendros, G., 2008. Humic substances. In: Cheswort, W. (Ed.), Encyclopedia of Soil Science, Springer, Dordretch, pp. 97-99. [5] Kögel-Knabner, I., Hatcher, P.G., Tegelaar, E.W., de Leeuw J.W., 1992. The Science of the Total Environment 113, 89-105. [6] Hernández, Z., Almendros, G., Carral, P., Álvarez, A., Knicker, H., Pérez-Trujillo, J.P., 2012. European Journal of Soil Science 63, 603-615.

  10. Geomorphological evidence of the influence of pre-volcanic basement structure on emplacement and deformation of volcanic edifices at the Cofre de Perote Pico de Orizaba chain and implications for avalanche generation

    Science.gov (United States)

    Concha-Dimas, Aline; Cerca, Mariano; Rodríguez, Sergio R.; Watters, Robert J.

    2005-12-01

    Pre-volcanic structure of the basement influences volcanism distribution and avalanche generation in volcanic edifices. Therefore, systematic studies of basement structure below volcanic chains are necessary to understand the deformation effects observed in the surface and vice versa. Based on a compilation of pre-existing data, interpretation of aerial photographs and satellite images, and a collection of structural data we analyzed morphological and structural features of the Cofre de Perote-Pico de Orizaba (CP-PO) volcanic chain and its basement. We have identified three sets of regional lineaments that are related to basement trends. (1) NW 55° SE fractures are parallel to anticline folds observed in Cretaceous rocks that originated during Laramide shortening. These folds present an abrupt morphology observed only in the eastern flank but that is likely to continue below the volcanic chain. (2) NE 55° SW fractures are parallel to normal faults at the basement. We infer that these basement faults confine the CP-PO chain within a stepped graben with a total normal displacement of about 400 m. These faults have been active through time since they have affected volcanic deposits and induced the emplacement of monogenetic vents. Notably, lineaments of monogenetic vents concentrate where the basement is relatively shallow. (3) Another set of faults, oriented N-S, has been observed affecting the scarce basement outcrops at the western flank of the chain covered by lacustrine deposits. Lineaments measured in the volcanic edifice of Pico de Orizaba correlate with the regional trends. In particular, the NE 55° SW alignment of monogenetic vents and fractures at Pico de Orizaba suggest that the same dike trend exists within the volcanic edifice. A normal fault with similar orientation was documented at the NE continuation of an alignment crossing the volcanic edifice along the Jamapa canyon. In the absence of magmatic activity related to collapses, the displacement of

  11. Quantitative micro-Raman analysis of volcanic glasses: influence and correction of matrix effects

    Science.gov (United States)

    Di Muro, Andrea

    2014-05-01

    . Geochimica et Cosmochimica Acta, 74, 5641-5656. Mercier, M., Di Muro, A., Giordano, D., Métrich, N.,Pichavant, M., Clocchiatti, R., Montagnac, G. (2009) The influence of glass polymerization and oxidation on micro-Raman water analysis in alumino-silicate glasses. Geochimica et Cosmochimica Acta, 73, 197-217 Di Muro, A., Métrich, N., Mercier, M., Giordano, D., Massare, D., Montagnac, G. (2009) Micro-Raman determination of iron redox state in dry natural glasses : application to peralkaline rhyolites and basalts. Chemical Geology (Special volume on experimental techniques for the study of hydrothermal fluids and silicate melts) 259:78-88. Di Muro A, Villemant B, Montagnac G, Scaillet B, Reynard B (2006) The influence of glass composition on the determination of water content and speciation by Raman spectrometry. Geochimica and Cosmochimica Acta, 70, 2868-2884 Di Muro A, Giordano D., Villemant B, Montagnac G, Romano C. (2006) Influence of composition and thermal history of volcanic glasses on water content determination by microRaman spectrometry. Applied Geochemistry (Special volume on developments in analytical geochemistry). 21, 802-812. Application Di Muro, A., Staudacher, T., Ferrazzini, V., Villemant, B., Besson, P., Garofalo, C. (2014) Tracking magma injection in the Piton de la Fournaise volcanic edifice after the 2007 Summit Caldera Collapse by Pele's Hair Composition. Chapman Special Volume on Hawaiian volcanoes, AGU Books. Ardia, P., Di Muro, A., Giordano, D., Massare, D., Sanchez-Valle, C., Schmidt, M.W. (2014) Densification mechanisms of haplogranite glasses as a function of water content and pressure based on density and Raman data. Under review, submitted to Geochimica et Cosmochimica Acta. Métrich, N, Allard, P., Aiuppa, A., Bani, P., Bertagnini, A., Belhadj, O., Di Muro, A., Garaebiti, E., Massare, D., Parello, F., Shinohara, H. (2011) Magma and volatile feeding of post-caldera Yasur volcanism and block resurgence in Tanna island (Vanuatu arc). Journal of

  12. Influence of periodic traffic congestion on epidemic spreading

    Science.gov (United States)

    Zheng, Muhua; Ruan, Zhongyuan; Tang, Ming; Do, Younghae; Liu, Zonghua

    2016-11-01

    In the metropolis, traffic congestion has become a very serious problem, especially in rush hours. This congestion causes people to have more chance to contact each other and thus will accelerate epidemic spreading. To explain this observation, we present a reaction-diffusion (RD) model with a periodic varying diffusion rate to represent the daily traveling behaviors of human beings and its influence to epidemic spreading. By extensive numerical simulations, we find that the epidemic spreading can be significantly influenced by traffic congestion where the amplitude, period and duration of diffusion rate are the three key parameters. Furthermore, a brief theory is presented to explain the effects of the three key parameters. These findings suggest that except the normal ways of controlling contagion in working places and long-distance traveling, controlling the contagion in daily traffic congestion may be another effective way to reduce epidemic spreading.

  13. Influence of volcanic tephra on photovoltaic (PV)-modules: An experimental study with application to the 2010 Eyjafjallajokull eruption, Iceland

    Science.gov (United States)

    Zorn, Edgar; Walter, Thomas R.

    2016-04-01

    Large volcanic eruptions may lead to significant tephra dispersion, crossing borders and affecting distant and industrial societies in various ways. While the effects of volcanic ash clouds on the aviation industry have been recognized, damaging effects on the photovoltaic energy sector are poorly investigated. Here we describe the influence of volcanic tephra deposition on photovoltaic (PV) modules that we experimentally analyzed and evaluated. A systematic set of experiments was conducted under controlled conditions using an artificial light source and measuring the electrical power generated from the PV-modules with the aim to determine the dependency of the amount of tephra covering a module and its subsequent loss in power production (measured in voltage and current) as well as the influence of the tephra grain size. We find that a mass of fine tephra has a stronger influence on the PV-modules power generation than the same mass of coarser particles. An application to the fine-grained 2010 Eyjafjallajökull eruption in Iceland and the resulting ash-cloud reveals that the power produced by PV-modules in continental Europe might have been affected significantly. Deposits were thick enough to cause complete failures of PV-modules up to a distance of about 300 km downwind. Although this distance is largely over the ocean in this particular case, our results imply that similar and larger eruptions of other volcanoes elsewhere might harm commercial or private energy production at distances of hundreds to thousands of kilometers from the volcano. Given that volcanic eruptions are frequent and the fact that the PV-industry is growing rapidly, negative impacts are expected in the future, requiring close tephra dispersion monitoring and PV-maintenance strategies.

  14. Technical progress report of biological research on the Volcanic Island Surtsey and its environs for the period 1965--1978

    Energy Technology Data Exchange (ETDEWEB)

    Fridriksson, S.

    1978-01-01

    Progress is reported on the following research projects: changes in shoreline and surface of the island due to volcanic activity; colonization of microorganisms, algae, lichens, and vascular plants; introduction of insects and other arthropods by wind, water, and man; transport of invertebrates to the island by flotsam of the sea; species and nesting habits of birds on the island; behavior of seals on beaches of the island; and future trends of Surtsey ecosystems. (HLW)

  15. The Probation Period for Debutant Civil Servants. Influencing Expectancy

    Directory of Open Access Journals (Sweden)

    Leonina Emilia SUCIU

    2012-10-01

    Full Text Available This study is part of a broader research on work motivation in the Romanian local public administration, based on Vroom’s motivational model. The research has tried to diagnose Romanian local public institutions (city halls in particular regarding the work motivation level of their civil servants. Since the research was too broad to be presented entirely in this article, the authors will show only the findings obtained in one city hall from a city, county residence. Due to the same reason, this paper refers to just one of the Vroom’s model elements (the expectancy and to one of the aspects that could influence it: the probation period for the debutant civil servants. The probation period is critical in preparing civil servants for their future job and career within the local public administration. That is why it can influence the expectancy of civil servants, which in its turn, (from Vroom’s’ model perspective influences work motivation.

  16. Relationship between volcanic ash fallouts and seismic tremor: quantitative assessment of the 2015 eruptive period at Cotopaxi volcano, Ecuador

    Science.gov (United States)

    Bernard, Benjamin; Battaglia, Jean; Proaño, Antonio; Hidalgo, Silvana; Vásconez, Francisco; Hernandez, Stephen; Ruiz, Mario

    2016-11-01

    Understanding the relationships between geophysical signals and volcanic products is critical to improving real-time volcanic hazard assessment. Thanks to high-frequency sampling campaigns of ash fallouts (15 campaigns, 461 samples), the 2015 Cotopaxi eruption is an outstanding candidate for quantitatively comparing the amplitude of seismic tremor with the amount of ash emitted. This eruption emitted a total of 1.2E + 9 kg of ash ( 8.6E + 5 m3) during four distinct phases, with masses ranging from 3.5E + 7 to 7.7E + 8 kg of ash. We compare the ash fallout mass and the corresponding cumulative quadratic median amplitude of the seismic tremor and find excellent correlations when the dataset is divided by eruptive phase. We use scaling factors based on the individual correlations to reconstruct the eruptive process and to extract synthetic Eruption Source Parameters (daily mass of ash, mass eruption rate, and column height) from the seismic records. We hypothesize that the change in scaling factor through time, associated with a decrease in seismic amplitudes compared to ash emissions, is the result of a more efficient fragmentation and transport process. These results open the possibility of feeding numerical models with continuous geophysical data, after adequate calibration, in order to better characterize volcanic hazards during explosive eruptions.

  17. Influences of RVG Positions on the Periodic Flow Profiles

    OpenAIRE

    Withada Jedsadaratanachai

    2014-01-01

    The effects on the positions of rib vortex generators (RVGs) for periodic laminar flow behavior are presented numerically in three-dimensional. The RVGs with constant blockage ratio (b/H, BR = 0.15), the pitch ratio (P/H, PR = 1), and flow attack angle (α=30°) are inserted in isothermal walls of the square channel. The SIMPLE algorithm and the finite volume method (FVM) are applied for the computational domain. The influences of different gap ratios (g/H = 0–0.35) for Reynolds number based on...

  18. Mechanisms of aggradation in fluvial systems influenced by explosive volcanism: An example from the Upper Cretaceous Bajo Barreal Formation, San Jorge Basin, Argentina

    Science.gov (United States)

    Umazano, Aldo M.; Bellosi, Eduardo S.; Visconti, Graciela; Melchor, Ricardo N.

    2008-01-01

    The Late Cretaceous succession of the San Jorge Basin (Patagonia, Argentina) records different continental settings that interacted with explosive volcanism derived from a volcanic arc located in the western part of Patagonia. This paper discusses the contrasting aggradational mechanisms in fluvial systems strongly influenced by explosive volcanism which took place during sedimentation of the Bajo Barreal Formation. During deposition of the lower member of the unit, common ash-fall events and scarce sandy debris-flows occurred, indicating syn-eruptive conditions. However, the record of primary pyroclastic deposits is scarce because they were reworked by river flows. The sandy fluvial channels were braided and show evidence of important variations in water discharge. The overbank flows (sheet-floods) represent the main aggradational mechanism of the floodplain. In places, subordinate crevasse-splays and shallow lakes also contributed to the floodplain aggradation. In contrast, deposition of the upper member occurred in a fluvial-aeolian setting without input of primary volcaniclastic detritus, indicating inter-eruptive conditions. The fluvial channels were also braided and flowed across low-relief floodplains that mainly aggraded by deposition of silt-sized sediments of aeolian origin (loess) and, secondarily by sheet-floods. The Bajo Barreal Formation differs from the classic model of syn-eruptive and inter-eruptive depositional conditions in the presence of a braided fluvial pattern during inter-eruptive periods, at least at one locality. This braided fluvial pattern is attributed to the high input of fine-grained pyroclastic material that composes the loessic sediments.

  19. The influence of cooling, crystallisation and re-melting on the interpretation of geodetic signals in volcanic systems

    Science.gov (United States)

    Caricchi, Luca; Biggs, Juliet; Annen, Catherine; Ebmeier, Susanna

    2014-02-01

    Deformation of volcanic edifices is typically attributed to the movement of magma within the volcanic plumbing system, but a wide range of magmatic processes are capable of producing significant volume variations and may also produce deformation. In order to understand the evolution of magmatic systems prior to eruption and correctly interpret monitoring signals, it is necessary to quantify the patterns and timescales of surface deformation that processes such as crystallisation, degassing and expansion of the hydrothermal system can produce. We show how the combination of petrology and thermal modelling can be applied to geodetic observations to identify the processes occurring in a magmatic reservoir during volcanic unrest. Thermal modelling and petrology were used to determine the timescales and volumetric variations associated with cooling, crystallisation and gas exsolution. These calculations can be performed rapidly and highlight the most likely processes responsible for the variation of a set of monitoring parameters. We then consider the magnitude and timescales of deformation produced by other processes occurring within the vicinity of an active magma system. We apply these models to a time series of geodetic data spanning the period between the 1997 and 2008 eruptions of Okmok volcano, Aleutians, examining scenarios involving crystallisation, degassing and remelting of the crystallising shallow magmatic body and including a viscoelastic shell or hydrothermal system. The geodetic observations are consistent with the injection of a water-saturated basalt, followed by minor crystallisation and degassing. Other scenarios are not compatible either with the magnitude or rate of the deformation signals.

  20. The influence of volcanic activity in the Campi Flegrei coastal depositional system

    Science.gov (United States)

    Violante, Crescenzo; Esposito, Eliana; Molisso, Flavia; Porfido, Sabina; Sacchi, Marco

    2010-05-01

    The Campi Flegrei coastal area includes the bay of Pozzuoli, Procida and Ischia islands, characterized by active tectonics and volcanism since the Pleistocene. Numerous monogenic volcanoes occur close to the shoreline and volcanic debris interpreted as submarine counterpart of subaerial flows and surges, have been detected offshore. In the Pozzuoli area the most recent eruptive volcanic activity occurred from 10.0 to 8.0 ky B.P and 4.5 to 3.7 ky B.P. followed by the September 1538 Monte Nuovo eruption. Here magma-related activity is testified by extensive hydrothermalism, and recent episodes (1970-71 and 1982-84 on Pozzuoli coast) of shallow seismicity and ground deformation, exceeding rates of 100 cm/year in the years 1983-1984. The most recent volcanic activity on Ischia island starts around 10.0 ky B.P. to which associates several eruptive centres mostly located in the western sector. The last eruption dates back to Arso flow in 1302. Nevertheless the landscape of Ischia is dominated by Mount Epomeo in the central part of the island, which is the highest peak (788 m). It is a volcano-tectonic structure that raised above sea level between 33 and 28 ka BP, due to the intrusion of magma at shallow depth. Procida island is composed of five monogenic Volcanoes (Vivara, Terra Murata, Pozzo Vecchio, Fiumicello and Solchiaro) that have been active over the last 80 ky producing pyroclastic deposits and a lava dome. A sixth volcanic structure has been reported recently off P.ta Serra by marine investigations and confirmed by airborne magnetic surveys. The emplacement of large amount of volcanoclastic material from volcanic and volcano-tectonic activity in the Campi Flegrei coastal area produced extensive avalanche deposits off Ischia island, seafloor instabilities in the form of creep/slump, channelled sediment flow and deep sedimentary fans, and is largely responsible for aggradation/progradation of the coastal area during the Quaternary. Moreover, numerous volcanic bank

  1. Io's volcanic influence on the Io plasma torus: HISAKI observation in 2015

    Science.gov (United States)

    Tsuchiya, F.; Yoshioka, K.; Kimura, T.; Murakami, G.; Yoneda, M.; Koga, R.; Kagitani, M.; Sakanoi, T.; Kasaba, Y.; Yamazaki, A.; Yoshikawa, I.

    2015-12-01

    The satellite Io which has many active volcanos supplies volcanic gases to the Jovian magnetosphere with typical rate of 1 ton/sec and has been known be a primary source of plasmas in the magnetosphere. Change in the volcanic activity on Io should cause change of the supply rate and could affect structure of the magnetosphere and dynamics occurs in it. However, responses of the magnetosphere to the volcanic activity is still not fully understood; one of the reasons is lack of continuous and long term observations of Io' volcanic gas extended around Io, plasmas in the Io torus, and activity of the magnetosphere. The extreme ultraviolet (EUV) spectroscope, EXCEED, onboard the HISAKI satellite has capability to measure ion and atomic emission lines in EUV range (55-145nm) and is dedicated to observing solar system planets. The satellite has been successfully launched on Sep. 2013 and 2nd campaign of Io plasma torus and Jovian northern EUV aurora observation has been done from the end of Nov. 2014 to middle of May 2015. On middle of Jan. 2015, HISAKI detected gradual increase in intensity of S+ emission lines and decrease of S3+ ones in the plasma torus. The S+ intensity showed a maximum around the end of Feb. and S++ and S3+ intensities also showed maxima subsequently. Simultaneous ground based observation of the sodium nebula showed increase of the emission intensity from the middle of Jan. to the beginning of Mar. These observations suggest that the volcanic activity began at the middle of Jan. and increase neutral atom and ion densities in the Io torus. The intensities of S+ and S2+ ions returned to the pre-increase level by the middle of May 2015. S3+ had still been in the decay phase at the end of the observation. Change in radial structure of the plasma torus was also found during the volcanic event. The intensity of S+ ion began to increase around the orbit of Io (6 Jovian radii). The brightened region propagated outward and reached at 8.5 Jovian radii from

  2. Satellite observations of atmospheric SO 2 from volcanic eruptions during the time-period of 1996-2002

    Science.gov (United States)

    Khokhar, M. F.; Frankenberg, C.; Van Roozendael, M.; Beirle, S.; Kühl, S.; Richter, A.; Platt, U.; Wagner, T.

    In this article, we present satellite observations of atmospheric sulfur dioxide (SO 2) from volcanic eruptions. Global ozone monitoring experiment (GOME) data for the years 1996-2002 is analyzed using a DOAS based algorithm with the aim of retrieving SO 2 slant column densities (SCD). The retrieval of SO 2 SCD in the UV spectral region is difficult due to strong and interfering ozone absorptions. It is also likely affected by instrumental effects. We investigated these effects in detail to obviate systematic biases in the SO 2 retrieval. A quantitative study of about 20 volcanoes from Italy, Iceland, Congo/Zaire, Ecuador, Japan, Vanuatu Island and Mexico is presented. The focus is on both eruption and out gassing scenarios. We prepared a 7-year mean map (1996-2002) of SO 2 SCD observed by GOME and tabulated the ratios of the maximum SO 2 SCD observed to the average SO 2 SCD as seen in the 7-year mean map. The further aim of this study is to provide information about unknown volcanic eruptions, e.g., Bandai Honshu Japan, Central Islands Vanuatu, Piton de la Fournaise Réunion Island France, Kamchatka region of Russia and from Indonesia especially. The results demonstrate a high sensitivity of the GOME instrument towards SO 2 emissions during both eruption and degassing episodes.

  3. Influence of seismic processes and volcanic activity on the formation of disastrous floods

    Science.gov (United States)

    Trifonov, Dmitriy

    2014-05-01

    models of hydraulic systems, but ultimately due to difference of pressures in their respective segments and areas of the transport network. At the exit of the groundwater on the surface such change in pressure is connected both with the state of the actual water flow in underground cavities, or violations of the structure (topology) of 3D-network. As one of the major and sudden reasons of change of pressure in the underground system can serve seismic processes, including volcanic eruptions (as magmatic and ash). During these processes enormous underground space can be freed from the dense rock. This leads to rapid changes in pressure and that, in principle, a new topology of 3D network and water flows in it. It is important that such dynamic processes occur over huge distances in underground basins of thousands of kilometers [3], of course, with a certain time delay. In the result of the analysis of large-scale flooding in Russia in 2001-2002, as well as the catastrophic floods in Western Europe, in the Amur region of Russia and in the state of Colorado USA in 2013, a correlation between seismic and volcanic activities and floods, expressed by specific numerical correlation coefficients, has been revealed. For example, knowing the date, location and magnitude of an earthquake, we can identify potentially dangerous territories in the aspect of the probability of occurrence of floods, because the stresses in the crust, spreading from the hypocenter of earthquakes, and their subsequent relaxation are one of the most important factors of floods. Mechanisms of distribution of these stresses are well-studied today [2] unlike their influence on the groundwater. The defined boundaries of potentially dangerous sites are broad enough; with regard to the direction of distribution of stress, it is about the sectors in 40 degrees (from the line of the movement of the crustal plate) in the direction from the boundaries of lithospheric plates. Distribution of this impact occurs, as a

  4. Tectonic evolution of the central-eastern sector of Trans Mexican Volcanic Belt and its influence on the eruptive history of the Nevado de Toluca volcano (Mexico)

    Science.gov (United States)

    Bellotti, F.; Capra, L.; Groppelli, G.; Norini, G.

    2006-11-01

    The Nevado de Toluca is an andesitic to dacitic stratovolcano of Late Pliocene-Holocene age located within the central and eastern sectors of the Trans Mexican Volcanic Belt. Morphostructural analysis, aerial photograph and satellite image interpretation, structural analysis and geological fieldwork were methods used to investigate the relationship between the evolution of the volcano and the tectonic framework of its basement. The study revealed that the area of Nevado de Toluca is affected by three main fault systems that intersect close to the volcanic edifice. These are from oldest to youngest, the Taxco-Querétaro, San Antonio and Tenango fault systems. The NNW-SSE Taxco-Querétaro fault system was active in the area since Early Miocene, and is characterized by right-lateral transtensive movement. Its reactivation during Early to Middle Pleistocene was responsible for the emplacement of andesitic to dacitic lava flows and domes of La Cieneguilla Supersynthem. The NE-SW San Antonio fault system was active during Late Pliocene, before the reactivation of the Taxco-Querétaro fault system, and is characterized by extensional left-lateral oblique-slip kinematics. The youngest is the E-W Tenango fault system that has been active since Late Pleistocene. This fault system is characterized by transtensive left-lateral strike-slip movement, and partly coeval with the youngest eruptive phase, the Nevado Supersynthem, which formed the present summit cone of the Nevado de Toluca volcano. The stress re-orientation from the Taxco-Querétaro to the Tenango fault system during Late Pleistocene is responsible for the ˜ 1 Ma hiatus in the magmatic activity between 1.15 Ma and 42 ka. After this period of repose, the eruptive style drastically changed from effusive to explosive with the emission of dacitic products. The methodology presented here furnish new data that can be used to better assess the complex structural evolution of this sector of the Trans Mexican Volcanic Belt

  5. Climate effects on volcanism: influence on magmatic systems of loading and unloading from ice mass variations, with examples from Iceland.

    Science.gov (United States)

    Sigmundsson, Freysteinn; Pinel, Virginie; Lund, Björn; Albino, Fabien; Pagli, Carolina; Geirsson, Halldór; Sturkell, Erik

    2010-05-28

    Pressure influences both magma production and the failure of magma chambers. Changes in pressure interact with the local tectonic settings and can affect magmatic activity. Present-day reduction in ice load on subglacial volcanoes due to global warming is modifying pressure conditions in magmatic systems. The large pulse in volcanic production at the end of the last glaciation in Iceland suggests a link between unloading and volcanism, and models of that process can help to evaluate future scenarios. A viscoelastic model of glacio-isostatic adjustment that considers melt generation demonstrates how surface unloading may lead to a pulse in magmatic activity. Iceland's ice caps have been thinning since 1890 and glacial rebound at rates exceeding 20 mm yr(-1) is ongoing. Modelling predicts a significant amount of 'additional' magma generation under Iceland due to ice retreat. The unloading also influences stress conditions in shallow magma chambers, modifying their failure conditions in a manner that depends critically on ice retreat, the shape and depth of magma chambers as well as the compressibility of the magma. An annual cycle of land elevation in Iceland, due to seasonal variation of ice mass, indicates an annual modulation of failure conditions in subglacial magma chambers.

  6. Deep long-period earthquakes west of the volcanic arc in Oregon: evidence of serpentine dehydration in the fore-arc mantle wedge

    Science.gov (United States)

    Vidale, John E.; Schmidt, David A.; Malone, Stephen D.; Hotovec-Ellis, Alicia J.; Moran, Seth C.; Creager, Kenneth C.; Houston, Heidi

    2014-01-01

    Here we report on deep long-period earthquakes (DLPs) newly observed in four places in western Oregon. The DLPs are noteworthy for their location within the subduction fore arc: 40–80 km west of the volcanic arc, well above the slab, and near the Moho. These “offset DLPs” occur near the top of the inferred stagnant mantle wedge, which is likely to be serpentinized and cold. The lack of fore-arc DLPs elsewhere along the arc suggests that localized heating may be dehydrating the serpentinized mantle wedge at these latitudes and causing DLPs by dehydration embrittlement. Higher heat flow in this region could be introduced by anomalously hot mantle, associated with the western migration of volcanism across the High Lava Plains of eastern Oregon, entrained in the corner flow proximal to the mantle wedge. Alternatively, fluids rising from the subducting slab through the mantle wedge may be the source of offset DLPs. As far as we know, these are among the first DLPs to be observed in the fore arc of a subduction-zone system.

  7. Examining the influence of meteorological simulations forced by different initial and boundary conditions in volcanic ash dispersion modelling

    Science.gov (United States)

    Mulena, Gabriela C.; Allende, David G.; Puliafito, Salvador E.; Lakkis, Susan G.; Cremades, Pablo G.; Ulke, Ana G.

    2016-07-01

    The performance of the combination of the FALL3D ash dispersion model with the Weather Research and Forecast (WRF) meteorological model in the southern cone of South America under two initial and boundary conditions was evaluated. ERA-Interim and NCEP-GFS datasets were used as dynamic conditions by WRF to simulate meteorological fields for FALL3D. As a study case, we used the eruption of the Puyehue-Cordón Caulle Volcanic Complex occurred in Chile in June 2011. The simulated meteorological results were compared with the horizontal wind direction, meridional and zonal wind components, air and dew point temperatures of 7 radio sounding stations using a set of error indicators. In addition, the ash mass load simulated by FALL3D for a day of maximum dispersion of volcanic ash was evaluated using the Moderate Resolution Imaging Spectroradiometer (MODIS) data, on which the Prata algorithm was applied. As well as this, the WRF-dominant physical processes with both dynamic conditions were analyzed for that same date. Meteorological results indicated that the simulation performed with WRF and NCEP-GFS shows the lowest errors at levels between 925 and 300 hPa. Ash dispersion simulated with FALL3D and WRF in both dynamic conditions shows a different perfomance, which from the synoptic and dynamic viewpoint can be explained for the result of wind intensity and geopotential height. Moreover, WRF intiliazed with NCEP-GFS and FALL3D has a higher degree of concordance with the MODIS image. Based on the analysis and results, it was concluded that for the southern cone of South America, 1) it was not trivial for the simulation of volcanic ash dispersion to use one dynamic condition or another in WRF; 2) in that sense, meteorological variables that influenced the differences in volcanic ash dispersion were horizontal wind intensity and direction and geopotential heights; 3) the system generated from the combination of the WRF model initialized with NCEP-GFS and the FALL3D dispersion

  8. A detailed seismic anisotropy study during the 2011-2012 unrest period in the Santorini Volcanic Complex

    Science.gov (United States)

    Kaviris, G.; Papadimitriou, P.; Kravvariti, Ph.; Kapetanidis, V.; Karakonstantis, A.; Voulgaris, N.; Makropoulos, K.

    2015-01-01

    The Santorini Volcanic Complex (SVC) is an area in the Southern Aegean (Greece) which has been characterized by low seismicity rates for the last decades, especially in the Santorini Caldera where they have been very low until 2010. This pattern changed completely in February 2011, when intense microseismic activity was initiated within the Caldera. During the manual analysis of the events, the shear-wave splitting phenomenon was observed, revealing the existence of an anisotropic upper crust in the SVC area. A detailed anisotropy study has been conducted using 231 events within the shear-wave window that fulfilled the selection criteria. The polarization direction of the fast shear-wave, the time-delay between the two split shear-waves and the source polarization direction were calculated after visual inspection, using both the polarigram and the hodogram representations. This procedure, applied for eight local stations, resulted in the determination of 340 splitting parameters. The obtained mean anisotropy directions are not homogeneous, revealing a complex regime in the activated area. Nevertheless, these results are explained by the APE model, related to the stress-sensitive behavior of fluid-saturated microcracked rocks. A detailed analysis of the temporal evolution of both the time-delay and anisotropy direction was carried out. The time-delays measured in the “band-1” window exhibit gradual increase and sudden drop that can be related to imminent bursts of seismicity, as well as to the major Mw = 5.1 and 5.2 events which took place about 40 km SW of Santorini on 26 and 27 January 2012, respectively. On the other hand, no significant temporal variations or 90° flips of the Sfast polarization direction were observed.

  9. Volcanic Catastrophes

    Science.gov (United States)

    Eichelberger, J. C.

    2003-12-01

    The big news from 20th century geophysics may not be plate tectonics but rather the surprise return of catastrophism, following its apparent 19th century defeat to uniformitarianism. Divine miracles and plagues had yielded to the logic of integrating observations of everyday change over time. Yet the brilliant interpretation of the Cretaceous-Tertiary Boundary iridium anomaly introduced an empirically based catastrophism. Undoubtedly, decades of contemplating our own nuclear self-destruction played a role in this. Concepts of nuclear winter, volcanic winter, and meteor impact winter are closely allied. And once the veil of threat of all-out nuclear exchange began to lift, we could begin to imagine slower routes to destruction as "global change". As a way to end our world, fire is a good one. Three-dimensional magma chambers do not have as severe a magnitude limitation as essentially two-dimensional faults. Thus, while we have experienced earthquakes that are as big as they get, we have not experienced volcanic eruptions nearly as great as those preserved in the geologic record. The range extends to events almost three orders of magnitude greater than any eruptions of the 20th century. Such a calamity now would at the very least bring society to a temporary halt globally, and cause death and destruction on a continental scale. At maximum, there is the possibility of hindering photosynthesis and threatening life more generally. It has even been speculated that the relative genetic homogeneity of humankind derives from an evolutionary "bottleneck" from near-extinction in a volcanic cataclysm. This is somewhat more palatable to contemplate than a return to a form of Original Sin, in which we arrived at homogeneity by a sort of "ethnic cleansing". Lacking a written record of truly great eruptions, our sense of human impact must necessarily be aided by archeological and anthropological investigations. For example, there is much to be learned about the influence of

  10. Source mechanisms of volcanic tsunamis.

    Science.gov (United States)

    Paris, Raphaël

    2015-10-28

    Volcanic tsunamis are generated by a variety of mechanisms, including volcano-tectonic earthquakes, slope instabilities, pyroclastic flows, underwater explosions, shock waves and caldera collapse. In this review, we focus on the lessons that can be learnt from past events and address the influence of parameters such as volume flux of mass flows, explosion energy or duration of caldera collapse on tsunami generation. The diversity of waves in terms of amplitude, period, form, dispersion, etc. poses difficulties for integration and harmonization of sources to be used for numerical models and probabilistic tsunami hazard maps. In many cases, monitoring and warning of volcanic tsunamis remain challenging (further technical and scientific developments being necessary) and must be coupled with policies of population preparedness. © 2015 The Author(s).

  11. Heavy metal capture by autochthonous yeasts from a volcanic influenced environment of Patagonia.

    Science.gov (United States)

    Russo, Gabriel; Libkind, Diego; Giraudo, María Rosa; Delgado, Osvaldo Daniel

    2016-11-01

    Heavy metals at elevated concentrations are a major threat to agricultural and human health. Typically, human activities tend to release these metals to the environment in aqueous solutions, generating high levels of pollution due to the mobility of the heavy metals. The aim of the present work was to assess heavy metal tolerance in yeasts isolated from Río Agrio - Lake Caviahue volcanic acidic aquatic environment and to evaluate the capacity of selected strains to capture metals in acidic culture media conditions. The ability of three yeast species, Cryptococcus agrionensis, Cryptococcus sp. 2, and Coniochaeta fodinicola, to tolerate and capture metals in live cultures has been evaluated. These three yeast species showed high tolerance to low pH and elevated concentrations of metals, thus implying their autochthonous status. Minimal inhibitory concentration (MIC) for growth obtained for these isolates showed elevated tolerance to the six heavy metals evaluated and were significantly higher than those registered for other microorganisms. C. agrionensis was able to capture 15.80 mg (g biomass)(-1) of Cu(2+) (MIC: 0.22 g L(-1) ), Cryptococcus sp. 2 was able to capture 36.25 and 65.28 mg (g biomass)(-1) of Ni(2+) and Zn(2+) , respectively (MIC: 0.56 and 1.68, respectively), and C. fodinicola was able to capture 67.11 mg (g biomass)(-1) of Zn(2+) (MIC: 3.75). This work reported the ability of yeasts to capture metals in acidic conditions for the first time. We hope that it represents the step-stone for future researches in the ability and metabolism of yeasts form acidic aquatic environment related to metal tolerance and capture. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Local influences of geothermal anomalies on permafrost distribution in an active volcanic island (Deception Island, Antarctica)

    Science.gov (United States)

    Goyanes, G.; Vieira, G.; Caselli, A.; Cardoso, M.; Marmy, A.; Santos, F.; Bernardo, I.; Hauck, C.

    2014-11-01

    This study aims at understanding the spatial distribution and characteristics of the frozen and unfrozen terrain in an alluvial fan on Deception Island, which is an active strato-volcano located in the Bransfield Strait (South Shetland Islands) with recent eruptions in 1967, 1969 and 1970. The alluvial fan is dominated by debris-flow, run-off and rock fall processes and permafrost occurs in several parts in the vicinity of anomalous geothermal heat flux. The aim is to assess the ways volcanic activity controls permafrost development and associated geomorphic dynamics using shallow subsurface, surface and air temperature measurements as well as thaw depth and electrical resistivity tomography (ERT) surveys. Results show a temperature increase with depth in the lower part of the fan reaching 13 °C at 0.80 m depth, without the presence of permafrost. The shallow borehole located at this site showed a stable thermal stratification all year-round, with only the upper 0.20 m reacting to meteorological forcing. In the upper part of the alluvial fan and debris cones, c. 100 m from the coast, frozen ground is present at c. 0.70 m depth. There, the shallow borehole shows a good coupling with air temperatures and the thermal regime favours the presence of permafrost. ERT shows the lowest resistivity values in the lower part of the alluvial fan and a highly resistivity zone in the upper sector of the fan and in the debris cones. These large variations in resistivity mark the presence of a saline water wedge from the sea into the fan, reaching frozen ground conditions about 100 m inland. It can be shown that the volcano-hydrothermal activity only inhibits frost development very locally, with frozen ground conditions occurring about 100 m away.

  13. Catastrophic volcanism

    Science.gov (United States)

    Lipman, Peter W.

    1988-01-01

    Since primitive times, catastrophes due to volcanic activity have been vivid in the mind of man, who knew that his activities in many parts of the world were threatened by lava flows, mudflows, and ash falls. Within the present century, increasingly complex interactions between volcanism and the environment, on scales not previously experienced historically, have been detected or suspected from geologic observations. These include enormous hot pyroclastic flows associated with collapse at source calderas and fed by eruption columns that reached the stratosphere, relations between huge flood basalt eruptions at hotspots and the rifting of continents, devastating laterally-directed volcanic blasts and pyroclastic surges, great volcanic-generated tsunamis, climate modification from volcanic release of ash and sulfur aerosols into the upper atmosphere, modification of ocean circulation by volcanic constructs and attendent climatic implications, global pulsations in intensity of volcanic activity, and perhaps triggering of some intense terrestrial volcanism by planetary impacts. Complex feedback between volcanic activity and additional seemingly unrelated terrestrial processes likely remains unrecognized. Only recently has it become possible to begin to evaluate the degree to which such large-scale volcanic processes may have been important in triggering or modulating the tempo of faunal extinctions and other evolutionary events. In this overview, such processes are examined from the viewpoint of a field volcanologist, rather than as a previous participant in controversies concerning the interrelations between extinctions, impacts, and volcanism.

  14. Influence of African Dust and Volcanic Ash on the Chemical Composition of Cloud/Rain Water Collected in a Tropical Montane Cloud Forest in Puerto Rico

    Science.gov (United States)

    Reyes-Rodríguez, G. J.; Gioda, A.; Mayol-Bracero, O. L.; Collett, J.

    2007-12-01

    Some organic compounds present in aerosols are surface active and their presence in cloud condensation nuclei can affect the surface tension of cloud droplets. The nature of these surface active compounds in clouds and rainwater is not well understood and there is very little information about their content in remote tropical environments. Therefore, our study focuses on the chemical characterization of the organic component of cloud and rainwater samples collected in a tropical montane cloud forest on the island of Puerto Rico. Samples were collected during periods of varying air mass origin, including periods of influence by African dust and by volcanic ash. Cloud samples were collected using a compact version of the single-stage Caltech Active Strand Cloudwater Collector. Rain samples were collected using a passive collector. The organic fraction of collected samples was characterized using a total organic carbon and total nitrogen analyzer (TOC/TN) and nuclear magnetic resonance (1H-NMR) spectroscopy. Elemental and organic carbon (EC, OC) were determined for suspended particles contained in collected cloud and rainwater samples. These particles were also analyzed using scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) to determine their elemental compositions. Preliminary results indicate that average concentrations of cloud water TOC ranged from 0.9 to 1.2 mg/L. Lower concentrations were observed in rainwater, 0.3 to 0.7 mg/L. TN concentrations were higher than TOC in cloud water samples when air masses came from the African continent. The suspended aerosol particles had a content of 2.0 µg of OC per mL of cloud water, but EC was not detected. Suspended particle analysis by SEM-EDS showed Si, Al, and Fe, which have crustal origin, as the predominant species. The 1H-NMR spectra showed alcohols in large quantities, suggesting the presence of biogenic material or polyols when air masses arrived from the African continent. A more complete set

  15. The influence of eruption season on the global aerosol evolution and radiative impact of tropical volcanic eruptions

    Directory of Open Access Journals (Sweden)

    M. Toohey

    2011-08-01

    Full Text Available Simulations of tropical volcanic eruptions using a general circulation model with coupled aerosol microphysics are used to assess the influence of season of eruption on the aerosol evolution and radiative impacts at the Earth's surface. This analysis is presented for eruptions with SO2 injection magnitudes of 17 and 700 Tg, the former consistent with estimates of the 1991 Mt. Pinatubo eruption, the later a near-"super eruption". For each eruption magnitude, simulations are performed with eruptions at 15° N, at four equally spaced times of year, and sensitivity to eruption season is quantified as the difference between the maximum and minimum cumulative anomalies.

    Eruption season has a significant influence on aerosol optical depth (AOD and clear-sky shortwave (SW radiative flux anomalies for both eruption magnitudes. The sensitivity to eruption season for both fields is generally weak in the tropics, but increases in the mid- and high latitudes, reaching maximum values of ~80 %. Global mean AOD and clear-sky SW anomalies show sensitivity to eruption season on the order of 15–20 %, which results from differences in aerosol effective radius for the different eruption seasons. Smallest aerosol size and largest cumulative impact result from a January eruption for the Pinatubo-magnitude, and from a July eruption for the near-super eruption. In contrast to AOD and clear-sky SW anomalies, all-sky SW anomalies are found to be insensitive to season of eruption for the Pinatubo-magnitude eruption experiment, due to the reflection of solar radiation by clouds in the mid- to high latitudes. However, differences in all-sky SW anomalies between eruptions in different seasons are significant for the larger eruption magnitude, and the ~15 % sensitivity to eruption season of the global mean all-sky SW anomalies is comparable to the sensitivity of global mean AOD and clear-sky SW anomalies. Our estimates of sensitivity to eruption season

  16. The influence of eruption season on the global aerosol evolution and radiative impact of tropical volcanic eruptions

    Directory of Open Access Journals (Sweden)

    M. Toohey

    2011-12-01

    Full Text Available Simulations of tropical volcanic eruptions using a general circulation model with coupled aerosol microphysics are used to assess the influence of season of eruption on the aerosol evolution and radiative impacts at the Earth's surface. This analysis is presented for eruptions with SO2 injection magnitudes of 17 and 700 Tg, the former consistent with estimates of the 1991 Mt. Pinatubo eruption, the later a near-"super eruption". For each eruption magnitude, simulations are performed with eruptions at 15° N, at four equally spaced times of year. Sensitivity to eruption season of aerosol optical depth (AOD, clear-sky and all-sky shortwave (SW radiative flux is quantified by first integrating each field for four years after the eruption, then calculating for each cumulative field the absolute or percent difference between the maximum and minimum response from the four eruption seasons. Eruption season has a significant influence on AOD and clear-sky SW radiative flux anomalies for both eruption magnitudes. The sensitivity to eruption season for both fields is generally weak in the tropics, but increases in the mid- and high latitudes, reaching maximum values of ~75 %. Global mean AOD and clear-sky SW anomalies show sensitivity to eruption season on the order of 15–20 %, which results from differences in aerosol effective radius for the different eruption seasons. Smallest aerosol size and largest cumulative impact result from a January eruption for Pinatubo-magnitude eruption, and from a July eruption for the near-super eruption. In contrast to AOD and clear-sky SW anomalies, all-sky SW anomalies are found to be insensitive to season of eruption for the Pinatubo-magnitude eruption experiment, due to the reflection of solar radiation by clouds in the mid- to high latitudes. However, differences in all-sky SW anomalies between eruptions in different seasons are significant for the larger eruption magnitude, and the ~15 % sensitivity to

  17. Influence of volcanic history on groundwater patterns on the west slope of the Oregon High Cascades.

    Science.gov (United States)

    A. Jefferson; G. Grant; T. Rose

    2006-01-01

    Spring systems on the west slope of the Oregon High Cascades exhibit complex relationships among modern topography, lava flow geometries, and groundwater flow patterns. Seven cold springs were continuously monitored for discharge and temperature in the 2004 water year, and they were periodically sampled for ?18O, ?D, tritium, and dissolved noble gases. Anomalously high...

  18. Volcanic signals in oceans

    KAUST Repository

    Stenchikov, Georgiy L.

    2009-08-22

    Sulfate aerosols resulting from strong volcanic explosions last for 2–3 years in the lower stratosphere. Therefore it was traditionally believed that volcanic impacts produce mainly short-term, transient climate perturbations. However, the ocean integrates volcanic radiative cooling and responds over a wide range of time scales. The associated processes, especially ocean heat uptake, play a key role in ongoing climate change. However, they are not well constrained by observations, and attempts to simulate them in current climate models used for climate predictions yield a range of uncertainty. Volcanic impacts on the ocean provide an independent means of assessing these processes. This study focuses on quantification of the seasonal to multidecadal time scale response of the ocean to explosive volcanism. It employs the coupled climate model CM2.1, developed recently at the National Oceanic and Atmospheric Administration\\'s Geophysical Fluid Dynamics Laboratory, to simulate the response to the 1991 Pinatubo and the 1815 Tambora eruptions, which were the largest in the 20th and 19th centuries, respectively. The simulated climate perturbations compare well with available observations for the Pinatubo period. The stronger Tambora forcing produces responses with higher signal-to-noise ratio. Volcanic cooling tends to strengthen the Atlantic meridional overturning circulation. Sea ice extent appears to be sensitive to volcanic forcing, especially during the warm season. Because of the extremely long relaxation time of ocean subsurface temperature and sea level, the perturbations caused by the Tambora eruption could have lasted well into the 20th century.

  19. Influence of Curing Age and Mix Composition on Compressive Strength of Volcanic Ash Blended Cement Laterized Concrete

    Directory of Open Access Journals (Sweden)

    Babafemi A.J.

    2012-01-01

    Full Text Available This study investigates the influence of curing age and mix proportions on the compressive strength of volcanic ash (VA blended cement laterized concrete. A total of 288 cubes of 100mm dimensions were cast and cured in water for 3, 7, 28, 56, 90 and 120 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively while a control mix of 28-day target strength of 25N/mm2 (using British Method was adopted. The results show that the compressive strength of the VA-blended cement laterized concrete increased with the increase in curing age but decreased as the VA and laterite (LAT contents increased. The optimum replacement level was 20%LAT/20%VA. At this level the compressive strength increased with curing age at a decreasing rate beyond 28 days. The target compressive strength of 25N/mm2 was achieved for this mixture at 90 days of curing. VA content and curing age was noted to have significant effect (α ≤ 0.5 on the compressive strength of the VA-blended cement laterized concrete.

  20. The excitation and characteristic frequency of the long-period volcanic event: An approach based on an inhomogeneous autoregressive model of a linear dynamic system

    Science.gov (United States)

    Nakano, M.; Kumagai, H.; Kumazawa, M.; Yamaoka, K.; Chouet, B.A.

    1998-01-01

    We present a method to quantify the source excitation function and characteristic frequencies of long-period volcanic events. The method is based on an inhomogeneous autoregressive (AR) model of a linear dynamic system, in which the excitation is assumed to be a time-localized function applied at the beginning of the event. The tail of an exponentially decaying harmonic waveform is used to determine the characteristic complex frequencies of the event by the Sompi method. The excitation function is then derived by operating an AR filter constructed from the characteristic frequencies to the entire seismogram of the event, including the inhomogeneous part of the signal. We apply this method to three long-period events at Kusatsu-Shirane Volcano, central Japan, whose waveforms display simple decaying monochromatic oscillations except for the beginning of the events. We recover time-localized excitation functions lasting roughly 1 s at the start of each event and find that the estimated functions are very similar to each other at all the stations of the seismic network for each event. The phases of the characteristic oscillations referred to the estimated excitation function fall within a narrow range for almost all the stations. These results strongly suggest that the excitation and mode of oscillation are both dominated by volumetric change components. Each excitation function starts with a pronounced dilatation consistent with a sudden deflation of the volumetric source which may be interpreted in terms of a choked-flow transport mechanism. The frequency and Q of the characteristic oscillation both display a temporal evolution from event to event. Assuming a crack filled with bubbly water as seismic source for these events, we apply the Van Wijngaarden-Papanicolaou model to estimate the acoustic properties of the bubbly liquid and find that the observed changes in the frequencies and Q are consistently explained by a temporal change in the radii of the bubbles

  1. Influence of volcanic activity and anthropic impact in the trace element contents of fishes from the North Patagonia in a global context.

    Science.gov (United States)

    Bubach, D F; Macchi, P J; Pérez Catán, S

    2015-11-01

    The elemental contents in salmonid muscle and liver tissues from different lakes around the world were investigated. Fish from pristine areas were compared with those fishes from impacted environments, both by volcanic and anthropogenic activities. Within the data, special attention was given to fishes from the Andean Patagonian lakes in two contexts: local and global. The local evaluation includes geological and limnological parameters and diet composition which were obtained through a data search from published works. The volcanic influence in Andean Patagonian lakes was mainly observed by an increase of cesium (Cs) and rubidium (Rb) concentrations in fishes, influenced by calcium (Ca) and potassium (K) water contents. Zinc (Zn), selenium (Se), iron (Fe), silver (Ag), and mercury (Hg) contents in fishes showed the effect of the geological substratum, and some limnological parameters. The diet composition was another factor which affects the elemental concentration in fishes. The analyzed data showed that the fishes from Andean Patagonian lakes had elemental content patterns corresponding to those of pristine regions with volcanic influence. Selenium and Ag contents from Andean Patagonian fishes were the highest reported.

  2. The influence of volcanism on paleoclimate in the northeast of China: Insights from Jinchuan peat, Jilin Province, China

    Institute of Scientific and Technical Information of China (English)

    MAO Xumei; CHENG Shenggao; HONG Yetang; ZHU Yongxuan; WANG Fenglin

    2009-01-01

    Just like contemporary sediments, peat itself is a good repository of information about climate change, the effects of volcanic activity on climate change have been truly recorded in peat, since it is a major archive of volcanic eruption incidents. A section of sand was identified as tephra from the Jinchuan peat, Jilin Province, China, for the grains look like slag with surface bubbles and pits, characterized by high porosity, and loose structure with irregular edges and corners. According to the peat characteristics of uniform deposition, the tephra was dated at 2002-1976 a B.P. by way of linear interpolation, so the time of volcanic eruption was 15 B.C.-26 A.D. (the calibrated age). While the geochemical characteristics of tephra in this study are quite the same as those of tephra from the Jinlongdingzi volcano at Longgang and from alkaline basaltic magma, with the contents of SiO2K2O. We speculated that the tephra in this study came from the Longgang volcano group. Compared with 11 recorded volcanic eruption events as shown on the carbon and oxygen isotope curves of the Jinchuan peat cellulose, it is obviously seen that adjacent or large-scale volcanic eruptions are precisely corresponding to the minimum temperature and humidity. It seems that these volcanic eruptions indeed affected the local climate, leading to the drop of regional temperature and humidity. As a result, there was prevailing a cold and dry climate there, and all these changes can be well recorded in peat. So the comparison of volcanic eruption events with information about climate change developed from peat, can provide strong evidence for the impact of volcanism on climate change.

  3. Relationship between Volcanic Rocks and Hydrocarbon Accumulation during Dominant Period of Basin Formation in Liaohe Depression%主成盆期火山岩与油气成藏关系探讨

    Institute of Scientific and Technical Information of China (English)

    陈振岩; 仇劲涛; 王璞珺; 李湃; 张培先; 刘鑫; 郝涛; 聂桂民

    2011-01-01

    The dominant period of basin formation is defined as the period with the strongest tectonic movements,the largest extent of subsidence and the best development of source rocks.The sedimentary period of the 3rd member(Shasan,E2s3) and 4th member(Shasi,E2s4) of Shahejie Formation is the dominant period for basin formation.There were many episodes of volcanic movements during Cenozoic in Liaohe Depression,forming distribution of volcanic rocks with many series and types,which changes with the tectonic center and has the less strong activity in the earlier stages.The volcanic movements in the dominant period of Liaohe depression are abnormally strong and the appearances of volcanic rocks are frequent.The reservoirs which are altered by structural fractures and the corrosion and dissolution by formation water are favorable for oil and gas accumulation.The superposition in plane and the alternation in profile provide enough provision conditions of oil and gas sources for volcanic rock reservoirs.Furthermore,the volcanic rocks from dominant period of basin are of large thickness,widespread distribution and various traps and accumulation types,owning many advantages for oil and/or gas accumulation in many respects.The volcanic rock reservoirs for oil and/or gas in the areas of Huangshatuo and Oulituozi are typical representations among the above favorable reservoirs.The volcanic rocks from the dominant period of basin formation with favorable combination of oil and/or gas accumulation,enriching the content of oil and /or gas accumulation and the types of oil and /or gas exploration,are the important field for hydrocarbon discovery and exploration.%裂陷盆地的主成盆期是构造活动性最强、沉降幅度最大、烃源岩发育最好的时期,辽河坳陷的主成盆期是E2s4~E2s3时期。辽河坳陷新生代发生了多期火山活动,形成了多套、多类型的火山岩分布,火山活动总体上具有早强晚弱、平面上具有随沉降中

  4. Lidar Observations of Aerosol Disturbances of the Stratosphere over Tomsk (56.5∘N; 85.0∘E in Volcanic Activity Period 2006–2011

    Directory of Open Access Journals (Sweden)

    Oleg E. Bazhenov

    2012-01-01

    Full Text Available The lidar measurements (Tomsk: 56.5∘N; 85.0∘E of the optical characteristics of the stratospheric aerosol layer (SAL in the volcanic activity period 2006–2011 are summarized and analyzed. The background SAL state with minimum aerosol content, observed since 1997 under the conditions of long-term volcanically quiet period, was interrupted in October 2006 by series of explosive eruptions of volcanoes of Pacific Ring of Fire: Rabaul (October 2006, New Guinea; Okmok and Kasatochi (July-August 2008, Aleutian Islands; Redoubt (March-April 2009, Alaska; Sarychev Peak (June 2009, Kuril Islands; Grimsvötn (May 2011, Iceland. A short-term and minor disturbance of the lower stratosphere was also observed in April 2010 after eruption of the Icelandic volcano Eyjafjallajokull. The developed regional empirical model of the vertical distribution of background SAL optical characteristics was used to identify the periods of elevated stratospheric aerosol content after each of the volcanic eruptions. Trends of variations in the total ozone content are also considered.

  5. Reactive bromine chemistry in Mt. Etna's volcanic plume: the influence of total Br, high temperature processing, aerosol loading and plume-air mixing

    Directory of Open Access Journals (Sweden)

    T. J. Roberts

    2014-03-01

    Full Text Available Volcanic emissions present a source of reactive halogens to the troposphere, through rapid plume chemistry that converts the emitted HBr to more reactive forms such as BrO. The nature of this process is poorly quantified, yet is of interest to understand volcanic impacts on the troposphere, and infer volcanic activity from volcanic gas measurements (i.e. BrO / SO2 ratios. Recent observations from Etna report an initial increase and subsequent plateau or decline in BrO / SO2 ratios with distance downwind. We present daytime PlumeChem model simulations that reproduce and explain the reported trend in BrO / SO2 at Etna including the initial rise and subsequent plateau. Through suites of model simulations we also investigate the influences of volcanic aerosol loading, bromine emission, and plume-air mixing rate on the downwind plume chemistry. Emitted volcanic HBr is converted into reactive bromine by autocatalytic bromine chemistry cycles whose onset is accelerated by the model high-temperature initialisation. These rapid chemistry cycles also impact the reactive bromine speciation through inter-conversion of Br, Br2, BrO, BrONO2, BrCl, HOBr. Formation of BrNO2 is also discussed. We predict a new evolution of Br-speciation in the plume, with BrO, Br2, Br and HBr as the main plume species in the near downwind plume whilst BrO, and HOBr are present in significant quantities further downwind (where BrONO2 and BrCl also make up a minor fraction. The initial rise in BrO / SO2 occurs as ozone is entrained into the plume whose reaction with Br promotes net formation of BrO. Aerosol has a modest impact on BrO / SO2 near-downwind (2 occurs as entrainment of oxidants HO2 and NO2 promotes net formation of HOBr and BrONO2, whilst the plume dispersion dilutes volcanic aerosol so slows the heterogeneous loss rates of these species. A higher volcanic aerosol loading enhances BrO / SO2 in the (> 6 km downwind plume. Simulations assuming low/medium and high Etna

  6. American Influencies in Brazilian Physical Education: Clues in the Specialised Periodical Press (1932-1950)

    Science.gov (United States)

    Schneider, Omar; Neto, Amarílio Ferreira; da Silva Mello, André; dos Santos, Wagner; Votre, Sebastião Josué; Assunção, Wallace Rocha

    2016-01-01

    This study investigates the American presence and influences in the physical education press to understand the way in which that presence influenced and contributed to the production of a sports culture in the first half of the twentieth century. As historical sources, the study uses periodicals in the field that were published in the period…

  7. Precambrian Lunar Volcanic Protolife

    Directory of Open Access Journals (Sweden)

    Jack Green

    2009-06-01

    Full Text Available Five representative terrestrial analogs of lunar craters are detailed relevant to Precambrian fumarolic activity. Fumarolic fluids contain the ingredients for protolife. Energy sources to derive formaldehyde, amino acids and related compounds could be by flow charging, charge separation and volcanic shock. With no photodecomposition in shadow, most fumarolic fluids at 40 K would persist over geologically long time periods. Relatively abundant tungsten would permit creation of critical enzymes, Fischer-Tropsch reactions could form polycyclic aromatic hydrocarbons and soluble volcanic polyphosphates would enable assembly of nucleic acids. Fumarolic stimuli factors are described. Orbital and lander sensors specific to protolife exploration including combined Raman/laser-induced breakdown spectrocsopy are evaluated.

  8. A quantitative model for volcanic hazard assessment

    OpenAIRE

    W. Marzocchi; Sandri, L.; Furlan, C

    2006-01-01

    Volcanic hazard assessment is a basic ingredient for risk-based decision-making in land-use planning and emergency management. Volcanic hazard is defined as the probability of any particular area being affected by a destructive volcanic event within a given period of time (Fournier d’Albe 1979). The probabilistic nature of such an important issue derives from the fact that volcanic activity is a complex process, characterized by several and usually unknown degrees o...

  9. Volcanism-sedimentation interaction in the Campo de Calatrava Volcanic Field (Spain): a magnetostratigraphic and geochronological study

    Science.gov (United States)

    Herrero-Hernández, Antonio; López-Moro, Francisco Javier; Gallardo-Millán, José Luis; Martín-Serrano, Ángel; Gómez-Fernández, Fernando

    2015-01-01

    This work focuses on the influence of Cenozoic volcanism of the Campo de Calatrava volcanic field on the sedimentation of two small continental basins in Spain (Argamasilla and Calzada-Moral basins). The volcanism in this area was mainly monogenetic, according to the small-volume volcanic edifices of scoria cones that were generated and the occurrence of tuff rings and maars. A sedimentological analysis of the volcaniclastic deposits led to the identification of facies close to the vents, low-density (dilute) pyroclastic surges, secondary volcanic deposits and typical maar deposits. Whole-rock K/Ar dating, together with palaeomagnetic constraints, yielded an age of 3.11-3.22 Ma for the onset of maar formation, the deposition finished in the Late Gauss-Early Matuyana. Using both techniques and previous paleontological data allowed it to be inferred that the maar formation and the re-sedimentation stage that occurred in Argamasilla and Calzada-Moral basins were roughly coeval. The occurrence of syn-eruption volcaniclastic deposits with small thicknesses that were separated by longer inter-eruption periods, where fluvial and lacustrine sedimentation was prevalent, together with the presence of small-volume volcanic edifices indicated that there were short periods of volcanic activity in this area. The volcanic activity was strongly controlled by previous basement faults that favoured magma feeding, and the faults also controlled the location of volcanoes themselves. The occurrence of the volcanoes in the continental basins led to the creation of shallow lakes that were related to the maar formation and the modification of sedimentological intra-basinal features, specifically, valley slope and sediment load.

  10. Geology of the Ivanhoe Hg-Au district, northern Nevada: Influence of Miocene volcanism, lakes, and active faulting on epithermal mineralization

    Science.gov (United States)

    Wallace, A.R.

    2003-01-01

    The mercury-gold deposits of the Ivanhoe mining district in northern Nevada formed when middle Miocene rhyolitic volcanism and high-angle faulting disrupted a shallow lacustrine environment. Sinter and replacement mercury deposits formed at and near the paleosurface, and disseminated gold deposits and high-grade gold-silver veins formed beneath the hot spring deposits. The lacustrine environment provided abundant meteoric water; the rhyolites heated the water; and the faults, flow units, and lakebeds provided fluid pathways for the hydrothermal fluids. A shallow lake began to develop in the Ivanhoe area about 16.5 Ma. The lake progressively expanded and covered the entire area with fine-grained lacustrine sediments. Lacustrine sedimentation continued to at least 14.4 Ma, and periodic fluctuations in the size and extent of the lake may have been responses to both climate and nearby volcanism. The eruption of rhyolite and andesite flows and domes periodically disrupted the lacustrine environment and produced interfingered flows and lake sediments. The major pulse of rhyolitic volcanism took place between 15.16 ± 0.05 and 14.92 ± 0.05 Ma. High-angle faulting began in the basement about 15.2 Ma, penetrated to and disrupted the paleosurface after 15.10 ± 0.06 Ma, and largely ceased by 14.92 ± 0.05 Ma. Ground motion related to both faulting and volcanism created debris flows and soft-sediment deformation in the lakebeds. Mercury-gold mineralization was coeval with rhyolite volcanism and high-angle faulting, and it took place about 15.2 to 14.9 Ma. At and near the paleosurface, hydrothermal fluids migrated through tuffaceous sediments above relatively impermeable volcanic and Paleozoic units, creating chalcedonic, cinnabar-bearing replacement bodies and sinters. Disseminated gold was deposited in sedimentary and volcanic rocks beneath the mercury deposits, although the hydrologic path between the two ore types is unclear. Higher-grade gold-silver deposits formed in

  11. Influence of margin segmentation and anomalous volcanism upon the break-up of the Hatton Bank rifted margin, west of the UK

    Science.gov (United States)

    Elliott, G. M.; Parson, L. M.

    2007-12-01

    leading to high melt production and subsidence rates forming the dipping reflectors. Shortly after break-up the eruption of Endymion Spur occurred. The nature of the magma erupted is unknown but from the steepness of the cones, it is inferred to be viscous and considering the setting, mostly likely a tholeiitic cumulate. A possible trigger for the Endymion Spur is the passage of a pulse of hotter than normal asthenospheric material along the margin, which interacted with lower crustal material to produce melt to feed the volcanic centres. Enhanced asthenospheric heat flow has been invoked to explain the V-shaped ridges along the present day Reykjanes Ridge and it is probable that the Endymion Spur represents previous such pulses along the margin/spreading axis. The location of the enhanced volcanism is itself controlled by crustal segmentation, with the Endymion Spur limited to the southern sector. The crustal thickness in this sector is approx. 2 to 3 km thinner than that found in the central segment, in which Endymion Spur is absent. The role of the segmentation along the margin has influenced the break-up style (presence or absence of SDR) and also the location and nature of post break-up volcanism.

  12. To what extent can global warming events influence scaling properties of climatic fluctuations in glacial periods?

    Science.gov (United States)

    Alberti, Tommaso; Lepreti, Fabio; Vecchio, Antonio; Carbone, Vincenzo

    2017-04-01

    The Earth's climate is an extremely unstable complex system consisting of nonlinear and still rather unknown interactions among atmosphere, land surface, ice and oceans. The system is mainly driven by solar irradiance, even if internal components as volcanic eruptions and human activities affect the atmospheric composition thus acting as a driver for climate changes. Since the extreme climate variability is the result of a set of phenomena operating from daily to multi-millennial timescales, with different correlation times, a study of the scaling properties of the system can evidence non-trivial persistent structures, internal or external physical processes. Recently, the scaling properties of the paleoclimate changes have been analyzed by distinguish between interglacial and glacial climates [Shao and Ditlevsen, 2016]. The results show that the last glacial record (20-120 kyr BP) presents some elements of multifractality, while the last interglacial period (0-10 kyr BP), say the Holocene period, seems to be characterized by a mono-fractal structure. This is associated to the absence of Dansgaard-Oeschger (DO) events in the interglacial climate that could be the cause for the absence of multifractality. This hypothesis is supported by the analysis of the period between 18 and 27 kyr BP, i.e. during the Last Glacial Period, in which a single DO event have been registred. Through the Empirical Mode Decomposition (EMD) we were able to detect a timescale separation within the Last Glacial Period (20-120 kyr BP) in two main components: a high-frequency component, related to the occurrence of DO events, and a low-frequency one, associated to the cooling/warming phase switch [Alberti et al., 2014]. Here, we investigate the scaling properties of the climate fluctuations within the Last Glacial Period, where abrupt climate changes, characterized by fast increase of temperature usually called Dansgaard-Oeschger (DO) events, have been particularly pronounced. By using the

  13. Impact of major volcanic eruptions on stratospheric water vapour

    Science.gov (United States)

    Löffler, Michael; Brinkop, Sabine; Jöckel, Patrick

    2016-05-01

    Volcanic eruptions can have a significant impact on the Earth's weather and climate system. Besides the subsequent tropospheric changes, the stratosphere is also influenced by large eruptions. Here changes in stratospheric water vapour after the two major volcanic eruptions of El Chichón in Mexico in 1982 and Mount Pinatubo on the Philippines in 1991 are investigated with chemistry-climate model simulations. This study is based on two simulations with specified dynamics of the European Centre for Medium-Range Weather Forecasts Hamburg - Modular Earth Submodel System (ECHAM/MESSy) Atmospheric Chemistry (EMAC) model, performed within the Earth System Chemistry integrated Modelling (ESCiMo) project, of which only one includes the long-wave volcanic forcing through prescribed aerosol optical properties. The results show a significant increase in stratospheric water vapour induced by the eruptions, resulting from increased heating rates and the subsequent changes in stratospheric and tropopause temperatures in the tropics. The tropical vertical advection and the South Asian summer monsoon are identified as sources for the additional water vapour in the stratosphere. Additionally, volcanic influences on tropospheric water vapour and El Niño-Southern Oscillation (ENSO) are evident, if the long-wave forcing is strong enough. Our results are corroborated by additional sensitivity simulations of the Mount Pinatubo period with reduced nudging and reduced volcanic aerosol extinction.

  14. Matrix diffusion coefficients in volcanic rocks at the Nevada test site: Influence of matrix porosity, matrix permeability, and fracture coating minerals

    Science.gov (United States)

    Reimus, Paul W.; Callahan, Timothy J.; Ware, S. Doug; Haga, Marc J.; Counce, Dale A.

    2007-08-01

    Diffusion cell experiments were conducted to measure nonsorbing solute matrix diffusion coefficients in forty-seven different volcanic rock matrix samples from eight different locations (with multiple depth intervals represented at several locations) at the Nevada Test Site. The solutes used in the experiments included bromide, iodide, pentafluorobenzoate (PFBA), and tritiated water ( 3HHO). The porosity and saturated permeability of most of the diffusion cell samples were measured to evaluate the correlation of these two variables with tracer matrix diffusion coefficients divided by the free-water diffusion coefficient ( Dm/ D*). To investigate the influence of fracture coating minerals on matrix diffusion, ten of the diffusion cells represented paired samples from the same depth interval in which one sample contained a fracture surface with mineral coatings and the other sample consisted of only pure matrix. The log of ( Dm/ D*) was found to be positively correlated with both the matrix porosity and the log of matrix permeability. A multiple linear regression analysis indicated that both parameters contributed significantly to the regression at the 95% confidence level. However, the log of the matrix diffusion coefficient was more highly-correlated with the log of matrix permeability than with matrix porosity, which suggests that matrix diffusion coefficients, like matrix permeabilities, have a greater dependence on the interconnectedness of matrix porosity than on the matrix porosity itself. The regression equation for the volcanic rocks was found to provide satisfactory predictions of log( Dm/ D*) for other types of rocks with similar ranges of matrix porosity and permeability as the volcanic rocks, but it did a poorer job predicting log( Dm/ D*) for rocks with lower porosities and/or permeabilities. The presence of mineral coatings on fracture walls did not appear to have a significant effect on matrix diffusion in the ten paired diffusion cell experiments.

  15. RESEARCH OF INFLUENCE OF FRONT TENSION AT ROLLING OF PERIODIC PROFILE IN NON-DRIVE ROLLERS

    Directory of Open Access Journals (Sweden)

    L. A. Isayevich

    2012-01-01

    Full Text Available Influence of a forward tension is theoretically investigated at a rolling of the periodic profiles used as elastic elements of spring suspension brackets. The power balance of rolling process with a tension is analyzed. Dependences for definition of a critical corner and size of its increment are received at a rolling with a forward tension.

  16. Volcanic gas

    Science.gov (United States)

    McGee, Kenneth A.; Gerlach, Terrance M.

    1995-01-01

    In Roman mythology, Vulcan, the god of fire, was said to have made tools and weapons for the other gods in his workshop at Olympus. Throughout history, volcanoes have frequently been identified with Vulcan and other mythological figures. Scientists now know that the “smoke" from volcanoes, once attributed by poets to be from Vulcan’s forge, is actually volcanic gas naturally released from both active and many inactive volcanoes. The molten rock, or magma, that lies beneath volcanoes and fuels eruptions, contains abundant gases that are released to the surface before, during, and after eruptions. These gases range from relatively benign low-temperature steam to thick hot clouds of choking sulfurous fume jetting from the earth. Water vapor is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide. Other volcanic gases are hydrogen sulfide, hydrochloric acid, hydrogen, carbon monoxide, hydrofluoric acid, and other trace gases and volatile metals. The concentrations of these gas species can vary considerably from one volcano to the next.

  17. Influence of an inner core on the long-period forced librations of Mercury

    Science.gov (United States)

    Yseboodt, Marie; Rivoldini, Attilio; Van Hoolst, Tim; Dumberry, Mathieu

    2013-09-01

    The planetary perturbations on Mercury’s orbit lead to long-period forced librations of Mercury’s mantle. These librations have previously been studied for a planet with two layers: a mantle and a liquid core. Here, we calculate how the presence of a solid inner core in the liquid outer core influences the long-period forced librations. Mantle-inner core coupling affects the long-period libration dynamics mainly by changing the free libration: first, it lengthens the period of the free libration of the mantle, and second, it adds a second free libration, closely related to the free gravitational oscillation between the mantle and inner core. The two free librations have periods between 2.5 and 18y depending on the internal structure. We show that large amplitude long-period librations of a few tens of arcsec are generated when the period of a planetary forcing approaches one of the two free libration periods. These amplitudes are sufficiently large to be detectable by spacecraft measurements of the libration of Mercury. The amplitudes of the angular velocity of Mercury’s mantle at planetary forcing periods are also amplified by the resonances, but remain much smaller than the current precision of Earth-based radar observations unless the period is very close to a free libration period. The inclusion of mantle-inner core coupling in the rotation model does not significantly improve the fit to the radar observations. This implies that it is not yet possible to determine the size of the inner core of Mercury on the basis of available observations of Mercury’s rotation rate. Future observations of the long-period librations may be used to constrain the interior structure of Mercury, including the size of its inner core.

  18. Pore Fluid Evolution Influenced by Volcanic Activities and Related Diagenetic Processes in a Rift Basin: Evidence from the Paleogene Medium-Deep Reservoirs of Huanghekou Sag, Bohai Bay Basin, China

    Directory of Open Access Journals (Sweden)

    Zhongheng Sun

    2017-01-01

    Full Text Available Volcanic activities exert a significant influence on pore fluid property and related diagenetic processes that substantially controlled reservoirs quality. Analysis of Paleogene medium-deep sandstones on the Huanghekou Sag provides insight into relating the diagenetic processes to pore fluid property evolution influenced by volcanic activities. Three distinct types of pore fluids were identified on the basis of an integrated and systematic analysis including core and thin section observation, XRD, SEM, CL, and trace element. Alkaline aqueous medium environment occurred in E2s1+2 where volcanic activities have insignificant influence on pore fluids, evidenced by typical alkaline diagenetic events such as K-feldspar albitization, quartz dissolution, feldspar dissolution, and carbonate cementation. During the deposition of E3d3, influx of terrestrial freshwater and alteration of ferromagnesian-rich pore water result in the formation of mixing aqueous medium environment through volcanic eruption dormancy causing zeolite dissolution, clay mineral transformation, and K-feldspar albitization. Ferromagnesian-rich aqueous medium environment developed resulting from the intensive hydrolysis of the unstable ferromagnesian minerals formed due to intense volcanic activities during E3d1+2 and corresponding predominant diagenetic processes were characterized by the precipitation and dissolution of low-silica zeolites. Therefore, the differential properties of pore fluids caused various diagenetic processes controlling reservoir quality.

  19. Influence of an inner core on the long-period forced librations of Mercury

    CERN Document Server

    Yseboodt, Marie; Van Hoolst, Tim; Dumberry, Mathieu

    2013-01-01

    The planetary perturbations on Mercury's orbit lead to long-period forced librations of Mercury's mantle. These librations have previously been studied for a planet with two layers: a mantle and a liquid core. Here, we calculate how the presence of a solid inner core in the liquid outer core influences the long-period forced librations. Mantle-inner core coupling affects the long-period libration dynamics mainly by changing the free libration: first, it lengthens the period of the free libration of the mantle, and second, it adds a second free libration, closely related to the free gravitational oscillation between the mantle and inner core. The two free librations have periods between 2.5 and 18 y depending on the internal structure. We show that large amplitude long-period librations of 10's of arcsec are generated when the period of a planetary forcing approaches one of the two free libration periods. These amplitudes are sufficiently large to be detectable by spacecraft measurements of the libration of Me...

  20. A Preliminary Study of the Types of Volcanic Earthquakes and Volcanic Activity at the Changbaishan Tianchi Volcano

    Institute of Scientific and Technical Information of China (English)

    Ming Yuehong; Su Wei; Fang Lihua

    2006-01-01

    Since 2002, a significant increase in seismicity, obvious ground deformation and geochemical anomalies have been observed in the Changbaishan Tianchi volcanic area. A series felt earthquakes occur near the caldera, causing great influence to society. In this paper, the types of volcanic earthquakes recorded by the temporal seismic network since 2002 have been classified by analyzing the spectrum, time-frequency characteristics and seismic waveforms at different stations. The risk of volcano eruptions was also estimated. Our results show that almost all earthquakes occurring in Tianchi volcano are volcanic-tectonic earthquakes. The low frequency seismic waveforms observed at a few stations may be caused by local mediums, and have no relation with long-period events. Although the level of seismicity increased obviously and earthquake swarms occurred more frequently than before, we considered that the magma activity is still in its early stage and the eruption risk of Changbaishan Tianchi volcano is still iow in the near future.

  1. Natural origin arsenic in aquatic organisms from a deep oligotrophic lake under the influence of volcanic eruptions.

    Science.gov (United States)

    Juncos, Romina; Arcagni, Marina; Rizzo, Andrea; Campbell, Linda; Arribére, María; Guevara, Sergio Ribeiro

    2016-02-01

    Volcanic eruptions are recognized sources of toxic elements to freshwater, including arsenic (As). In order to study the short term changes in the bioaccumulation of naturally occurring As by aquatic organisms in Lake Nahuel Huapi (Argentina), located close to the Puyehue-Cordón Caulle volcanic complex (PCCVC), we described As concentrations at different trophic levels and food web transfer patterns in three sites of the lake prior to the last PCCVC eruption (June 2011), and compared As concentrations in biota before and after the eruption. The highest As concentrations and greater variations both between sites and position in the water column, were observed in phytoplankton (3.9-64.8 µg g(-1) dry weight, DW) and small zooplankton (4.3-22.3 µg g(-1) DW). The pattern of As accumulation in aquatic organisms (whole body or muscle) was: primary producers (phytoplankton) > scrapper mollusks (9.3-15.3 µg g(-1) DW) > filter feeding mollusks (5.4-15.6 µg g(-1) DW) > omnivorous invertebrates (0.4-9.2 µg g(-1) DW) > zooplankton (1.2-3.5 µg g(-1) DW) > fish (0.2-1.9 µg g(-1) DW). We observed As biodilution in the whole food web, and in salmonids food chains, feeding on fish prey; but biomagnification in the food chain of creole perch, feeding on benthic crayfish. The impact of the 2011 PCCVC eruption on the As levels of biota was more evident in pelagic-associated organisms (zooplankton and planktivorous fish), but only in the short term, suggesting a brief high bioavailability of As in water after ash deposition. In benthic organisms As variations likely responded to shift in diet due to coverage of the littoral zone with ashes.

  2. The influence of Ryukyu subduction on magma genesis in the Northern Taiwan Volcanic Zone and Middle Okinawa Trough - Evidence from boron isotopes

    Science.gov (United States)

    Pi, Ju-Lien; You, Chen-Feng; Wang, Kuo-Lung

    2016-09-01

    Boron (B) is an excellent geochemical tracer for investigating crustal recycling processes at convergent margins, due to its high fluid mobility under high P-T conditions, distinct elemental abundances and isotopic compositions in the mantle wedge and subducting slabs. The Northern Taiwan Volcanic Zone (NTVZ), wherein the nature of magma genesis has long been a topic of debate, is located at the rear side of the Okinawa Trough (OT), an atypical back-arc rift in the Ryukyu subduction system. In this study, B and B isotopes (δ11B) were measured in 19 volcanic rocks collected from the NTVZ and the middle Okinawa Trough (MOT) to assess the influence of the Ryukyu subduction system on magma genesis. The B concentrations in the MOT and NTVZ volcanic rocks are 5.8 to 13.6 mg/L and 2.2 to 48.6 mg/L, respectively. The large B abundances variation in the NTVZ was caused mainly by variable degrees of partial melting. The Nb/B and δ11B in the MOT have small ranges of 0.5 to 0.6 and - 2.7‰ to 0.2‰, respectively, whereas they range widely from 0.4 to 2.5 and from - 8.6‰ to 2.4‰, respectively in the NTVZ. These Nb/B values suggest that the magma contains a smaller subduction component than that normally observed in arcs, although this component is still more substantial than in a typical back-arc setting. The δ11B results indicate insignificant influence of the subducting Philippine Sea Plate at 2.6 Ma, but it becomes more substantial later in the NTVZ. The mixing proportions of sediment derived fluids in onshore volcanoes in the NTVZ imply a rather heterogeneous mantle wedge near the plate boundary, most likely due to either a heterogeneous source of slab derived fluids or more complicated mantle flow. A substantial B flux from the subducting slab in the incipient back-arc rifting in the MOT and NTVZ may reflect characteristics of a cold, steep and fast subducting slab, which may be capable of carrying volatiles efficiently into greater depth in subduction zones. The

  3. Periodic Structure of Equatorial Envelope Rossby Wave Under Influence of Diabatic Heating

    Institute of Scientific and Technical Information of China (English)

    FUZun-Tao; CHENZhe; LIUShi-Da; LIUShi-Kuo

    2004-01-01

    A simple shallow-water model with influence of diabatic heating on a β-plane is applied to investigate the nonlinear equatorial Rossby waves in a shear flow. By the asymptotic method of multiple scales, the cubic nonlinear Schroedinger (NLS for short) equation with an external heating source is derived for large amplitude equatorial envelope Rossby wave in a shear flow. And then various periodic structures for these equatorial envelope Rossby waves are obtained with the help of Jacob/elliptic functions and elliptic equation. It is shown that phase-locked diabatic heating plays an important role in periodic structures of rational form.

  4. Periodic Structure of Equatorial Envelope Rossby Wave Under Influence of Diabatic Heating

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; CHEN Zhe; LIU Shi-Da; LIU Shi-Kuo

    2004-01-01

    A simple shallow-water model with influence of diabatic heating on aβ-plane is applied to investigate the nonlinear equatorial Rossby waves in a shear flow. By the asymptotic method of multiple scales, the cubic nonlinear Schrodinger (NLS for short) equation with an external heating source is derived for large amplitude equatorial envelope Rossby wave in a shear flow. And then various periodic structures for these equatorial envelope Rossby waves are obtained with the help of Jacobi elliptic functions and elliptic equation. It is shown that phase-locked diabatic heating plays an important role in periodic structures of rational form.

  5. Influence of lactation stages and rain periods on subclinical mastitis in meat producing ewes

    Directory of Open Access Journals (Sweden)

    Luiz Francisco Zafalon

    Full Text Available ABSTRACT: Mastitis negatively influences the survival and weight gain of ovines for meat production. The purpose of this study was to investigate, in sheep for meat production, the occurrence of subclinical mastitis in ewes at the end of lactation and beginning of the consecutive lactation and to assess the composition and cellular characteristics of milk as a function of different rainfall indices. Mammary halves (821 of Santa Ines (479 and Morada Nova (342 ewes were examined. Milk samples were collected in two different moments of lactation: at weaning and postpartum of the consecutive lactation. Sample collection periods were called "dry" or "rainy" according to the rainfall index in the month immediately before the month of collection. The occurrence of subclinical mastitis at weaning in the Santa Ines and Morada Nova ewes were 16.4 and 12.6% in the dry period, and 17.7 and 23.5% in the rainy period, respectively. In the consecutive lactation period, the occurrences were 26.7 and 27.7% in the dry period and 41.8 and 39.1% in the rainy period, for the Santa Ines and Morada Nova ewes, respectively. Postpartum stage was critical for the occurrence of subclinical mastitis, as compared to that at the end of the previous lactation. Occurrence of the disease negatively influenced the SCC in the milk at the beginning of lactation and changed its composition, mainly in the rainiest periods, probably due to a difficulty in maintaining hygiene in the environment where the animals remained.

  6. The Influence of Daily Periods on the Drinking Behavior in Romanian Black and White Primiparous Cows

    Directory of Open Access Journals (Sweden)

    Silvia Erina

    2011-10-01

    Full Text Available The study was carried out on 9 Romanian Black and White cows in their first one hundred days of lactation. The aim of this study was to determine some aspect of drinking behavior of the cows in 24 hours that were divided into 3 day periods (intervals: 07:00-14:00 (I1, 14:00-21:00 (I2, 21:00-07:00 (I3. During the experiments, the following drinking behavior aspects were determined: the number of drinkings and the length of drinking periods per 24 hours, in the fibrous-succulents administration order of forages (O1 and succulents-fibrous order (O2. Data was computed by ANOVA/MANOVA. Results showed that the daily periods had an influence on the number of drinkings and drinking length, the lowest number of drinkings occurred during the night interval I3 (4.20 and the highest number together with the longest drinking period occurred in the second interval I2 (12.47 and 1062.50 seconds. In both administration order of forages ( O1 and O2 there were a very significant differences (p<0.001 between I1 and I2 in favour of I2, between I1 and I3 in favour of I1 and between I2 and I3 in favour of I2, for number of drinkings periods and for length of drinking periods.

  7. The influence of resting periods on friction in the artificial hip.

    Science.gov (United States)

    Nassutt, Roman; Wimmer, Markus A; Schneider, Erich; Morlock, Michael M

    2003-02-01

    Insufficient tribologic performance of total joint components is a major cause of prostheses failure. Wear has been studied intensively using testing machines that apply continuous motions. Human locomotion, however, is not well represented by continuous motions alone. Singular events and resting periods are a substantial part of daily activities. Resting does influence adhesion in the artificial joint with possible effects on friction, wear, and loosening. The current study evaluated the effects of resting on the frictional properties of hip prosthesis components. The activity measurements of 32 patients with artificial hip replacements were analyzed for resting durations of the hip. A pin-on-ball screening device was used to determine friction after characteristic resting periods and during continuous oscillating motion. All common articulation pairings were investigated. Prolonged and frequent resting periods of the hip were found for the patients. Initial friction increased with increasing resting duration for all tested materials (between 41% and 191%). The metal-on-metal articulations showed the highest friction level (0.098 for sliding) and the highest increase (191%) in friction with resting duration (0.285 after resting periods of 60 seconds). A high static frictional moment after resting periods might present a risk for aseptic implant loosening. Therefore, large head diameters of metal-on-metal joints should be used with caution, especially when additional unfavorable risk factors such as obesity, weak bone-implant interface, or high activity level are present.

  8. Influence of Periodic and Quasi-periodic Gravitational Modulation on Convective Instability of Reaction Fronts in Porous Media

    Science.gov (United States)

    Allali, K.; Belhaq, M.

    This work gives an overview on the effect of vertical periodic and QP gravitational modulations on the convective instability of reaction fronts in porous media. The model consists of the heat equation, the equation for the depth of conversion and the equations of motion under the Darcy law. Attention is focused on two cases. The case of a periodic gravitational vibration with a modulated amplitude, and the case of quasi-periodic vibration having two incommensurate frequencies. In both cases the heating is acted from below such that the sense of reaction is opposite to the gravity sense. The convective instability threshold is obtained by reducing the original reaction-diffusion problem to a singular perturbation one using the matched asymptotic expansion. The obtained reduced problem is then solved numerically after performing the linear stability analysis of the steady-state solution for the interface. It is shown that in the case of the modulation of the periodic vibration amplitude, a destabilizing effect of reaction fronts can be gained for a frequency modulation equal to half the frequency of the vibration, whereas a stabilizing effect is observed when the frequency of the modulation is twice that of the vibration. In the case of a quasi-periodic gravitational vibration it is indicated that for appropriate values of amplitudes and frequencies ratio of the quasi-periodic excitation, a stabilizing effect of reaction fronts can be successfully achieved.

  9. Environmental and anthropogenic factors affecting the respiratory toxicity of volcanic ash in vitro

    Science.gov (United States)

    Tomašek, Ines; Horwell, Claire J.; Damby, David E.; Ayris, Paul M.; Barošová, Hana; Geers, Christoph; Petri-Fink, Alke; Rothen-Rutishauser, Barbara; Clift, Martin J. D.

    2016-04-01

    Human exposure to inhalable volcanic ash particles following an eruption is a health concern, as respirable-sized particles can potentially contribute towards adverse respiratory health effects, such as the onset or exacerbation of respiratory and cardiovascular diseases. Although there is substantial information on the mineralogical properties of volcanic ash that may influence its biological reactivity, knowledge as to how external factors, such as air pollution, contribute to and augment the potential reactivity is limited. To determine the respiratory effects of volcanic particle interactions with anthropogenic pollution and volcanic gases we will experimentally assess: (i) physicochemical characteristics of volcanic ash relevant to respiratory toxicity; (ii) the effects of simultaneously inhaling anthropogenic pollution (i.e. diesel exhaust particles (DEP)) and volcanic ash (of different origins); (iii) alteration of volcanic ash toxicity following interaction with volcanic gases. In order to gain a first understanding of the biological impact of the respirable fraction of volcanic ash when inhaled with DEP in vitro, we used a sophisticated 3D triple cell co-culture model of the human alveolar epithelial tissue barrier. The multi-cellular system was exposed to DEP [0.02 mg/mL] and then exposed to either a single or repeated dose of well-characterised respirable volcanic ash (0.26 ± 0.09 or 0.89 ± 0.29 μg/cm2, respectively) from the Soufrière Hills volcano, Montserrat for a period of 24 hours using a pseudo-air liquid interface approach. Cultures were subsequently assessed for adverse biological endpoints including cytotoxicity, oxidative stress and (pro)-inflammatory responses. Results indicated that the combination of DEP and respirable volcanic ash at sub-lethal concentrations incited a significant release of pro-inflammatory markers that was greater than the response for either DEP or volcanic ash, independently. Further work is planned, to determine if

  10. Volcanic eruptions and solar activity

    Science.gov (United States)

    Stothers, Richard B.

    1989-01-01

    The historical record of large volcanic eruptions from 1500 to 1980 is subjected to detailed time series analysis. In two weak but probably statistically significant periodicities of about 11 and 80 yr, the frequency of volcanic eruptions increases (decreases) slightly around the times of solar minimum (maximum). Time series analysis of the volcanogenic acidities in a deep ice core from Greenland reveals several very long periods ranging from about 80 to about 350 yr which are similar to the very slow solar cycles previously detected in auroral and C-14 records. Solar flares may cause changes in atmospheric circulation patterns that abruptly alter the earth's spin. The resulting jolt probably triggers small earthquakes which affect volcanism.

  11. Influence of quasi-periodic gravitational modulation on convective instability of reaction fronts in porous media

    Science.gov (United States)

    Allali, Karam; Belhaq, Mohamed; El Karouni, Kamal

    2012-04-01

    The influence of a time-dependent gravity on the convective instability of reaction fronts in porous media is investigated in this paper. It is assumed that the time-dependent modulation is quasi-periodic with two frequencies σ1 and σ2 that are incommensurate with each other. The model consists of the heat equation, the equation for the depth of conversion and the equations of motion under the Darcy law. The convective threshold is approximated performing a linear stability analysis on a reduced singular perturbation problem using the matched asymptotic expansion method. The reduced interface problem is solved using numerical simulations. It is shown that if the reacting fluid is heated from below, a stabilizing effect of a reaction fronts in a porous medium can be gained for appropriate values of amplitudes and frequencies ratio σ={σ2}/{σ1} of the quasi-periodic vibration.

  12. Changes in Climatic Factors Influencing the Growth Period of Corn in Fengjie County

    Institute of Scientific and Technical Information of China (English)

    Xiaozhen; MAO; Xinli; MOU; Chen; MA; Jiang; HUANG; Lin; YUAN

    2014-01-01

    Under the background of global climate change,we analyze the change tendency of average temperature and amount of precipitation influencing the corn’s growth period. The results show that from March to August,the monthly temperatures show an upward trend,but the rise is different in different months,and the maximum temperature rise is in May. Precipitation in different months has different trends. Climate change brings about favorable conditions at high altitudes in Fengjie,reduces production due to the temperature drop after the beginning of autumn,and increases the pressure on the corn supply.

  13. Gastric antrectomy with selective gastric vagotomy does not influence gallbladder motility during interdigestive and postprandial periods

    DEFF Research Database (Denmark)

    Qvist, N; Oster-Jørgensen, E; Pedersen, S A;

    1996-01-01

    Fasting gastrointestinal motility and gallbladder motility during the interdigestive state and in the postprandial period was studied in eight patients who were operated for ulcer disease with an antrectomy and selective gastric vagotomy. Nocturnal motility recording revealed all three phases.......77%/min (0.33-0.86%/min). The values in the control group were 0 min (-9 to 13.5 min) and 0.76%/min (0.54-2.25%/min), respectively. These differences between the patients and controls were not significant. In conclusion, antrectomy and selective gastric vagotomy do not influence fasting gastrointestinal...

  14. Sr- and Nd- isotope variations along the Pleistocene San Pedro - Linzor volcanic chain, N. Chile: Tracking the influence of the upper crustal Altiplano-Puna Magma Body

    Science.gov (United States)

    Godoy, Benigno; Wörner, Gerhard; Le Roux, Petrus; de Silva, Shanaka; Parada, Miguel Ángel; Kojima, Shoji; González-Maurel, Osvaldo; Morata, Diego; Polanco, Edmundo; Martínez, Paula

    2017-07-01

    Subduction-related magmas that erupted in the Central Andes during the past 10 Ma are strongly affected by crustal assimilation as revealed by an increase in 87Sr/86Sr isotope ratios with time that in turn are correlated with increased crustal thickening during the Andean orogeny. However, contamination is not uniform and can be strongly influenced locally by crustal composition, structure and thermal condition. This appears to be the case along the NW-SE San Pedro - Linzor volcanic chain (SPLVC) in northern Chile, which straddles the boundary of a major zone of partial melt, the Altiplano_Puna Magma Body (APMB). Herein we report 40Ar/39Ar ages, compositional and isotope data on lavas from the SPLVC that track the influence of this zone of partial melting on erupted lavas with geochronological and geochemical data. Ages reported here indicate that SPLVC has evolved in the last 2 M.y., similar to other volcanoes of the Western Cordillera (e.g. Lascar, Uturuncu, Putana). 87Sr/86Sr ratios increase systematically along the chain from a minimum value of 0.7057 in San Pedro dacites to a maximum of 0.7093-0.7095 for the Toconce and Cerro de Leon dacites in the SE. These changes are interpreted to reflect the increasing interaction of SPLVC parental magmas with partial melt within the APMB eastwards across the chain. The 87Sr/86Sr ratio and an antithetic trend in 143Nd/144Nd is therefore a proxy for the contribution of melt from the APMB beneath this volcanic chain. Similar 87Sr/86Sr increases and 143Nd/144Nd decreases are observed in other transects crossing the boundary of the APMB. Such trends can be recognized from NW to SE between Aucanquilcha, Ollagüe, and Uturuncu volcanoes, and from Lascar volcano to the N-S-trending Putana-Sairecabur-Licancabur volcanic chain to the north. We interpret these isotopic trends as reflecting different degrees of interaction of mafic parental melts with the APMB. High 87Sr/86Sr, and low 143Nd/144Nd reveal zones where the APMB is

  15. Consideration of tidal influences in determining measurement periods when monitoring built-environment radon levels

    Energy Technology Data Exchange (ETDEWEB)

    Crockett, R.G.M.; Phillips, P.S. [Northampton Univ., School of Applied Sciences (United Kingdom); Gillmore, G.K. [Bradford Univ., School of Archaeological, Geographical and Environmental Sciences (United Kingdom); Denman, A.R.; Groves-Kirkby, C.J. [Northampton General Hospital, Medical Physics Dept. (United Kingdom)

    2006-07-01

    Using three hourly-sampling continuous radon monitors, deployed at separate locations in and around the town of Northampton, UK, during the period May 2002 to September 2005, evidence has been identified of tidal influences on built environment radon levels. The data-sets from these deployments, together with additional data-sets collected from a house in Devon, UK, over the period May 1994 to October 1996, and made available by the UK Building Research Establishment, have been analysed using a number of analytical techniques, including a novel cortion technique developed during the investigation. Radon concentration levels in all of the investigated sites exhibit cyclic variation with a period of approximately 14-15 days, equivalent to the spring-tide interval, and lag the corresponding new and full moons by varying periods. The tide/radon lag interval for the two public-sector buildings changes abruptly in September/October, indicating that a significant characteristic of these buildings changes at this time. For domestic properties, the lag is relatively unchanged during the year, but is greater in Devon, in the South-West of England, than in Northampton, in the English East Midlands. These differences are attributed to location relative to coastlines (the South-West experiences greater tidal-loading than the Midlands), underlying geology and rock/soil hydration. Depending on its position within the local 14 to 15-day tidally-induced radon cycle, an individual 7-day radon measurement may yield an erroneous estimate of longer term average levels, up to 46% higher or lower than the average level for one of the reported data-sets. Thus a building with a mean radon concentration below the local Action Level could appear to be unsafe if measured around a tidal-cyclic radon maximum: conversely, a building with a mean radon concentration above the Action Level could appear to be safe when measured around a tidal-cyclic radon minimum. A minimum radon-measurement period

  16. Influence of standing wave phase error on super-resolution optical inspection for periodic microstructures

    Science.gov (United States)

    Kudo, R.; Usuki, S.; Takahashi, S.; Takamasu, K.

    2012-05-01

    The miniaturization of microfabricated structures such as patterned semiconductor wafers continues to advance, thereby increasing the demand for a high-speed, nondestructive and high-resolution measurement technique. We propose a novel optical inspecting method for a microfabricated structure using the standing wave illumination (SWI) shift as such a measurement technique. This method is based on a super-resolution algorithm in which the inspection system's resolution exceeds the diffraction limit by shifting the SWI. Resolution beyond the diffraction limit has previously been studied theoretically and realized experimentally. The influence of various experimental error factors needs to be investigated and calibration needs to be performed accordingly when actual applications that utilize the proposed method are constructed. These error factors include errors related to the phase, pitch and shift step size of the standing wave. Identifying the phase accurately is extremely difficult and greatly influences the resolution result. Hence, the SWI phase was focused upon as an experimental error factor. The effect of the phase difference between the actual experimental standing wave and the computationally set standing wave was investigated using a computer simulation. The periodic structure characteristic of a microfabricated structure was analyzed. The following findings were obtained as a result. The influence of an error is divided into three modes depending on the pitch of the periodic structure: (1) if the pitch is comparatively small, the influence of the error is cancelled, allowing the structure of a sample to be resolved correctly; (2) if the pitch of the structure is from 150 to 350 nm, the reconstructed solution shifts in a transverse direction corresponding to a phase gap of SWI; and (3) if it is a comparatively large pitch, then it is difficult to reconstruct the right pitch. Verification was experimentally attempted for mode (2), and the same result as

  17. Link of volcanic activity and climate change in Altai studied in the ice core from Belukha Mountain

    Directory of Open Access Journals (Sweden)

    N. S. Malygina

    2013-01-01

    Full Text Available In the present research we discuss a role of volcanic activity in Altai thermal regime. Here we analyses the sulfate and temperature data reconstructed from the natural paleoarchive – ice core from the Belukha Mountain saddle. Sulfate ice-core reconstructions can serve as volcanic markers. The both – sulfate and temperature reconstructions – are for the last 750 years. As the characteristic of volcanic activity we consider Volcanic Explosivity Index (VEI, Dust Veil Index (DVI and Ice core volcanic index (IVI. The analysis was done using wavelet analysis and analysis of wavelet cross coherence and phase. As the result, we conclude that observed increases in the values of the indexes VEI, DVI, IVI basically correspond to decreases of temperature and increases of sulfate concentrations. This confirms the dependence of changes in the thermal regime of the Altai from volcanic activity. But in the 1750–1850 years period there is a delay of the changes in temperature with respect to the changes in volcanic activity. We suggest that it can be due to the superposition of the influence of solar and volcanic activity on changes in the thermal regime of Altai.

  18. Volcanic hazard management in dispersed volcanism areas

    Science.gov (United States)

    Marrero, Jose Manuel; Garcia, Alicia; Ortiz, Ramon

    2014-05-01

    Traditional volcanic hazard methodologies were developed mainly to deal with the big stratovolcanoes. In such type of volcanoes, the hazard map is an important tool for decision-makers not only during a volcanic crisis but also for territorial planning. According to the past and recent eruptions of a volcano, all possible volcanic hazards are modelled and included in the hazard map. Combining the hazard map with the Event Tree the impact area can be zoned and defining the likely eruptive scenarios that will be used during a real volcanic crisis. But in areas of disperse volcanism is very complex to apply the same volcanic hazard methodologies. The event tree do not take into account unknown vents, because the spatial concepts included in it are only related with the distance reached by volcanic hazards. The volcanic hazard simulation is also difficult because the vent scatter modifies the results. The volcanic susceptibility try to solve this problem, calculating the most likely areas to have an eruption, but the differences between low and large values obtained are often very small. In these conditions the traditional hazard map effectiveness could be questioned, making necessary a change in the concept of hazard map. Instead to delimit the potential impact areas, the hazard map should show the expected behaviour of the volcanic activity and how the differences in the landscape and internal geo-structures could condition such behaviour. This approach has been carried out in La Palma (Canary Islands), combining the concept of long-term hazard map with the short-term volcanic scenario to show the expected volcanic activity behaviour. The objective is the decision-makers understand how a volcanic crisis could be and what kind of mitigation measurement and strategy could be used.

  19. Quaternary basaltic volcanism in the Payenia volcanic province, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina

    primitive basalts and trachybasalts but also more evolved samples from the retroarc region and the larger volcanoes Payún Matrú and Payún Liso are presented. The samples cover a broad range of compositions from intraplate lavas similar to ocean island basalts to arc andesites. A common feature found...... Pleistocene times. These basalts mark the end of a period of shallow subduction of the Nazca slab beneath the Payenia province and volcanism in the Nevado volcanic field apparently followed the downwarping slab in a north-northwest direction ending in the Northern Segment. The northern Payenia basalts...... the literature. The Nevado basalts have been modelled by 4-10 % melting of a primitive mantle added 1-5 % upper continental crust. In the southern Payenia province, intraplate basalts dominate. The samples from the Payún Matrú and Río Colorado volcanic fields are apparently unaffected by the subducting slab...

  20. Influence of explosive volcanic events on the activation versus de-activation of a modern turbidite system: the example of the Dohrn canyon-fan in the continental slope of the Campania volcanic district (Naples Bay, Italy - Western Mediterranean)

    Science.gov (United States)

    Roca, M.; Budillon, F.; Pappone, G.; Insinga, D.

    2015-12-01

    The interplay between volcanic activity, volcano-clastic yield and activation/deactivation of a turbidite system can be evaluated along the continental margin of Campania region (Tyrrhenian Sea - Italy), an active volcanic area, where three wide canyon-fans occur at short distances one to another. Actually, the Dohrn, Magnaghi and Cuma canyons cut the continental slope and shelf off Ischia and Procida volcanic islands and off the Campania Plain where Phlegraean Field and Mt. Vesuvius active vents are located. This research, partly supported by the Italian Flagship Project Ritmare, is based on single-channel, high-resolution seismic profiles (Sparker-One 16 kJ, 0.5 s twtt), swath-bathymetry and litho- and tephra-stratigraphy of gravity cores. We focused on the stratigraphic constraint of paleo-thalweg features and channel/levees deposits in seismics, debris flow, turbidites and hemipelagites in cores, to learn more on the activation/deactivation stages of the canyon Dohrn, in the frame of relative eustatic sea level variations over the Middle Pleistocene-Holocene time span.Preliminary outcomes suggest that even major volcanic events occurred in the last 300 ky, such as ignimbrite eruptions or large fallouts, have caused the infilling of the canyon head and the cover of pre-existing seabed morphology. As a consequence, the temporary deactivation of the turbidite system has occurred, despite the volcano-clastic overload in the coastal environment. Phases of renewed activities of the thalweg are observed to be in step with falling stages of sea level, which have driven the re-incision of canyon valleys through continuous volcano-clastic debris and turbidites down-flows. Since Holocene, the quiescence of the Dohrn Canyon has been documented, despite the intense volcano-tectonic activity in the area.

  1. Mineralogy and geochemistry of a superhigh-organic-sulfur coal, Yanshan Coalfield, Yunnan, China: Evidence for a volcanic ash component and influence by submarine exhalation

    Science.gov (United States)

    Dai, S.; Ren, D.; Zhou, Y.; Chou, C.-L.; Wang, X.; Zhao, L.; Zhu, Xudong

    2008-01-01

    The mineralogy and geochemistry of a superhigh-organic-sulfur (SHOS) coal of Late Permian age from the Yanshan Coalfield, Yunnan Province, southwestern China, have been studied using optical microscope, low-temperature ashing plus X-ray diffraction analysis, scanning electron microscope equipped with energy-dispersive X-ray spectrometer, a sequential chemical extraction procedure, and inductively coupled plasma mass spectrometry. The M9 Coal from the Yanshan Coalfield is a SHOS coal that has a total sulfur content of 10.12%-11.30% and an organic sulfur content of 8.77%-10.30%. The minerals in the coal consist mainly of high-temperature quartz, sanidine, albite, muscovite, illite, pyrite, and trace amounts of kaolinite, plagioclase, akermanite, rutile, and dawsonite. As compared with ordinary worldwide (bituminous coals and anthracite) and Chinese coals, the M9 Coal is remarkably enriched in B (268????g/g), F (841????g/g), V (567????g/g), Cr (329????g/g), Ni (73.9????g/g), Mo (204????g/g), and U (153????g/g). In addition, elements including Se (25.2????g/g), Zr (262????g/g), Nb (20.1????g/g), Cd (2.07????g/g), and Tl (2.03????g/g) are also enriched in the coal. Occurrence of high-temperature quartz, sanidine, muscovite, and illite in the M9 Coal is evidence that there is a volcanic ash component in the coal that was derived from acid volcanic ashes fallen into the swamp during peat accumulation. Occurrence of albite and dawsonite in the coal and strong enrichment of some elements, including F, S, V, Cr, Ni, Mo and U, are attributed to the influence by submarine exhalation which invaded along with seawater into the anoxic peat swamp. Abundances of lithophile elements, including rare earth elements, Nb, Y, Zr, and TiO2, indicate that the silicate minerals in the coal were derived from the northern Vietnam Upland to the south of the basin. ?? 2008 Elsevier B.V. All rights reserved.

  2. Volcanic hazard assessment in monogenetic volcanic fields

    OpenAIRE

    Bartolini, Stefania

    2014-01-01

    [eng] One of the most important tasks of modern volcanology, which represents a significant socio-economic implication, is to conduct hazard assessment in active volcanic systems. These volcanological studies are aimed at hazard that allows to constructing hazard maps and simulating different eruptive scenarios, and are mainly addressed to contribute to territorial planning, definition of emergency plans or managing volcanic crisis. The impact of a natural event, as a volcanic eruption, can s...

  3. Influence of the stress response for dexmedetomidine and remifentanil TCI in ICU patients in sedative period

    Institute of Scientific and Technical Information of China (English)

    Dan-Dan Chen; Wei Wang

    2016-01-01

    Objective:To investigate the influence of the stress response for dexmedetomidine and remifentanil TCI in ICU patients in sedative period.Methods:A total of 60 patients receiving mechanical ventilation and requiring sedation were randomly divided into three groups: group given dexmedetomidine (M), remifentanil group (R), combination group (MR). Concentration of serum cortisol and IL-6 were tested in each group patients at different time points.Results:Compared with medication alone group, cortisol concentrations of patients in MR at T4-T9 time point were significantly lower, with its relatively significant statistical difference; Serum IL-6 concentrations of patients in MR at T3-T9 time point were significantly lower, with its relatively significant statistically difference.Conclusion:Dexmedetomidine combined with remifentanil TCI can control high stress reaction of ICU patients, reduce the complications.

  4. The forced sound transmission of finite ribbed plates, investigating the influence of point connections and periodicity

    DEFF Research Database (Denmark)

    Brunskog, Jonas

    2015-01-01

    Many engineering structures consist of plates being stiffened by ribs. The ribs can be connected to the plate in a line connection (welded or glued) or in point connections (screwed). It is well known that the rib stiffeners can significantly change the vibration field and the radiation behavior...... been derived, using a variational technique based on integral-differential equations of the fluid loaded plate. In this way an optimal solution is derived, using a very simple initial guess of the vibration field. The finite plate is assumed being mounted in a rigid baffle. The approach is based...... the model. The influence of point versus line connections, as well as periodicity effects, is investigated....

  5. Factors influencing the presence of circulating differentiated thyroid cancer cells in the thyroidectomy perioperative period*

    Institute of Scientific and Technical Information of China (English)

    Wentao Wei; Qinjiang Liu; Wei Yao

    2015-01-01

    Objective The aim of the study was to detect circulating differentiated thyroid cancer (DTC) micrometas-tasis and to investigate the factors influencing their presence in the perioperative thyroidectomy period. Methods DTC micrometastases in the peripheral blood were detected with flow cytometry, and patient clinical and pathological factors were analyzed in 327 DTC patients.Results Circulating blood micrometastases were present in the peripheral circulation at a higher rate 1 week postoperatively than preoperatively and at 4 weeks postoperatively (P 0.05). At 4 weeks postoperatively, the presence of circulating micrometastasis was not associated with tumor size or lymph node stage (P > 0.05), but was associated with poorly differentiated tumors (P < 0.05). Conclusion The presence of circulating DTC micrometastases correlates to tumor size, lymph node stage, and operative manipulation. The differentiation degree of the tumors were associated with the persistent presence of micrometastasis in the circulating blood.

  6. Urea Fertilizer and pH Influence on Sorption Process of Flumetsulam and MCPA Acidic Herbicides in a Volcanic Soil.

    Science.gov (United States)

    Palma, Graciela; Jorquera, Milko; Demanet, Rolando; Elgueta, Sebastian; Briceño, Gabriela; de la Luz Mora, María

    2016-01-01

    The aim of this study was to evaluate the influence of urea fertilizer and pH on the sorption process of two acidic herbicides, flumetsulam (2',6'-difluoro-5-methyl[1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonanilide) and MCPA (4-chloro--tolyloxyacetic acid), on an Andisol. Urea reduced the adsorption of MCPA but not that of flumetsulam. The Freundlich parameter of MCPA decreased from 8.5 to 5.1 mg L kg. This finding could be attributed to an increase in dissolved organic C due to an initial increase in soil pH for urea application. The higher acidic character of MCPA compared with that of flumetsulam produced a greater hydrolysis of urea, leading to a further pH increase. A marked effect of pH on the adsorption of both herbicides was observed. The organic C distribution coefficient () values for flumetsulam were in the range of 74 to 10 L kg, while those of MCPA were in the range of 208 to 45 L kg. In the kinetic studies, the pseudo-second-order model appeared to fit the data best ( > 0.994). The initial adsorption rates () ranged from 20.00 to 4.59 mg kg h for flumetsulam and from 125.00 to 25.60 mg kg hfor MCPA. Both herbicides were adsorbed rapidly during the first stage of the sorption process, and the rates of sorption were dependent on pH. The application of the Elovich and Weber-Morris models led us to conclude that mass transfer through the boundary layer and, to a lesser degree, intraparticle diffusion were influenced by the chemical character of the herbicide. These results suggest that urea application could increase leaching of acid herbicides in soils.

  7. Osteoporosis influences the middle and late periods of fracture healing in a rat osteoporotic model

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-wei; LI Wei; XU Shao-wen; YANG Di-sheng; WANG Yun; LIN Min; ZHAO Guang-feng

    2005-01-01

    Objective: To evaluate the influence of osteoporosis on the middle and late periods of fracture healing process through observing the histomorphological changes, bone mineral density and biomechanical properties in ovariectomized rats. Methods: Eighty-four female SD rats of 4 months old were randomly divided into osteoporosis group and sham operation group, 42 in each. Rats in osteoporosis group were performed ovariectomy operation while those in sham operation group were given sham operation. A midshaft tibia fracture model was established 10 weeks after ovariectomy. Tibias were harvested 2, 4, 6, 12, 18 weeks after fracture for bone mineral density, histomorphological and biomechanical evaluation. Results: Compared with the sham operation group, callus bone mineral density was 12.8%, 18.0%, 17.0% lower in osteoporosis group 6, 12, 18 weeks after fracture, respectively (P<0.05); callus failure load was 24.3%, 31.5%, 26.6%, 28.8% lower in osteoporosis group, and callus failure stress was 23.9%, 33.6%, 19.1%, 24.9% lower in osteoporosis group 4, 6, 12, 18 weeks after fracture, respectively (P<0.05). In osteoporosis group, endochondral bone formation was delayed, more osteoclast cells could be seen around the trabecula, and the new bone trabecula arranged loosely and irregularly. Conclusions: Osteoporosis influences the middle and late periods of fracture healing in the rat osteoporotic model. The impairment is considered to be the result of combined effects of prolonged endochondral calcification, high activated osteoclast cell and the deceleration of the increase in bone mineral density.

  8. Ambient air quality monitoring during the H1N1 influence period in Pune (India).

    Science.gov (United States)

    Pathak, M; Deshpande, A; Mirashe, P K; Sorte, R B; Ojha, A

    2010-10-01

    Ambient air quality in an urban area is directly linked with activity level in the city including transport, business and industrial activities. Maharashtra Pollution Control Board (MPCB) has established an ambient air quality network in the city including state-of-the-art continuous air quality monitoring stations which indicate short duration air quality variations for criteria and non-criteria pollutants. The influence of H1N1 outbreak in Pune hitting its worst pandemic condition, led the civic authorities to implement stringent isolation measures including closure of schools, colleges, business malls, cinema halls, etc. Additionally, the fear of such a pandemic brought the city to a stand still. It was therefore necessary to assess the impacts of such activity level on ambient air quality in the city. It has been observed that such events have positive impacts on air quality of the city. There was a decrease in PM concentration almost to the tune of 30 to 40% if the impacts of precipitation, i.e. seasonal variations, are taken into account. Similarly, the non criteria pollutants too showed a marked but unusual decrease in their concentrations in this ever growing city. The influence of these in turn led to lowered concentrations of secondary pollutants, i.e. O3. Overall, the ambient air quality of Pune was found to be improved during the study period.

  9. The External Periodic Influence Effect on the Kinetics of Metals Fragmentationduring the Severe Plastic Deformation

    Directory of Open Access Journals (Sweden)

    A.V. Khomenko

    2015-03-01

    Full Text Available Using the Landau theory of phase transitions, the solids fragmentation during the process of severe plastic deformation is studied. The density of grain boundaries, dislocations and entropy are introduced for describing the defect structures appearing. This allows us to take into account the two channels of energy dissipation (thermal one and defects formation. The phase diagram that establishes the domains of realization of different limiting structures types is obtained. The interaction of several defect types on the formation of limiting structure in terms of internal energy is studied. The formation conditions for two limiting structures are found. They correspond to the mode, in which there is a mixture of different grain sizes. The kinetics of setting in the steady-state values of the defects density is investigated within the scope of the adiabatic approximation, at which the dislocations density change follows the evolution of the grain boundaries density. The external periodic influence is also analyzed. It is shown that frequency and amplitude of external influence change the system behavior.

  10. Influence of periodic water level increase on flow in Poznań Water Ways System

    Directory of Open Access Journals (Sweden)

    Tomasz Kałuża

    2013-06-01

    Full Text Available In the period 1968-1972, a project named “Rebuilding of the Poznań Water Ways System” was carried out. Within the scope of the project the Chwaliszewo Meander of the Warta river was cut off and covered. A discussion about reconstruction of Chwaliszewo Meander has been run for many years. The results of hydraulic computations of the influence of a weir on water table distribution in Poznań Water Ways System have been presented in the paper. Two different localizations of the weir were considered. Initial maximum water level of upper side of the weir was calculated. The influence of damming up on water level distribution in the Poznań Water Ways System was analysed. One-dimensional unsteady open channel flow computer systems HEC-RAS and SPRuNeR were used to carry out calculations. Building the weir, regardless of its localization, allows to raise water level in the main channel of the Warta river, increase minimum water depth and point to the architecture and recreation values of the Warta river. It is assumed that damming up is necessary only for flow rate below 100 m3/s in both localizations of the weir. The weir in focus should not create obstacles to the inland navigation and fish migration. To meet these requirements two additional hydraulic constructions must be projected: sluice and fish migration water gate.

  11. Mode of Birth Influences Preterm Infant Intestinal Colonization With Bacteroides Over the Early Neonatal Period.

    Science.gov (United States)

    Gregory, Katherine E; LaPlante, Rose D; Shan, Gururaj; Kumar, Deepak Vijaya; Gregas, Matt

    2015-12-01

    Intestinal colonization during infancy is important to short- and long-term health outcomes. Bacteroides, an early member of the intestinal microbiome, is necessary for breaking down complex molecules within the intestine and function to assist the body's immune system in fighting against potentially harmful pathogens. Little is known about the colonization pattern of Bacteroides in preterm infants during the early neonatal period. This study measured Bacteroides colonization during the early neonatal period in a population of preterm infants, based on clinical factors including mode of birth, antibiotics, and nutrition. Bacterial DNA was isolated from 144 fecal samples from 29 preterm infants and analyzed using quantitative real-time polymerase chain reaction. Analyses included liner mixed models to determine which clinical factors affect Bacteroides colonization of the infant gut. We found that infants born via vaginal canal had a higher rate of increase in Bacteroides than infants born via cesarean section (P Bacteroides colonization. These findings highlight the significant influence of mode of birth on Bacteroides colonization. While mode of birth is not always modifiable, these study findings may help develop interventions for preterm infants born via cesarean section aimed at overcoming delayed Bacteroides colonization. Greater study of the intestinal microbiome and the clinical factors relevant to the preterm infant is needed so that interventions may be developed and tested, resulting in optimal microbial and immune health.

  12. The influence of rest period instructions on the default mode network

    Directory of Open Access Journals (Sweden)

    Christopher eBenjamin

    2010-12-01

    Full Text Available The default mode network (DMN refers to regional brain activity that is greater during rest periods than during attention-demanding tasks and many studies have reported DMN alterations in patient populations. It has also been shown that the DMN is suppressed by scanner background noise (SBN, which is the noise produced by functional magnetic resonance imaging (fMRI. However, it is unclear whether different approaches to rest in the noisy MR environment can alter the DMN and constitute a confound in studies investigating the DMN in particular patient populations (e.g., individuals with schizophrenia, Alzheimer’s disease. We examined twenty-seven healthy adult volunteers who completed an fMRI experiment with 3 different instructions for rest: (1 relax and be still, (2 attend to SBN, or (3 ignore SBN. Region of interest (ROI analyses were performed to determine the influence of rest period instructions on core regions of the DMN and DMN regions previously reported to be altered in patients with or at risk for Alzheimer’s disease or schizophrenia. The dorsal medial prefrontal cortex (dmPFC exhibited greater activity when specific resting instructions were given (i.e. attend to or ignore SBN compared to when non-specific resting instructions were given. Condition-related differences in connectivity were also observed between regions of the dmPFC and inferior parietal/posterior superior temporal cortex. We conclude that rest period instructions and SBN levels should be carefully considered for fMRI studies on the DMN, especially studies on clinical populations and groups that may have different approaches to rest, such as first-time research participants and children.

  13. The Influence of Rest Period Instructions on the Default Mode Network

    Science.gov (United States)

    Benjamin, Christopher; Lieberman, Daniel A.; Chang, Maria; Ofen, Noa; Whitfield-Gabrieli, Sue; Gabrieli, John D. E.; Gaab, Nadine

    2010-01-01

    The default mode network (DMN) refers to regional brain activity that is greater during rest periods than during attention-demanding tasks; many studies have reported DMN alterations in patient populations. It has also been shown that the DMN is suppressed by scanner background noise (SBN), which is the noise produced by functional magnetic resonance imaging (fMRI). However, it is unclear whether different approaches to “rest” in the noisy MR environment can alter the DMN and constitute a confound in studies investigating the DMN in particular patient populations (e.g., individuals with schizophrenia, Alzheimer's disease). We examined 27 healthy adult volunteers who completed an fMRI experiment with three different instructions for rest: (1) relax and be still, (2) attend to SBN, or (3) ignore SBN. Region of interest analyses were performed to determine the influence of rest period instructions on core regions of the DMN and DMN regions previously reported to be altered in patients with or at risk for Alzheimer's disease or schizophrenia. The dorsal medial prefrontal cortex (dmPFC) exhibited greater activity when specific resting instructions were given (i.e., attend to or ignore SBN) compared to when non-specific resting instructions were given. Condition-related differences in connectivity were also observed between regions of the dmPFC and inferior parietal/posterior superior temporal cortex. We conclude that rest period instructions and SBN levels should be carefully considered for fMRI studies on the DMN, especially studies on clinical populations and groups that may have different approaches to rest, such as first-time research participants and children. PMID:21151779

  14. Depositional model of Permian Luodianian volcanic island and its impact on the distribution of fusulinid assemblage in southern Qinghai, Northwest China

    Institute of Scientific and Technical Information of China (English)

    NIU ZhiJun; XU AnWu; WANG JianXiong; DUAN QiFa; ZHAO XiaoMing; YAO HuaZhou

    2008-01-01

    Pan-riftizational tectonic activity reached climax at Luodianian (Permian) in the East Tethyan Domain,Qinghai-Tibet Plateau. Because of eruptive volcanics and influence of terrigenous materials, a complex volcanic-sedimentary landform formed on the sea floor in southern Qinghai. Four sedimentary facies types were recognized based on detailed field mapping. Spatially, platform facies volcanic-limestone type was located at the center belt approximately trending NWW, surrounded by shallow water slope facies tuff/tuffite type at the two flanks and deep water slope facies breccia/calcirudite at the most outside. The depression facies sandstone-mudstone type, which comprised mainly mudstone, deposited between volcanic islands (platform facies volcanic-limestone type). Based on the field mapping and stratigraphic section data, seven rift-related sedimentary facies were recognized and a depositional model for volcanic island was proposed. It is revealed that some volcanic island chain formed quickly and intermittently in the Qamdo Block during violent eruption, and small carbonate reef, shoal,platform occurred above or on edge of volcanic island, and some slope sedimentary facies surrounded volcano island chain during dormant period of volcanic activities. Three types of fusulinid assemblages were distinguished in the carbonate rocks, which deposited in varied positions of a palaeo-volcanic island: (1) Misellina- Schwagerina assemblage occurred above or on edge of volcanic island, (2) Parafusulina assemblage was located at restricted depression facies among volcanic islands or carbonate platform, and (3) the reworked Pseudofusulina-Schwagerina assemblage occurred at slope facies near margin of volcanic island, which originally deposited in the shallow-water carbonate platform, then collapsed along the volcanic island margin with fusulinid-bearing grain-supported carbonate conglomerate or calcirudite, and finally re-deposited on the deeper slope. The sedimentary sequence

  15. Depositional model of Permian Luodianian volcanic island and its impact on the distribution of fusulinid assemblage in southern Qinghai,Northwest China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Pan-riftizational tectonic activity reached climax at Luodianian (Permian) in the East Tethyan Domain, Qinghai-Tibet Plateau. Because of eruptive volcanics and influence of terrigenous materials, a complex volcanic-sedimentary landform formed on the sea floor in southern Qinghai. Four sedimentary facies types were recognized based on detailed field mapping. Spatially, platform facies volcanic-limestone type was located at the center belt approximately trending NWW, surrounded by shallow water slope facies tuff/tuffite type at the two flanks and deep water slope facies breccia/calcirudite at the most outside. The depression facies sandstone-mudstone type, which comprised mainly mudstone, de-posited between volcanic islands (platform facies volcanic-limestone type). Based on the field map-ping and stratigraphic section data, seven rift-related sedimentary facies were recognized and a depo-sitional model for volcanic island was proposed. It is revealed that some volcanic island chain formed quickly and intermittently in the Qamdo Block during violent eruption, and small carbonate reef, shoal, platform occurred above or on edge of volcanic island, and some slope sedimentary facies surrounded volcano island chain during dormant period of volcanic activities. Three types of fusulinid assemblages were distinguished in the carbonate rocks, which deposited in varied positions of a palaeo-volcanic island: (1) Misellina-Schwagerina assemblage occurred above or on edge of volcanic island, (2) Para-fusulina assemblage was located at restricted depression facies among volcanic islands or carbonate platform, and (3) the reworked Pseudofusulina-Schwagerina assemblage occurred at slope facies near margin of volcanic island, which originally deposited in the shallow-water carbonate platform, then collapsed along the volcanic island margin with fusulinid-bearing grain-supported carbonate con-glomerate or calcirudite, and finally re-deposited on the deeper slope. The sedimentary

  16. An interdisciplinary approach to volcanic risk reduction under conditions of uncertainty: a case study of Tristan da Cunha

    Science.gov (United States)

    Hicks, A.; Barclay, J.; Simmons, P.; Loughlin, S.

    2013-12-01

    This research project adopted an interdisciplinary approach to volcanic risk reduction on the remote volcanic island of Tristan da Cunha (South Atlantic). New data were produced that: (1) established no spatio-temporal pattern to recent volcanic activity; (2) quantified the high degree of scientific uncertainty around future eruptive scenarios; (3) analysed the physical vulnerability of the community as a consequence of their geographical isolation and exposure to volcanic hazards; (4) evaluated social and cultural influences on vulnerability and resilience. Despite their isolation and prolonged periods of hardship, islanders have demonstrated an ability to cope with and recover from adverse events. This resilience is likely a function of remoteness, strong kinship ties, bonding social capital, and persistence of shared values and principles established at community inception. While there is good knowledge of the styles of volcanic activity on Tristan, given the high degree of scientific uncertainty about the timing, size and location of future volcanism, a qualitative scenario planning approach was used as a vehicle to convey this information to the islanders. This deliberative, anticipatory method allowed on-island decision makers to take ownership of risk identification, management and capacity building within their community. This paper demonstrates the value of integrating social and physical sciences with development of effective, tailored communication strategies in volcanic risk reduction.

  17. Local to global: a collaborative approach to volcanic risk assessment

    Science.gov (United States)

    Calder, Eliza; Loughlin, Sue; Barsotti, Sara; Bonadonna, Costanza; Jenkins, Susanna

    2017-04-01

    Volcanic risk assessments at all scales present challenges related to the multitude of volcanic hazards, data gaps (hazards and vulnerability in particular), model representation and resources. Volcanic hazards include lahars, pyroclastic density currents, lava flows, tephra fall, ballistics, gas dispersal and also earthquakes, debris avalanches, tsunamis and more ... they can occur in different combinations and interact in different ways throughout the unrest, eruption and post-eruption period. Volcanoes and volcanic hazards also interact with other natural hazards (e.g. intense rainfall). Currently many hazards assessments consider the hazards from a single volcano but at national to regional scales the potential impacts of multiple volcanoes over time become important. The hazards that have the greatest tendency to affect large areas up to global scale are those transported in the atmosphere: volcanic particles and gases. Volcanic ash dispersal has the greatest potential to directly or indirectly affect the largest number of people worldwide, it is currently the only volcanic hazard for which a global assessment exists. The quantitative framework used (primarily at a regional scale) considers the hazard at a given location from any volcano. Flow hazards such as lahars and floods can have devastating impacts tens of kilometres from a source volcano and lahars can be devastating decades after an eruption has ended. Quantitative assessment of impacts is increasingly undertaken after eruptions to identify thresholds for damage and reduced functionality. Some hazards such as lava flows could be considered binary (totally destructive) but others (e.g. ash fall) have varying degrees of impact. Such assessments are needed to enhance available impact and vulnerability data. Currently, most studies focus on physical vulnerability but there is a growing emphasis on social vulnerability showing that it is highly variable and dynamic with pre-eruption socio

  18. A long period grating-based chemical sensor insensitive to the influence of interfering parameters.

    Science.gov (United States)

    James, Stephen W; Korposh, Serhiy; Lee, Seung-Woo; Tatam, Ralph P

    2014-04-07

    An optical fibre chemical sensor that is insensitive to interfering parameters including temperature and surrounding refractive index is described. The sensor is based upon a Mach-Zehnder interferometer formed by a pair of identical cascaded long period gratings (LPGs), with the entire device coated with a mesoporous coating of silica nanoparticles. A functional material is infused only into the coating over the section of optical fibre separating the LPGs. The transmission spectrum of the device consists of a channeled spectrum arising from interference of the core and cladding modes within the envelope of the LPG resonance band. Parameters such as temperature, strain and surrounding refractive perturb the entire device, causing the phase of the channeled spectrum and the central wavelength of the envelope shift at the same rate. Exposure of the device to the analyte of interest perturbs only the optical characteristics of the section of fibre into which the functional material was infused, thus influencing only the phase of the channeled spectrum. Measurement of the phase of the channeled spectrum relative to the central wavelength of the envelope allows the monitoring of the concentration of the analyte with no interference from other parameters.

  19. Supercomputer modeling of volcanic eruption dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Kieffer, S.W. [Arizona State Univ., Tempe, AZ (United States); Valentine, G.A. [Los Alamos National Lab., NM (United States); Woo, Mahn-Ling [Arizona State Univ., Tempe, AZ (United States)

    1995-06-01

    Our specific goals are to: (1) provide a set of models based on well-defined assumptions about initial and boundary conditions to constrain interpretations of observations of active volcanic eruptions--including movies of flow front velocities, satellite observations of temperature in plumes vs. time, and still photographs of the dimensions of erupting plumes and flows on Earth and other planets; (2) to examine the influence of subsurface conditions on exit plane conditions and plume characteristics, and to compare the models of subsurface fluid flow with seismic constraints where possible; (3) to relate equations-of-state for magma-gas mixtures to flow dynamics; (4) to examine, in some detail, the interaction of the flowing fluid with the conduit walls and ground topography through boundary layer theory so that field observations of erosion and deposition can be related to fluid processes; and (5) to test the applicability of existing two-phase flow codes for problems related to the generation of volcanic long-period seismic signals; (6) to extend our understanding and simulation capability to problems associated with emplacement of fragmental ejecta from large meteorite impacts.

  20. Toward Forecasting Volcanic Eruptions using Seismic Noise

    CERN Document Server

    Brenguier, Florent; Campillo, Michel; Ferrazzini, Valerie; Duputel, Zacharie; Coutant, Olivier; Nercessian, Alexandre

    2007-01-01

    During inter-eruption periods, magma pressurization yields subtle changes of the elastic properties of volcanic edifices. We use the reproducibility properties of the ambient seismic noise recorded on the Piton de la Fournaise volcano to measure relative seismic velocity variations of less than 0.1 % with a temporal resolution of one day. Our results show that five studied volcanic eruptions were preceded by clearly detectable seismic velocity decreases within the zone of magma injection. These precursors reflect the edifice dilatation induced by magma pressurization and can be useful indicators to improve the forecasting of volcanic eruptions.

  1. Spatio-temporal evolution of the Tuxtla Volcanic Field

    Science.gov (United States)

    Kobs Nawotniak, S. E.; Espindola, J.; Godinez, L.

    2010-12-01

    Mapping of the Tuxtla Volcanic Field (TVF), located in Veracruz, Mexico, through the use of digital elevation models, aerial photography, and field confirmation has found 353 distinct cones, 4 large composite volcanoes, and 42 maars. Eruptive activity in the TVF began in the late Miocene, underwent a quiescent period approximately 2.6-0.8 Ma, and continues into historic times with the most recent eruption occurring at San Martín Tuxtla volcano in 1793. The covariance of the minimum cone separation in the TVF indicates that, despite the influence of clear vent alignments following regional faulting trends, the field as a whole is anticlustered. Dividing the cones by morphometric age shows that while the older cones have an anti-clustered distribution, the younger cones (Catemaco. These areas of concentrated volcanism roughly correspond to the locations of two gravity anomalies previously identified in the area. While the average height/width ratio is equal between the two clusters, the cones in the eastern group are significantly smaller than their counterparts in the western group. The maars of the TVF are mostly located within the younger volcanic series, west of Laguna Catemaco, and have an anticlustered distribution; many of the maars are evenly spaced along curved lines, where they are weakly grouped according to crater diameter. Results indicate volcanism TVF has undergone continued spatial restriction over time, concentrating in the western half of the TVF with the onset of the eruption of the younger volcanic series 0.8 Ma and further contracting along the principle fault system within the last 50 Ka.

  2. A possible influence of the Great White Spot on Saturn kilometric radiation periodicity

    National Research Council Canada - National Science Library

    G. Fischer; S.-Y. Ye; J. B. Groene; A. P. Ingersoll; K. M. Sayanagi; J. D. Menietti; W. S. Kurth; D. A. Gurnett

    2014-01-01

    The periodicity of Saturn kilometric radiation (SKR) varies with time, and its two periods during the first 5 years of the Cassini mission have been attributed to SKR from the northern and southern hemisphere...

  3. Influence of Chest Compressions on Circulation during the Peri-Cardiac Arrest Period in Porcine Models.

    Directory of Open Access Journals (Sweden)

    Jun Xu

    Full Text Available Starting chest compressions immediately after a defibrillation shock might be harmful, if the victim already had a return of spontaneous circulation (ROSC and yet was still being subjected to external compressions at the same time. The objective of this study was to study the influence of chest compressions on circulation during the peri-cardiac arrest period.Prospective, randomized controlled study.Animal experimental center in Peking Union Medical Collage Hospital, Beijing, China.Healthy 3-month-old male domestic pigs.44 pigs (28±2 kg were randomly assigned to three groups: Group I (non-arrested with compressions (n = 12; Group II (arrested with compressions only (n = 12; Group III (ROSC after compressions and defibrillation (n = 20. In Groups I and II, compressions were performed to a depth of 5cm (Ia and IIa, n = 6 or a depth of 3cm (Ib and IIb, n = 6 respectively, while in Group III, the animals which had just achieved ROSC (n = 18 were compressed to a depth of 5cm (IIIa, n = 6, a depth of 3cm (IIIb, n = 6, or had no compressions (IIIc, n = 6. Hemodynamic parameters were collected and analyzed.Hemodynamics were statistically different between Groups Ia and Ib when different depths of compressions were performed (p < 0.05. In Group II, compressions were beneficial and hemodynamics correlated with the depth of compressions (p < 0.05. In Group III, compressions that continued after ROSC produced a reduction in arterial pressure (p < 0.05.Chest compressions might be detrimental to hemodynamics in the early post-ROSC stage. The deeper the compressions were, the better the effect on hemodynamics during cardiac arrest, but the worse the effect on hemodynamics after ROSC.

  4. Controls on volcanism at intraplate basaltic volcanic fields

    Science.gov (United States)

    van den Hove, Jackson C.; Van Otterloo, Jozua; Betts, Peter G.; Ailleres, Laurent; Cas, Ray A. F.

    2017-02-01

    A broad range of controlling mechanisms is described for intraplate basaltic volcanic fields (IBVFs) in the literature. These correspond with those relating to shallow tectonic processes and to deep mantle plumes. Accurate measurement of the physical parameters of intraplate volcanism is fundamental to gain an understanding of the controlling factors that influence the scale and location of a specific IBVF. Detailed volume and geochronology data are required for this; however, these are not available for many IBVFs. In this study the primary controls on magma genesis and transportation are established for the Pliocene-Recent Newer Volcanics Province (NVP) of south-eastern Australia as a case-study for one of such IBVF. The NVP is a large and spatio-temporally complex IBVF that has been described as either being related to a deep mantle plume, or upper mantle and crustal processes. We use innovative high resolution aeromagnetic and 3D modelling analysis, constrained by well-log data, to calculate its dimensions, volume and long-term eruptive flux. Our estimates suggest volcanic deposits cover an area of 23,100 ± 530 km2 and have a preserved dense rock equivalent of erupted volcanics of least 680 km3, and may have been as large as 900 km3. The long-term mean eruptive flux of the NVP is estimated between 0.15 and 0.20 km3/ka, which is relatively high compared with other IBVFs. Our comparison with other IBVFs shows eruptive fluxes vary up to two orders of magnitude within individual fields. Most examples where a range of eruptive flux is available for an IBVF show a correlation between eruptive flux and the rate of local tectonic processes, suggesting tectonic control. Limited age dating of the NVP has been used to suggest there were pulses in its eruptive flux, which are not resolvable using current data. These changes in eruptive flux are not directly relatable to the rate of any interpreted tectonic driver such as edge-driven convection. However, the NVP and other

  5. Friction in volcanic environments

    Science.gov (United States)

    Kendrick, Jackie E.; Lavallée, Yan

    2016-04-01

    Volcanic landscapes are amongst the most dynamic on Earth and, as such, are particularly susceptible to failure and frictional processes. In rocks, damage accumulation is frequently accompanied by the release of seismic energy, which has been shown to accelerate in the approach to failure on both a field and laboratory scale. The point at which failure occurs is highly dependent upon strain-rate, which also dictates the slip-zone properties that pertain beyond failure, in scenarios such as sector collapse and pyroclastic flows as well as the ascent of viscous magma. High-velocity rotary shear (HVR) experiments have provided new opportunities to overcome the grand challenge of understanding faulting processes during volcanic phenomena. Work on granular ash material demonstrates that at ambient temperatures, ash gouge behaves according to Byerlee's rule at low slip velocities, but is slip-weakening, becoming increasingly lubricating as slip ensues. In absence of ash along a slip plane, rock-rock friction induces cataclasis and heating which, if sufficient, may induce melting (producing pseudotachylyte) and importantly, vesiculation. The viscosity of the melt, so generated, controls the subsequent lubrication or resistance to slip along the fault plane thanks to non-Newtonian suspension rheology. The shear-thinning behaviour and viscoelasticity of frictional melts yield a tendency for extremely unstable slip, and occurrence of frictional melt fragmentation. This velocity-dependence acts as an important feedback mechanism on the slip plane, in addition to the bulk composition, mineralogy and glass content of the magma, that all influence frictional behaviour. During sector collapse events and in pyroclastic density currents it is the frictional properties of the rocks and ash that, in-part, control the run-out distance and associated risk. In addition, friction plays an important role in the eruption of viscous magmas: In the conduit, the rheology of magma is integral

  6. Automatic classification of seismo-volcanic signatures

    Science.gov (United States)

    Malfante, Marielle; Dalla Mura, Mauro; Mars, Jérôme; Macedo, Orlando; Inza, Adolfo; Métaxian, Jean-Philippe

    2017-04-01

    The prediction of volcanic eruptions and the evaluation of their associated risks is still a timely and open issue. For this purpose, several types of signals are recorded in the proximity of volcanoes and then analysed by experts. Typically, seismic signals that are considered as precursor or indicator of an active volcanic phase are detected and manually classified. In this work, we propose an architecture for automatic classification of seismo-volcanic waves. The system we propose is based on supervised machine learning. Specifically, a prediction model is built from a large dataset of labelled examples by the means of a learning algorithm (Support Vector Machine or Random Forest). Four main steps are involved: (i) preprocess the signals, (ii) from each signal, extract features that are useful for the classes discrimination, (iii) use an automatic learning algorithm to train a prediction model and (iv) classify (i.e., assign a semantic label) newly recorded and unlabelled examples. Our main contribution lies in the definition of the feature space used to represent the signals (i.e., in the choice of the features to extract from the data). Feature vectors describe the data in a space of lower dimension with respect to the original one. Ideally, signals are separable in the feature space depending on their classes. For this work, we consider a large set of features (79) gathered from an extensive state of the art in both acoustic and seismic fields. An analysis of this feature set shows that for the application of interest, 11 features are sufficient to discriminate the data. The architecture is tested on 4725 seismic events recorded between June 2006 and September 2011 at Ubinas, the most active volcano of Peru. Six main classes of signals are considered: volcanic tremors (TR), long period (LP), volcano-tectonic (VT), explosion (EXP), hybrids (HIB) and tornillo (TOR). Our model reaches above 90% of accuracy, thereby validating the proposed architecture and the

  7. A possible influence of the Great White Spot on Saturn kilometric radiation periodicity

    Science.gov (United States)

    Fischer, G.; Ye, S.-Y.; Groene, J. B.; Ingersoll, A. P.; Sayanagi, K. M.; Menietti, J. D.; Kurth, W. S.; Gurnett, D. A.

    2014-12-01

    The periodicity of Saturn kilometric radiation (SKR) varies with time, and its two periods during the first 5 years of the Cassini mission have been attributed to SKR from the northern and southern hemisphere. After Saturn equinox in August 2009, there were long intervals of time (March 2010 to February 2011 and September 2011 to June 2012) with similar northern and southern SKR periods and locked SKR phases. However, from March to August 2011 the SKR periods were split up again, and the phases were unlocked. In this time interval, the southern SKR period slowed down by ~ 0.5% on average, and there was a large jump back to a faster period in August 2011. The northern SKR period speeded up and coalesced again with the southern period in September 2011. We argue that this unusual behavior could be related to the so-called Great White Spot (GWS), a giant thunderstorm that raged in Saturn's atmosphere around that time. For several months in 2011, the visible head of the GWS had the same period of ~ 10.69 h as the main southern SKR modulation signal. The GWS was most likely a source of intense gravity waves that may have caused a global change in Saturn's thermospheric winds via energy and momentum deposition. This would support the theory that Saturn's magnetospheric periodicities are driven by the upper atmosphere. Since the GWS with simultaneous SKR periodicity measurements have only been made once, it is difficult to prove a physical connection between these two phenomena, but we provide plausible mechanisms by which the GWS might modify the SKR periods.

  8. Experimental generation of volcanic lightning

    Science.gov (United States)

    Cimarelli, Corrado; Alatorre-Ibargüengoitia, Miguel; Kueppers, Ulrich; Scheu, Bettina; Dingwell, Donald B.

    2014-05-01

    Ash-rich volcanic plumes that are responsible for injecting large quantities of aerosols into the atmosphere are often associated with intense electrical activity. Direct measurement of the electric potential at the crater, where the electric activity in the volcanic plume is first observed, is severely impeded, limiting progress in its investigation. We have achieved volcanic lightning in the laboratory during rapid decompression experiments of gas-particle mixtures under controlled conditions. Upon decompression (from ~100 bar argon pressure to atmospheric pressure), loose particles are vertically accelerated and ejected through a nozzle of 2.8 cm diameter into a large tank filled with air at atmospheric conditions. Because of their impulsive character, our experiments most closely represent the conditions encountered in the gas-thrust region of the plume, when ash is first ejected from the crater. We used sieved natural ash with different grain sizes from Popocatépetl (Mexico), Eyjafjallajökull (Iceland), and Soufrière Hills (Montserrat) volcanoes, as well as micrometric glass beads to constrain the influence of material properties on lightning. We monitored the dynamics of the particle-laden jets with a high-speed camera and the pressure and electric potential at the nozzle using a pressure transducer and two copper ring antennas connected to a high-impedance data acquisition system, respectively. We find that lightning is controlled by the dynamics of the particle-laden jet and by the abundance of fine particles. Two main conditions are required to generate lightning: 1) self-electrification of the particles and 2) clustering of the particles driven by the jet fluid dynamics. The relative movement of clusters of charged particles within the plume generates the gradient in electrical potential, which is necessary for lightning. In this manner it is the gas-particle dynamics together with the evolving particle-density distribution within different regions of

  9. The Genome-Wide Influence on Human BMI Depends on Physical Activity, Life Course, and Historical Period.

    Science.gov (United States)

    Guo, Guang; Liu, Hexuan; Wang, Ling; Shen, Haipeng; Hu, Wen

    2015-10-01

    In this analysis, guided by an evolutionary framework, we investigate how the human genome as a whole interacts with historical period, age, and physical activity to influence body mass index (BMI). The genomic influence is estimated by (1) heritability or the proportion of variance in BMI explained by genome-wide genotype data, and (2) the random effects or the best linear unbiased predictors (BLUPs) of genome-wide association studies (GWAS) data on BMI. Data were used from the Framingham Heart Study (FHS) in the United States. The study was initiated in 1948, and the obesity data were collected repeatedly over the subsequent decades. The analyses draw analysis samples from a pool of >8,000 individuals in the FHS. The hypothesis testing based on Pitman test, permutation Pitman test, F test, and permutation F test produces three sets of significant findings. First, the genomic influence on BMI is substantially larger after the mid-1980s than in the few decades before the mid-1980s within each age group of 21-40, 41-50, 51-60, and >60. Second, the genomic influence on BMI weakens as one ages across the life course, or the genomic influence on BMI tends to be more important during reproductive ages than after reproductive ages within each of the two historical periods. Third, within the age group of 21-50 and not in the age group of >50, the genomic influence on BMI among physically active individuals is substantially smaller than the influence on those who are not physically active. In summary, this study provides evidence that the influence of human genome as a whole on obesity depends on historical period, age, and level of physical activity.

  10. Sensitive Periods of Emotion Regulation: Influences of Parental Care on Frontoamygdala Circuitry and Plasticity

    Science.gov (United States)

    Gee, Dylan G.

    2016-01-01

    Early caregiving experiences play a central role in shaping emotional development, stress physiology, and refinement of limbic circuitry. Converging evidence across species delineates a sensitive period of heightened neuroplasticity when frontoamygdala circuitry is especially amenable to caregiver inputs early in life. During this period, parental…

  11. Revisiting 154-day periodicity in the occurrence of hard flares. A planetary influence?

    CERN Document Server

    Edmonds, Ian

    2016-01-01

    Rieger et al (1984) reported observations of a 154 day periodicity in flares during solar cycle 21. This paper discusses the observations in the light of a simple empirical planetary model of sunspot emergence. The planetary model predicts sunspot emergence when Mercury and Earth approach conjunction and Mercury approaches the Sun. We show that the reported times of flare activity are coherent with the planetary model. While the base period of the model is 170 days, the average model period, over the interval of flare recordings, is 157 days due to a 180 degree phase change in the planetary forcing near the middle of the record interval. We conclude that the periodicity at 154 days arises when the phase change in planetary forcing and the resulting progressive phase change in total sunspot area emergence and flare occurrence shifts the major peak in the flare spectrum from the planetary forcing period, 170 days, to 154 days.

  12. Volcanic geology of Admiralty Bay, King George Island, Antarctica

    Institute of Scientific and Technical Information of China (English)

    邢光福; 王德滋; 金庆民; 沈渭洲; 陶奎元

    2002-01-01

    At Admiralty Bay of central King George Island, Keller Peninsula, Ullman Spur and Point Hennequin are main Tertiary volcanic terranes. Field investigation and isotopic datings indicate that, there occurred three periods of eruptions ( three volcanic cycles) and accompanying N-toward migration of the volcanic center on Keller Peninsula. After the second period of eruptions, the crater collapsed and a caldera was formed, then later eruptions were limited at the northern end of the peninsula and finally migrated to Ullman Spur. Thus Keller Peninsula is a revived caldera, and its volcanism migrated toward E with time. Point Hennequin volcanism happened more or less simultaneously with the above two areas, but has no clear relation in chemical evolution with them, frequently it belongs to another independent volcanic center.

  13. The influence of antidepressants on restless legs syndrome and periodic limb movements: A systematic review.

    Science.gov (United States)

    Kolla, Bhanu Prakash; Mansukhani, Meghna P; Bostwick, J Michael

    2017-06-15

    Restless legs syndrome is commonly co-morbid with medical conditions that are treated with antidepressant medications, such as depression, anxiety, fibromyalgia, and chronic insomnia disorder. Evidence from case reports and cross-sectional studies suggests that antidepressants may induce or worsen restless legs syndrome and increase periodic limb movements. We undertook a systematic review of the literature to identify and collate all prospective studies that measured restless legs syndrome symptoms and/or periodic limb movements following the introduction of an antidepressant. Eighteen studies were eligible for inclusion. Current data indicate that onset or exacerbation of restless legs syndrome and rise in frequency of periodic limb movements are uncommon following the initiation of an antidepressant. Among the various antidepressants, mirtazapine may be associated with higher rates of restless legs syndrome and periodic limb movements. One small study of normal volunteers suggested that venlafaxine may be associated with an increase in restless legs syndrome symptoms and periodic limb movements. Sertraline, fluoxetine, and amitriptyline appear to increase periodic limb movements that do not disrupt sleep and are thus unlikely to be clinically significant. On the other hand, bupropion may reduce restless legs syndrome symptoms, at least in the short term. Sedating antidepressants such as trazodone, nefazodone, and doxepin do not seem to aggravate periodic limb movements. The current evidence is limited by poor study design, inadequate use of standardized questionnaires, and heterogeneous populations studied for variable lengths of time. Future research should attempt to remedy these shortcomings. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Influences of diagenetic effects on volcanic rock reservoirs under two different sedimentary environments%两种不同沉积环境下火山岩储层成岩作用研究

    Institute of Scientific and Technical Information of China (English)

    王盛鹏; 林潼; 孙平; 梁浩; 王东良; 苟红光

    2012-01-01

    According to the studies of rock types and reservoir space features of Carboniferous volcanic rocks in the Santanghu Basin, there were two kinds of environments for volcanic rock generation including subaerial and subaqueous in the study area. Based on core description, casting chip, scanning electron microscopy and element analysis, the generation features of volcanic rocks under the two different environments and the corresponding influences on reservoirs were discussed from the aspects of diagenetic effects. It was concluded that different diagenetic effects influenced volcanic reservoirs in different extents. The volcanic rocks which erupted and deposited on land in the study area were severely filled by zeolites and chlorites, and then improved obviously due to weathering and leaching. The extent of weathering and leaching was closely related to the improvement of reservoir. The volcanic reservoirs which deposited under water were improved owing to organic acid erosion. Primary pores were seldom found and a large amount of matrix dissolved holes generated. The generation mechanisms of subaqueous volcanic reservoirs pointed out new areas for explorations in the future.%基于三塘湖盆地石炭系火山岩储层的岩石类型、储集空间特征研究,识别出该区存在陆上喷发沉积和水下沉积2种环境.并通过岩心描述、铸体薄片和扫描电镜微观显示以及元素分析等手段,重点从成岩作用的角度对这2种环境下火山岩储层的发育特征及影响作用开展研究.研究认为,各种成岩作用对火山岩储层起到了不同程度的影响作用.该区陆上喷发沉积的火山岩受沸石和绿泥石填充较强烈,后期又遭受风化淋滤作用,使得储层发生明显的改善;风化强度与储层改善有着密切关系.水下沉积的火山岩储层改善主要受有机酸溶蚀作用影响,其原生孔隙不发育,但发育大量的基质溶孔.对水下沉积火山岩储层发育机理的认

  15. Episodes of volcanic activity and their environmental effects in the Okinawa Trough during the last 150 ka

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A piston core Z14-6 was used in this study. The core, 896 cm long, was collected from eastern slope of the Okinawa Trough (27°07′N, 127°27′E, water depth 739m). The δ18O and δ13C values of the sediment bearing planktonic foraminifera G. sacculifer and N. dutertrei were determined; and the abundance of volcanic glass was analyzed. The volcanic glass content high occurred in early stage of polar ice-sheet growth period, or the beginning of cold climate periods corresponding to Milankovitch cycles (Peak Ⅰ, Ⅱ and Ⅴ are corresponding to the beginnings of oxygen isotopic stages 2, 4 and 6, and Peak Ⅲ and Ⅳ are matching oxygen isotopic stage 5b-5d.). It might be possible that volcanic episodes and climate changes were responding to orbital forcing in the Okinawa Trough in late Quaternary. The δ18O difference between N. dutertrei and G. sacculifer shows no clear correlation to the volcanic glass content high, which suggests that the volcanic eruptions did not influence the structure of upper water column. However, the low δ13C difference between G. sacculifer and N. dutertrei is coeval with the volcanic glass high or sub-high content. This fact suggests that volcanic eruptions might influence the reduction in vertical nutritional gradient and carbon cycle process in upper water column. A possible mechanism is that huge quantity of ash and dust had weakened the light intensity, resulting in photosynthesis reduction, productivity decrease, and biological pumping.

  16. Influence of Kinesitherapy on Gait in Patients with Ischemic Stroke in the Chronic Period

    Directory of Open Access Journals (Sweden)

    Danche Vasileva

    2015-10-01

    CONCLUSION: The applied specialized kinesitherapeutic methodology continued later as exercise program at home, which significantly improved gait cadence and speed of movement in patients with ischemic stroke in the chronic period and is with a supportive prolonged exposure.

  17. Exploring the influence of age and the role of critical period in second language acquisition

    Institute of Scientific and Technical Information of China (English)

    刘雨彤

    2016-01-01

    In the process of second language acquisition, age is one of the influencial factors.This article will mainly focus on the effect of age on second language acquisition and the role of critical period, whether it is the only best time to achieve proficiency? If the critical period really exists what should we do in teaching to make advantage of this chance to master a second language successfully?

  18. A Proposed Community Network For Monitoring Volcanic Emissions In Saint Lucia, Lesser Antilles

    Science.gov (United States)

    Joseph, E. P.; Beckles, D. M.; Robertson, R. E.; Latchman, J. L.; Edwards, S.

    2013-12-01

    Systematic geochemical monitoring of volcanic systems in the English-speaking islands of the Lesser Antilles was initiated by the UWI Seismic Research Centre (SRC) in 2000, as part of its volcanic surveillance programme for the English-speaking islands of the Lesser Antilles. This programme provided the first time-series observations used for the purpose of volcano monitoring in Dominica and Saint Lucia, permitted the characterization of the geothermal fluids associated with them, and established baseline studies for understanding of the hydrothermal systems during periods of quiescence (Joseph et al., 2011; Joseph et al., 2013). As part of efforts to improve and expand the capacity of SRC to provide volcanic surveillance through its geothermal monitoring programme, it is necessary to develop economically sustainable options for the monitoring of volcanic emissions/pollutants. Towards this effort we intend to work in collaboration with local authorities in Saint Lucia, to develop a monitoring network for quantifying the background exposure levels of ambient concentrations of volcanic pollutants, SO2 in air and As in waters (as health significant marker elements in the geothermal emissions) that would serve as a model for the emissions monitoring network for other volcanic islands. This programme would facilitate the building of local capacity and training to monitor the hazardous exposure, through the application and transfer of a regionally available low-cost and low-technology SO2 measurement/detection system in Saint Lucia. Existing monitoring technologies to inform evidence based health practices are too costly for small island Caribbean states, and no government policies or health services measures currently exist to address/mitigate these influences. Gases, aerosols and toxic elements from eruptive and non-eruptive volcanic activity are known to adversely affect human health and the environment (Baxter, 2000; Zhang et al., 2008). Investigations into the

  19. Influence of temperature of the short-period heat treatment on mechanical properties of the NiTi alloy

    Directory of Open Access Journals (Sweden)

    Jaroslav Čapek

    2014-01-01

    Full Text Available The equiatomic alloy of nickel and titanium, known as nitinol, possesses unique properties such as superelasticity, pseudoplasticity, shape memory, while maintaining good corrosion resistance and sufficient biocompatibility. Therefore it is used for production of various devices including surgery implants. Heat treatment of nickel-rich NiTi alloys can result in precipitation of nickel-rich phases, which strongly influence tensile and fatigue behaviour of the material.In this work we have studied influence of short-period heat treatment on tensile behaviour and fatigue life of the NiTi (50.9 at. % Ni wire intended for fabrication of surgery stents.

  20. Atrazine Adsorption Behavior on a Fluvo-Aquic Soil as Influenced by Contact Periods

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A batch experiment was performed to investigate nonequilibrium adsorption behavior of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) on a fluvo-aquic soil. The amount of atrazine sorbed increased with increasing adsorption contact periods. For a range of initial atrazine concentrations, the percentage of atrazine sorbed within 24 h ranged from 24% to 77% of the observed total amount sorbed for the longest contact period; when adsorption contact periods were more than 72 h, the deviations in curves fitted using a nonlinear Freundlich equation gradually became less. The opposite trend was observed for the atrazine concentrations in solution. The effect of adsorption contact periods on atrazine adsorption behavior was evaluated by interpreting the temporal variations in linear and nonlinear Freundlich equation parameters obtained from the phase-distribution relationships. As the adsorption contact period increased, the nonlinear Freundlich capacity coefficient kf showed a significant linear increase (r2 = 0.9063, P < 0.001). However, a significant negative linear correlation was observed for the nonlinear coefficient n, a dimensionless parameter (r2 = 0.5666,P < 0.05).Furthermore, the linear distribution coefficient kd ranged from 0.38 to 1.44 and exhibited a significant linear correlation to the adsorption contact period (r2 = 0.72, P < 0.01). The parameters k f and n obtained from a time-dependent isotherm rather than the distribution coefficient kd estimated using the linear Freundlich equation were more appropriate to predict the herbicide residue in the field and thus more meaningful for environmental assessment.

  1. How Volcanism Controls Climate Change

    Science.gov (United States)

    Ward, P. L.

    2013-12-01

    km decrease in tropopause height. Changes in the rates and types of volcanism have been the primary cause of climate change throughout geologic time. Large explosive volcanoes erupting as frequently as once per decade increment the world into ice ages. Extensive, effusive basaltic volcanism warms the world out of ice ages. Twelve of the 13 dated basaltic table mountains in Iceland experienced their final eruptive phase during the last deglaciation when deposits of sulfate and volcanic ash fell over Greenland at their highest rates. Massive flood basalts are typically accompanied by extreme warming, ozone depletion, and major mass extinctions. The Paleocene-Eocene Thermal Maximum occurred when subaerial extrusion of basalts related to the opening of the Greenland-Norwegian Sea suddenly increased to rates greater than 3000 cubic km per km of rift per million years. Dansgaard-Oeschger sudden warming events are contemporaneous with increased volcanism especially in Iceland and last longer when that volcanism lasts longer. Sudden influxes of fresh water often observed in the North Atlantic during these events are most likely caused by extensive sub-glacial volcanism. The Medieval Warm Period, Little Ice Age, major droughts, and many sudden changes in human civilization began with substantial increases in volcanism. Extensive submarine volcanism does not affect climate directly but is linked with increases in ocean acidity and anoxic events.

  2. Volcanic Alert System (VAS) developed during the (2011-2013) El Hierro (Canary Islands) volcanic process

    Science.gov (United States)

    Ortiz, Ramon; Berrocoso, Manuel; Marrero, Jose Manuel; Fernandez-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Garcia, Alicia

    2014-05-01

    In volcanic areas with long repose periods (as El Hierro), recently installed monitoring networks offer no instrumental record of past eruptions nor experience in handling a volcanic crisis. Both conditions, uncertainty and inexperience, contribute to make the communication of hazard more difficult. In fact, in the initial phases of the unrest at El Hierro, the perception of volcanic risk was somewhat distorted, as even relatively low volcanic hazards caused a high political impact. The need of a Volcanic Alert System became then evident. In general, the Volcanic Alert System is comprised of the monitoring network, the software tools for the analysis of the observables, the management of the Volcanic Activity Level, and the assessment of the threat. The Volcanic Alert System presented here places special emphasis on phenomena associated to moderate eruptions, as well as on volcano-tectonic earthquakes and landslides, which in some cases, as in El Hierro, may be more destructive than an eruption itself. As part of the Volcanic Alert System, we introduce here the Volcanic Activity Level which continuously applies a routine analysis of monitoring data (particularly seismic and deformation data) to detect data trend changes or monitoring network failures. The data trend changes are quantified according to the Failure Forecast Method (FFM). When data changes and/or malfunctions are detected, by an automated watchdog, warnings are automatically issued to the Monitoring Scientific Team. Changes in the data patterns are then translated by the Monitoring Scientific Team into a simple Volcanic Activity Level, that is easy to use and understand by the scientists and technicians in charge for the technical management of the unrest. The main feature of the Volcanic Activity Level is its objectivity, as it does not depend on expert opinions, which are left to the Scientific Committee, and its capabilities for early detection of precursors. As a consequence of the El Hierro

  3. INFLUENCE OF A PERIOD OF ARTIFICIAL LIGHTING ON FORMATION OF LETTUCE SEEDLINGS

    Directory of Open Access Journals (Sweden)

    Abyan M. V.

    2014-09-01

    Full Text Available The article presents a research of reaction of seedlings of lettuce on light duration with sodium lamps when grown in a greenhouse. It was shown that in winter conditions of the Krasnodar Region the intensity of natural light to produce quality seedlings of lettuce is insufficient and additional lighting has a significant influence on the morphology of lettuce seedlings

  4. Influence of Body Composition on Gait Kinetics throughout Pregnancy and Postpartum Period

    Science.gov (United States)

    Branco, Marco; Santos-Rocha, Rita; Vieira, Filomena; Silva, Maria-Raquel; Aguiar, Liliana; Veloso, António P.

    2016-01-01

    Pregnancy leads to several changes in body composition and morphology of women. It is not clear whether the biomechanical changes occurring in this period are due exclusively to body composition and size or to other physiological factors. The purpose was to quantify the morphology and body composition of women throughout pregnancy and in the postpartum period and identify the contribution of these parameters on the lower limb joints kinetic during gait. Eleven women were assessed longitudinally, regarding anthropometric, body composition, and kinetic parameters of gait. Body composition and body dimensions showed a significant increase during pregnancy and a decrease in the postpartum period. In the postpartum period, body composition was similar to the 1st trimester, except for triceps skinfold, total calf area, and body mass index, with higher results than at the beginning of pregnancy. Regression models were developed to predict women's internal loading through anthropometric variables. Four models include variables associated with the amount of fat; four models include variables related to overall body weight; three models include fat-free mass; one model includes the shape of the trunk as a predictor variable. Changes in maternal body composition and morphology largely determine kinetic dynamics of the joints in pregnant women. PMID:27073713

  5. Influence of Temperature on Induction Period of Denitration During Concentration of Radioactive Acid Liquid Waste

    Institute of Scientific and Technical Information of China (English)

    YANG; Hui; LI; Chuan-bo; YAN; Tai-hong; ZHENG; Wei-fang

    2013-01-01

    To minimize the volume of waste and recycle nitric acid,the high-and middle-level radioactive liquid waste from reprocessing plant need to be concentrated and de-nitrated,and formic acid and formaldehyde are widely applied as denitration agents.Temperature can affect the induction period of denitration reaction and the safety of process.

  6. Influence of Body Composition on Gait Kinetics throughout Pregnancy and Postpartum Period.

    Science.gov (United States)

    Branco, Marco; Santos-Rocha, Rita; Vieira, Filomena; Silva, Maria-Raquel; Aguiar, Liliana; Veloso, António P

    2016-01-01

    Pregnancy leads to several changes in body composition and morphology of women. It is not clear whether the biomechanical changes occurring in this period are due exclusively to body composition and size or to other physiological factors. The purpose was to quantify the morphology and body composition of women throughout pregnancy and in the postpartum period and identify the contribution of these parameters on the lower limb joints kinetic during gait. Eleven women were assessed longitudinally, regarding anthropometric, body composition, and kinetic parameters of gait. Body composition and body dimensions showed a significant increase during pregnancy and a decrease in the postpartum period. In the postpartum period, body composition was similar to the 1st trimester, except for triceps skinfold, total calf area, and body mass index, with higher results than at the beginning of pregnancy. Regression models were developed to predict women's internal loading through anthropometric variables. Four models include variables associated with the amount of fat; four models include variables related to overall body weight; three models include fat-free mass; one model includes the shape of the trunk as a predictor variable. Changes in maternal body composition and morphology largely determine kinetic dynamics of the joints in pregnant women.

  7. 松辽盆地火山岩高含CO2气藏包裹体特征及成藏期次%Inclusions Characteristics and Pool-Forming Periods of High CO2 Volcanic Gas Reservoirs in Songliao Basin

    Institute of Scientific and Technical Information of China (English)

    魏立春; 鲁雪松; 宋岩; 柳少波; 洪峰

    2012-01-01

    On the basis of detailed observation of petrography, and this study defined the types, periods and compositions of fluid inclusions in the volcanic rocks of the Yingcheng Formation in Songliao basin, using the characteristics of fluid inclusion, homogenization temperature, gas composition and carbon isotopes. In addition, the pool-forming periods of volcanic gas reservoirs with a high content of CO2 were analyzed. Integrated geological and geochemical evidence shows that hydrocarbon accumulation features in the volcanic CO2 -bearing reservoir in Songliao basin contain two accumulation periods characterized by-successive recharging process, I. E. , sedimentary period of Quantou-Qingshankou formations and the middle-late stage of Nenjiang Formation deposition. CO- was recharged in the Himalaya period, later than hydrocarbon gas.%在详细岩相学观察的基础上,充分利用包裹体的岩相学特征、均一温度特征、气体组分特征以及碳同位素特征等,确定了松辽盆地营城组火山岩中包裹体的类型、期次和成分特征,并对火山岩高含CO2气藏的成藏期次进行了分析.综合各种地质地化证据,确定松辽盆地火山岩高含CO2气藏中烃类气成藏特征是连续充注基础上的两期成藏,即泉头组—青山口组沉积时期和嫩江组沉积中后期;CO2充注发生在喜山期,CO2的充注晚于烃类气的充注.

  8. Moisture content behaviour in extensive green roofs during dry periods: the influence of vegetation and substrate characteristics

    OpenAIRE

    Berretta, C; Poe, S.; Stovin, V.

    2014-01-01

    Evapotranspiration (ET) is a key parameter that influences the stormwater retention capacity, and thus the hydrological performance, of green roofs. This paper investigates how the moisture content in extensive green roofs varies during dry periods due to evapotranspiration. The study is supported by 29 months continuous field monitoring of the moisture content within four green roof test beds. The beds incorporated three different substrates, with three being vegetated with sedum and one lef...

  9. Influence of the substrate on maar-diatreme volcanoes — An example of a mixed setting from the Pali Aike volcanic field, Argentina

    Science.gov (United States)

    Ross, Pierre-Simon; Delpit, Séverine; Haller, Miguel J.; Németh, Károly; Corbella, Hugo

    2011-04-01

    The morphologic parameters, pyroclastic deposits and evolution of maar-diatreme volcanoes are affected by the type of environment in which they are emplaced. End-member cases are a hard substrate (rocks) and a soft substrate (unconsolidated volcaniclastic or sedimentary deposits). In this paper, we present an example of a volcanic complex emplaced in a mixed hard-soft setting from the Pali Aike volcanic field (PAVF) near the Argentina-Chile border. The Plio-Pleistocene PAVF is an alkaline, mafic, back-arc monogenetic field which contains over 100 phreatomagmatic volcanoes. The studied volcanic complex contains two large coalescent maars overlain by scoria and spatter. The 1.4 × 1.3 km East Maar has better exposures than the shallower, 1.9 km-wide West Maar and seems to have been less modified by post-eruptive processes. The tephra rim of the East Maar was studied in detail and we infer it was produced mostly by base surges from phreatomagmatic eruption columns, with rare instances of intercalated scoria fall layers. Based on regional information, the general pre-maar stratigraphy is dominated by sedimentary and volcaniclastic rocks of the Magallanes Basin, including a thick poorly consolidated upper unit dating from the Miocene. These are overlain by Plio-Pleistocene fluvio-glacial deposits and PAVF lavas, some of which are exposed in the East Maar just below the phreatomagmatic deposits. All of these units are represented as lithic clasts in the tephra rim of the East Maar, the most abundant being the clasts from the earlier basaltic lavas and rock fragments derived from the glacial deposits. There is no specific evidence for a deep diatreme under the East Maar, and in this particular case, the mixed environment seems to have produced a maar-diatreme volcano typical of a soft substrate.

  10. Reduction of noise influence during the periodical inspection of the nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Hikono, Masaru [Inst. of Nuclear Safety System Inc., Mihama, Fukui (Japan)

    2002-09-01

    At the nuclear power plant under the regular inspection, the sound level and the worker's impression of the environmental noises were measured. The environmental noise was the level with a possibility to cause the noise-induced deafness and have the psychological influence on the workers such as ''Get irritated''. These results imply the necessity of the noise countermeasure. For the noise influence relaxation, we examined the effectiveness of ear protections (e.g., ear plugs) and the intelligibility improvement of the paging system, prepared the noise management manual and the educational leaflet for the support of worker's self-defense. The results of the examinations showed that ear plug was effective especially in the high-noise environment and that the improvement of paging system increased the intelligibility. (author)

  11. Strong influence of periodic boundary conditions on lateral diffusion in lipid bilayer membranes

    Energy Technology Data Exchange (ETDEWEB)

    Camley, Brian A. [Center for Theoretical Biological Physics and Department of Physics, University of California, San Diego, California 92093 (United States); Department of Physics, University of California, Santa Barbara, California 93106 (United States); Lerner, Michael G. [Department of Physics and Astronomy, Earlham College, Richmond, Indiana 47374 (United States); Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892 (United States); Pastor, Richard W. [Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892 (United States); Brown, Frank L. H. [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106 (United States)

    2015-12-28

    The Saffman-Delbrück hydrodynamic model for lipid-bilayer membranes is modified to account for the periodic boundary conditions commonly imposed in molecular simulations. Predicted lateral diffusion coefficients for membrane-embedded solid bodies are sensitive to box shape and converge slowly to the limit of infinite box size, raising serious doubts for the prospects of using detailed simulations to accurately predict membrane-protein diffusivities and related transport properties. Estimates for the relative error associated with periodic boundary artifacts are 50% and higher for fully atomistic models in currently feasible simulation boxes. MARTINI simulations of LacY membrane protein diffusion and LacY dimer diffusion in DPPC membranes and lipid diffusion in pure DPPC bilayers support the underlying hydrodynamic model.

  12. Strong influence of periodic boundary conditions on lateral diffusion in lipid bilayer membranes

    Science.gov (United States)

    Camley, Brian A.; Lerner, Michael G.; Pastor, Richard W.; Brown, Frank L. H.

    2015-12-01

    The Saffman-Delbrück hydrodynamic model for lipid-bilayer membranes is modified to account for the periodic boundary conditions commonly imposed in molecular simulations. Predicted lateral diffusion coefficients for membrane-embedded solid bodies are sensitive to box shape and converge slowly to the limit of infinite box size, raising serious doubts for the prospects of using detailed simulations to accurately predict membrane-protein diffusivities and related transport properties. Estimates for the relative error associated with periodic boundary artifacts are 50% and higher for fully atomistic models in currently feasible simulation boxes. MARTINI simulations of LacY membrane protein diffusion and LacY dimer diffusion in DPPC membranes and lipid diffusion in pure DPPC bilayers support the underlying hydrodynamic model.

  13. Age-related sensitive periods influence visual language discrimination in adults

    OpenAIRE

    2013-01-01

    Adults as well as infants have the capacity to discriminate languages based on visual speech alone. Here, we investigated whether adults' ability to discriminate languages based on visual speech cues is influenced by the age of language acquisition. Adult participants who had all learned English (as a first or second language) but did not speak French were shown faces of bilingual (French/English) speakers silently reciting sentences in either language. Using only visual speech information, a...

  14. Influence of the harvesting time, temperature and drying period on basil (Ocimum basilicum L.) essential oil

    OpenAIRE

    Carvalho Filho,José Luiz S de; Arie F Blank; Péricles B. Alves; Polyana A.D. Ehlert; Alberto S. de Melo; Sócrates C. H. Cavalcanti; Arrigoni-Blank, Maria de Fátima; Silva-Mann,Renata

    2006-01-01

    Ocimum basilicum L. essential oil with high concentration of linalool is valuable in international business. O. basilicum essential oil is widely used as seasoning and in cosmetic industry. To assure proper essential oil yield and quality, it is crucial to determine which environmental and processing factors are affecting its composition. The goal of our work is to evaluate the effects of harvesting time, temperature, and drying period on the yield and chemical composition of O. basilicum ess...

  15. PERIODIC MOTIONS OF SPINNING RIGID SPACECRAFT UNDER INFLUENCE OF GRAVITATIONAL AND MAGNETIC FIELDS

    Institute of Scientific and Technical Information of China (English)

    Yehia A. Abdel-aziz; M.H. Yehia; F. A. Abd El-Salam; M. Radwan

    2006-01-01

    The motion of a magnetized axisymmetric spacecraft about its center of mass in a circular orbit is considered, taking the gravitational and magnetic effects of the central body into account. Equations of motion of the reduced system are transformed to equations of plane motion of a charged particle under the action of electric and magnetic fields. Stationary motions of the system are determined and periodic motions near to them are constructed using the Lyapounoff theorem of the holomorphic integral.

  16. Influence of lipolysis and ketogenesis to metabolic and hematological parameters in dairy cows during periparturient period

    OpenAIRE

    Cincović R.M.; Belić Branislava; Radojičić Biljana; Hristov S.; Đoković R.

    2012-01-01

    The aim of this study was to examine the characteristics of the metabolic profile and complete blood count in cows in the periparturient period on the basis of the intensity of lipolysis and ketogenesis (concentration of non esterified fatty acid - NEFA and betahydroxybutyrate - BHB). Based on median values of NEFA and BHB cows were divided into 3 groups: cows physiologically burdened with catabolism (NEFA and BHB levels above the median one week after part...

  17. Influence of the placement period on the development of professional identity for social education students

    Directory of Open Access Journals (Sweden)

    Susana María Garcia Vargas

    2016-06-01

    Full Text Available The Social Education Degree placement for the National University for Distance Education (UNED allows students to experience and reflect upon the labour situation. Its influence on the development of the student professional identity is an important subject for both placement tutors and teachers. The study combines the search for and analysis of qualitative and quantitative data to assess the influence of the Professional Placement III course, the students’ first contact with the real business world, on the development of their professional identity. Throughout the research it has been possible to determine an emerging concept in the professional identity of students before the start of the placement, which changes and consolidates depending on their experience within the placement programme; these results are similar to those obtained in research relating to other professions similar to Social Education (Pontes, Ariza & Del Rey, 2010. Therefore, it can be stated that this course is an important variable that especially influences the development of the professional identities of future social educators.

  18. WATER ACTIVITY INFLUENCE ON THE SAFE AGING PERIOD OF CONDENSED MILK

    Directory of Open Access Journals (Sweden)

    Ilona Šostakienė

    2010-01-01

    Full Text Available The majority of chemical and biological processes causing the change of nutrients and finally their spoilage are dependent on water. Microbiological growth is directly related to water activity. Water activity (aw was introduced by an Australian microbiologist W.J. Scott in 1952. He defined this concept as a “fundamental property of water solutions” and i.e. a ratio between pure water (p0 and steam pressure solution (p. The water activity of the unsweetened condensed milk packed into canister remains unchanged during the storage period (aw.= 0,902. The water activity in the sweetened condensed milk slightly increases after 18 months (aw.= 0,784, after 18 months aw = 0,787. Though water activity does not actually change the storage of such a product and does not create a possibility for the growth of microorganisms. However, milk is a system of array compounds and a limitless storage of such a product is impossible. It is determined that the allowed storage period of 12 months is justified as after this period a major part of milk changes become accelerated

  19. The influence of cultivation period on growth and biodiesel properties of microalga Nannochloropsis gaditana 1049.

    Science.gov (United States)

    Hu, Qunju; Xiang, Wenzhou; Dai, Shikun; Li, Tao; Yang, Fangfang; Jia, Qikun; Wang, Guanghua; Wu, Hualian

    2015-09-01

    This work reported for the first time the detailed impacts of cultivation period on growth dynamics and biochemical composition of a microalga strain Nannochloropsis gaditana 1049. The results shown either the biomass accumulation, lipid content, neutral lipid content, monounsaturated fatty acids composition or the favorable fatty acid profile of C16-C18 increased along with the cultivation period extension, but the lipid productivity displayed a decrease since cultured for 16 days, with the highest value reached 289.51 ± 16.34 mg L(-1) d(-1). Biodiesel properties of this microalga also changed with the cultivation period extension, with average unsaturated degree decreased from 1.24 ± 0.03 to 0.59 ± 0.02, cloud point increased from 3.39 ± 0.40 °C to 12.14 ± 0.32 °C, cetane number increased from 54.59 ± 0.20 to 58.96 ± 0.16 and iodine number reduced sharply from 105.15 ± 2.24 gI2/100g to 56.44 ± 1.76 gI2/100g, which all satisfied the specifications of biodiesel standard.

  20. Sphene and zircon in the Highland Range volcanic sequence (Miocene, southern Nevada, USA): Elemental partitioning, phase relations, and influence on evolution of silicic magma

    Science.gov (United States)

    Colombini, L.L.; Miller, C.F.; Gualda, G.A.R.; Wooden, J.L.; Miller, J.S.

    2011-01-01

    Sphene is prominent in Miocene plutonic rocks ranging from diorite to granite in southern Nevada, USA, but it is restricted to rhyolites in coeval volcanic sequences. In the Highland Range volcanic sequence, sphene appears as a phenocryst only in the most evolved rocks (72-77 mass% SiO2; matrix glass 77-78 mass% SiO2). Zr-in-sphene temperatures of crystallization are mostly restricted to 715 and 755??C, in contrast to zircon (710-920??C, Ti-in-zircon thermometry). Sphene rim/glass Kds for rare earth elements are extremely high (La 120, Sm 1200, Gd 1300, Lu 240). Rare earth elements, especially the middle REE (MREE), decrease from centers to rims of sphene phenocrysts along with Zr, demonstrating the effect of progressive sphene fractionation. Whole rocks and glasses have MREE-depleted, U-shaped REE patterns as a consequence of sphene fractionation. Within the co-genetic, sphene-rich Searchlight pluton, only evolved leucogranites show comparable MREE depletion. These results indicate that sphene saturation in intruded and extruded magmas occurred only in highly evolved melts: abundant sphene in less silicic plutonic rocks represents a late-stage 'bloom' in fractionated interstitial melt. ?? 2011 Springer-Verlag.

  1. Volcanic Rocks and Features

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Volcanoes have contributed significantly to the formation of the surface of our planet. Volcanism produced the crust we live on and most of the air we breathe. The...

  2. Influence of substrate microcrystallinity on the orientation of laser-induced periodic surface structures

    Energy Technology Data Exchange (ETDEWEB)

    Nürnberger, P.; Reinhardt, H.; Kim, H-C.; Yang, F. [Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße 4, 35032 Marburg (Germany); Peppler, K.; Janek, J. [Department of Physical-Chemistry, Justus-Liebig-University Gießen, Heinrich-Buff-Ring 58, 35392 Gießen (Germany); Hampp, N. [Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße 4, 35032 Marburg (Germany); Materials Science Center, 35032 Marburg (Germany)

    2015-10-07

    The research in this paper deals with the angular dependence of the formation of laser-induced periodic surface structures (LIPSS) by linearly polarized nanosecond laser pulses on polycrystalline austenitic stainless steel. Incident angles ranging from 45° to 70° lead to the generation of superimposed merely perpendicular oriented LIPSS on steel as well as on monocrystalline (100) silicon which was used as a reference material. Additional extraordinary orientations of superimposing LIPSS along with significantly different periodicities are found on polycrystalline steel but not on (100) silicon. Electron backscatter diffraction measurements indicate that the expansion of these LIPSS is limited to the grain size and affected by the crystal orientation of the individual grains. Atomic force microscopy imaging shows that LIPSS fringe heights are in good agreement with the theoretically predicted penetration depths of surface plasmon polaritons into stainless steel. These results indicate that optical anisotropies must be taken into account to fully describe the theory of light-matter interaction leading to LIPSS formation.

  3. Influence of substrate microcrystallinity on the orientation of laser-induced periodic surface structures

    Science.gov (United States)

    Nürnberger, P.; Reinhardt, H.; Kim, H.-C.; Yang, F.; Peppler, K.; Janek, J.; Hampp, N.

    2015-10-01

    The research in this paper deals with the angular dependence of the formation of laser-induced periodic surface structures (LIPSS) by linearly polarized nanosecond laser pulses on polycrystalline austenitic stainless steel. Incident angles ranging from 45° to 70° lead to the generation of superimposed merely perpendicular oriented LIPSS on steel as well as on monocrystalline (100) silicon which was used as a reference material. Additional extraordinary orientations of superimposing LIPSS along with significantly different periodicities are found on polycrystalline steel but not on (100) silicon. Electron backscatter diffraction measurements indicate that the expansion of these LIPSS is limited to the grain size and affected by the crystal orientation of the individual grains. Atomic force microscopy imaging shows that LIPSS fringe heights are in good agreement with the theoretically predicted penetration depths of surface plasmon polaritons into stainless steel. These results indicate that optical anisotropies must be taken into account to fully describe the theory of light-matter interaction leading to LIPSS formation.

  4. Influence of anisotropy of magnetic susceptibility (AMS) on paleomagnetic sampling in volcanic glasses: a case study on rheomorphic ignimbrites of the Yellowstone hotspot-track, southern Idaho

    Science.gov (United States)

    Finn, D.; Coe, R. S.; Murphy, J.; Bodiford, S.; Kelly, H.; Foster, S.; Spinardi, F.; Reichow, M. K.; Knott, T.; Branney, M. J.

    2012-12-01

    Large-scale explosive volcanism, associated with the Yellowstone hotspot, occurred in the central Snake River Plain between 12.5-8 Ma. It is characterized by unusually high-temperature, intensely welded, rheomorphic rhyolitic ignimbrites, typical of what is now known as 'Snake River (SR)-type volcanism'. Individual eruption volumes likely exceed 450 km3 but are poorly known due to the difficulty of correlating units between widely spaced (50-200 km) exposures along the north and south of the plain, when some occurred too close-spaced in time for radiometric resolution. Our goal is to use a combination of paleomagnetic, petrographic, chemical and field characterization to establish robust correlations, allowing us to develop a regional stratigraphy, and constrain ignimbrite eruption volumes and frequencies. This presentation focuses on how to sample rheomorphic, SR-type ignimbrites for paleomagnetic studies given the potential effects of hot, rheomorphic deformation. Individual SR-type ignimbrite cooling-units have an upper and lower glassy margins (vitrophyre) enclosing a lithoidal (microcrystalline) zone. We have sampled dozens of ignimbrites in detail and have observed that the lithoidal interiors are preferable to the glassy margins for paleomagnetic studies. We hypothesize that the glassy margins retain an anisotropic fabric related to emplacement compaction and/or shearing that affects their ability to accurately record the magnetic field during cooling. In the lithoidal interiors this anisotropic fabric was overprinted by continued grain growth and/or alteration and, therefore, may accurately record the paleomagnetic field. Paleomagnetic samples from vitrophyres generally have a higher anisotropy in magnetic susceptibility than lithoidal samples. The remanent magnetic directions recorded in samples with high anisotropy of magnetic susceptibility are often deflected away from the site mean and closer to the plane of easy magnetic susceptibility. Since the

  5. Model-based aviation advice on distal volcanic ash clouds by assimilating aircraft in situ measurements

    NARCIS (Netherlands)

    Fu, G.; Heemink, A.; Lu, S.; Segers, A.; Weber, K.; Lin, H.X.

    2016-01-01

    The forecast accuracy of distal volcanic ash clouds is important for providing valid aviation advice during volcanic ash eruption. However, because the distal part of volcanic ash plume is far from the volcano, the influence of eruption information on this part becomes rather indirect and uncertain,

  6. Influence of the recall period on a beverage-specific weekly drinking measure for alcohol intake

    DEFF Research Database (Denmark)

    Ekholm, O.; Strandberg-Larsen, Katrine; Grønbæk, M.

    2011-01-01

    Background/Objectives: Our knowledge of the association between alcohol intake and alcohol-related health outcomes depends, to a large extent, on the validity and reliability of self-reported alcohol intake. Weekly drinking measures are frequently used in epidemiological surveys, but it has been......-reported weekly alcohol intake. Subjects/Methods: The data is derived from the Danish Health Interview Survey 2005, which is based on a region-stratified random sample of 21¿832 Danish citizens aged =16 years (response rate: 67%). The data were collected via face-to-face interviews. Results: A beverage......-specific question on alcohol intake on each day during the last week did not alter the strong association between the recall period and self-reported alcohol intake. However, the overall self-reported alcohol intake increased substantially when using the beverage-specific question instead of asking for the overall...

  7. The influence of canon law on ius commune in its formative period

    Directory of Open Access Journals (Sweden)

    Mehmeti Sami

    2015-12-01

    Full Text Available In the Medieval period, Roman law and canon law formed ius commune or the common European law. The similarity between Roman and canon law was that they used the same methods and the difference was that they relied on different authoritative texts. In their works canonists and civilists combined the ancient Greek achievements in philosophy with the Roman achievements in the field of law. Canonists were the first who carried out research on the distinctions between various legal sources and systematized them according to a hierarchical order. The Medieval civilists sought solutions in canon law for a large number of problems that Justinian’s Codification did not hinge on or did it only superficially. Solutions offered by canon law were accepted not only in the civil law of Continental Europe, but also in the English law.

  8. Allen's rule revisited: temperature influences bone elongation during a critical period of postnatal development.

    Science.gov (United States)

    Serrat, Maria A

    2013-10-01

    Limbs of animals raised at warm ambient temperature are significantly and permanently longer than those of siblings housed in the cold. These highly reproducible lab results closely parallel the ecogeographical tenet described by Allen's extremity size rule, which states that appendage length correlates with temperature and latitude. It is unclear what mechanisms underlie these differences and in what pattern they emerge, since the morphology is traditionally thought to reflect naturally selected genomic adaptations for thermoregulation. This study tests the a posteriori hypothesis that adult extremity length is subject to substantial modification by temperature during a brief but critical period of early postnatal development. Weanling mice (N = 28) were divided into three groups and housed at 7°C, 21°C, or 27°C for eight weeks. Tail lengths and body mass were measured weekly. Mass did not differ at any age. Analysis of tail elongation curves revealed two distinct phases: an initial period of rapid temperature-sensitive growth in which elongation rate was directly impacted by temperature; and a second phase of continued growth in which rates were identical among groups. Comparable growth reactions occur in response to other environmental variables such as exercise, suggesting that the skeleton is most responsive to external stimuli during a window of heightened sensitivity when growth occurs most rapidly. Knowledge of the timing and degree to which growth plasticity permits mammals to immediately adjust to novel temperature conditions will be important for analyzing skeletal variation in fluctuating climates, particularly for assessing factors that may accelerate skeletal evolution at temperature extremes.

  9. Anoxic atmospheres on Mars driven by volcanism: Implications for past environments and life

    Science.gov (United States)

    Sholes, Steven F.; Smith, Megan L.; Claire, Mark W.; Zahnle, Kevin J.; Catling, David C.

    2017-07-01

    Mars today has no active volcanism and its atmosphere is oxidizing, dominated by the photochemistry of CO2 and H2O. Mars experienced widespread volcanism in the past and volcanic emissions should have included reducing gases, such as H2 and CO, as well as sulfur-bearing gases. Using a one-dimensional photochemical model, we consider whether plausible volcanic gas fluxes could have switched the redox-state of the past martian atmosphere to reducing conditions. In our model, the total quantity and proportions of volcanic gases depend on the water content, outgassing pressure, and oxygen fugacity of the source melt. We find that, with reasonable melt parameters, the past martian atmosphere (∼3.5 Gyr to present) could have easily reached reducing and anoxic conditions with modest levels of volcanism, >0.14 km3 yr-1, which are well within the range of estimates from thermal evolution models or photogeological studies. Counter-intuitively we also find that more reducing melts with lower oxygen fugacity require greater amounts of volcanism to switch a paleo-atmosphere from oxidizing to reducing. The reason is that sulfur is more stable in such melts and lower absolute fluxes of sulfur-bearing gases more than compensate for increases in the proportions of H2 and CO. These results imply that ancient Mars should have experienced periods with anoxic and reducing atmospheres even through the mid-Amazonian whenever volcanic outgassing was sustained at sufficient levels. Reducing anoxic conditions are potentially conducive to the synthesis of prebiotic organic compounds, such as amino acids, and are therefore relevant to the possibility of life on Mars. Also, anoxic reducing conditions should have influenced the type of minerals that were formed on the surface or deposited from the atmosphere. We suggest looking for elemental polysulfur (S8) as a signature of past reducing atmospheres. Finally, our models allow us to estimate the amount of volcanically sourced atmospheric

  10. Diffuse emissions of Volatile Organic Compounds (VOCs) from soil in volcanic and hydrothermal systems: evidences for the influence of microbial activity on the carbon budget

    Science.gov (United States)

    Venturi, Stefania; Tassi, Franco; Fazi, Stefano; Vaselli, Orlando; Crognale, Simona; Rossetti, Simona; Cabassi, Jacopo; Capecchiacci, Francesco

    2017-04-01

    Soils in volcanic and hydrothermal areas are affected by anomalously high concentrations of gases released from the deep reservoirs, which consists of both inorganic (mainly CO2 and H2S) and organic (volatile organic compounds; VOCs) species. VOCs in volcanic and hydrothermal fluids are mainly composed of saturated and unsaturated hydrocarbons (alkanes, aromatics, alkenes, and cyclics), with variable concentrations of O- and S-bearing compounds and halocarbons, depending on the physicochemical conditions at depth. VOCs in interstitial soil gases and fumarolic emissions from four volcanic and hydrothermal systems in the Mediterranean area (Solfatara Crater, Poggio dell'Olivo and Cava dei Selci, in Italy, and Nisyros Island, in Greece) evidenced clear compositional differences, suggesting that their behavior is strongly affected by secondary processes occurring at shallow depths and likely controlled by microbial activity. Long-chain saturated hydrocarbons were significantly depleted in interstitial soil gases with respect to those from fumarolic discharges, whereas enrichments in O-bearing compounds (e.g. aldehydes, ketones), DMSO2 and cyclics were commonly observed. Benzene was recalcitrant to degradation processes, whereas methylated aromatics were relatively instable. The chemical and isotopic (δ13C in CO2 and CH4) composition of soil gases collected along vertical profiles down to 50 cm depth at both Solfatara Crater and Poggio dell'Olivo (Italy) showed evidences of relevant oxidation processes in the soil, confirming that microbial activity likely plays a major role in modifying the composition of deep-derived VOCs. Despite their harsh conditions, being typically characterized by high temperatures, low pH, and high toxic gases and metal contents, the variety of habitats characterizing volcanic and hydrothermal environments offers ideal biomes to extremophilic microbes, whose metabolic activity can consume and/or produce VOCs. In the Solfatara Crater, microbial

  11. Sediment transport in headwaters of a volcanic catchment—Kamchatka Peninsula case study

    Science.gov (United States)

    Chalov, Sergey R.; Tsyplenkov, Anatolii S.; Pietron, Jan; Chalova, Aleksandra S.; Shkolnyi, Danila I.; Jarsjö, Jerker; Maerker, Michael

    2017-09-01

    Due to specific environmental conditions, headwater catchments located on volcanic slopes and valleys are characterized by distinctive hydrology and sediment transport patterns. However, lack of sufficient monitoring causes that the governing processes and patterns in these areas are rarely well understood. In this study, spatiotemporal water discharge and sediment transport from upstream sources was investigated in one of the numerous headwater catchments located in the lahar valleys of the Kamchatka Peninsula Sukhaya Elizovskaya River near Avachinskii and Koryakskii volcanoes. Three different subcatchments and corresponding channel types (wandering rivers within lahar valleys, mountain rivers within volcanic slopes and rivers within submountain terrains) were identified in the studied area. Our measurements from different periods of observations between years 2012-2014 showed that the studied catchment was characterized by extreme diurnal fluctuation of water discharges and sediment loads that were influenced by snowmelt patterns and high infiltration rates of the easily erodible lahar deposits. The highest recorded sediment loads were up to 9•104 mg/L which was related to an increase of two orders of magnitude within a one day of observations. Additionally, to get a quantitative estimate of the spatial distribution of the eroded material in the volcanic substrates we applied an empirical soil erosion and sediment yield model-modified universal soil loss equation (MUSLE). The modeling results showed that even if the applications of the universal erosion model to different non-agricultural areas (e.g., volcanic catchments) can lead to irrelevant results, the MUSLE model delivered might be acceptable for non-lahar areas of the studied volcanic catchment. Overall the results of our study increase our understanding of the hydrology and associated sediment transport for prediction of risk management within headwater volcanic catchments.

  12. Sediment transport in headwaters of a volcanic catchment—Kamchatka Peninsula case study

    Science.gov (United States)

    Chalov, Sergey R.; Tsyplenkov, Anatolii S.; Pietron, Jan; Chalova, Aleksandra S.; Shkolnyi, Danila I.; Jarsjö, Jerker; Maerker, Michael

    2017-01-01

    Due to specific environmental conditions, headwater catchments located on volcanic slopes and valleys are characterized by distinctive hydrology and sediment transport patterns. However, lack of sufficient monitoring causes that the governing processes and patterns in these areas are rarely well understood. In this study, spatiotemporal water discharge and sediment transport from upstream sources was investigated in one of the numerous headwater catchments located in the lahar valleys of the Kamchatka Peninsula Sukhaya Elizovskaya River near Avachinskii and Koryakskii volcanoes. Three different subcatchments and corresponding channel types (wandering rivers within lahar valleys, mountain rivers within volcanic slopes and rivers within submountain terrains) were identified in the studied area. Our measurements from different periods of observations between years 2012-2014 showed that the studied catchment was characterized by extreme diurnal fluctuation of water discharges and sediment loads that were influenced by snowmelt patterns and high infiltration rates of the easily erodible lahar deposits. The highest recorded sediment loads were up to 9•104 mg/L which was related to an increase of two orders of magnitude within a one day of observations. Additionally, to get a quantitative estimate of the spatial distribution of the eroded material in the volcanic substrates we applied an empirical soil erosion and sediment yield model-modified universal soil loss equation (MUSLE). The modeling results showed that even if the applications of the universal erosion model to different non-agricultural areas (e.g., volcanic catchments) can lead to irrelevant results, the MUSLE model delivered might be acceptable for non-lahar areas of the studied volcanic catchment. Overall the results of our study increase our understanding of the hydrology and associated sediment transport for prediction of risk management within headwater volcanic catchments.

  13. Age-related sensitive periods influence visual language discrimination in adults.

    Science.gov (United States)

    Weikum, Whitney M; Vouloumanos, Athena; Navarra, Jordi; Soto-Faraco, Salvador; Sebastián-Gallés, Núria; Werker, Janet F

    2013-01-01

    Adults as well as infants have the capacity to discriminate languages based on visual speech alone. Here, we investigated whether adults' ability to discriminate languages based on visual speech cues is influenced by the age of language acquisition. Adult participants who had all learned English (as a first or second language) but did not speak French were shown faces of bilingual (French/English) speakers silently reciting sentences in either language. Using only visual speech information, adults who had learned English from birth or as a second language before the age of 6 could discriminate between French and English significantly better than chance. However, adults who had learned English as a second language after age 6 failed to discriminate these two languages, suggesting that early childhood exposure is crucial for using relevant visual speech information to separate languages visually. These findings raise the possibility that lowered sensitivity to non-native visual speech cues may contribute to the difficulties encountered when learning a new language in adulthood.

  14. Age-related sensitive periods influence visual language discrimination in adults

    Directory of Open Access Journals (Sweden)

    Whitney M. Weikum

    2013-11-01

    Full Text Available Adults as well as infants have the capacity to discriminate languages based on visual speech alone. Here, we investigated whether adults’ ability to discriminate languages based on visual speech cues is influenced by the age of language acquisition. Adult participants who had all learned English (as a first or second language but did not speak French were shown faces of bilingual (French/English speakers silently reciting sentences in either language. Using only visual speech information, adults who had learned English from birth or as a second language before the age of 6 could discriminate between French and English significantly better than chance. However, adults who had learned English as a second language after age 6 failed to discriminate these two languages, suggesting that early childhood exposure is crucial for using relevant visual speech information to separate languages visually. These findings raise the possibility that lowered sensitivity to non-native visual speech cues may contribute to the difficulties encountered when learning a new language in adulthood.

  15. The influence of periodic wind turbine noise on infrasound array measurements

    Science.gov (United States)

    Pilger, Christoph; Ceranna, Lars

    2017-02-01

    Aerodynamic noise emissions from the continuously growing number of wind turbines in Germany are creating increasing problems for infrasound recording systems. These systems are equipped with highly sensitive micro pressure sensors accurately measuring acoustic signals in a frequency range inaudible to the human ear. Ten years of data (2006-2015) from the infrasound array IGADE in Northern Germany are analysed to quantify the influence of wind turbine noise on infrasound recordings. Furthermore, a theoretical model is derived and validated by a field experiment with mobile micro-barometer stations. Fieldwork was carried out 2004 to measure the infrasonic pressure level of a single horizontal-axis wind turbine and to extrapolate the sound effect for a larger number of nearby wind turbines. The model estimates the generated sound pressure level of wind turbines and thus enables for specifying the minimum allowable distance between wind turbines and infrasound stations for undisturbed recording. This aspect is particularly important to guarantee the monitoring performance of the German infrasound stations I26DE in the Bavarian Forest and I27DE in Antarctica. These stations are part of the International Monitoring System (IMS) verifying compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), and thus have to meet stringent specifications with respect to infrasonic background noise.

  16. Age-related sensitive periods influence visual language discrimination in adults

    Science.gov (United States)

    Weikum, Whitney M.; Vouloumanos, Athena; Navarra, Jordi; Soto-Faraco, Salvador; Sebastián-Gallés, Núria; Werker, Janet F.

    2013-01-01

    Adults as well as infants have the capacity to discriminate languages based on visual speech alone. Here, we investigated whether adults' ability to discriminate languages based on visual speech cues is influenced by the age of language acquisition. Adult participants who had all learned English (as a first or second language) but did not speak French were shown faces of bilingual (French/English) speakers silently reciting sentences in either language. Using only visual speech information, adults who had learned English from birth or as a second language before the age of 6 could discriminate between French and English significantly better than chance. However, adults who had learned English as a second language after age 6 failed to discriminate these two languages, suggesting that early childhood exposure is crucial for using relevant visual speech information to separate languages visually. These findings raise the possibility that lowered sensitivity to non-native visual speech cues may contribute to the difficulties encountered when learning a new language in adulthood. PMID:24312020

  17. Spherical accretion: the influence of inner boundary and quasi-periodic oscillations

    Science.gov (United States)

    Dhang, Prasun; Sharma, Prateek; Mukhopadhyay, Banibrata

    2016-09-01

    Bondi accretion assumes that there is a sink of mass at the centre - which in the case of a black hole (BH) corresponds to the advection of matter across the event horizon. Other stars, such as a neutron star (NS), have surfaces and hence the infalling matter has to slow down at the surface. We study the initial value problem in which the matter distribution is uniform and at rest at t = 0. We consider different inner boundary conditions for BHs and NSs: outflow boundary condition (mimicking mass sink at the centre) valid for BHs; and reflective and steady-shock (allowing gas to cross the inner boundary at subsonic speeds) boundary conditions for NSs. We also obtain a similarity solution for cold accretion on to BHs and NSs. 1D simulations show the formation of an outward-propagating and a standing shock in NSs for reflective and steady-shock boundary conditions, respectively. Entropy is the highest at the bottom of the subsonic region for reflective boundary conditions. In 2D this profile is convectively unstable. Using steady-shock inner boundary conditions, the flow is unstable to the standing accretion shock instability in 2D, which leads to global shock oscillations and may be responsible for quasi-periodic oscillations seen in the light curves of accreting systems. For steady accretion in the quiescent state, spherical accretion rate on to an NS can be suppressed by orders of magnitude compared to that on to a BH.

  18. The influence of training on the attentional blink and psychological refractory period.

    Science.gov (United States)

    Garner, K G; Tombu, M N; Dux, P E

    2014-05-01

    A growing body of research suggests that dual-task interference in sensory consolidation (e.g., the attentional blink, AB) and response selection (e.g., the psychological refractory period, PRP) stems from a common central bottleneck of information processing. With regard to response selection, it is well known that training reduces dual-task interference. We tested whether training that is known to be effective for response selection can also reduce dual-task interference in sensory consolidation. Over two experiments, performance on a PRP paradigm (Exp. 1) and on AB paradigms (differing in their stimuli and task demands, Exps. 1 and 2) was examined after participants had completed a relevant training regimen (T1 practice for both paradigms), an irrelevant training regimen (comparable sensorimotor training, not related to T1 for both tasks), a visual-search training regimen (Exp. 2 only), or after participants had been allocated to a no-training control group. Training that had shown to be effective for reducing dual-task interference in response selection was also found to be effective for reducing interference in sensory consolidation. In addition, we found some evidence that training benefits transferred to the sensory consolidation of untrained stimuli. Collectively, these findings show that training benefits can transfer across cognitive operations that draw on the central bottleneck in information processing. These findings have implications for theories of the AB and for the design of cognitive-training regimens that aim to produce transferable training benefits.

  19. Sedimentary response to volcanic activity in the Okinawa Trough since the last deglaciation

    Institute of Scientific and Technical Information of China (English)

    蒋富清; 李安春; 李铁刚

    2010-01-01

    To investigate the relationship between volcanic activity and sediment record on regional and temporal scales,158 surface sediment samples were collected from the East China Sea Shelf to the northern Okinawa Trough (OT),and two cores recovered in the northern and southern OT,respectively.Mineralogy,grain-size,and geochemical analyses of those samples show that:1) volcanic glass,volcanic-type pyroxene,hypersthenes,and magnetite increase in sediment influenced by volcanic activity;2) sediment grain sizes (and...

  20. Dynamical Study of the Galactic Influence on the A(orig) Distribution of the Long Period Comets

    Science.gov (United States)

    Brunini, A.

    1990-11-01

    RESUMEN. Analizamos el efecto de la Galaxia como un todo, en la fronte- ra exterior de la nube de Oort de cometas, asi como la influencia de las estrellas vecinas en la distribucion observada de semi ejes mayores originales de los cometas de largo periodo. ABSTRACT. By means of a very simple formulation, in a Sun-centered reference frame, we analyze the effect of the Galaxy as a whole, on the exterior bound of the Oort cloud of comets, as well as the influence of the neighbour stars in the observed distribution of original semimajor axis of long period comets. Kaq wo : COMETS

  1. Influence of temperature and exploitation period on fatigue crack growth parameters in different regions of welded joints

    Directory of Open Access Journals (Sweden)

    Ivica Camagic

    2016-03-01

    Full Text Available The influence of exploitation period and temperature on the fatigue crack growth parameters indifferent regions of a welded joint is analysed for new and exploited low-alloyed Cr-Mo steel A-387 Gr. B. The parent metal is a part of a reactor mantle which was exploited for over 40 years, and recently replaced with new material. Fatigue crack growth parameters, threshold value Kth, coefficient C and exponent m, have been determined, both at room and exploitation temperature. Based on testing results, fatigue crack growth resistance in different regions of welded joint is analysed in order to justify the selected welding procedure specification.

  2. Influence of crystal orientation on the formation of femtosecond laser-induced periodic surface structures and lattice defects accumulation

    Science.gov (United States)

    Sedao, Xxx; Maurice, Claire; Garrelie, Florence; Colombier, Jean-Philippe; Reynaud, Stéphanie; Quey, Romain; Pigeon, Florent

    2014-04-01

    The influence of crystal orientation on the formation of femtosecond laser-induced periodic surface structures (LIPSS) has been investigated on a polycrystalline nickel sample. Electron Backscatter Diffraction characterization has been exploited to provide structural information within the laser spot on irradiated samples to determine the dependence of LIPSS formation and lattice defects (stacking faults, twins, dislocations) upon the crystal orientation. Significant differences are observed at low-to-medium number of laser pulses, outstandingly for (111)-oriented surface which favors lattice defects formation rather than LIPSS formation.

  3. Influence of crystal orientation on the formation of femtosecond laser-induced periodic surface structures and lattice defects accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Sedao, Xxx; Garrelie, Florence, E-mail: florence.garrelie@univ-st-etienne.fr; Colombier, Jean-Philippe; Reynaud, Stéphanie; Pigeon, Florent [Université de Lyon, CNRS, UMR5516, Laboratoire Hubert Curien, Université de Saint Etienne, Jean Monnet, F-42023 Saint-Etienne (France); Maurice, Claire; Quey, Romain [Ecole Nationale Supérieure des Mines de Saint-Etienne, CNRS, UMR5307, Laboratoire Georges Friedel, F-42023 Saint-Etienne (France)

    2014-04-28

    The influence of crystal orientation on the formation of femtosecond laser-induced periodic surface structures (LIPSS) has been investigated on a polycrystalline nickel sample. Electron Backscatter Diffraction characterization has been exploited to provide structural information within the laser spot on irradiated samples to determine the dependence of LIPSS formation and lattice defects (stacking faults, twins, dislocations) upon the crystal orientation. Significant differences are observed at low-to-medium number of laser pulses, outstandingly for (111)-oriented surface which favors lattice defects formation rather than LIPSS formation.

  4. INFLUENCE OF MOLECULAR WEIGHT AND PERIODATE-MODIFICATION OF β-D-GLUCANS FROM PORIA COCOS SCLEROTIUM ON ANTITUMOR ACTIVITIES

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    In this work, influence of molecular weight and periodate modification of β-D-glucans isolated from Poria cocos sclerotium on the antitumor activities against Sarcoma 180 and Ehrlich ascites carcinoma (EAC) tumor was studied. The results show that two glucans PC3 (linear β-(1 → 3)-D-glucan) and PC4 [β-(1 → 3)-D-glucan with a few of branches and glucuronic acid] are devoid of antitumor activity. However, when the glucans were modified by periodate oxidation, borohydride reduction and mild hydrolysis or partially hydrolysis, the derivatives have obvious antitumor activities. The decrease in molecular weight of glucans after periodate modification hardly affects their antitumor actions, but on the other hand, the decrease of molecular weight without periodate modification could lead to an enhancement of the antitumor activities. Moreover, the glucans and these derivatives have much higher enhancement ratios of body weight of mice than that of 5-Fluorouracil (5-Fu), suggesting that they are less toxic than 5-Fu.

  5. Influence of lipolysis and ketogenesis to metabolic and hematological parameters in dairy cows during periparturient period

    Directory of Open Access Journals (Sweden)

    Cincović R.M.

    2012-01-01

    Full Text Available The aim of this study was to examine the characteristics of the metabolic profile and complete blood count in cows in the periparturient period on the basis of the intensity of lipolysis and ketogenesis (concentration of non esterified fatty acid - NEFA and betahydroxybutyrate - BHB. Based on median values of NEFA and BHB cows were divided into 3 groups: cows physiologically burdened with catabolism (NEFA and BHB levels above the median one week after parturition, cows significantly burdened with catabolism (NEFA and BHB levels above the median one week before and after parturition and cows that are not burdened with catabolism (NEFA and BHB below the median, i.e. the control group. The median value of NEFA was 0.27 mmol/L one week before parturition and 0.61 mmol/L one week after it. The median value of BHB was 0.51 mmol/L one week before parturition and 0.99 mmol/L one week after it. A significant group effect was shown for each week separately, so that cows physiologically burdened with catabolism and/or cows significantly burdened with catabolism compared to the control group have the following features of the metabolic profile and complete blood count: higher concentrations of NEFA and BHB (weeks: -1, 1, 2, 4, 8, lower concentrations of glucose (weeks: 1, 4, lower concentration of cholesterol (week 8, lower concentrations of total protein (weeks: 1, 2, lower concentrations of urea (weeks: 1, 2, 4, 8 and a higher concentration of bilirubin (weeks: - 1, 1, 2, 4, 8, increased levels of AST (weeks: -1, 1 and ALT (weeks: -1, 2, lower value of Ca (week -1, lower hemoglobin concentration (week -1, lower white blood cell count (week 4, a larger number of neutrophils (weeks: -1, 1, 2 and a higher number of lymphocytes (week 4. Using the method of factor analysis and principal components showed that NEFA, BHB and glucose are the major components that affect the metabolic profile and blood count, making 71.8% of the variability of all parameters. Cows

  6. Volcanic hazards to airports

    Science.gov (United States)

    Guffanti, M.; Mayberry, G.C.; Casadevall, T.J.; Wunderman, R.

    2009-01-01

    Volcanic activity has caused significant hazards to numerous airports worldwide, with local to far-ranging effects on travelers and commerce. Analysis of a new compilation of incidents of airports impacted by volcanic activity from 1944 through 2006 reveals that, at a minimum, 101 airports in 28 countries were affected on 171 occasions by eruptions at 46 volcanoes. Since 1980, five airports per year on average have been affected by volcanic activity, which indicates that volcanic hazards to airports are not rare on a worldwide basis. The main hazard to airports is ashfall, with accumulations of only a few millimeters sufficient to force temporary closures of some airports. A substantial portion of incidents has been caused by ash in airspace in the vicinity of airports, without accumulation of ash on the ground. On a few occasions, airports have been impacted by hazards other than ash (pyroclastic flow, lava flow, gas emission, and phreatic explosion). Several airports have been affected repeatedly by volcanic hazards. Four airports have been affected the most often and likely will continue to be among the most vulnerable owing to continued nearby volcanic activity: Fontanarossa International Airport in Catania, Italy; Ted Stevens Anchorage International Airport in Alaska, USA; Mariscal Sucre International Airport in Quito, Ecuador; and Tokua Airport in Kokopo, Papua New Guinea. The USA has the most airports affected by volcanic activity (17) on the most occasions (33) and hosts the second highest number of volcanoes that have caused the disruptions (5, after Indonesia with 7). One-fifth of the affected airports are within 30 km of the source volcanoes, approximately half are located within 150 km of the source volcanoes, and about three-quarters are within 300 km; nearly one-fifth are located more than 500 km away from the source volcanoes. The volcanoes that have caused the most impacts are Soufriere Hills on the island of Montserrat in the British West Indies

  7. Factors influencing the chance of cows being pregnant 30 days after the herd voluntary waiting period.

    Science.gov (United States)

    Löf, E; Gustafsson, H; Emanuelson, U

    2014-01-01

    The objective of this study was to study factors affecting a reproductive performance indicator at the cow level adjusted for herd management strategy. Associations between the outcome variable, pregnant or not at the herd voluntary waiting period (VWP) plus 30d (pregnant at VWP+30), and the predictor variables were analyzed using a multivariable, generalized estimation equations model that adjusted for clustering of the data at the herd level. The statistical analysis was stratified on parity. In total, 132,721 cows were retained for analyses, of which 29,113 (22%) were pregnant at VWP+30d. Of the nonpregnant cows, 81,483 cows had records of artificial inseminations (AI) and 22,125 cows had no records of AI. The chance of pregnancy was higher for cows of the Swedish Red and for other/crossbreeds compared with Swedish Holstein, for cows from herds with high heat detection efficiency compared with cows from herds with medium and low heat detection efficiency, for cows from herds with long VWP (i.e., >51d) compared with cows from herds with short VWP (cows in freestalls compared with cows in tiestalls. The chance for pregnancy was lower for cows with severe problems at claw trimming compared with cows with no problems at trimming (only for second- and higher-parity cows), for cows that had a record of reproduction-related disease, for cows that had a record of any other disease compared with cows without record, for second- and higher-parity cows with records of dystocia compared with cows with no record of dystocia, for first-parity cows in the group with the highest milk yield compared with first-parity cows in the group with the lowest milk yield, for cows of third and higher parity in the group with the lowest milk yield compared with cows in higher yielding groups, for cows bred in summer compared with those bred in winter-spring (not significant for first-parity cows), and for cows with a twin birth had compared with cows with a single birth. We observed

  8. Volcanic activity: a review for health professionals.

    Science.gov (United States)

    Newhall, C G; Fruchter, J S

    1986-03-01

    Volcanoes erupt magma (molten rock containing variable amounts of solid crystals, dissolved volatiles, and gas bubbles) along with pulverized pre-existing rock (ripped from the walls of the vent and conduit). The resulting volcanic rocks vary in their physical and chemical characteristics, e.g., degree of fragmentation, sizes and shapes of fragments, minerals present, ratio of crystals to glass, and major and trace elements composition. Variability in the properties of magma, and in the relative roles of magmatic volatiles and groundwater in driving an eruption, determine to a great extent the type of an eruption; variability in the type of an eruption in turn influences the physical characteristics and distribution of the eruption products. The principal volcanic hazards are: ash and larger fragments that rain down from an explosion cloud (airfall tephra and ballistic fragments); flows of hot ash, blocks, and gases down the slopes of a volcano (pyroclastic flows); "mudflows" (debris flows); lava flows; and concentrations of volcanic gases in topographic depressions. Progress in volcanology is bringing improved long- and short-range forecasts of volcanic activity, and thus more options for mitigation of hazards. Collaboration between health professionals and volcanologists helps to mitigate health hazards of volcanic activity.

  9. Flash annealing influence on structural and electrical properties of TiO{sub 2}/TiO/Ti periodic multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Cacucci, Arnaud; Heintz, Olivier; Tsiaoussis, Ioannis; Avril, Ludovic [ICB — Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS — Université de Bourgogne, 9, Avenue Alain Savary, BP47870, 21078 Dijon Cedex (France); Potin, Valérie, E-mail: valerie.potin@u-bourgogne.fr [ICB — Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS — Université de Bourgogne, 9, Avenue Alain Savary, BP47870, 21078 Dijon Cedex (France); Imhoff, Luc [ICB — Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS — Université de Bourgogne, 9, Avenue Alain Savary, BP47870, 21078 Dijon Cedex (France); Martin, Nicolas [Institut FEMTO-ST, UMR 6174, Université de Franche-Comté, CNRS, ENSMM, UTBM, 32, Avenue de l' observatoire, 25044 Besancon Cedex (France); Solid State Electronics, The Ångström Laboratory, Uppsala University, Box 534, 75121 Uppsala (Sweden)

    2014-02-28

    Multilayered structures with a 40 nm period composed of titanium and two different titanium oxides, TiO and TiO{sub 2}, were accurately produced by DC magnetron sputtering using the reactive gas pulsing process. These multilayers were sputtered onto Al{sub 2}O{sub 3} sapphire to avoid substrate compound diffusion during flash annealing (ranging from 350 °C to 550 °C). Structure and composition of these periodic TiO{sub 2}/TiO/Ti stacks were investigated by X-ray diffraction, X-ray photoemission spectroscopy and transmission electronic microscopy techniques. Two crystalline phases α-Ti and fcc-TiO were identified in the metallic-rich sub-layers whereas the oxygen-rich ones were composed of a mixture of amorphous and rutile TiO{sub 2} phase. DC electrical resistivity ρ measured for temperatures ranging from 25 to 200 °C was influenced by the thermal treatments. The temperature coefficients of resistance of these periodic TiO{sub 2}/TiO/Ti multilayers were modified from 11.7 × 10{sup −04} to − 8.81 × 10{sup −04} K{sup −1}. Local changes of crystallinity were reported and the resistivity responses of these annealed films could be linked to the typical electrical behavior of a metal–oxide mixture. - Highlights: • TiO{sub 2}/TiO/Ti periodic multilayers deposited by reactive gas pulsing sputtering. • Periodic multilayers are always observed after flash annealing. • Electrical properties of multilayers are modified by thermal treatments. • Film temperature coefficient of resistance tuned from positive to negative.

  10. The influence of the type of birth and the mother´s diet on the breastfeeding period.

    Directory of Open Access Journals (Sweden)

    Daniela Benites

    2014-09-01

    Full Text Available The prenatal aspects may influence the duration of breastfeeding of newborns, which when reduced harm to their development brings cranio-orofacial. Correlate the type of delivery and maternal diet with breastfeeding period. This was a descriptive study based on the records of the medical records of 820 dyads of mothers and newborns participating in the University Extension Baby Clinic. The results were analyzed, considering a significance level of 5%. The absence of complications during pregnancy was a positive factor for the occurrence of vaginal delivery in 94% of the sample (p<0.001. It was found a high percentage of cesarean delivery (43%. The number of caesarean sections in women with cariogenic diet was higher than in women with non-cariogenic diet. The women who have a cariogenic diet does not have a tendency to breastfeed their children for more than 6 months (p<0.01. Also there was an association between vaginal delivery and longer period of 6 months of breastfeeding (p<0.001. The collected sample mode of delivery and maternal diet influence the duration of breastfeeding.

  11. The influence of informal caregivers on the rehabilitation of the elderly in the postoperative period of proximal femoral fracture.

    Science.gov (United States)

    Rocha, Suelen Alves; Avila, Marla Andréia Garcia de; Bocchi, Silvia Cristina Mangini

    2016-03-01

    Objective To analyze the influence of informal caregivers on the functional independence of older adults in the postoperative period of proximal femoral fracture due to falls. Method It is an integrative review of a corpus for analysis that gathered 23 articles, between 2002 and 2012, from databases "Literatura Latino-Americana e do Caribe em Ciências da Saúde" (Latin-American and Caribbean Health Sciences Literature in Health Sciences), Cumulative Index to Nursing and Allied Health Literature, US National Library of Medicine and Scopus. Results There was a predominance of studies by Chinese authors and nurses. The analysis of the studies evidenced that falls followed by fractures lead to dependence of older adults and, consequently, an overload to caregivers. Moreover, older adults and caregivers showed a need for support in the rehabilitation process. Conclusions Informal caregivers still need to be included in care planning and to be qualified for such care by health professionals, since they positively influence functional independence in the postoperative period.

  12. Direct observational evidence of the influence of absorbing aerosols on surface energy partitioning during the monsoon onset period over Kanpur

    Science.gov (United States)

    Tripathi, S. N.; Sarangi, C.

    2016-12-01

    Detailed understanding of the radiative impact of ambient aerosols on land-atmosphere energy interactions during the onset period over the Indian summer monsoon region (ISMR) is essential for improving spatiotemporal prediction of the Indian summer monsoon. Transportation of air masses influenced by biomass burning outbreaks in the Himalayan foothills to Kanpur, located in ISMR, during May 2016 provides a unique opportunity to investigate the influence of absorbing aerosols on the Bowen ratio. Collocated half hourly observations of aerosol properties, surface energy balance and fluxes and carbon dioxide (CO2) fluxes over Kanpur under clear sky conditions were used. During this period, increase in aerosol optical depth (AOD) was associated with decrease in single scattering albedo and increase in near surface PM2.5 concentrations indicating that the increase in columnar aerosol loading was primarily due to increase in absorbing aerosols near the surface. Our results show that the net radiation (NR) decreases by 130 Wm-2 per unit increase in AOD at the surface, most of which is due to interactions of aerosols with incoming shortwave radiation. Comparison of observed Bowen ratio for low- and high AOD scenarios illustrates that the increase in aerosol is associated with a reduction in the Bowen ratio for all values of NR. The decrease in sensible heat fluxes relative to the net radiation (SH/NR) per unit increase in AOD is 50 % during midday. We found that aerosol-induced stability in near surface temperature gradient suppresses energy dissipation by the sensible heat flux. Further, relative latent heat flux was found to increase 25 % per unit increase in AOD, mainly due to enhanced photosynthesis as a function of a greater fraction of diffuse radiation. This is evident from the more negative CO2 flux with AOD. Thus, this study provides the first observational evidence of the influence of absorbing aerosols on the Bowen ratio over this region of climatic importance.

  13. Inorganic particles in the skin of inhabitants of volcanic areas of Central America: their possible immunomodulatory influence in leishmaniasis and leprosy.

    Science.gov (United States)

    Convit, J; Ulrich, M; Castillo, J; De Lima, H; Pérez, M; Caballero, N; Hung, J; Arana, B; Pérez, P

    2006-08-01

    We have evaluated biopsies from patients with atypical nodular and typical ulcerated lesions of cutaneous leishmaniasis, from leishmanin reactions and skin from normal individuals from Nicaragua, Honduras and Guatemala for the presence of inorganic particles using confocal microscopy with a polarised light source and conventional histopathological techniques. Analysis by semiquantitative confocal microscopy permitted the demonstration of significantly larger numbers of particles in atypical lesions. Silica and aluminium, important components of these particles, were less abundant in particles from normal skin. The histology of these atypical lesions, characterised by 'naked' sarcoidal granulomas with epithelioid differentiation but very few lymphocytes, was very similar to the histological reaction observed after 14 days in persisting inflammation at leishmanin skin test sites. The presence of these unusual lesions in areas of Central American countries characterised by the presence of large amounts of volcanic ash, as well the unexpectedly low prevalence of leprosy in Central America, suggest that environmental factors may contribute significantly to the frequency and clinical manifestations of these infections. Among possible environmental features, the presence of inorganic particles with immunomodulatory properties in the skin may be a significant factor.

  14. Influence of growing altitude, shade and harvest period on quality and biochemical composition of Ethiopian specialty coffee.

    Science.gov (United States)

    Tolessa, Kassaye; D'heer, Jolien; Duchateau, Luc; Boeckx, Pascal

    2017-07-01

    Coffee quality is a key characteristic for the international market, comprising cup quality and chemical bean constituents. In Ethiopia, using total specialty cup scores, coffees are grouped into Q1 (specialty 1) ≥ 85 and Q2 (80-84.75). This classification results in market segmentation and higher prices. Although different studies have evaluated the effects of altitude and shade on bean quality, optimum shade levels along different altitudinal ranges are not clearly indicated. Information on effects of harvest periods on coffee quality is also scanty. The present study examined the influences of these factors and their interactions on Ethiopian coffee quality RESULTS: Coffee from high altitude with open or medium shade and early to middle harvest periods had a superior bean quality. These growing conditions also favoured the production of beans with lower caffeine. An increasing altitude, from mid to high, at approximately 400 m, decreased caffeine content by 10%. At high altitude, dense shade decreased Q1 coffee by 50%. Compared to late harvesting, early harvesting increased the percentage from 27% to 73%. At mid altitude, > 80% is Q2 coffee. Changes of quality scores driven by altitude, shade and harvest period are small, although they may induce dramatic switches in the fraction Q1 versus Q2 coffee. The latter affects both farmers' profits and competitiveness in international markets. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  15. Soil uses during the sugarcane fallow period: influence on soil chemical and physical properties and on sugarcane productivity

    Directory of Open Access Journals (Sweden)

    Roniram Pereira da Silva

    2014-04-01

    Full Text Available The planting of diversified crops during the sugarcane fallow period can improve the chemical and physical properties and increase the production potential of the soil for the next sugarcane cycle. The primary purpose of this study was to assess the influence of various soil uses during the sugarcane fallow period on soil chemical and physical properties and productivity after the first sugarcane harvest. The experiment was conducted in two areas located in Jaboticabal, São Paulo State, Brazil (21º 14' 05'' S, 48º 17' 09'' W with two different soil types, namely: an eutroferric Red Latosol (RLe with high-clay texture (clay content = 680 g kg-1 and an acric Red Latosol (RLa with clayey texture (clay content = 440 g kg-1. A randomized block design with five replications and four treatments (crop sequences was used. The crop sequences during the sugarcane fallow period were soybean/millet/soybean, soybean/sunn hemp/soybean, soybean/fallow/soybean, and soybean. Soil use was found not to affect chemical properties and sugarcane productivity of RLe or RLa. The soybean/millet/soybean sequence improved aggregation in the acric Latosol.

  16. Lung problems and volcanic smog

    Science.gov (United States)

    ... releases gases into the atmosphere. Volcanic smog can irritate the lungs and make existing lung problems worse. ... deep into the lungs. Breathing in volcanic smog irritates the lungs and mucus membranes. It can affect ...

  17. Volcanism and Oil & Gas In Northeast China

    Institute of Scientific and Technical Information of China (English)

    Shan Xuanlong

    2000-01-01

    Based on study on the relation with volcanic rock and oil & gas in Songliao Basin and Liaohe Basin in northeast China, author proposes that material from deep by volcanism enrichs the resources in basins, that heat by volcanism promotes organic matter transforming to oil and gas, that volcanic reservoir is fracture, vesicular, solution pore, intercrystal pore.Lava facies and pyroclastic facies are favourable reservoir. Mesozoic volcanic reservoir is majority of intermediate, acid rock,but Cenozoic volcanic reservoir is majority of basalt. Types of oil and gas pool relating to volcanic rock include volcanic fracture pool, volcanic unconformity pool, volcanic rock - screened pool, volcanic darpe structural pool.

  18. Radon levels in the volcanic region of La Garrotxa, Spain

    Energy Technology Data Exchange (ETDEWEB)

    Baixeras, C. [Grup de Fisica de les Radiacions. Edifici Cc, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)]. E-mail: carmen.baixeras@uab.es; Bach, J. [Unitat de Geodinamica Externa. Departament de Geologia. Edifici Cs, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Amgarou, K. [Grup de Fisica de les Radiacions. Edifici Cc, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Moreno, V. [Grup de Fisica de les Radiacions. Edifici Cc, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Font, Ll. [Grup de Fisica de les Radiacions. Edifici Cc, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)

    2005-11-15

    A preliminary survey in the city of Olot, the main town of the volcanic region of La Garrotxa, showed that dwellings built on volcanic formations present higher indoor radon levels than dwellings on non-volcanic materials. The soil of the area is not especially rich in radium. However, some of the volcanic materials present very high permeability and therefore radon entering the houses might have travelled over long distances. In this paper we present indoor radon values measured in a larger survey carried out during April-July 2004. The influence of the volcanic materials found in the preliminary survey has been confirmed. The results obtained suggest the possibility that radon comes from the degassification of mantle through active faults. The values obtained in working places do not constitute a relevant radiological risk for workers.

  19. Is volcanic phenomena of fractal nature?

    Science.gov (United States)

    Quevedo, R.; Lopez, D. A. L.; Alparone, S.; Hernandez Perez, P. A.; Sagiya, T.; Barrancos, J.; Rodriguez-Santana, A. A.; Ramos, A.; Calvari, S.; Perez, N. M.

    2016-12-01

    A particular resonance waveform pattern has been detected beneath different physical volcano manifestations from recent 2011-2012 period of volcanic unrest at El Hierro Island, Canary Islands, and also from other worldwide volcanoes with different volcanic typology. This mentioned pattern appears to be a fractal time dependent waveform repeated in different time scales (periods of time). This time dependent feature suggests this resonance as a new approach to volcano phenomena for predicting such interesting matters as earthquakes, gas emission, deformation etc. as this fractal signal has been discovered hidden in a wide typical volcanic parameters measurements. It is known that the resonance phenomenon occurring in nature usually denote a structure, symmetry or a subjacent law (Fermi et al., 1952; and later -about enhanced cross-sections symmetry in protons collisions), which, in this particular case, may be indicative of some physical interactions showing a sequence not completely chaotic but cyclic provided with symmetries. The resonance and fractal model mentioned allowed the authors to make predictions in cycles from a few weeks to months. In this work an equation for this waveform has been described and also correlations with volcanic parameters and fractal behavior demonstration have been performed, including also some suggestive possible explanations of this signal origin.

  20. Modeling volcanic ash dispersal

    CERN Document Server

    CERN. Geneva

    2010-01-01

    The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard...

  1. VOLCANIC TSUNAMI GENERATING SOURCE MECHANISMS IN THE EASTERN CARIBBEAN REGION

    Directory of Open Access Journals (Sweden)

    George Pararas-Carayannis

    2004-01-01

    Full Text Available Earthquakes, volcanic eruptions, volcanic island flank failures and underwater slides have generated numerous destructive tsunamis in the Caribbean region. Convergent, compressional and collisional tectonic activity caused primarily from the eastward movement of the Caribbean Plate in relation to the North American, Atlantic and South American Plates, is responsible for zones of subduction in the region, the formation of island arcs and the evolution of particular volcanic centers on the overlying plate. The inter-plate tectonic interaction and deformation along these marginal boundaries result in moderate seismic and volcanic events that can generate tsunamis by a number of different mechanisms. The active geo-dynamic processes have created the Lesser Antilles, an arc of small islands with volcanoes characterized by both effusive and explosive activity. Eruption mechanisms of these Caribbean volcanoes are complex and often anomalous. Collapses of lava domes often precede major eruptions, which may vary in intensity from Strombolian to Plinian. Locally catastrophic, short-period tsunami-like waves can be generated directly by lateral, direct or channelized volcanic blast episodes, or in combination with collateral air pressure perturbations, nuéss ardentes, pyroclastic flows, lahars, or cascading debris avalanches. Submarine volcanic caldera collapses can also generate locally destructive tsunami waves. Volcanoes in the Eastern Caribbean Region have unstable flanks. Destructive local tsunamis may be generated from aerial and submarine volcanic edifice mass edifice flank failures, which may be triggered by volcanic episodes, lava dome collapses, or simply by gravitational instabilities. The present report evaluates volcanic mechanisms, resulting flank failure processes and their potential for tsunami generation. More specifically, the report evaluates recent volcanic eruption mechanisms of the Soufriere Hills volcano on Montserrat, of Mt. Pel

  2. Climate impact of volcanic aerosol in the stratosphere and upper troposphere - CALIPSO observations from 2006-2015

    Science.gov (United States)

    Friberg, Johan; Martinsson, Bengt G.; Andersson, Sandra M.; Sandvik, Oscar S.; Hermann, Markus; van Velthoven, Peter F. J.; Zahn, Andreas

    2017-04-01

    We have investigated the climate impact of volcanic eruptions in the period 2006-2015, and found that the volcanic perturbations of the stratospheric aerosol is stronger and lasts longer than previously thought. Recent studies (Ridley et al., 2014, Andersson et al., 2015) show that a large portion of volcanic climate impact stems from aerosol in the LMS (lowermost stratosphere). Although the LMS holds >40% of the stratospheric mass (Appenzeller et al., 1996) it is generally neglected in estimations of the stratospheric AOD (aerosol optical depth). In the past decade the stratospheric aerosol load was perturbed by a number of volcanic eruptions. We cover that period by using the CALIPSO level 1b night-time data to study the volcanic influence on the global and regional climate. CALIPSO data were averaged to a resolution of 180 m vertically and 1×1° horizontally, cleaned from ice clouds by means of the depolarization ratio (Vernier et al., 2009), and a method was developed to remove polar stratospheric clouds (PSC). This approach enables identification of aerosol also at low altitudes (currently using 4 km minimum altitude) and in the Antarctic region (60 to 90°S) where PSCs are frequent during winter. In the current study, we estimate the total stratospheric AOD and radiative forcing and find that significant fractions of volcanic aerosol were located below the static tropopause after volcanic eruptions. Volcanic aerosol was generally observed down to the dynamic tropopause, and detected down to potential vorticities of 1.5-2 PVU (almost 1 km below the static tropopause). Hence, the dynamic tropopause was found to better enclose the volcanic aerosol. Furthermore, large concentrations of aerosol from the Kasatochi eruption (Aug 2008) is found to linger in the extratropical UT (upper troposphere) for several months after the eruption. Sulphate-rich volcanic aerosol transported from the LMS may influence cirrus clouds in the extratropical UT, inducing an indirect

  3. "Nothing special, everything is maamuli": socio-cultural and family practices influencing the perinatal period in urban India.

    Science.gov (United States)

    Raman, Shanti; Srinivasan, Krishnamachari; Kurpad, Anura; Razee, Husna; Ritchie, Jan

    2014-01-01

    Globally, India contributes the largest share in sheer numbers to the burden of maternal and infant under-nutrition, morbidity and mortality. A major gap in our knowledge is how socio-cultural practices and beliefs influence the perinatal period and thus perinatal outcomes, particularly in the rapidly growing urban setting. Using data from a qualitative study in urban south India, including in-depth interviews with 36 women who had recently been through childbirth as well as observations of family life and clinic encounters, we explored the territory of familial, cultural and traditional practices and beliefs influencing women and their families through pregnancy, childbirth and infancy. We found that while there were some similarities in cultural practices to those described before in studies from low resource village settings, there are changing practices and ideas. Fertility concerns dominate women's experience of married life; notions of gender preference and ideal family size are changing rapidly in response to the urban context; however inter-generational family pressures are still considerable. While a rich repertoire of cultural practices persists throughout the perinatal continuum, their existence is normalised and even underplayed. In terms of diet and nutrition, traditional messages including notions of 'hot' and 'cold' foods, are stronger than health messages; however breastfeeding is the cultural norm and the practice of delayed breastfeeding appears to be disappearing in this urban setting. Marriage, pregnancy and childbirth are so much part of the norm for women, that there is little expectation of individual choice in any of these major life events. A greater understanding is needed of the dynamic factors shaping the perinatal period in urban India, including an acknowledgment of the health promoting as well as potentially harmful cultural practices and the critical role of the family. This will help plan culturally appropriate integrated perinatal

  4. "Nothing special, everything is maamuli": socio-cultural and family practices influencing the perinatal period in urban India.

    Directory of Open Access Journals (Sweden)

    Shanti Raman

    Full Text Available Globally, India contributes the largest share in sheer numbers to the burden of maternal and infant under-nutrition, morbidity and mortality. A major gap in our knowledge is how socio-cultural practices and beliefs influence the perinatal period and thus perinatal outcomes, particularly in the rapidly growing urban setting.Using data from a qualitative study in urban south India, including in-depth interviews with 36 women who had recently been through childbirth as well as observations of family life and clinic encounters, we explored the territory of familial, cultural and traditional practices and beliefs influencing women and their families through pregnancy, childbirth and infancy. We found that while there were some similarities in cultural practices to those described before in studies from low resource village settings, there are changing practices and ideas. Fertility concerns dominate women's experience of married life; notions of gender preference and ideal family size are changing rapidly in response to the urban context; however inter-generational family pressures are still considerable. While a rich repertoire of cultural practices persists throughout the perinatal continuum, their existence is normalised and even underplayed. In terms of diet and nutrition, traditional messages including notions of 'hot' and 'cold' foods, are stronger than health messages; however breastfeeding is the cultural norm and the practice of delayed breastfeeding appears to be disappearing in this urban setting. Marriage, pregnancy and childbirth are so much part of the norm for women, that there is little expectation of individual choice in any of these major life events.A greater understanding is needed of the dynamic factors shaping the perinatal period in urban India, including an acknowledgment of the health promoting as well as potentially harmful cultural practices and the critical role of the family. This will help plan culturally appropriate

  5. Influence of method and period of storage on the microtensile bond strength of indirect composite resin restorations to dentine

    Directory of Open Access Journals (Sweden)

    Fernanda Ribeiro Santana

    2008-12-01

    Full Text Available This study evaluated the influence of the method and period of storage on the adhesive bond strength of indirect composite resin to bovine dentin. Ninety bovine incisors were stored in three different solutions: 0.2% thymol, 10% formalin, and 0.2% sodium azide, during 3 periods of storage: 7 days, 30 days and 6 months, resulting in 9 groups (n = 10. The roots were cut off and the buccal surface was ground with #600-grit silicon carbide paper. The surface was conditioned with 37% phosphoric acid for 15 s and a composite resin restoration (TPH Spectrum was fixed using a one-bottle adhesive system (Adper Single Bond and a dual-cured resinous cement (Rely X ARC under a load of 500 g for 5 minutes. The samples were serially cut perpendicular to the bonded interface to obtain slices of 1.2 mm in thickness. Each slab was trimmed with a cylindrical diamond bur resulting in an hourglass shape with a cross-sectional area of approximately 1 mm². The microtensile bond strength (μTBS testing was performed in a testing machine (EMIC 2000 DL at a 0.5 mm/minute crosshead-speed until failure. After fracture, the specimens were examined under SEM to analyze the mode of fracture. μTBS Means were expressed in MPa and the data were analyzed by two-way ANOVA (3X3 and the Tukey test (α = 0.05. The storage times of 7 and 30 days produced no significant difference irrespective of the solution type. The formalin and thymol solutions, however, did have a negative influence on bond strength when the teeth were stored for 6 months.

  6. Traumatic episodes experienced during the genocide period in Rwanda influence life circumstances in young men and women 17 years later.

    Science.gov (United States)

    Rugema, Lawrence; Mogren, Ingrid; Ntaganira, Joseph; Gunilla, Krantz

    2013-12-28

    During Rwanda's genocide period in 1994, about 800,000 people were killed. People were murdered, raped and seriously injured. This retrospective study investigated prevalence and frequency of traumatic episodes and associated psychosocial effects in young adults in Rwanda over the lifetime, during the genocide period and in the past three years. This is a cross-sectional population-based study conducted among men and women, aged 20 to 35 years, residing in the Southern province of Rwanda. The study population, randomly selected in a multi stage procedure, included 477 females and 440 males. Data collection was performed through individual interviewing with a structured questionnaire during the period December 2011- January 2012. The Harvard Trauma Questionnaire was used to assess traumatic episodes. All data was sex-disaggregated. Differences between groups were measured by chi square and Fischer's exact test. Associations with socio-demographic and psychosocial factors were estimated by use of odds ratios with 95% confidence intervals in bi- and multivariate analyses. The participants in this study were 3 to 18 years of age in 1994, the year of the genocide. Our sample size was 917 participants, 440 men and 477 women. Women were to a higher extent exposed to traumatic episodes than men during their lifetime, 83.6% (n = 399) and 73.4% (n = 323), respectively. During the genocide period, 37.5% of the men/boys and 35.4% of the women/girls reported such episodes while in the past three years (2009-2011) 25.0% of the men and 23.1% of the women did. Women were more exposed to episodes related to physical and sexual violence, while men were exposed to imprisonment, kidnapping and mass killings. Victims of such violence during the genocide period were 17 years later less educated although married (men OR 1.47; 0.98-2.19; women OR 1.54; 1.03-2.30), without children (men OR 1.59; 1.08-2.36; women OR 1.86; 1.11-3.08) and living under extremely poor circumstances. The

  7. Moisture content behaviour in extensive green roofs during dry periods: The influence of vegetation and substrate characteristics

    Science.gov (United States)

    Berretta, Christian; Poë, Simon; Stovin, Virginia

    2014-04-01

    Evapotranspiration (ET) is a key parameter that influences the stormwater retention capacity, and thus the hydrological performance, of green roofs. This paper investigates how the moisture content in extensive green roofs varies during dry periods due to evapotranspiration. The study is supported by 29 months continuous field monitoring of the moisture content within four green roof test beds. The beds incorporated three different substrates, with three being vegetated with sedum and one left unvegetated. Water content reflectometers were located at three different soil depths to measure the soil moisture profile and to record temporal changes in moisture content at a five-minute resolution. The moisture content vertical profiles varied consistently, with slightly elevated moisture content levels being recorded at the deepest substrate layer in the vegetated systems. Daily moisture loss rates were influenced by both temperature and moisture content, with reduced moisture loss/evapotranspiration when the soil moisture was restricted. The presence of vegetation resulted in higher daily moisture loss. Finally, it is demonstrated that the observed moisture content data can be accurately simulated using a hydrologic model based on water balance and two conventional Potential ET models (Hargreaves and FAO56 Penman-Monteith) combined with a soil moisture extraction function. Configuration-specific correction factors have been proposed to account for differences between green roof systems and standard reference crops.

  8. Influence of long-period pesticide force on genetic polymorphism of wolf spider Pardosa pseudoannulata (Lycosidae: Araneae)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Wolf spiders are predators in large quantities in the fields. How wolf spiders keep their dominant species status under long-period pesticide force? To answer this question, eight geographical populations of Pardosa pseudoannulata were used as materials to test the influence of geographical habitats on their genomic DNA polymorphism. The RAPD pattern showed polymorphic variations among and within different populations. Total 84 bands amplified by 10 random primers, of which 62 (73.81% ) are polymorphic, were generated from 55 individuals of eight geographical populations. Meanwhile, Shannon's index (Ho = 0.5177) showed a rich genetic diversity of P. pseudoannulata, and most of the genetic variation (64.24%) was found within populations. Multiple regression analysis suggested that it is the climatic variation (such as annual average temperature etc. ) that results in adaptive eco-geographic differentiation, and it is the long-period pesticide force that speeds up the genetic differentiation of P. pseudoannulata which changed the genetic diversity of the population.

  9. The influence of dry matter, applied heat treatment and storage period on the viscosity of stirred yogurt

    Directory of Open Access Journals (Sweden)

    Denin-Đurđević Jelena D.

    2002-01-01

    Full Text Available Skim milk powder reconstituted to 8.44% TS, 9.65% TS and 10.84% TS respectively was used for investigation. Untreated milk and milk heat treated at 85ºC/20 min and 90ºC/10 min, respectively, were used for the investigation. Milk was inoculated with 2.5% of yogurt culture (containing Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus in the ratio 1:1 at 43ºC. Samples were incubated until pH 4.6 was reached. Samples were immediately cooled to 4ºC and held at that temperature during 14 days. Acid casein gel was stirred after 1, 7 and 14 days of storage. Measurements were done at 30 rpm during 2 min, at 20ºC. According to the investigation, it could be concluded that both applied heat treatment and dry matter content influence viscosity of stirred yogurt. Viscosity increases when dry matter content increases. The smallest viscosity had yogurt produced from untreated milk with 8.44% TS, while samples produced from milk with 10.84% TS had the highest viscosity. Applied heat treatments had significant influence on viscosity of yogurt gained by stirring of acid casein gels after 7 and 14 days of storage. Stirred yogurt produced from milk heat treated at 90ºC/10 min had a higher viscosity than samples produced from milk heat treated at 85ºC/20 min. Storage period influenced average viscosity of stirred yogurt. Samples of stirred yogurt produced from milk with 8.44% TS showed a decrease of average viscosity during storage regardless of the applied heat treatment of milk. The highest average viscosity had samples produced from milk with 10.84% TS.

  10. Volcanic hazard studies for the Yucca Mountain project

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, B.; Harrington, C. [Los Alamos National Lab., NM (USA); Turrin, B.; Champion, D. [US Geological Survey (US); Wells, S.; Perry, F.; McFadden, L.; Renault, C. [New Mexico Univ., Albuquerque, NM (USA)

    1989-12-31

    Volcanic hazard studies are ongoing to evaluate the risk of future volcanism with respect to siting of a repository for disposal of high-level radioactive waste at the Yucca Mountain site. Seven Quaternary basaltic volcanic centers are located between 8 and 47 km from the outer boundary of the exploration block. The conditional probability of disruption of a repository by future basaltic volcanism is bounded by the range of 10-8 to 10-10 yr-1. These bounds are currently being reexamined based on new developments in the understanding of the evolution of small volume, basaltic volcanic centers including: Many of the volcanic centers exhibit brief periods of eruptive activity separated by longer periods of inactivity, The centers may be active for time spans exceeding 105 yrs, There is a decline in the volume of eruptions of the centers through time, and Small volume eruptions occurred at two of the Quaternary centers during latest Pleistocene or Holocene. The authors classify the basalt centers as polycyclic, and distinguish them from polygenetic volcanoes. Polycyclic volcanism is characterized by small volume, episodic eruptions of magma of uniform composition over time spans of 103 to 105 yrs. magma eruption rates are low and the time between eruptions exceeds the cooling time of the magma volumes.

  11. Volcanic hazard studies for the Yucca Mountain project

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, B.; Turrin, B.; Wells, S.; Perry, F.; McFadden, L.; Renault, C.E.; Champion, D.; Harrington, C.

    1989-05-01

    Volcanic hazard studies are ongoing to evaluate the risk of future volcanism with respect to siting of a repository for disposal of high-level radioactive waste at the Yucca Mountain site. Seven Quaternary basaltic volcanic centers are located a minimum distance of 12 km and a maximum distance of 47 km from the outer boundary of the exploration block. The conditional probability of disruption of a repository by future basaltic volcanism is bounded by the range of 10{sup {minus}8} to 10{sup {minus}10} yr{sup {minus}1}. These values are currently being reexamined based on new developments in the understanding of the evaluation of small volume, basaltic volcanic centers including: (1) Many, perhaps most, of the volcanic centers exhibit brief periods of eruptive activity separated by longer periods of inactivity. (2) The centers may be active for time spans exceeding 10{sup 5} yrs, (3) There is a decline in the volume of eruptions of the centers through time, and (4) Small volume eruptions occurred at two of the Quaternary centers during latest Pleistocene or Holocene time. We classify the basalt centers as polycyclic, and distinguish them from polygenetic volcanoes. Polycyclic volcanism is characterized by small volume, episodic eruptions of magma of uniform composition over time spans of 10{sup 3} to 10{sup 5} yrs. Magma eruption rates are low and the time between eruptions exceeds the cooling time of the magma volumes. 25 refs., 2 figs.

  12. Development of a low cost and low power consumption system for monitoring CO_{2} soil concentration in volcanic areas.

    Science.gov (United States)

    Awadallah Estévez, Shadia; Moure-García, David; Torres-González, Pedro; Acosta Sánchez, Leopoldo; Domínguez Cerdeña, Itahiza

    2017-04-01

    Volatiles dissolved in magma are released as gases when pressure or stress conditions change. H2O, CO2, SO2 and H2S are the most abundant gases involved in volcanic processes. Emission rates are related to changes in the volcanic activity. Therefore, in order to predict possible eruptive events, periodic measurements of CO2 concentrations from the soil should be carried out. In the last years, CO2 monitoring has been widespread for many reasons. A direct relationship between changes in volcanic activity and variations in concentration, diffuse flux and isotope ratios of this gas, have been observed prior to some eruptions or unrest processes. All these factors have pointed out the fact that CO2 emission data are crucial in volcanic monitoring programs. In addition, relevant instrumentation development has also taken place: improved accuracy, cost reduction and portability. Considering this, we propose a low cost and a low power consumption system for measuring CO2 concentration in the soil based on Arduino. Through a perforated pick-axe buried at a certain depth, gas samples are periodically taken with the aid of a piston. These samples are injected through a pneumatic circuit in the spectrometer, which measures the CO2 concentration. Simultaneously, the system records the following meteorological parameters: atmospheric pressure, precipitation, relative humidity and air and soil temperature. These parameters are used to correct their possible influence in the CO2 soil concentration. Data are locally stored (SD card) and transmitted via GPRS or WIFI to a data analysis center.

  13. Noise-induced variability of volcanic extrusions

    Science.gov (United States)

    Alexandrov, D. V.; Bashkirtseva, I. A.; Ryashko, L. B.

    2016-11-01

    Motivated by important physical applications, we study a non-linear dynamics of volcanic extrusions on the basis of a simple pressure-mass flow model. We demonstrate that the deterministic phase portrait represents either the bulbous-type curves or closed paths stretched to their left depending on the initial conditions. The period of phase trajectories therewith increases when the pressure drop between the conduit top and bottom compensates the lava column pressure in it. Stochastic forcing changes the system dynamics drastically. We show that a repetitive scenario of volcanic behaviour with intermittency of stochastic oscillations of different extrusion amplitudes and frequencies appears in the presence of noises. As this takes place, the mean values of interspike intervals characterizing the system periodicity have a tendency to grow with increasing the noise intensity. The probability distribution functions confirming this dynamic behaviour are constructed.

  14. Exploring Hawaiian Volcanism

    Science.gov (United States)

    Poland, Michael P.; Okubo, Paul G.; Hon, Ken

    2013-02-01

    In 1912 the Hawaiian Volcano Observatory (HVO) was established by Massachusetts Institute of Technology professor Thomas A. Jaggar Jr. on the island of Hawaii. Driven by the devastation he observed while investigating the volcanic disasters of 1902 at Montagne Pelée in the Caribbean, Jaggar conducted a worldwide search and decided that Hawai`i provided an excellent natural laboratory for systematic study of earthquake and volcano processes toward better understanding of seismic and volcanic hazards. In the 100 years since HVO's founding, surveillance and investigation of Hawaiian volcanoes have spurred advances in volcano and seismic monitoring techniques, extended scientists' understanding of eruptive activity and processes, and contributed to development of global theories about hot spots and mantle plumes.

  15. Exploring Hawaiian volcanism

    Science.gov (United States)

    Poland, Michael P.; Okubo, Paul G.; Hon, Ken

    2013-01-01

    In 1912 the Hawaiian Volcano Observatory (HVO) was established by Massachusetts Institute of Technology professor Thomas A. Jaggar Jr. on the island of Hawaii. Driven by the devastation he observed while investigating the volcanic disasters of 1902 at Montagne Pelée in the Caribbean, Jaggar conducted a worldwide search and decided that Hawai‘i provided an excellent natural laboratory for systematic study of earthquake and volcano processes toward better understanding of seismic and volcanic hazards. In the 100 years since HVO’s founding, surveillance and investigation of Hawaiian volcanoes have spurred advances in volcano and seismic monitoring techniques, extended scientists’ understanding of eruptive activity and processes, and contributed to development of global theories about hot spots and mantle plumes.

  16. Cretaceous Volcanic Events in Southeastern Jilin Province, China: Evidence from Single Zircon U-Pb Ages

    Institute of Scientific and Technical Information of China (English)

    CHEN Yuejun; SUN Chunlin; SUN Yuewu; SUN Wei

    2008-01-01

    Mesozoic volcanic rocks in southeastern Jilin Province are an important component of the huge Mesozoic volcanic belt in the northeastern area. Study of the age of their formation is of great significance to recognize Mesozoic volcanic rule in northeastern China. Along with the research of rare Mesozoic biota and extensive Mesozoic mineralization in western Liaoning, a number of researchers have focused on Mesozoic volcanic events. The authors studied the ages of the Cretaceous volcanic rocks in southeastern Jilin Province using single Zircon U-Pb. The result shows that the Sankeyushu Formation volcanic rocks in the Tonghua area are 119.2 Ma in age, the Yingcheng Formation in the Jiutai area 113.4±3.1 Ma, the Jinjiatun Formation in Pinggang Town of Liaoyuan City and the Wufeng volcanic rocks in the Yanji area 103.2±4.7 Ma and 103.6±1 Ma, respectively. Combined with the data of recent publication on volcanic rocks ages; the Cretaceous volcanic events in southeastern Jilin Province can be tentatively subdivided into three eruption periods: 119 Ma, 113 Ma and 103 Ma. The result not only provides important chronology data for subdividing Mesozoic strata in southeastern Jilin Province, establishing Mesozoic volcanic event sequence, discussing geological tectonic background, and surveying the relation between noble metals to the Cretaceous volcanic rocks, but also otters important information of Mesozoic volcanism in northeastern China.

  17. Subdiffusion of volcanic earthquakes

    CERN Document Server

    Abe, Sumiyoshi

    2016-01-01

    A comparative study is performed on volcanic seismicities at Mt.Eyjafjallajokull in Iceland and Mt. Etna in Sicily, Italy, from the viewpoint of science of complex systems, and the discovery of remarkable similarities between them regarding their exotic spatio-temporal properties is reported. In both of the volcanic seismicities as point processes, the jump probability distributions of earthquakes are found to obey the exponential law, whereas the waiting-time distributions follow the power law. In particular, a careful analysis is made about the finite size effects on the waiting-time distributions, and accordingly, the previously reported results for Mt. Etna [S. Abe and N. Suzuki, EPL 110, 59001 (2015)] are reinterpreted. It is shown that spreads of the volcanic earthquakes are subdiffusive at both of the volcanoes. The aging phenomenon is observed in the "event-time-averaged" mean-squared displacements of the hypocenters. A comment is also made on presence/absence of long term memories in the context of t...

  18. Burst conditions of explosive volcanic eruptions recorded on microbarographs

    Science.gov (United States)

    Morrissey, M.M.; Chouet, B.A.

    1997-01-01

    Explosive volcanic eruptions generate pressure disturbances in the atmosphere that propagate away either as acoustic or as shock waves, depending on the explosivity of the eruption. Both types of waves are recorded on microbarographs as 1- to 0.1-hertz N-shaped signals followed by a longer period coda. These waveforms can be used to estimate burst pressures end gas concentrations in explosive volcanic eruptions and provide estimates of eruption magnitudes.

  19. [Influence of compendium of Materia Medica on the materia medica in the late period of the Chosun Dynasty].

    Science.gov (United States)

    Oh, Chae-Kun

    2012-08-31

    In this paper, I investigated the influence of Compendium of Materia Medica (CM) on Records for Rural Life of Chosun Gentlemen (RRC), and refuted Miki Sakae's opinion, CM did not have much impact on the Materia Medica in the late period of the Chosun Dynasty. When Li Shizhen published CM, it resulted in a shift of mainstream of Materia Medica in Eastern Asia from Classified Emergency Materia Medica to CM and a new categorizing system of Materia Medica by CM led to the division of Materia Medica into medicine and natural history. It is obvious that doctors of the Chosun Dynasty also adopted the latest achievements of Materia Medica by CM, but so far there have been few studies to clarify this. Seo yugu was a scholar of the Realist School of Confucianism during the late period of the Chosun Dynasty, and RRC is his representative work. RRC is a massive encyclopedia of natural history that covers vast areas of science from agriculture, floriculture, writing and drawing, architecture, diet, and medicine, among others which absorbed the achievements of CM, the best Materia Medica book at that time. Miki Sakae also highly regarded the encyclopedic knowledge of RRC, but devalued the results of Materia Medica. He only described a part of RRC's Materia Medica, nurturing volume, on the view of life nurturing and mentioned that it had been strongly influenced by China. According to this study, a large portion of RRC, especially regarding Materia Medica, depends on CM. Seo yugu had accepted the categorizing system and new medicinal information of CM, at the same time he modified the categorizing system of CM practically by the subject of each volume of RRC. We can find many quotations of CM except the nurturing volume, but other books, Treasured Mirror of Eastern Medicine, Materia Medica for Relief of Famines are also quoted. Furthermore, Seo yugu emphasized the differences of natural environments between Chosun and China, and specified the editing criteria, "to be useful in

  20. Volcanic alert system (VAS) developed during the 2011-2014 El Hierro (Canary Islands) volcanic process

    Science.gov (United States)

    García, Alicia; Berrocoso, Manuel; Marrero, José M.; Fernández-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Ortiz, Ramón

    2014-06-01

    The 2011 volcanic unrest at El Hierro Island illustrated the need for a Volcanic Alert System (VAS) specifically designed for the management of volcanic crises developing after long repose periods. The VAS comprises the monitoring network, the software tools for analysis of the monitoring parameters, the Volcanic Activity Level (VAL) management, and the assessment of hazard. The VAS presented here focuses on phenomena related to moderate eruptions, and on potentially destructive volcano-tectonic earthquakes and landslides. We introduce a set of new data analysis tools, aimed to detect data trend changes, as well as spurious signals related to instrumental failure. When data-trend changes and/or malfunctions are detected, a watchdog is triggered, issuing a watch-out warning (WOW) to the Monitoring Scientific Team (MST). The changes in data patterns are then translated by the MST into a VAL that is easy to use and understand by scientists, technicians, and decision-makers. Although the VAS was designed specifically for the unrest episodes at El Hierro, the methodologies may prove useful at other volcanic systems.

  1. The influence of choice feeding and cereal type (corn or triticale) during the finishing period on performance of mule ducks.

    Science.gov (United States)

    Arroyo, J; Fortun-Lamothe, L; Dubois, J P; Lavigne, F; Bijja, M; Molette, C

    2014-09-01

    The aim of this trial was to study the influence of choice feeding and cereal type (corn or triticale) during the finishing period on performance of ducks. In total, 624 one-day-old male mule ducks (Cairina moschata × Anas platyrhynchos) were divided into 3 groups differing in the diet they received between 56 and 84 d of age: a commercial complete pelleted diet (control group; AMEn 12.1 MJ/kg, CP 15%), or corn whole seeds (AMEn 14.4 MJ/kg, CP 7.3%) and protein-rich pellets (AMEn 9.9 MJ/kg, CP 22.7%) in 2 separated feeders [choice feeding with corn (CFC) group]; or triticale whole seeds (AMEn 13.0 MJ/kg, CP 10.5%) and protein-rich pellets (AMEn 11.2 MJ/kg, CP 19.5%) in 2 separated feeders [choice feeding with triticale (CFT) group]. From 85 to 96 d, 96 birds/group were overfed with corn. Feed intake (complete pellets or cereal and protein-rich pellets) per pen was measured at 60, 62, 65, 69, 78, and 84 d of age. Body weight and body traits were measured at 56 to 84 d of age. Over the entire period, from 56 to 84 d, the feed intake of the CFC group was 7% lower than the control group, and 5% lower than that in the CFT group (P = 0.002). Whatever the diet tested, at 56 and 84 d of age, the BW (4,099 and 4,779 g, P = 0.42 and P = 0.35, respectively) and the carcass traits (P > 0.05) of ducks were similar in the 3 groups. During and after overfeeding, the performances of the ducks were also similar (P > 0.05). The present results suggest that CFC during the finishing period is a solution to reduce the cost of diet destined to ducks. Indeed, using locally grown grains could reduce the economic and environmental impacts of duck feeding, reducing the transportation and crushing processes.

  2. Assessment of volcanic hazards, vulnerability, risk and uncertainty (Invited)

    Science.gov (United States)

    Sparks, R. S.

    2009-12-01

    A volcanic hazard is any phenomenon that threatens communities . These hazards include volcanic events like pyroclastic flows, explosions, ash fall and lavas, and secondary effects such as lahars and landslides. Volcanic hazards are described by the physical characteristics of the phenomena, by the assessment of the areas that they are likely to affect and by the magnitude-dependent return period of events. Volcanic hazard maps are generated by mapping past volcanic events and by modelling the hazardous processes. Both these methods have their strengths and limitations and a robust map should use both approaches in combination. Past records, studied through stratigraphy, the distribution of deposits and age dating, are typically incomplete and may be biased. Very significant volcanic hazards, such as surge clouds and volcanic blasts, are not well-preserved in the geological record for example. Models of volcanic processes are very useful to help identify hazardous areas that do not have any geological evidence. They are, however, limited by simplifications and incomplete understanding of the physics. Many practical volcanic hazards mapping tools are also very empirical. Hazards maps are typically abstracted into hazards zones maps, which are some times called threat or risk maps. Their aim is to identify areas at high levels of threat and the boundaries between zones may take account of other factors such as roads, escape routes during evacuation, infrastructure. These boundaries may change with time due to new knowledge on the hazards or changes in volcanic activity levels. Alternatively they may remain static but implications of the zones may change as volcanic activity changes. Zone maps are used for planning purposes and for management of volcanic crises. Volcanic hazards maps are depictions of the likelihood of future volcanic phenomena affecting places and people. Volcanic phenomena are naturally variable, often complex and not fully understood. There are

  3. 火山岩气藏储层岩相特征及其对储层物性的影响——以徐深气田徐东地区白垩系营城组一段火山岩为例%Lithofacies characteristics of volcanic gas reservoirs and their influence on reservoir physical properties: a case study of Member 1 of Cretaceous Yingcheng Formation in Xudong area of the Xushen gas field

    Institute of Scientific and Technical Information of China (English)

    陈欢庆; 胡永乐; 冉启全; 闫林; 孙作兴

    2011-01-01

    Taking the volcanic reservoir of Member 1 of Yingcheng Formation in Xudong area of the Xushen gas field as an example, the authors studied lithofacies characteristics of the volcanic gas reservoir and their influences on reservoir physical properties with the purpose of effectively forecasting and exploiting the volcanic reservoir.On the basis of identification of volcanic rock types and recognition of volcanic rock bodies by combining geological data with logging data and seismic data, the authors analyzed volcanic lithofacies characteristics and their relationship with reservoir physical properties and forecast the favorable prospecting areas by using data from wells, sections and plane lithofacies.The results indicate that the volcanic reservoir of the Member 1 of Yingcheng Formation in Xudong area of the Xushen gas field was formed by repeated volcanic eruptions, with the lithologies consisting of 10 types.The rhyolite, rhyolite tuff and sedimentary volcanic breccia played the preponderant role.The eruption type in the study area was cranny-center eruption, and crater and volcanic lithofacies were obviously controlled by ruptures.The volcanic bodies were dominated by craters, and different volcanic lithofacies were developed in different positions of volcanic bodies.The volcanic fades inside the volcanic bodies in the study area can be divided into five types and sixteen sub-facies.The results indicate that the volcanic lithology and its combination constitute the basis of the division of volcanic fades, and the spreading of volcanic fades controls the distribution of gas reservoirs.The reservoir development areas include the lower part and upper part and top overflow sub-facies of overflow facies, splash down sub-facies and air falling sub-facies, middle extrusive sub-facies, exterior sub-facies of extrusive facies and volcanic neck sub-facies of volcanic channels facies.The sub-facies of the volcanic reservoir include volcanic sub-lithfacies of volcanic neck

  4. Volcanic lake systematics II. Chemical constraints

    Science.gov (United States)

    Varekamp, J.C.; Pasternack, G.B.; Rowe, G.L.

    2000-01-01

    A database of 373 lake water analyses from the published literature was compiled and used to explore the geochemical systematics of volcanic lakes. Binary correlations and principal component analysis indicate strong internal coherence among most chemical parameters. Compositional variations are influenced by the flux of magmatic volatiles and/or deep hydrothermal fluids. The chemistry of the fluid entering a lake may be dominated by a high-temperature volcanic gas component or by a lower-temperature fluid that has interacted extensively with volcanic rocks. Precipitation of minerals like gypsum and silica can strongly affect the concentrations of Ca and Si in some lakes. A much less concentrated geothermal input fluid provides the mineralized components of some more dilute lakes. Temporal variations in dilution and evaporation rates ultimately control absolute concentrations of dissolved constituents, but not conservative element ratios. Most volcanic lake waters, and presumably their deep hydrothermal fluid inputs, classify as immature acid fluids that have not equilibrated with common secondary silicates such as clays or zeolites. Many such fluids may have equilibrated with secondary minerals earlier in their history but were re-acidified by mixing with fresh volcanic fluids. We use the concept of 'degree of neutralization' as a new parameter to characterize these acid fluids. This leads to a classification of gas-dominated versus rock-dominated lake waters. A further classification is based on a cluster analysis and a hydrothermal speedometer concept which uses the degree of silica equilibration of a fluid during cooling and dilution to evaluate the rate of fluid equilibration in volcano-hydrothermal systems.

  5. Volcanisme, activité anthropique et circulation des masses océaniques : leur influence respective sur la distribution des populations d'ostracodes dans la baie de Kagoshima (île de Kyushu, Japon)Impact of volcanism, human activities, and water mass circulation on the distribution of ostracod populations in Kagoshima Bay (Kyushu Island, southern Japan)

    Science.gov (United States)

    Bodergat, Anne-Marie; Oki, Kimihiko; Ishizaki, Kunihiro; Rio, Michel

    2002-11-01

    The distribution of ostracod populations in Kagoshima Bay (Japan) is analysed with reference to different environmental parameters. The bay is an area of volcanic activity of Sakurajima volcano under the influence of the Kuroshio Current. Most of the Head environment is occupied by an acidic water mass. Numbers of individual and species decrease from the Mouth of the bay towards the Basin and Head environments. In this latter, acidic water mass has a drastic effect on ostracod populations, whereas volcanic ashes and domestic inputs are not hostile. Ostracod distribution is influenced by the quality and structure of water masses. To cite this article: A.-M. Bodergat et al., C. R. Geoscience 334 (2002) 1053-1059.

  6. Volcanism on Mars. Chapter 41

    Science.gov (United States)

    Zimbelman, J. R.; Garry, W. B.; Bleacher, J. E.; Crown, D. A.

    2015-01-01

    Spacecraft exploration has revealed abundant evidence that Mars possesses some of the most dramatic volcanic landforms found anywhere within the solar system. How did a planet half the size of Earth produce volcanoes like Olympus Mons, which is several times the size of the largest volcanoes on Earth? This question is an example of the kinds of issues currently being investigated as part of the space-age scientific endeavor called "comparative planetology." This chapter summarizes the basic information currently known about volcanism on Mars. The volcanoes on Mars appear to be broadly similar in overall morphology (although, often quite different in scale) to volcanic features on Earth, which suggests that Martian eruptive processes are not significantly different from the volcanic styles and processes on Earth. Martian volcanoes are found on terrains of different age, and Martian volcanic rocks are estimated to comprise more than 50% of the Martian surface. This is in contrast to volcanism on smaller bodies such as Earth's Moon, where volcanic activity was mainly confined to the first half of lunar history (see "Volcanism on the Moon"). Comparative planetology supports the concept that volcanism is the primary mechanism for a planetary body to get rid of its internal heat; smaller bodies tend to lose their internal heat more rapidly than larger bodies (although, Jupiter's moon Io appears to contradict this trend; Io's intense volcanic activity is powered by unique gravitational tidal forces within the Jovian system; see "Volcanism on Io"), so that volcanic activity on Mars would be expected to differ considerably from that found on Earth and the Moon.

  7. Volcanic Ash Nephelometer Probe Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced dropsondes that could effectively be guided through atmospheric regions of interest such as volcanic plumes may enable unprecedented observations of...

  8. Volcanic Eruptions and Climate

    Science.gov (United States)

    Robock, A.

    2012-12-01

    Large volcanic eruptions inject sulfur gases into the stratosphere, which convert to sulfate aerosols with an e-folding residence time of about one year. The radiative and chemical effects of these aerosol clouds produce responses in the climate system. Observations and numerical models of the climate system show that volcanic eruptions produce global cooling and were the dominant natural cause of climate change for the past millennium, on timescales from annual to century. Major tropical eruptions produce winter warming of Northern Hemisphere continents for one or two years, while high latitude eruptions in the Northern Hemisphere weaken the Asian and African summer monsoon. The Toba supereruption 74,000 years ago caused very large climate changes, affecting human evolution. However, the effects did not last long enough to produce widespread glaciation. An episode of four large decadally-spaced eruptions at the end of the 13th century C.E. started the Little Ice Age. Since the Mt. Pinatubo eruption in the Philippines in 1991, there have been no large eruptions that affected climate, but the cumulative effects of small eruptions over the past decade had a small effect on global temperature trends. The June 13, 2011 Nabro eruption in Eritrea produced the largest stratospheric aerosol cloud since Pinatubo, and the most of the sulfur entered the stratosphere not by direct injection, but by slow lofting in the Asian summer monsoon circulation. Volcanic eruptions warn us that while stratospheric geoengineering could cool the surface, reducing ice melt and sea level rise, producing pretty sunsets, and increasing the CO2 sink, it could also reduce summer monsoon precipitation, destroy ozone, allowing more harmful UV at the surface, produce rapid warming when stopped, make the sky white, reduce solar power, perturb the ecology with more diffuse radiation, damage airplanes flying in the stratosphere, degrade astronomical observations, affect remote sensing, and affect

  9. System of Volcanic activity

    Directory of Open Access Journals (Sweden)

    P. HÉDERVARI

    1972-06-01

    Full Text Available A comparison is made among the systems of B. G.
    Escher (3, of R. W. van Bemmelen (1 and that of the author (4. In this
    connection, on the basis of Esclier's classification, the terms of "constructiv
    e " and "destructive" eruptions are introduced into the author's system and
    at the same time Escher's concept on the possible relation between the depth
    of magma-chamber and the measure of the gas-pressure is discussed briefly.
    Three complementary remarks to the first paper (4 011 the subject of system
    of volcanic activity are added.

  10. Volcanism Studies: Final Report for the Yucca Mountain Project

    Energy Technology Data Exchange (ETDEWEB)

    Bruce M. Crowe; Frank V. Perry; Greg A. Valentine; Lynn M. Bowker

    1998-12-01

    This report synthesizes the results of volcanism studies conducted by scientists at the Los Alamos National Laboratory and collaborating institutions on behalf of the Department of Energy's Yucca Mountain Project. An assessment of the risk of future volcanic activity is one of many site characterization studies that must be completed to evaluate the Yucca Mountain site for potential long-term storage of high-level radioactive waste. The presence of several basaltic volcanic centers in the Yucca Mountain region of Pliocene and Quaternary age indicates that there is a finite risk of a future volcanic event occurring during the 10,000-year isolation period of a potential repository. Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certainty but instead are estimated using formal methods of probabilistic volcanic hazard assessment (PVHA). Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the younger postcaldera basalt (<5 Ma). The Lathrop Wells volcanic center is described in detail because it is the youngest basalt center in the YMR. The age of the Lathrop Wells center is now confidently determined to be about 75 thousand years old. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. The Crater Flat volcanic zone is

  11. Volcanism Studies: Final Report for the Yucca Mountain Project

    Energy Technology Data Exchange (ETDEWEB)

    Bruce M. Crowe; Frank V. Perry; Greg A. Valentine; Lynn M. Bowker

    1998-12-01

    This report synthesizes the results of volcanism studies conducted by scientists at the Los Alamos National Laboratory and collaborating institutions on behalf of the Department of Energy's Yucca Mountain Project. An assessment of the risk of future volcanic activity is one of many site characterization studies that must be completed to evaluate the Yucca Mountain site for potential long-term storage of high-level radioactive waste. The presence of several basaltic volcanic centers in the Yucca Mountain region of Pliocene and Quaternary age indicates that there is a finite risk of a future volcanic event occurring during the 10,000-year isolation period of a potential repository. Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certainty but instead are estimated using formal methods of probabilistic volcanic hazard assessment (PVHA). Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the younger postcaldera basalt (<5 Ma). The Lathrop Wells volcanic center is described in detail because it is the youngest basalt center in the YMR. The age of the Lathrop Wells center is now confidently determined to be about 75 thousand years old. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. The Crater Flat volcanic zone is

  12. Magnetic nanocomposites of periodic mesoporous silica: The influence of the silica substrate dimensionality on the inter-particle magnetic interactions

    Energy Technology Data Exchange (ETDEWEB)

    Zeleňáková, Adriana, E-mail: azelenak@upjs.sk [Department of Solid State Physics, P.J. Šafárik University, Park Angelinum 9, Košice (Slovakia); Zeleňák, Vladimir [Department of Inorganic Chemistry, P.J. Šafárik University, Moyzesova 11, Košice (Slovakia); Bednarčík, Jozef [DESY-Hasylab, Notkestrasse 85, Hamburg (Germany); Hrubovčák, Pavol [Department of Solid State Physics, P.J. Šafárik University, Park Angelinum 9, Košice (Slovakia); Kováč, Jozef [Institute of Experimental Physics, SAS, Watsonova 41, Košice (Slovakia)

    2014-01-05

    Highlights: • Hematite particles inside porous silica with 2D hexagonal and 3D cubic symmetry. • Magnetic properties are strongly affected by the dimensionality of porous matrix. • Weak dipolar interactions observed in superparamagnetic hexagonal α-Fe{sub 2}O{sub 3}@SBA-15. • Strong interactions leading to superspin-glass observed in cubic α-Fe{sub 2}O{sub 3}@SBA-16. -- Abstract: Magnetic nanocomposites consisting of iron oxide (hematite, α-Fe{sub 2}O{sub 3}) nanoparticles loaded into the pores of the periodically ordered mesoporous silica with hexagonal (SBA-15) or cubic (SBA-16) symmetry were investigated. The characterization of the samples was carried out by N{sub 2} adsorption/desorption, Small-angle X-ray scattering (SAXS), High-energy X-ray diffraction (HE-XRD) and HRTEM measurements. The magnetic properties of the prepared nanocomposites were investigated by the SQUID magnetometry. It was shown, that in spite of its non-magnetic nature the silica matrix significantly influences the magnetism of the samples. The magnetic properties are strongly affected by the strength of inter-particle interactions and dimensionality of the porous matrix. Weak dipolar interactions between superparamagnetic (SPM) hematite nanoparticles were observed in the nanocomposite with hexagonally ordered silica channels (α-Fe{sub 2}O{sub 3}@SBA-15), while the strong interactions between hematite nanoparticles, suggesting the superspin glass behavior (SSG), were observed in the nanocomposite with silica matrix of cubic symmetry (α-Fe{sub 2}O{sub 3}@SBA-16)

  13. Volcanic impact on the Atlantic ocean over the last millennium

    Directory of Open Access Journals (Sweden)

    J. Mignot

    2011-08-01

    Full Text Available The oceanic response to volcanic eruptions over the last 1000 years is investigated with a focus on the North Atlantic Ocean, using a fully coupled AOGCM forced by a realistic time series of volcanic eruptions, total solar irradiance (TSI and atmospheric greenhouse gases concentration. The model simulates little response to TSI variations but a strong and long-lasting thermal and dynamical oceanic adjustment to volcanic forcing, which is shown to be a function of the time period of the volcanic eruptions, probably due to their different seasonality. The thermal response consists of a fast tropical cooling due to the radiative forcing by the volcanic eruptions, followed by a penetration of this cooling in the subtropical ocean interior one to five years after the eruption, and propagation of the anomalies toward the high latitudes. The oceanic circulation first adjusts rapidly to low latitude anomalous wind stress induced by the strong cooling. The Atlantic Meridional Overturning Circulation (AMOC shows a significant intensification 5 to 10 years after the eruptions of the period post-1400 AD, in response to anomalous atmospheric momentum forcing, and a slight weakening in the following decade. In response to the stronger eruptions occurring between 1100 and 1300, the AMOC shows no intensification and a stronger reduction after 10 years. This study thus stresses the diversity of AMOC response to volcanic eruptions in climate models and tentatively points to an important role of the seasonality of the eruptions.

  14. Lunar Pyroclastic Eruptions: Basin Volcanism's Dying Gasps

    Science.gov (United States)

    Kramer, G. Y.; Nahm, A.; McGovern, P. J.; Kring, D. A.

    2011-12-01

    The relationship between mare volcanism and impact basins has long been recognized, although the degree of influence basin formation has on volcanism remains a point of contention. For example, did melting of magma sources result from thermal energy imparted by a basin-forming event? Did basin impacts initiate mantle overturn of the unstable LMO cumulate pile, causing dense ilmenite to sink and drag radioactive KREEPy material to provide the thermal energy to initiate melting of the mare sources? Did the dramatically altered stress states provide pathways ideally suited for magma ascent? The chemistry of sampled lunar volcanic glasses indicates that they experienced very little fractional crystallization during their ascent to the surface - they have pristine melt compositions. Volatile abundances, including recent measurements of OH [1,2] suggest that the mantle source of at least the OH-analyzed glasses have a water abundance of ~700 ppm - comparable to that of Earth's upper mantle. More recently, [3] showed that the abundance of OH and other volatiles measured in these glasses is positively correlated with trace element abundances, which is expected since water is incompatible in a magma. Volatile enrichment in a deep mantle source would lower the melting temperature and provide the thrust for magma ascent through 500 km of mantle and crust [4]. We are exploring the idea that such basin-related lunar pyroclastic volcanism may represent the last phase of basaltic volcanism in a given region. Remote sensing studies have shown volcanic glasses are fairly common, and often found along the perimeter of mare-filled basins [5]. Recent modeling of the stresses related to the basin-forming process [6,7] show that basin margins provide the ideal conduit for low-volume lunar pyroclastic volcanism (compared with the high output of mare volcanism). Schrödinger's basin floor is largely composed of a compositionally uniform impact breccia. The exceptions are two distinct and

  15. An interdisciplinary approach to volcanic risk reduction under conditions of uncertainty: a case study of Tristan da Cunha

    Directory of Open Access Journals (Sweden)

    A. Hicks

    2013-12-01

    analysed the physical vulnerability of the community as a consequence of their geographical isolation and exposure to volcanic hazards; (4 evaluated social and cultural influences on vulnerability and resilience. Despite their isolation and prolonged periods of hardship, islanders have demonstrated an ability to cope with and recover from adverse events. This resilience is likely a function of remoteness, strong kinship ties, bonding social capital, and persistence of shared values and principles established at community inception. While there is good knowledge of the styles of volcanic activity on Tristan, given the high degree of scientific uncertainty about the timing, size and location of future volcanism, a qualitative scenario planning approach was used as a vehicle to convey this information to the islanders. This deliberative, anticipatory method allowed on-island decision makers to take ownership of risk identification, management and capacity building within their community. This paper demonstrates the value of integrating social and physical sciences with development of effective, tailored communication strategies in volcanic risk reduction.

  16. Influence of fasting period, ligation time, sex, age and bodyweight on the gastric secretory response of pylorus-ligated Wistar rats.

    Science.gov (United States)

    Schiantarelli, P; Toson, G; Guelfi, M; Murmann, W

    1978-01-01

    A study on variables influencing the gastric secretory response of pylorus-ligated Wistar rat, shows that: 1. 24 h is a sufficient fasting period for satisfactory emptying of the stomach, periods of up to 48 h yielding no advantage; 2. between 2 and 4 h is the most appropriate pyloric ligation time because in this range there are no variations in volume of gastric secretion, concentration and output of acid per unit of ligation time; 3. sex has no influence on any of the parameters; 4. animals should be age-selected because only above a given age threshold the gastric secretory response per unit of bodyweight is constant.

  17. Volcan Reventador's Unusual Umbrella

    Science.gov (United States)

    Chakraborty, P.; Gioia, G.; Kieffer, S. W.

    2005-12-01

    In the past two decades, field observations of the deposits of volcanoes have been supplemented by systemmatic, and sometimes, opportunistic photographic documentation. Two photographs of the umbrella of the December 3, 2002 eruption of Volcan Reventador, Ecuador, reveal a prominently scalloped umbrella that is unlike any umbrella previously documented on a volcanic column. The material in the umbrella was being swept off a descending pyroclastic flow, and was, therefore, a co-ignimbrite cloud. We propose that the scallops are the result of a turbulent Rayleigh-Taylor (RT) instability with no precedents in volcanology. We ascribe the rare loss of buoyancy that drives this instability to the fact that the Reventador column fed on a cool co-ignimbrite cloud. On the basis of the observed wavelength of the scallops, we estimate a value for the eddy viscosity of the umbrella of 4000 ~m2/s. This value is consistent with a previously obtained lower bound (200 ~m2/s, K. Wohletz, priv. comm., 2005). We do not know the fate of the material in the umbrella subsequent to the photos. The analysis suggests that the umbrella was negatively buoyant. Field work on the co-ignimbrite deposits might reveal whether or not the material reimpacted, and if so, where and whether or not this material was involved in the hazardous flows that affected the main oil pipeline across Ecuador.

  18. Uranium series, volcanic rocks

    Science.gov (United States)

    Vazquez, Jorge A.

    2014-01-01

    Application of U-series dating to volcanic rocks provides unique and valuable information about the absolute timing of crystallization and differentiation of magmas prior to eruption. The 238U–230Th and 230Th-226Ra methods are the most commonly employed for dating the crystallization of mafic to silicic magmas that erupt at volcanoes. Dates derived from the U–Th and Ra–Th methods reflect crystallization because diffusion of these elements at magmatic temperatures is sluggish (Cherniak 2010) and diffusive re-equilibration is insignificant over the timescales (less than or equal to 10^5 years) typically associated with pre-eruptive storage of nearly all magma compositions (Cooper and Reid 2008). Other dating methods based on elements that diffuse rapidly at magmatic temperatures, such as the 40Ar/39Ar and (U–Th)/He methods, yield dates for the cooling of magma at the time of eruption. Disequilibrium of some short-lived daughters of the uranium series such as 210Po may be fractionated by saturation of a volatile phase and can be employed to date magmatic gas loss that is synchronous with volcanic eruption (e.g., Rubin et al. 1994).

  19. Volcanic Eruptions and Climate

    Science.gov (United States)

    LeGrande, Allegra N.; Anchukaitis, Kevin J.

    2015-01-01

    Volcanic eruptions represent some of the most climatically important and societally disruptive short-term events in human history. Large eruptions inject ash, dust, sulfurous gases (e.g. SO2, H2S), halogens (e.g. Hcl and Hbr), and water vapor into the Earth's atmosphere. Sulfurous emissions principally interact with the climate by converting into sulfate aerosols that reduce incoming solar radiation, warming the stratosphere and altering ozone creation, reducing global mean surface temperature, and suppressing the hydrological cycle. In this issue, we focus on the history, processes, and consequences of these large eruptions that inject enough material into the stratosphere to significantly affect the climate system. In terms of the changes wrought on the energy balance of the Earth System, these transient events can temporarily have a radiative forcing magnitude larger than the range of solar, greenhouse gas, and land use variability over the last millennium. In simulations as well as modern and paleoclimate observations, volcanic eruptions cause large inter-annual to decadal-scale changes in climate. Active debates persist concerning their role in longer-term (multi-decadal to centennial) modification of the Earth System, however.

  20. Insulation effects of Icelandic dust and volcanic aerosols on snow and ice

    Science.gov (United States)

    Dragosics, Monika; Meinander, Outi; Jónsdóttir, Tinna; Dürig, Tobias; De Leeuw, Gerrit; Pálsson, Finnur; Dagsson-Waldhauserová, Pavla; Thorsteinsson, Throstur

    2016-04-01

    In the Arctic region, Iceland is an important source of dust due to ash production from volcanic eruptions. In addition dust is resuspended from the surface into the atmosphere as several dust storms occur each year. During volcanic eruptions and dust storms, material is deposited on the glaciers where it influences their energy balance. The effects of deposited volcanic ash on ice and snow melt were examined using laboratory and outdoor experiments. These experiments were made during the snow melt period using two different ash grain sizes (1 ϕ and 3.5 ϕ) from the Eyjafjallajökull 2010 eruption, collected on the glacier. Different amounts of ash were deposited on snow or ice after which the snow properties and melt were measured. The results show that a thin ash layer increases the snow and ice melt but an ash layer exceeding a certain critical thickness caused insulation. Ash with 1 ϕ in grain size insulated the ice below at a thickness of 9-15 mm. For the 3.5 ϕ grain size the insulation thickness is 13 mm. The maximum melt occurred at a thickness of 1 mm for the 1 ϕ and only 1-2 mm for 3.5 ϕ ash. A map of dust concentrations on Vatnajökull that represents the dust deposition during the summer of 2013 is presented with concentrations ranging from 0.2 up to 16.6 g m-2.

  1. Volcanic CO2 Emissions and Glacial Cycles: Coupled Oscillations

    Science.gov (United States)

    Burley, J. M.; Huybers, P. J.; Katz, R. F.

    2016-12-01

    Following the mid-Pleistocene transition, the dominant period of glacial cycles changed from 40 ka to 100 ka. It is broadly accepted that the 40 ka glacial cycles were driven by cyclical changes in obliquity. However, this forcing does not explain the 100 ka glacial cycles. Mechanisms proposed for 100 ka cycles include isostatic bed depression and proglacial lakes destabilising the Laurentide ice sheet, non-linear responses to orbital eccentricity, and Antarctic ice sheets influencing deep-ocean stratification. None of these are universally accepted. Here we investigate the hypothesis that variations in volcanic CO2 emissions can cause 100 ka glacial cycles. Any proposed mechanism for 100 ka glacial cycles must give the Earth's climate system a memory of 10^4 - 10^5years. This timescale is difficult to achieve for surface processes, however it is possible for the solid Earth. Recent work suggests volcanic CO2 emissions change in response to glacial cycles [1] and that there could be a 50 ka delay in that response [2]. Such a lagged response could drive glacial cycles from 40 ka cycles to an integer multiple of the forcing period. Under what conditions could the climate system admit such a response? To address this, we use a simplified climate model modified from Huybers and Tziperman [3]. Our version comprises three component models for energy balance, ice sheet growth and atmospheric CO2 concentration. The model is driven by insolation alone with other components varying according to a system of coupled, differential equations. The model is run for 500 ka to produce several glacial cycles and the resulting changes in global ice volume and atmospheric CO2 concentration.We obtain a switch from 40 ka to 100 ka cycles as the volcanic CO2 response to glacial cycles is increased. These 100 ka cycles are phase-locked to obliquity, lasting 80 or 120 ka. Whilst the MOR response required (in this model) is larger than plausible estimates based on [2], it illustrates the

  2. Bankruptcy prediction: The influence of the year prior to failure selected for model building and the effects in a period of economic decline

    NARCIS (Netherlands)

    Pompe, P.P.M.; Bilderbeek, J.

    2005-01-01

    Using large amounts of data from small and medium-sized industrial firms, this study examines two aspects of bankruptcy prediction: the influence of the year prior to failure selected for model building and the effects in a period of economic decline. The results show that especially models

  3. Influence of calendar period on the association between BMI and coronary heart disease: a meta-analysis of 31 cohorts : Review

    NARCIS (Netherlands)

    Hollander, de E.L.; Bogers, R.P.; Boshuizen, H.C.; Rosengren, A.; Shipley, M.J.; Knekt, P.; Ducimetiere, P.; Menotti, A.; Groot, de C.P.G.M.; Bemelmans, W.J.E.

    2013-01-01

    Objective: The association between obesity and coronary heart disease (CHD) may have changed over time, for example due to improved pharmacological treatment of CHD risk factors. This meta-analysis of 31 prospective cohort studies explores the influence of calendar period on CHD risk associated with

  4. Bankruptcy prediction: The influence of the year prior to failure selected for model building and the effects in a period of economic decline

    NARCIS (Netherlands)

    Pompe, P.P.M.; Bilderbeek, J.

    2005-01-01

    Using large amounts of data from small and medium-sized industrial firms, this study examines two aspects of bankruptcy prediction: the influence of the year prior to failure selected for model building and the effects in a period of economic decline. The results show that especially models generate

  5. Volcanic studies at Katmai

    Energy Technology Data Exchange (ETDEWEB)

    1989-12-31

    The Continental Scientific Drilling Program (CSDP) is a national effort supported by the Department of Energy, the US Geological Survey, and the National Science Foundation. One of the projects proposed for the CSDP consists of drilling a series of holes in Katmai National Park in Alaska to give a third dimension to the model of the 1912 eruption of Novarupta, and to investigate the processes of explosive volcanism and hydrothermal transport of metals (Eichelberger et al., 1988). The proposal for research drilling at Katmai states that ``the size, youth, elevated temperature, and simplicity of the Novarupta vent make it a truly unique scientific target.`` The National Park Service (NPS), which has jurisdiction, is sympathetic to aims of the study. However, NPS wishes to know whether Katmai is indeed uniquely suited to the research, and has asked the Interagency Coordinating Group to support an independent assessment of this claim. NPS suggested the National Academy of Sciences as an appropriate organization to conduct the assessment. In response, the National Research Council -- the working arm of the Academy -- established, under the aegis of its US Geodynamics Committee, a panel whose specific charge states: ``The proposed investigation at Katmai has been extensively reviewed for scientific merit by the three sponsoring and participating agencies. Thus, the scientific merit of the proposed drilling at Katmai is not at issue. The panel will review the proposal for scientific drilling at Katmai and prepare a short report addressing the specific question of the degree to which it is essential that the drilling be conducted at Katmai as opposed to volcanic areas elsewhere in the world.``

  6. Quaternary basaltic volcanism in the Payenia volcanic province, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina

    The extensive Quaternary volcanism in the Payenia volcanic province, Mendoza, Argentina, is investigated in this study by major and trace element analyses, Sr, Nd, Hf and Pb-isotopic analyses and Zr-Hf isotope dilution data on samples from almost the entire province. The samples are mainly...... in basalts from all the studied volcanic fields in Payenia is signs of lower crustal contamination indicating assimilation of, in some cases, large amounts of trace element depleted, mafic, plagioclase-bearing rocks. The northern Payenia is dominated by backarc basalts erupted between late Pliocene to late...

  7. Impact of volcanism on the evolution of Lake Van (eastern Anatolia) III: Periodic (Nemrut) vs. episodic (Süphan) explosive eruptions and climate forcing reflected in a tephra gap between ca. 14 ka and ca. 30 ka

    Science.gov (United States)

    Schmincke, Hans-Ulrich; Sumita, Mari

    2014-09-01

    Fifteen Lateglacial to Holocene rhyolitic, dominantly primary tephra layers piston-cored and drilled (ICDP Paleovan drilling project) in western Lake Van (eastern Anatolia, Turkey) were precisely correlated to either of the two adjacent and active large volcanoes Nemrut and Süphan based on shard textures, mineralogy and mineral and glass compositions. The young peralkaline (comenditic to pantelleritic) primary rhyolitic Nemrut tephras are characterized by anorthoclase, hedenbergitic to augitic clinopyroxene, fayalitic olivine, minor quartz, and rare accessory chevkinite and zircon. Phenocrysts in subalkaline primary rhyolitic Süphan tephras are chiefly oligoclase-labradorite, with minor K-rich sanidine in some, biotite, amphibole, hypersthene, rare augitic clinopyroxene, relatively common allanite and rare zircon. Two contrasting explosive eruptive modes are distinguished from each other: episodic (Süphan) and periodic (Nemrut). The Lateglacial Süphan tephra swarm covers a short time interval of ca. 338 years between ca. 13,078 vy BP and 12,740 vy BP, eruptions having occurred statistically every ca. 42 years with especially short intervals between V-11 (reworked) and V-14. Causes for the strongly episodic Süphan explosive behavior might include seismic triggering of a volcano-magma system unable to erupt explosively without the benefit of external triggering, as reflected in pervasive faulting preceding the Süphan tephra swarm. Seismic triggering may have caused the rise of more mafic ("trachyandesitic") parent magma, heating near-surface pockets of highly evolved magma - that might have formed silicic domes during this stage of volcano evolution - resulting in ascent and finally explosive fragmentation of magma essentially by external factors, probably significantly enhanced by magma-water/ice interaction. Explosive eruptions of the Nemrut volcano system, interpreted to be underlain by a large fractionating magma reservoir, follow a more periodic mode of (a

  8. Landscape formation and soil genesis in volcanic parent materials in humid tropical lowlands of Costa Rica.

    NARCIS (Netherlands)

    Nieuwenhuyse, A.

    1996-01-01

    The influence of volcanism on landscape genesis, and formation of soils on volcanic parent material was studied in the Atlantic lowland of Costs Rica. This lowland is a subduction basin of tectonic origin, in which thick alluvial and marine sediments are accumulated. At its southwestern side it is b

  9. Io. [theories concerning volcanic activity

    Science.gov (United States)

    Johnson, T. V.; Soderblom, L. A.

    1983-01-01

    A report on the continuing investigation of Io is presented. Gravitational resonance is discussed as the cause of Io's volcanism, and the volcanic activity is explained in terms of sulfur chemistry. Theories concerning the reasons for the two main types of volcanic eruptions on Io are advanced and correlated with geographical features of the satellite. The sulfur and silicate models of the calderas are presented, citing the strengths and weaknesses of each. Problems of the gravitational resonance theory of Io's heat source are then described. Finally, observations of Io planned for the Galileo mission are summarized.

  10. Atmospheric and environmental impacts of volcanic ash particle emissions

    Science.gov (United States)

    Durant, Adam

    2010-05-01

    Globally, at any one time, there may be 20 volcanoes erupting that collectively emit a constant flux of gases and aerosol, including silicate particles (tephra), to the atmosphere which influences processes including cloud microphysics, heterogeneous chemistry and radiative balance. The nature and impact of atmospheric volcanic particle fluxes depend on total mass erupted, emission rate, emission source location, physical and chemical properties of the particles, and the location and residence time of the particles in the atmosphere. Removal of ash particles from the atmosphere through sedimentation is strongly influenced by particle aggregation through hydrometeor formation, and convective instabilities such as mammatus. I will address the following questions: What are the atmospheric impacts of volcanic ash emissions? What controls the residence time of volcanic particles in the atmosphere? What affects particle accumulation at the surface? And what are the human and environmental impacts of ash fallout?

  11. Age, distance, and geochemical evolution within a monogenetic volcanic field: Analyzing patterns in the Auckland Volcanic Field eruption sequence

    Science.gov (United States)

    Corvec, Nicolas Le; Bebbington, Mark S.; Lindsay, Jan M.; McGee, Lucy E.

    2013-09-01

    The Auckland Volcanic Field (AVF) is a young active monogenetic basaltic field, which contains ˜50 volcanoes scattered across the Auckland metropolitan area. Understanding the temporal, spatial, and chemical evolution of the AVF during the last c.a. 250 ka is crucial in order to forecast a future eruption. Recent studies have provided new age constraints and potential temporal sequences of the past eruptions within the AVF. We use this information to study how the spatial distribution of the volcanic centers evolves with time, and how the chemical composition of the erupted magmas evolves with time and space. We seek to develop a methodology which compares successive eruptions to describe the link between geochemical and spatiotemporal evolution of volcanic centers within a monogenetic volcanic field. This methodology is tested with the present day data of the AVF. The Poisson nearest neighbor analysis shows that the spatial behavior of the field has been constant overtime, with the spatial distribution of the volcanic centers fitting the Poisson model within the significance levels. The results of the meta-analysis show the existence of correlations between the chemical composition of the erupted magmas and distance, volume, and time. The apparent randomness of the spatiotemporal evolution of the volcanic centers observed at the surface is probably influenced by the activity of the source. The methodology developed in this study can be used to identify possible relationships between composition trends and volume, time and/or distance to the behavior of the source, for successive eruptions of the AVF.

  12. 2003-2004 Campaign GPS Geodetic Monitoring of Surface Deformation Proximal to Volcanic Centers, Commonwealth of Dominica, Lesser Antilles.

    Science.gov (United States)

    Davidson, R. T.; Turner, H. L.; Blessing, B. C.; Parra, J.; Fitzgibbon, K.; Jansma, P.; Mattioli, G.

    2004-12-01

    The Commonwealth of Dominica, located midway along the Lesser Antilles island arc, is home to several (at least eight) potentially active volcanic centers. Spurred by recent seismic crises on the island - in the south from 1998-2000 and in the north in 2003 - twelve GPS monuments were installed in two field campaigns in 2001 and 2003. All twelve sites, along with five of six newly installed sites, were occupied continuously for ~2.5 or more UTC days in 2004 using Ashtech Z-12 dual-frequency, code-phase receivers and choke ring antenna to assess the highly complex and possibly interconnected volcanic systems of Dominica. We examine data from the 2003-2004 epochs because of the highly variable, shallow seismicity preceding this period. This way one can potentially isolate the changes that occurred without the data from previous observations influencing the results. Although only two epochs have been included, data quality and reliability can be established from sites distant from volcanic centers, as such sites show consistent velocities from all three epochs of observation over the 2001-2004 period. Between 2003 and 2004, multiple sites show velocities that are inconsistent with a simple tectonic interpretation of elastic strain accumulation along the plate interface. Sites located in the vicinity of the volcanic centers in the south central part of the island are moving faster than the 3 epoch 2001-2004 average of the velocities, which is approximately 7mm/year. The four sites at which greater movement has been noted have velocities ranging from approximately 10 to 27 mm/year. We note that the largest surface deformation signal is seen in the south during the same period when the shallow seismicity was at a maximum in the north of the island. While the spatial distribution of sites remains sparse and the velocities relatively imprecise, the preliminary results may indicate shallow magmatic emplacement, geothermal fluctuations, or structural instability in that part

  13. period-1 encodes an ATP-dependent RNA helicase that influences nutritional compensation of the Neurospora circadian clock

    Energy Technology Data Exchange (ETDEWEB)

    Emerson, Jillian M.; Bartholomai, Bradley M.; Ringelberg, Carol; Baker, Scott E.; Loros, Jennifer J.; Dunlap, Jay C.

    2015-12-22

    Mutants in the period-1 (prd-1) gene, characterized by a recessive allele, display a reduced growth rate and period lengthening of the developmental cycle controlled by the circadian clock. We refined the genetic location of prd-1 and used whole genome sequencing to find the mutation defining it, confirming the identity of prd-1 by rescuing the mutant circadian phenotype via transformation. PRD-1 is an RNA helicase whose orthologs, DDX5 and DDX17 in humans and Dbp2p in yeast, are implicated in various processes including transcriptional regulation, elongation, and termination, 23 ribosome biogenesis, and RNA decay. Although prdi-1smutantssiois an ATP-dependent RNA helicase, member of a sub-family display a long period (~25 hrs) circadian developmental cycle, they interestingly display a wild type period when the core circadian oscillator is tracked using a frq-luciferase transcriptional fusion under conditions of limiting nutritional carbon; the core oscillator runs with a long period under glucose-sufficient conditions. Thus PRD-1 clearly impacts the circadian oscillator and is not only part of a metabolic oscillator ancillary to the core clock. PRD-1 is an essential protein and its expression is neither light-regulated nor clock-regulated. However, it is transiently induced by glucose; in the presence of sufficient glucose PRD-1 is in the nucleus until glucose runs out which elicits its disappearance from the nucleus. Because circadian period length is carbon concentration-dependent, prd­-1 may be formally viewed as clock mutant with defective nutritional compensation of circadian period length.

  14. The Atmospheric Radiation Measurement Program May 2003 Intensive Operations Period Examining Aerosol Properties and Radiative Influences: Preface to Special Section

    Science.gov (United States)

    Ferrare, Richard; Feingold, Graham; Ghan, Steven; Ogren, John; Schmid, Beat; Schwartz, Stephen E.; Sheridan, Pat

    2006-01-01

    Atmospheric aerosols influence climate by scattering and absorbing radiation in clear air (direct effects) and by serving as cloud condensation nuclei, modifying the microphysical properties of clouds, influencing radiation and precipitation development (indirect effects). Much of present uncertainty in forcing of climate change is due to uncertainty in the relations between aerosol microphysical and optical properties and their radiative influences (direct effects) and between microphysical properties and their ability to serve as cloud condensation nuclei at given supersaturations (indirect effects). This paper introduces a special section that reports on a field campaign conducted at the Department of Energy Atmospheric Radiation Measurement site in North Central Oklahoma in May, 2003, examining these relations using in situ airborne measurements and surface-, airborne-, and space-based remote sensing.

  15. Hierarchical periodic micro/nano-structures on nitinol and their influence on oriented endothelialization and anti-thrombosis.

    Science.gov (United States)

    Nozaki, Kosuke; Shinonaga, Togo; Ebe, Noriko; Horiuchi, Naohiro; Nakamura, Miho; Tsutsumi, Yusuke; Hanawa, Takao; Tsukamoto, Masahiro; Yamashita, Kimihiro; Nagai, Akiko

    2015-12-01

    The applications of hierarchical micro/nano-structures, which possess properties of two-scale roughness, have been studied in various fields. In this study, hierarchical periodic micro/nano-structures were fabricated on nitinol, an equiatomic Ni-Ti alloy, using a femtosecond laser for the surface modification of intravascular stents. By controlling the laser fluence, two types of surfaces were developed: periodic nano- and micro/nano-structures. Evaluation of water contact angles indicated that the nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. Endothelial cells aligned along the nano-structures on both surfaces, whereas platelets failed to adhere to the micro/nano-surface. Decorrelation between the responses of the two cell types and the results of water contact angle analysis were a result of the pinning effect. This is the first study to show the applicability of hierarchical periodic micro/nano-structures for surface modification of nitinol.

  16. Volcanic eruptions observed with infrasound

    Science.gov (United States)

    Johnson, Jeffrey B.; Aster, Richard C.; Kyle, Philip R.

    2004-07-01

    Infrasonic airwaves produced by active volcanoes provide valuable insight into the eruption dynamics. Because the infrasonic pressure field may be directly associated with the flux rate of gas released at a volcanic vent, infrasound also enhances the efficacy of volcanic hazard monitoring and continuous studies of conduit processes. Here we present new results from Erebus, Fuego, and Villarrica volcanoes highlighting uses of infrasound for constraining quantitative eruption parameters, such as eruption duration, source mechanism, and explosive gas flux.

  17. Los volcanes y los hombres

    OpenAIRE

    García, Carmen

    2007-01-01

    Desde las entrañas de la tierra, los volcanes han creado la atmósfera, el agua de los océanos, y esculpido los relieves del planeta: son, pues, los zahoríes de la vida. Existen volcanes que los hombres explotan o cultivan, y otros sobre los cuales se han construido observatorios en los que se llevan a cabo avanzadas investigaciones científicas.

  18. Volcanic hazards and aviation safety

    Science.gov (United States)

    Casadevall, Thomas J.; Thompson, Theodore B.; Ewert, John W.; ,

    1996-01-01

    An aeronautical chart was developed to determine the relative proximity of volcanoes or ash clouds to the airports and flight corridors that may be affected by volcanic debris. The map aims to inform and increase awareness about the close spatial relationship between volcanoes and aviation operations. It shows the locations of the active volcanoes together with selected aeronautical navigation aids and great-circle routes. The map mitigates the threat that volcanic hazards pose to aircraft and improves aviation safety.

  19. Pharmacogenetics May Influence Tacrolimus Daily Dose, But Not Urinary Tubular Damage Markers In The Long-Term Period After Renal Transplantation

    Directory of Open Access Journals (Sweden)

    Stefanović Nikola Z.

    2015-10-01

    Full Text Available Background: The primary goal of this study was to evaluate the influence of cytochrome P450 (CYP 3A5 (6986A>G and ABCB1 (3435C>T polymorphisms on tacrolimus (TAC dosage regimen and exposure. Second, we evaluated the influence of TAC dosage regimen and the tested polymorphisms on renal oxidative injury, as well as the urinary activities of tubular ectoenzymes in a long-term period after transplantation. Also, we aimed to determine the association between renal oxidative stress and tubular damage markers in the renal transplant patients.

  20. Volcanic Zone, New Zealand

    Directory of Open Access Journals (Sweden)

    Graham J. Weir

    2001-01-01

    Full Text Available A conceptual model of the Taupo Volcanic Zone (TVZ is developed, to a depth of 25 km, formed from three constant density layers. The upper layer is formed from eruption products. A constant rate of eruption is assumed, which eventually implies a constant rate of extension, and a constant rate of volumetric creation in the middle and bottom layers. Tectonic extension creates volume which can accomodate magmatic intrusions. Spreading models assume this volume is distributed throughout the whole region, perhaps in vertical dykes, whereas rifting models assume the upper crust is thinned and the volume created lies under this upper crust. Bounds on the heat flow from such magmatic intrusions are calculated. Heat flow calculations are performed and some examples are provided which match the present total heat output from the TVZ of about 4200 MW, but these either have extension rates greater than the low values of about 8 ± 4 mm/a being reported from GPS measurements, or else consider extension rates in the TVZ to have varied over time.

  1. Intra-operative remifentanil might influence pain levels in the immediate post-operative period after major abdominal surgery

    DEFF Research Database (Denmark)

    Hansen, E G; Duedahl, T H; Rømsing, J;

    2005-01-01

    Remifentanil, a widely used analgesic agent in anaesthesia, has a rapid onset and short duration of action. In clinical settings, this requires an appropriate pain strategy to prevent unacceptable pain in the post-operative period. The aim of this study was to investigate whether remifentanil had...... any impact on post-operative pain and opioid consumption after major abdominal surgery.......Remifentanil, a widely used analgesic agent in anaesthesia, has a rapid onset and short duration of action. In clinical settings, this requires an appropriate pain strategy to prevent unacceptable pain in the post-operative period. The aim of this study was to investigate whether remifentanil had...

  2. INFLUENCE OF EUROPEAN FUNDS ON THE SECTOR OF BOVINE MILK AND MEAT IN ROMANIA IN THE PERIOD 2007-2013

    Directory of Open Access Journals (Sweden)

    Andrei-Marius SANDU

    2014-12-01

    Full Text Available This study aims to analyze the bovine meat and milk sector for the period 2007-2013. In the analyzed period, Romania has benefited from EU funding through the National Rural Development Programme 2007-2013. In this programme there were measures that addressed exclusively to the animal husbandry sector in Romania. This paper presents the results of the analysis on bovine production of meat, milk and livestock in Romania, but also on the price and impact that the European Funds implementation had on them.

  3. Intra-operative remifentanil might influence pain levels in the immediate postoperative period after major abdominal surgery

    DEFF Research Database (Denmark)

    Hansen, EG; Duedahl, Tina H; Rømsing, Janne

    2005-01-01

    Remifentanil, a widely used analgesic agent in anaesthesia, has a rapid onset and short duration of action. In clinical settings, this requires an appropriate pain strategy to prevent unacceptable pain in the post-operative period. The aim of this study was to investigate whether remifentanil had...

  4. The Analysis on the Influence of Water Conservancy Investment on Agricultural Economic Growth: An Empirical Study Based on the Boom Period of Shandong Agriculture

    Institute of Scientific and Technical Information of China (English)

    Jinping; CAO; Zhe; FENG; Jilian; HU

    2014-01-01

    This paper uses econometric methods to carry out a Granger causality test on the construction of water conservancy infrastructure construction and agricultural economic growth in the boom period(1981- 2002) of Shandong agriculture. Empirical results indicate that there exists two-way Granger causality between Shandong water conservancy infrastructure construction and Shandong agricultural economic growth.Therefore,water conservancy infrastructure construction has a significant influence on agricultural economic growth in Shandong.

  5. [The influence of frequency and blockade of the autonomic nervous system on the functional behaviour of the human conduction system. Part B: Refractory periods (author's transl)].

    Science.gov (United States)

    Runge, M; Luckmann, E; Narula, O S

    1976-01-01

    32 patients were studied by His-bundle-electrocardiogram and programmed atrial stimulation to examine to which extent frequency and autonomic tone participate in influencing the effective (ERP) and functional (FRP) refractory periods of the atrium and AV-node. The measurements were performed during three electrically induced atrial frequencies before and after intravenous injection of 1 mg Atropine (15 patients) and 0.4 mg Visken (17 patients). For the atrium, frequency dominates the blockade of both components of the autonomic nervous system in influencing both refractory periods. Increase in frequency shortens both ERP and FRP of the atriu. The blockade of parasympathicus and sympathicus does not significantly influence the changes in atrial ERP and FRP induced by atrial pacing. The AV-node responses most sensitive to both pacing induced cycle length shortening and blockade of the autonomic tone. Cycle length shortening prolongs the nodal ERP. the FRP is either shortened or prolonged. Blockade of the parasympathicus shortens both nodal ERP and FRP. Blockade of the sympathicus lengthens both parameters. This behaviour of both refractory periods in response to atrial pacing and blockade of the autonomic tone are discussed with respect to the "gate mechanism" in the conduction system. In the majority of patients blockade of the parasympathicus shifts the "gate" from the AV-node to the atrium. Blockade of the sympathicus has the opposite effect in some cases.

  6. Field evidence of the influence of aquatic macrophytes on water quality in a shallow eutrophic lake over a 13-year period

    Directory of Open Access Journals (Sweden)

    Edélti Faria Albertoni

    2014-06-01

    Full Text Available AIM: The main objective of this work is to describe the changes in water characteristics of a shallow subtropical lake, in periods with and without growing of macrophytes, related to periods of clear-macrophyte dominance and turbid-phytoplankton dominance states. METHODS: The study was conducted in Biguás Lake, in the south coastal plain of Brazil (32° 04' 43" S and 52° 10' 03" W. Samplings were carried out monthly between October 2000 and November 2013. The limnological variables measured in the water column were dissolved oxygen (DO, water temperature, pH, electrical conductivity (EC, chlorophyll-a, total nitrogen (TN, total phosphorous (TP and suspended material (SM. Data were grouped according to periods with macrophyte growth dominance (MD and without macrophytes, with phytoplankton dominance (PD, and applied t- tests among TP, TN, Chlorophyll-a and SM. During macrophyte growth we estimated the coverage (% and biomass variation of plants. RESULTS: Over the 13 years, the lake was well oxygenated, alkaline, and with a temperature variation according to subtropical seasonality. The lower values of all of the limnological variables were verified during periods of macrophyte growth, characterizing periods of clear and turbid waters. CONCLUSIONS: The influence of aquatic macrophytes in improving water quality in this shallow lake during the studied period, reducing nutrient concentrations, chlorophyll-a and suspended material in water, favoring the maintenance of a clear water state, was verified.

  7. The Boring Volcanic Field of the Portland-Vancouver area, Oregon and Washington: tectonically anomalous forearc volcanism in an urban setting

    Science.gov (United States)

    Evarts, Russell C.; Conrey, Richard M.; Fleck, Robert J.; Hagstrum, Jonathan T.; O'Connor, Jim; Dorsey, Rebecca; Madin, Ian P.

    2009-01-01

    More than 80 small volcanoes are scattered throughout the Portland-Vancouver metropolitan area of northwestern Oregon and southwestern Washington. These volcanoes constitute the Boring Volcanic Field, which is centered in the Neogene Portland Basin and merges to the east with coeval volcanic centers of the High Cascade volcanic arc. Although the character of volcanic activity is typical of many monogenetic volcanic fields, its tectonic setting is not, being located in the forearc of the Cascadia subduction system well trenchward of the volcanic-arc axis. The history and petrology of this anomalous volcanic field have been elucidated by a comprehensive program of geologic mapping, geochemistry, 40Ar/39Ar geochronology, and paleomag-netic studies. Volcanism began at 2.6 Ma with eruption of low-K tholeiite and related lavas in the southern part of the Portland Basin. At 1.6 Ma, following a hiatus of ~0.8 m.y., similar lavas erupted a few kilometers to the north, after which volcanism became widely dispersed, compositionally variable, and more or less continuous, with an average recurrence interval of 15,000 yr. The youngest centers, 50–130 ka, are found in the northern part of the field. Boring centers are generally monogenetic and mafic but a few larger edifices, ranging from basalt to low-SiO2 andesite, were also constructed. Low-K to high-K calc-alkaline compositions similar to those of the nearby volcanic arc dominate the field, but many centers erupted magmas that exhibit little influence of fluids derived from the subducting slab. The timing and compositional characteristics of Boring volcanism suggest a genetic relationship with late Neogene intra-arc rifting.

  8. Influence of the pattern shape on the photonic efficiency of front-side periodically patterned ultrathin crystalline silicon solar cells

    CERN Document Server

    Herman, Aline; Depauw, Valerie; Daif, Ounsi El; Deparis, Olivier

    2012-01-01

    Patterning the front side of an ultra-thin crystalline silicon (c Si) solar cell helps keeping the energy conversion efficiency high by compensating for the light absorption losses. A super-Gaussian mathematical expression was used in order to encompass a large variety of nanopattern shapes and to study their influence on the photonic performance. We prove that the enhancement in the maximum achievable photo-current is due to both impedance matching condition at short wavelengths and to the wave nature of light at longer wavelengths. We show that the optimal mathematical shape and parameters of the pattern depend on the c Si thickness. An optimal shape comes with a broad optimal parameter zone where fabricating errors would have much less influence on the efficiency. We prove that cylinders are not the best suited shape. To compare our model with a real slab, we fabricated a nanopatterned c Si slab via Nano Imprint Lithography.

  9. Socioeconomic and familial characteristics influence caretakers' adherence to the periodic vitamin A capsule supplementation program in Central Java, Indonesia.

    Science.gov (United States)

    Pangaribuan, Rosnani; Scherbaum, Veronika; Erhardt, Jürgen G; Sastroamidjojo, Soemilah; Biesalski, Hans K

    2004-06-01

    The adherence of program participants to periodic vitamin A capsule (VAC) supplementation among children aged 1-5 years (n = 677) in Central Java, Indonesia was assessed. Fourteen villages from five sub-districts and one ward from one sub-district in Central Java were included in the study to represent rural and suburban areas. All questions about demographic factors, socioeconomic conditions, current dietary practice and healthcare-seeking attitudes for common childhood illnesses, previous breastfeeding experience, their knowledge about vitamin A and adherence to the VAC program after capsule distribution (two periods in 2000) were asked. Caretakers with limited knowledge about the health benefits of vitamin A, households with more than one preschool child, and households with older children (> 36 months) were associated with a decreased likelihood of regular participation in the program with odds ratios of 0.38, 0.55, and 0.26, respectively (p program regularly with an odds ratio of 2.02 (p program.

  10. Evidence for sub-lacustrine volcanic activity in Lake Bolsena (central Italy) revealed by high resolution seismic data sets

    Science.gov (United States)

    Lindhorst, Katja; Krastel, Sebastian; Wagner, Bernd; Schuerer, Anke

    2017-06-01

    The Bolsena caldera that formed between 0.6 and 0.2 Ma has a well preserved structural rim, which makes it an ideal site to study the tectonic and volcanic evolution of calderas. However, the main area is covered by a 150 m deep lake which makes it rather difficult to investigate the subsurface structure directly. To overcome this problem new high resolution hydro-acoustic surveys using a multichannel reflection seismic system and a sediment echo-sounder system were conducted in September 2012. As space was limited we used a rowing boat towed by a rubber boat to handle a 36 m long and 24 channel streamer to receive seismic reflections produced using a Mini GI-Gun (0.25 l). The subsurface structure of Lake Bolsena was imaged up to a sediment depth of 190 m, which is estimated to have filled over a period of 333 kyrs. However, massive pyroclastic flow deposits found in the deeper parts of the basin indicate an initial infill of volcanic deposits from two adjacent younger calderas, the Latera (W) and Montefiascone (SE) calderas. Our data suggest that the caldera has a long history of active volcanism, because the lacustrine sediments show post-sedimentary influences of geothermal fluids. We mapped several mound structures at various stratigraphic depths. Two volcanic structures outcrop at the modern lake surface implying recent activity. One of these structures is hardly covered by sediments and has a crater-like feature in its summit. The other structure shows a pockmark-like depression on top. Another observable feature is a partially sediment filled crater located in the western part of the lake which further implies the existence of a magma chamber located beneath the Bolsena caldera. Since the late Pleistocene and Holocene, the sedimentation was mainly hemipelagic evidenced by a sediment drape of up to 10 m thick sediment drape on the uppermost sediments. Beneath the drape we found evidence for a distal tephra layer likely related to an explosive eruption from

  11. The influence of the dechanneling process on the photon emission by an ultra-relativistc positron channeling in a periodically bent crystal

    CERN Document Server

    Korol, A V; Greiner, W

    2001-01-01

    We investigate, both analytically and numerically, the influence of the dechanneling process on the parameters of undulator radiation generated by ultra-relativistic positron channelling along a crystal plane, which is periodically bent. The bending might be due either to the propagation of a transverse acoustic wave through the crystal, or due to the static strain as it occurs in superlattices. In either case the periodically bent crystal serves as an undulator which allows to generate X-ray and gamma-radiation. We propose the scheme for accurate quantitative treatment of the radiation in presence of the dechanneling. The scheme includes (i) the analytic expression for spectral-angular distribution which contains, as a parameter, the dechanneling length, (ii) the simulation procedure of the dechanneling process of a positron in periodically bent crystals. Using these we calculate the dechanneling lengths of 5 GeV positrons channeling in Si, Ge and W crystals, and the spectral-angular and spectral distributio...

  12. Factors influencing the progress of mobilization in hip fracture patients during the early postsurgical period?-A prospective observational study.

    Science.gov (United States)

    Buecking, Benjamin; Bohl, Katharina; Eschbach, Daphne; Bliemel, Christopher; Aigner, Rene; Balzer-Geldsetzer, Monika; Dodel, Richard; Ruchholtz, Steffen; Debus, Florian

    2015-01-01

    The aim of the present study was to determine the independent factors influencing mobilization progress after geriatric hip fractures. 392 Hip fracture patients older than 60 years were included in this prospective, observational, cohort study. The progress of mobilization was measured with walking ability 4 days post-surgery, ability to climb stairs until discharge and the Tinetti test at discharge. Factors correlated with the progress of mobilization were determined using multivariate analyses. The independent factors influencing walking ability 4 days post-surgery were the pre-fracture Charlson Comorbidity Index (OR=0.834, p=0.005), the American Society of Anesthesiologists Score (OR=0.550, p=0.013), pre-fracture Barthel Index ([BI], OR=1.019, p=0.012) and risk for depression, as measured by the Geriatric Depression Scale, (OR=0.896, p=0.013). The probability of climbing stairs until discharge was influenced by the patient's age (OR=0.840, pTinetti test ad discharge. While pre-fracture co-morbidities and function cannot be changed, the treatment of patients with cognitive impairment and depressive symptoms should be optimized. Efforts should be undertaken to ensure early surgery for all hip fractures. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  13. Hierarchical periodic micro/nano-structures on nitinol and their influence on oriented endothelialization and anti-thrombosis

    Energy Technology Data Exchange (ETDEWEB)

    Nozaki, Kosuke [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Shinonaga, Togo [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Ebe, Noriko; Horiuchi, Naohiro; Nakamura, Miho; Tsutsumi, Yusuke; Hanawa, Takao [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Tsukamoto, Masahiro [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Yamashita, Kimihiro [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan); Nagai, Akiko, E-mail: nag-bcr@tmd.ac.jp [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda, Tokyo 101-0062 (Japan)

    2015-12-01

    The applications of hierarchical micro/nano-structures, which possess properties of two-scale roughness, have been studied in various fields. In this study, hierarchical periodic micro/nano-structures were fabricated on nitinol, an equiatomic Ni–Ti alloy, using a femtosecond laser for the surface modification of intravascular stents. By controlling the laser fluence, two types of surfaces were developed: periodic nano- and micro/nano-structures. Evaluation of water contact angles indicated that the nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. Endothelial cells aligned along the nano-structures on both surfaces, whereas platelets failed to adhere to the micro/nano-surface. Decorrelation between the responses of the two cell types and the results of water contact angle analysis were a result of the pinning effect. This is the first study to show the applicability of hierarchical periodic micro/nano-structures for surface modification of nitinol. - Highlights: • Hierarchical micro/nano-structures were created on nitinol using a femtosecond laser. • The nano-surface was hydrophilic and the micro/nano-surface was hydrophobic. • Endothelial cells aligned along the nano-structures • Platelets failed to adhere to the micro/nano-surface.

  14. Influence of Tropical Cyclones Period 1970 TO 2010 IN the Region of Bahia de Banderas, Nayarit-Jalisco Mexico

    Science.gov (United States)

    Hernandez, J. M.

    2013-12-01

    This study evaluates the impacts of tropical cyclones (TC) that made landfall in populated areas along the Pacific coast of Mexico, especially in the region of Bahia de Banderas. During the period of 1970-2010 and used a database of international natural disasters to identify impacts. Were more than 13 events during the reporting period, of which 10 are examined more precipitation accumulated and 6 that caused further damage to the affected population in these cases ranged from 5000 to more than 15 000 inhabitants. Strong winds and heavy rainfall in periods of one to three days were associated with property damage and loss of life. The results of the study indicate that excessive accumulations of rain and daily intensity are important factors connected with the occurrence of disasters in densely populated areas. Six of the first 10 Tropical Cyclone associated with major disasters occurred in conditions of El Niño and four neutral conditions. With the analysis of satellite images using GOES-10 in the IDV software maps were obtained in the coastal impacts of Banderas Bay and describes the main features of each meteorological phenomena. In which concludes that no tropical cyclone entered directly to the Banderas Bay region, but its effects were very relevant, taking into account the topography, land use change and the vulnerability of the region. Tropical Cyclones that have affected the region of Bay of Banderas

  15. Building Better Volcanic Hazard Maps Through Scientific and Stakeholder Collaboration

    Science.gov (United States)

    Thompson, M. A.; Lindsay, J. M.; Calder, E.

    2015-12-01

    All across the world information about natural hazards such as volcanic eruptions, earthquakes and tsunami is shared and communicated using maps that show which locations are potentially exposed to hazards of varying intensities. Unlike earthquakes and tsunami, which typically produce one dominant hazardous phenomenon (ground shaking and inundation, respectively) volcanic eruptions can produce a wide variety of phenomena that range from near-vent (e.g. pyroclastic flows, ground shaking) to distal (e.g. volcanic ash, inundation via tsunami), and that vary in intensity depending on the type and location of the volcano. This complexity poses challenges in depicting volcanic hazard on a map, and to date there has been no consistent approach, with a wide range of hazard maps produced and little evaluation of their relative efficacy. Moreover, in traditional hazard mapping practice, scientists analyse data about a hazard, and then display the results on a map that is then presented to stakeholders. This one-way, top-down approach to hazard communication does not necessarily translate into effective hazard education, or, as tragically demonstrated by Nevado del Ruiz, Columbia in 1985, its use in risk mitigation by civil authorities. Furthermore, messages taken away from a hazard map can be strongly influenced by its visual design. Thus, hazard maps are more likely to be useful, usable and used if relevant stakeholders are engaged during the hazard map process to ensure a) the map is designed in a relevant way and b) the map takes into account how users interpret and read different map features and designs. The IAVCEI Commission on Volcanic Hazards and Risk has recently launched a Hazard Mapping Working Group to collate some of these experiences in graphically depicting volcanic hazard from around the world, including Latin America and the Caribbean, with the aim of preparing some Considerations for Producing Volcanic Hazard Maps that may help map makers in the future.

  16. Phreatomagmatic and water-influenced Strombolian eruptions of a small-volume parasitic cone complex on the southern ringplain of Mt. Ruapehu, New Zealand: Facies architecture and eruption mechanisms of the Ohakune Volcanic Complex controlled by an unstable fissure eruption

    Science.gov (United States)

    Kósik, S.; Németh, K.; Kereszturi, G.; Procter, J. N.; Zellmer, G. F.; Geshi, N.

    2016-11-01

    The Ohakune Volcanic Complex is a late Pleistocene tuff ring - scoria/spatter cone complex located south of Ruapehu volcano. This small-volume volcano consists of an outer E-W elongated compound tuff ring edifice, three inner scoria-spatter cones and further volcanic depressions, located on the Ohakune Fault. We quantified accurately the variations of the eruptive styles and processes through time by systematic sampling of key stratigraphic marker beds at proximal and distal locations, and the determination of grain size distribution, componentry, density and vesicularity. Using a Digital Terrain Model coupled with stratigraphic data, we also determined the spatial distribution and volume of each identified unit and individual edifices within the Ohakune Volcanic Complex. Activity began with a shallow phreatomagmatic phase characterized by an almost continuous generation of a low eruptive column, accompanied by wet pyroclastic density currents, together with the ejection of juvenile fragments and accidental lithics from the surrounding country rocks. Subsequent activity was dominated by a variety of Strombolian eruptions exhibiting differing intensities that were at times disrupted by phreatic blasts or phreatomagmatic explosions due to the interaction with external water and/or sudden changes in magma discharge rate. At least three major vent-shifting events occurred during the eruption, which is demonstrated by the truncation of the initial tuff ring and the infilling of the truncated area by several coarse grained surge units. Our study indicates that approx. 12 × 106 m3 DRE magma erupted within maximum 2.5 to 5 months through multiple vents. The erupted magma ascended from a depth of 16-18 km, and reached the surface within approximately 50 h. Alternating eruption styles, frequent vent-shifting and a variety of emplacement mechanisms inferred from the deposits of the Ohakune Volcanic Complex demonstrate the unpredictable nature of small-volume volcanism

  17. Model-based aviation advice on distal volcanic ash clouds by assimilating aircraft in situ measurements

    Science.gov (United States)

    Fu, Guangliang; Heemink, Arnold; Lu, Sha; Segers, Arjo; Weber, Konradin; Lin, Hai-Xiang

    2016-07-01

    The forecast accuracy of distal volcanic ash clouds is important for providing valid aviation advice during volcanic ash eruption. However, because the distal part of volcanic ash plume is far from the volcano, the influence of eruption information on this part becomes rather indirect and uncertain, resulting in inaccurate volcanic ash forecasts in these distal areas. In our approach, we use real-life aircraft in situ observations, measured in the northwestern part of Germany during the 2010 Eyjafjallajökull eruption, in an ensemble-based data assimilation system combined with a volcanic ash transport model to investigate the potential improvement on the forecast accuracy with regard to the distal volcanic ash plume. We show that the error of the analyzed volcanic ash state can be significantly reduced through assimilating real-life in situ measurements. After a continuous assimilation, it is shown that the aviation advice for Germany, the Netherlands and Luxembourg can be significantly improved. We suggest that with suitable aircrafts measuring once per day across the distal volcanic ash plume, the description and prediction of volcanic ash clouds in these areas can be greatly improved.

  18. Estimation of volcanic ash refractive index from satellite infrared sounder data

    Science.gov (United States)

    Ishimoto, H.; Masuda, K.

    2014-12-01

    The properties of volcanic ash clouds (cloud height, optical depth, and effective radius of the particles) are planned to estimate from the data of the next Japanese geostationary meteorological satellite, Himawari 8/9. The volcanic ash algorithms, such as those proposed by NOAA/NESDIS and by EUMETSAT, are based on the infrared absorption properties of the ash particles, and the refractive index of a typical volcanic rock (i.e. andesite) has been used in the forward radiative transfer calculations. Because of a variety of the absorption properties for real volcanic ash particles at infrared wavelengths (9-13 micron), a large retrieval error may occur if the refractive index of the observed ash particles was different from that assumed in the retrieval algorithm. Satellite infrared sounder provides spectral information for the volcanic ash clouds. If we can estimate the refractive index of the ash particles from the infrared sounder data, a dataset of the optical properties for similar rock type of the volcanic ash can be prepared for the ash retrieval algorithms of geostationary/polar-orbiting satellites in advance. Furthermore, the estimated refractive index can be used for a diagnostic and a correction of the ash particle model in the retrieval algorithm within a period of the volcanic activities. In this work, optimal estimation of the volcanic ash parameters was conducted through the radiative transfer calculations for the window channels of the atmospheric infrared sounder (AIRS). The estimated refractive indices are proposed for the volcanic ash particles of some eruption events.

  19. Neotectonics of Graciosa island (Azores: a contribution to seismic hazard assessment of a volcanic area in a complex geodynamic setting

    Directory of Open Access Journals (Sweden)

    Ana Hipólito

    2014-02-01

    Full Text Available Graciosa is a mid-Pleistocene to Holocene volcanic island that lies in a complex plate boundary between the North American, Eurasian, and Nubian plates. Large fault scarps displace the oldest (Middle Pleistocene volcanic units, but in the younger areas recent volcanism (Holocene to Upper Pleistocene conceals the surface expression of faulting, limiting neotectonic observations. The large displacement accumulated by the older volcanic units when compared with the younger formations suggests a variability of deformation rates and the possibility of alternating periods of higher and lower tectonic deformation rates; this would increase the recurrence interval of surface rupturing earthquakes. Nevertheless, in historical times a few destructive earthquakes affected the island attesting for its seismic hazard. Regarding the structural data, two main fault systems, incompatible with a single stress field, were identified at Graciosa Island. Thus, it is proposed that the region is affected by two alternating stress fields. The stress field #1 corresponds to the regional stress regime proposed by several authors for the interplate shear zone that constitutes the Azorean segment of the Eurasia-Nubia plate boundary. It is suggested that the stress field #2 will act when the area under the influence of the regional stress field #1 narrows as a result of variations in the differential spreading rates north and south of Azores. The islands closer to the edge of the sheared region will temporarily come under the influence of a different (external stress field (stress field #2. Such data support the concept that, in the Azores, the Eurasia-Nubia boundary corresponds to a complex and wide deformation zone, variable in time.

  20. Influence of elevation on bark beetle (Coleoptera: Curculionidae, Scolytinae) community structure and flight periodicity in ponderosa pine forests of Arizona.

    Science.gov (United States)

    Williams, Kelly K; McMillin, Joel D; DeGomez, Tom E; Clancy, Karen M; Miller, Andy

    2008-02-01

    We examined abundance and flight periodicity of five Ips and six Dendroctonus species (Coleoptera: Curculionidae, Scolytinae) among three different elevation bands in ponderosa pine (Pinus ponderosa Douglas ex. Lawson) forests of northcentral Arizona. Bark beetle populations were monitored at 10 sites in each of three elevation bands (low: 1,600-1,736 m; middle: 2,058-2,230 m; high: 2,505-2,651 m) for 3 yr (2004-2006) using pheromone-baited Lindgren funnel traps. Trap contents were collected weekly from March to December. We also studied temperature differences among the elevation bands and what role this may play in beetle flight behavior. Bark beetles, regardless of species, showed no consistent elevational trend in abundance among the three bands. The higher abundances of Ips lecontei Swaine, I. calligraphus ponderosae Swaine, Dendroctonus frontalis Zimmerman, and D. brevicomis LeConte at low and middle elevations offset the greater abundance of I. knausi Swaine, D. adjunctus Blandford, D. approximatus Dietz, and D. valens LeConte at high elevations. I. pini (Say) and I. latidens LeConte were found in similar numbers across the three bands. Flight periodicity of several species varied among elevation bands. In general, the flight period shortened as elevation increased; flight initiated later and terminated earlier in the year. The timing, number, and magnitude of peaks in flight activity also varied among the elevation bands. These results suggest that abundance and flight seasonality of several bark beetles are related to elevation and the associated temperature differences. The implications of these results are discussed in relation to bark beetle management and population dynamics.

  1. The influence of separation distance during the preconditioning period of the male effect approach on reproductive performance in sheep

    Directory of Open Access Journals (Sweden)

    Eduardo Luiz Cavalcanti Caldas

    2015-01-01

    Full Text Available The study was aimed to test the effect of the separation distance between males and females during the preconditioning period on the reproductive performance of Santa Inês ewes after the male effect. Santa Inês ewes were kept at distances of 3000 m (T1, 3 m (T2, and 300 m (T3 from rams for 60 days before starting 45-day mating seasons during the dry period (DP and rainy periods (RP. Mating events were observed daily at 6:00 h and 16:00 h by trained personnel for one hour intervals. Estrous were scored as synchronized when observed until day 5 after breeding season start. Pregnancy diagnosis was performed by ultrasonography. In the DP, the first estrous averaged at 15.45±10.36 (T1, 9.25±6.41 (T2 and 13.05±10.24 (T3 days and in RP was 8.73±5.84 (T1, 9.30±5.62 (T2 and 6.10±5.66 (T3 days. All females cycled during both DP and RP. Estrous synchronization occurred in 20% of the females during DP (T1: 30%, T2: 15%, and T3: 15%. In the RP, estrous synchronization occurred in 40% of all females (T1: 30%, T2: 35%, and T3: 45%. The pregnancy rates in DP and RP were T1: 85%, T2: 80%, and T3: 75%. The results show that the male effect can be obtained simply by avoiding physical contact between males and females throughout the year under tropical conditions.

  2. Influence of the turbulence on the processes formation and relaxation of periodical artificial irregularities in the lower ionosphere

    Science.gov (United States)

    Terina, Galina

    2016-07-01

    The periodic artificial irregularities (PAI) are formed in the standing wave field of powerful radio emission. The study the scattering of probing radio pulses on PAI allowed to create a method diagnostics of the ionospheric plasma parameters - the resonance scattering method (RSM) of radio waves on the periodic artificial irregularities. The different mechanisms of PAI formation in D and E ranges of the lower ionosphere were investigated (G.I. Terina, J.Atm.Terr.Phys., 1996, 58, 645). However the height range 75-90 km where there is turbulent diffusion, remained unstudied. In present paper the study results the processes formation and relaxation of periodic artificial irregularities in this height range are considered. For the analysis the processes of the formation and the relaxation of PAI one can use quasi-hydrodynamic equation for the homogeneous isotropic ionospheric plasma. Under the small disturbances, quasi-neutral plasma and some assumptions can to obtain the differential equations for regular and fluctuation PAI parts, which take account: the ambipolar diffusion, the temperature dependence of the coefficient of electrons recombination, the temperature dependence of the coefficient of the electrons attachment to the neutral molecules and also the turbulent diffusion and caused by it small-scale irregularities of the electron density. The solutions of the inhomogeneous and homogeneous equations present the processes of the formation and relaxation of PAI accordingly. The numerical estimations of obtained solutions showed that the main reasons of PAI formation in considered range of heights are the small-scale irregularities of the electron concentration and the turbulence diffusion. The obtained results qualitatively agree with results of experimental investigations. The experiments were carried out at the heating facilities "Zimenki" and "Sura". The heater transmitter periodically was switched on for several seconds and off for the same duration. The

  3. Atmospheric chemistry in volcanic plumes.

    Science.gov (United States)

    von Glasow, Roland

    2010-04-13

    Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis.

  4. Climatic impact of volcanic eruptions

    Science.gov (United States)

    Rampino, Michael R.

    1991-01-01

    Studies have attempted to 'isolate' the volcanic signal in noisy temperature data. This assumes that it is possible to isolate a distinct volcanic signal in a record that may have a combination of forcings (ENSO, solar variability, random fluctuations, volcanism) that all interact. The key to discovering the greatest effects of volcanoes on short-term climate may be to concentrate on temperatures in regions where the effects of aerosol clouds may be amplified by perturbed atmospheric circulation patterns. This is especially true in subpolar and midlatitude areas affected by changes in the position of the polar front. Such climatic perturbation can be detected in proxy evidence such as decrease in tree-ring widths and frost rings, changes in the treeline, weather anomalies, severity of sea-ice in polar and subpolar regions, and poor grain yields and crop failures. In low latitudes, sudden temperature drops were correlated with the passage overhead of the volcanic dust cloud (Stothers, 1984). For some eruptions, such as Tambora, 1815, these kinds of proxy and anectdotal information were summarized in great detail in a number of papers and books (e.g., Post, 1978; Stothers, 1984; Stommel and Stommel, 1986; C. R. Harrington, in press). These studies lead to the general conclusion that regional effects on climate, sometimes quite severe, may be the major impact of large historical volcanic aerosol clouds.

  5. Influence of reaction period on a new packing SBBR process treating high-salt and phosphorus deficiency

    Science.gov (United States)

    Fu, J. X.; Zhou, M. J.; Yu, P. F.; Sun, M.; Ji, X. Q.; Zhang, J.

    2016-08-01

    In order to solve the problem of high-salt ballast wastewater treatment, Sequencing Biofilm Batch Reactor of new packing activated sludge process used to simulate an experimental study. When Chloride ion concentration is 20±2g/L, the impacts of reaction period and anoxic time (Ta) / aerobic time (To) on the effect of the treatment process and sludge activity were investigated. The results show the salt acclimation SBBR process can effectively remove organic contaminants; when the reaction period was 49h, the removal rates of Chemical Oxygen Demand (COD) reached more than 91.0%, and the removal rate of NH+ 4 -N was 83.3%, the removal rate of Total Nitrogen (TN) was 67.7%, and the effluent concentration of COD, NH+ 4 -N and TN were respectively 45.7mg/L, 7.8mg/L and 18.6mg/L. At this time, TF reached 43.6pg/ml. With the Ta / To increase, the degree of denitrification increased and the nitrification rate reduced. When Ta/To 1:3, the optimal nitrogen removal appeared, ammonia removal efficiency was 83.8%, the effluent concentration was 7.8mg / L, TN removal rate was 67.7%, and the effluent concentration was 18.6mg / L, to reach effluent standards. Technical support was also provided to solve the problem of coastal salt waste low phosphorus wastewater.

  6. Influence of mesoscale eddies on primary production in the South China Sea during spring inter-monsoon period

    Institute of Scientific and Technical Information of China (English)

    HU Zifeng; TAN Yehui; SONG Xingyu; ZHOU Linbin; LIAN Xiping; HUANG Liangmin; HE Yinghui

    2014-01-01

    Mesoscale eddies have been suggested to have an impact on biological carbon fixation in the South China Sea (SCS). However, their overall contribution to primary production during the spring inter-monsoon pe-riod is still unknown. Based on large-scale biological and environmental in situ observations and synchro-nous remote sensing data, the distribution patterns of phytoplankton biomass and the primary production, and the role of mesoscale eddies in regulating primary production in different eddy-controlled waters were investigated. The results suggested that the surface chlorophyll a concentrations and water column inte-grated primary production (IPP) are significantly higher in cyclonic eddies and lower in the anticyclonic eddies as compared to that in non-eddy waters. Although eddies could affect various environmental factors, such as nutrients, temperature and light availability, nutrient supply is suggested to be the most important one through which mesoscale eddies regulated the distribution patterns of phytoplankton biomass and pri-mary production. The estimated IPP in cyclonic and anticyclonic eddies are about 29.5%higher and 16.6%lower than the total average in the whole study area, respectively, indicating that the promotion effect of mesoscale cold eddies on the primary production was much stronger than the inhibition effect of the warm eddies per unit area. Overall, mesoscale eddies are crucial physical processes that affect the biological car-bon fixation and the distribution pattern of primary production in the SCS open sea, especially during the spring inter-monsoon period.

  7. Multidimensional analysis and probabilistic model of volcanic and seismic activities

    Science.gov (United States)

    Fedorov, V.

    2009-04-01

    A search for space and time regularities in volcanic and seismic events for the purpose of forecast method development seems to be of current concern, both scientifically and practically. The seismic and volcanic processes take place in the Earth's field of gravity which in turn is closely related to gravitational fields of the Moon, the Sun, and the planets of the Solar System. It is mostly gravity and tidal forces that exercise control over the Earth's configuration and relief. Dynamic gravitational interaction between the Earth and other celestial bodies makes itself evident in tidal phenomena and other effects in the geospheres (including the Earth's crust). Dynamics of the tidal and attractive forces is responsible for periodical changes in gravity force, both in value and direction [Darwin, 1965], in the rate of rotation and orbital speed; that implies related changes in the endogenic activity of the Earth. The Earth's rotation in the alternating gravitational field accounts to a considerable extent for regular pattern of crustal deformations and dislocations; it is among principal factors that control the Earth's form and structure, distribution of oceans and continents and, probably, continental drift [Peive, 1969; Khain, 1973; Kosygin, 1983]. The energy of gravitational interaction is transmitted through the tidal energy to planetary spheres and feeds various processes there, including volcanic and seismic ones. To determine degree, character and special features of tidal force contribution to the volcanic and seismic processes is of primary importance for understanding of genetic and dynamic aspects of volcanism and seismicity. Both volcanic and seismic processes are involved in evolution of celestial bodies; they are operative on the planets of the Earth group and many satellites [Essays…, 1981; Lukashov, 1996]. From this standpoint, studies of those processes are essential with a view to development of scenarios of the Earth's evolution as a celestial

  8. Long-lived volcanism within Argyre basin, Mars

    Science.gov (United States)

    Williams, Jean-Pierre; Dohm, James M.; Soare, Richard J.; Flahaut, Jessica; Lopes, Rosaly M. C.; Pathare, Asmin V.; Fairén, Alberto G.; Schulze-Makuch, Dirk; Buczkowski, Debra L.

    2017-09-01

    The Argyre basin, one of the largest impact structures on Mars with a diameter >1200 km, formed in the Early Noachian ∼3.93 Ga. The basin has collected volatiles and other material through time, and experienced partial infilling with water evident from stratigraphic sequences, crater statistics, topography, and geomorphology. Although volcanism has not been previously associated with the Argyre basin, our study of the northwest portion of the basin floor has revealed landforms suggesting volcanic and tectonic activity occurred including Argyre Mons, a ∼50 km wide volcanic-structure formed ∼3 Ga. Giant polygons with a similar surface age are also identified on terrain adjacent to the base of Argyre Mons, indicating the structure may have formed in a water-rich environment. In addition to Argyre Mons, cones, vents, mounds, dikes, and cavi or hollows, many of which are associated with extensional tectonics, are observed in the region. Multiple features appear to disrupt icy (and largely uncratered) terrain indicating a relatively young, Late Amazonian, formation age for at least some of the volcanic and tectonic features. The discovery of Argyre Mons, along with additional endogenic modification of the basin floor, suggests that the region has experienced episodes of volcanism over a protracted period of time. This has implications for habitability as the basin floor has been a region of elevated heat flow coupled with liquid water, water ice, and accumulation of sediments of diverse provenance with ranging geochemistry, along with magma-water interactions.

  9. Months between rejuvenation and volcanic eruption at Yellowstone caldera, Wyoming

    Science.gov (United States)

    Till, Christy B.; Vazquez, Jorge A.; Boyce, Jeremy W

    2015-01-01

    Rejuvenation of previously intruded silicic magma is an important process leading to effusive rhyolite, which is the most common product of volcanism at calderas with protracted histories of eruption and unrest such as Yellowstone, Long Valley, and Valles, USA. Although orders of magnitude smaller in volume than rare caldera-forming super-eruptions, these relatively frequent effusions of rhyolite are comparable to the largest eruptions of the 20th century and pose a considerable volcanic hazard. However, the physical pathway from rejuvenation to eruption of silicic magma is unclear particularly because the time between reheating of a subvolcanic intrusion and eruption is poorly quantified. This study uses geospeedometry of trace element profiles with nanometer resolution in sanidine crystals to reveal that Yellowstone’s most recent volcanic cycle began when remobilization of a near- or sub-solidus silicic magma occurred less than 10 months prior to eruption, following a 220,000 year period of volcanic repose. Our results reveal a geologically rapid timescale for rejuvenation and effusion of ~3 km3 of high-silica rhyolite lava even after protracted cooling of the subvolcanic system, which is consistent with recent physical modeling that predict a timescale of several years or less. Future renewal of rhyolitic volcanism at Yellowstone is likely to require an energetic intrusion of mafic or silicic magma into the shallow subvolcanic reservoir and could rapidly generate an eruptible rhyolite on timescales similar to those documented here.

  10. Detection and Classification of Volcanic Earthquakes/Tremors in Central Anatolian Volcanic Province

    Science.gov (United States)

    Kahraman, Metin; Arda Özacar, A.; Bülent Tank, S.; Uslular, Göksu; Kuşcu, Gonca; Türkelli, Niyazi

    2017-04-01

    Central Anatolia has been characterized by active volcanism since 10 Ma which created the so called Central Anatolia Volcanic Province (CAVP) where a series of volcanoes are located along the NE-SW trend. The petrological investigations reveal that the magma source in the CAVP has both subduction and asthenospheric signature possibly due to tearing of ongoing northward subduction of African plate along Aegean and Cyprus arcs. Recently, a temporary seismic array was deployed within the scope of Continental Dynamics: Central Anatolian Tectonics (CD-CAT) project and provided a unique opportunity to study the deep seismic signature of the CAVP. Passive seismic imaging efforts and magnetotellurics (MT) observations revealed low velocity and high conductivity zones supporting the presence of localized partial melt bodies beneath the CAVP at varying depths, especially around Mt. Hasan which exhibits both geological and archeological evidences for its eruption around 7500 B.C. In Central Anatolia, local seismicity detected by the CD-CAT array coincides well with the active faults zones. However, active or potentially active volcanoes within CAVP are characterized by the lack of seismic activity. In this study, seismic data recorded by permanent stations of Regional Earthquake-Tsunami Monitoring Center were combined with temporary seismic data collected by the CD-CAT array to improve sampling density across the CAVP. Later, the continuous seismic waveforms of randomly selected time intervals were manually analyzed to identify initially undetected seismic sources which have signal characters matching to volcanic earthquakes/tremors. For candidate events, frequency spectrums are constructed to classify the sources according to their physical mechanisms. Preliminary results support the presence of both volcano-tectonic (VT) and low-period (LT) events within the CAVP. In the next stage, the spectral and polarization analyses techniques will be utilized to the entire seismic

  11. 狂犬病发病潜伏期及其影响因素分析%Analysis of rabies incubation period and its influencing factors

    Institute of Scientific and Technical Information of China (English)

    黄少新

    2013-01-01

    [Objective] To understand the rabies incubation period and its influencing factors,and provide scientific evidence for developing control measures.[Methods] The rabies incubation period and its influence factors were analyzed according to 249 questionnaires of rabies in Guilin City from 2004-2011 by using survival analysis method.[Results] The median incubation period of rabies was 51 days,95% CI (42.7,59.3) days,ranging from 1-3 650 days.Interquartile of incubation period was 69 days.Single variable analysis showed that the exposed way,the site of wound,the wound treatment and inoculation after exposure were related to the rabies incubation period.The incubation periods of cases with animal initiative attack,hurt on head or face,wound treatment by doctor,inoculation after exposure were shorter significantly than those of their corresponding ways.Cox model analysis showed that the wound treatment and inoculation after exposure were the real factors influencing latent period.The incubation periods of cases with wound on head or face was the shortest.The incubation period of cases with inoculation after exposure was shorter significantly than that of no inoculation after exposure.[Conclusion] The virus infection of attack animals,the anti-infected abilities of wounded persons,the opportunity and effect of inoculation are the influencing factors of rabies incubation period.It is suggested to note that the status of animal attacks,and receive timely immunization.%目的 了解狂犬病发病潜伏期及其影响因素,为制定预防控制措施提供科学依据.方法 采用生存分析方法对广西桂林市2004-2011年249份狂犬病个案资料就潜伏期及其影响因素进行分析.结果 桂林市狂犬病发病潜伏期最短1d,最长3 650 d,中位数51d,中位数的95%可信区间为42.7 ~59.3 d,潜伏期的四分位数间距为69 d.单因素分析发现暴露方式、伤口部位、伤口处理以及暴露后有无免疫接种与狂犬病发病的

  12. Role of volcanic forcing on future global carbon cycle

    Directory of Open Access Journals (Sweden)

    J. F. Tjiputra

    2011-06-01

    Full Text Available Using a fully coupled global climate-carbon cycle model, we assess the potential role of volcanic eruptions on future projection of climate change and its associated carbon cycle feedback. The volcanic-like forcings are applied together with a business-as-usual IPCC-A2 carbon emissions scenario. We show that very large volcanic eruptions similar to Tambora lead to short-term substantial global cooling. However, over a long period, smaller eruptions similar to Pinatubo in amplitude, but set to occur frequently, would have a stronger impact on future climate change. In a scenario where the volcanic external forcings are prescribed with a five-year frequency, the induced cooling immediately lower the global temperature by more than one degree before it returns to the warming trend. Therefore, the climate change is approximately delayed by several decades, and by the end of the 21st century, the warming is still below two degrees when compared to the present day period. Our climate-carbon feedback analysis shows that future volcanic eruptions induce positive feedbacks (i.e., more carbon sink on both the terrestrial and oceanic carbon cycle. The feedback signal on the ocean is consistently smaller than the terrestrial counterpart and the feedback strength is proportionally related to the frequency of the volcanic eruption events. The cooler climate reduces the terrestrial heterotrophic respiration in the northern high latitude and increases net primary production in the tropics, which contributes to more than 45 % increase in accumulated carbon uptake over land. The increased solubility of CO2 gas in seawater associated with cooler SST is offset by a reduced CO2 partial pressure gradient between the ocean and the atmosphere, which results in small changes in net ocean carbon uptake. Similarly, there is nearly no change in the seawater buffer capacity simulated between the different volcanic scenarios. Our study shows that even

  13. Role of volcanic forcing on future global carbon cycle

    Science.gov (United States)

    Tjiputra, J. F.; Otterå, O. H.

    2011-06-01

    Using a fully coupled global climate-carbon cycle model, we assess the potential role of volcanic eruptions on future projection of climate change and its associated carbon cycle feedback. The volcanic-like forcings are applied together with a business-as-usual IPCC-A2 carbon emissions scenario. We show that very large volcanic eruptions similar to Tambora lead to short-term substantial global cooling. However, over a long period, smaller eruptions similar to Pinatubo in amplitude, but set to occur frequently, would have a stronger impact on future climate change. In a scenario where the volcanic external forcings are prescribed with a five-year frequency, the induced cooling immediately lower the global temperature by more than one degree before it returns to the warming trend. Therefore, the climate change is approximately delayed by several decades, and by the end of the 21st century, the warming is still below two degrees when compared to the present day period. Our climate-carbon feedback analysis shows that future volcanic eruptions induce positive feedbacks (i.e., more carbon sink) on both the terrestrial and oceanic carbon cycle. The feedback signal on the ocean is consistently smaller than the terrestrial counterpart and the feedback strength is proportionally related to the frequency of the volcanic eruption events. The cooler climate reduces the terrestrial heterotrophic respiration in the northern high latitude and increases net primary production in the tropics, which contributes to more than 45 % increase in accumulated carbon uptake over land. The increased solubility of CO2 gas in seawater associated with cooler SST is offset by a reduced CO2 partial pressure gradient between the ocean and the atmosphere, which results in small changes in net ocean carbon uptake. Similarly, there is nearly no change in the seawater buffer capacity simulated between the different volcanic scenarios. Our study shows that even in the relatively extreme scenario where

  14. Aurorae and Volcanic Eruptions

    Science.gov (United States)

    2001-06-01

    Thermal-IR Observations of Jupiter and Io with ISAAC at the VLT Summary Impressive thermal-infrared images have been obtained of the giant planet Jupiter during tests of a new detector in the ISAAC instrument on the ESO Very Large Telescope (VLT) at the Paranal Observatory (Chile). . They show in particular the full extent of the northern auroral ring and part of the southern aurora. A volcanic eruption was also imaged on Io , the very active inner Jovian moon. Although these observations are of an experimental nature, they demonstrate a great potential for regular monitoring of the Jovian magnetosphere by ground-based telescopes together with space-based facilities. They also provide the added benefit of direct comparison with the terrestrial magnetosphere. PR Photo 21a/01 : ISAAC image of Jupiter (L-band: 3.5-4.0 µm) . PR Photo 21b/01 : ISAAC image of Jupiter (Narrow-band 4.07 µm) . PR Photo 21c/01 : ISAAC image of Jupiter (Narrow-band 3.28 µm) . PR Photo 21d/01 : ISAAC image of Jupiter (Narrow-band 3.21 µm) . PR Photo 21e/01 : ISAAC image of the Jovian aurorae (false-colour). PR Photo 21f/01 : ISAAC image of volcanic activity on Io . Addendum : The Jovian aurorae and polar haze. Aladdin Meets Jupiter Thermal-infrared images of Jupiter and its volcanic moon Io have been obtained during a series of system tests with the new Aladdin detector in the Infrared Spectrometer And Array Camera (ISAAC) , in combination with an upgrade of the ESO-developed detector control electronics IRACE. This state-of-the-art instrument is attached to the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory. The observations were made on November 14, 2000, through various filters that isolate selected wavebands in the thermal-infrared spectral region [1]. They include a broad-band L-filter (wavelength interval 3.5 - 4.0 µm) as well as several narrow-band filters (3.21, 3.28 and 4.07 µm). The filters allow to record the light from different components of the Jovian atmosphere

  15. Properties of volcanic soils in cold climate conditions

    Science.gov (United States)

    Kuznetsova, Elena

    2017-04-01

    studies on weathering of volcanic ash and developing volcanic soils under cold climatic conditions were carried out, especially in areas with permafrost (Bäumler, 2003). Most of research on volcanic permafrost soils was done in Yukon (Canada), Kamchatka (Russia), and Antarctica, or on seasonal frost in mountain area in Iceland, Japan, New Zealand, and Ecuador. Soils of Iceland and Antarctica are used as terrestrial analogs to Martian soils (Gooding & Keil, 1978; Allen et al., 1981). The review of existing data demonstrates that there is a strong correlation between the thermal conductivity, the water-ice content, and the mineralogy of the weathered part of the volcanic ash, enhanced amount of amorphous clay minerals (allophane, palagonite) increase the proportion of unfrozen water and decrease thermal conductivity (Kuznetsova et al., 2012, 2013; Kuznetsova & Motenko, 2014), and amorphous silica does not alter to halloysite or other clay minerals even in ashes of Early Pleistocene age (Kamchatka) or Miocene and Pliocene deposits (Antarctica) due to cold temperatures. The significance of these findings is discussed in relation to the reconstruction of past climates and the influence of volcanic ash on permafrost aggradation and degradation, snow and ice ablation, and the development of glaciers.

  16. Global volcanic earthquake swarm database and preliminary analysis of volcanic earthquake swarm duration

    Directory of Open Access Journals (Sweden)

    S. R. McNutt

    1996-06-01

    Full Text Available Global data from 1979 to 1989 pertaining to volcanic earthquake swarms have been compiled into a custom-designed relational database. The database is composed of three sections: 1 a section containing general information on volcanoes, 2 a section containing earthquake swarm data (such as dates of swarm occurrence and durations, and 3 a section containing eruption information. The most abundant and reliable parameter, duration of volcanic earthquake swarms, was chosen for preliminary analysis. The distribution of all swarm durations was found to have a geometric mean of 5.5 days. Precursory swarms were then separated from those not associated with eruptions. The geometric mean precursory swarm duration was 8 days whereas the geometric mean duration of swarms not associated with eruptive activity was 3.5 days. Two groups of precursory swarms are apparent when duration is compared with the eruption repose time. Swarms with durations shorter than 4 months showed no clear relationship with the eruption repose time. However, the second group, lasting longer than 4 months, showed a significant positive correlation with the log10 of the eruption repose period. The two groups suggest that different suites of physical processes are involved in the generation of volcanic earthquake swarms.

  17. Influence of the sample design on the strong light-matter coupling in ZnSe-based periodic structures

    Science.gov (United States)

    Sebald, K.; Rahman, SK. S.; Kaya, T.; Gutowski, J.; Klein, T.; Klembt, S.; Gust, A.; Hommel, D.

    2017-06-01

    Cavity-exciton polaritons have attracted much interest because these light-matter quasiparticles are very promising for various optoelectronic applications. Bragg-polaritons have been discussed as new tools for tailoring light-matter interactions. These structures can be created by incorporating quantum wells (QWs) periodically into a distributed Bragg reflector (DBR). The advantage of this sample type is the high number of QWs which can be embedded into the sample in order to increase the Rabi-splitting energy. Calculations show, that the coverage of the sample with a thin metal layer results in an increase of the temperature stability of the strong coupling regime. In addition, this concept enables a specific spectral variation of the cavity resonance allowing for the manipulation of the light-matter interaction.

  18. Geochemical study for volcanic surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Panichi, C.; La Ruffa, G. [Consiglio Nazionale delle Ricerche, International Institute for Geothermal Research Ghezzano, PI (Italy)

    2000-07-01

    For years, geologists have been striving to reconstruct volcanic eruptions from the analysis of pyroclastic deposits and lava flows on the surface of the earth and in the oceans. This effort has produced valuable information on volcanic petrology and magma generation, separation, mixing, crystallisation, and interaction with water in phreatomagmatic and submarine eruptions. The volcanological process are tied to the dynamics of the earth's crust and lithosphere. The mantle, subducted oceanic crust, and continental crust contain different rock types and are sources of different magmas. Magmas consist primarily of completely or partially molten silicates containing volatile materials either dissolved in the melt or as bubbles of gas. The silicate and volatile portions affect the physical properties of magma and, therefore, the nature of a volcanic eruption.

  19. Models of volcanic eruption hazards

    Energy Technology Data Exchange (ETDEWEB)

    Wohletz, K.H.

    1992-01-01

    Volcanic eruptions pose an ever present but poorly constrained hazard to life and property for geothermal installations in volcanic areas. Because eruptions occur sporadically and may limit field access, quantitative and systematic field studies of eruptions are difficult to complete. Circumventing this difficulty, laboratory models and numerical simulations are pivotal in building our understanding of eruptions. For example, the results of fuel-coolant interaction experiments show that magma-water interaction controls many eruption styles. Applying these results, increasing numbers of field studies now document and interpret the role of external water eruptions. Similarly, numerical simulations solve the fundamental physics of high-speed fluid flow and give quantitative predictions that elucidate the complexities of pyroclastic flows and surges. A primary goal of these models is to guide geologists in searching for critical field relationships and making their interpretations. Coupled with field work, modeling is beginning to allow more quantitative and predictive volcanic hazard assessments.

  20. Influence of ligands on metal speciation, transport and toxicity in a tropical river during wet (monsoon) period.

    Science.gov (United States)

    Gogoi, Anindita; Tushara Chaminda, G G; An, Alicia K J; Snow, Daniel D; Li, Yusong; Kumar, Manish

    2016-11-01

    Metal speciation and transport are seldom assessed in densely populated Tropical River. An evaluation of the phase distribution for Copper (Cu), Lead (Pb) and Zinc (Zn) along with chemical speciation, variance with different water quality parameters and toxicity were conducted in the Brahmaputra River of India from upstream to downstream during wet (monsoon) periods in July 2014. Results indicated that metal free ions and carbonates were dominant in the inorganic fractions whereas metal concentrations were negligible in the anionic inorganic fractions. Due to high sediment load in the river during monsoon, metals were substantially higher in the particulate fractions than in the aqueous phase. Partition coefficient for Cu (3.1-6.1), Pb (3.4-6.5) and Zn (3.5-6.9), demonstrated strong adsorption of the metals on suspended matter. Q-mode hierarchical cluster analysis (HCA) illustrated groupings mainly governed by quality parameters rather than by the river course. R-mode results imply selectivity of the affinities of metals for different ligands. Health risk index (HRI) values were less than 1 for dissolved metal for Cu, Pb and Zn while it was greater than 1 for total metal for Pb and Cu indicating potential human health risk. The study demonstrated that binding of metals with naturally occurring dissolved organic matter or suspended particulate matter affects metal bioavailability in river during wet periods when sediment load is particularly high. A combination of empirical, computational and statistical relationships between ionic species and fractions of metals provided greater certitude in identifying the resemblance among the different locations of the river.

  1. Kamchatkan Volcanic Eruption Response Team (KVERT), Russia: preventing the danger of volcanic eruptions to aviation.

    Science.gov (United States)

    Girina, O.; Neal, Ch.

    2012-04-01

    The Kamchatkan Volcanic Eruption Response Team (KVERT) has been a collaborative project of scientists from the Institute of Volcanology and Seismology, the Kamchatka Branch of Geophysical Surveys, and the Alaska Volcano Observatory (IVS, KB GS and AVO). The purpose of KVERT is to reduce the risk of costly, damaging, and possibly deadly encounters of aircraft with volcanic ash clouds. To reduce this risk, KVERT collects all possible volcanic information and issues eruption alerts to aviation and other emergency officials. KVERT was founded by Institute of Volcanic Geology and Geochemistry FED RAS in 1993 (in 2004, IVGG merged with the Institute of Volcanology to become IVS). KVERT analyzes volcano monitoring data (seismic, satellite, visual and video, and pilot reports), assigns the Aviation Color Code, and issues reports on eruptive activity and unrest at Kamchatkan (since 1993) and Northern Kurile (since 2003) volcanoes. KVERT receives seismic monitoring data from KB GS (the Laboratory for Seismic and Volcanic Activity). KB GS maintains telemetered seismic stations to investigate 11 of the most active volcanoes in Kamchatka. Data are received around the clock and analysts evaluate data each day for every monitored volcano. Satellite data are provided from several sources to KVERT. AVO conducts satellite analysis of the Kuriles, Kamchatka, and Alaska as part of it daily monitoring and sends the interpretation to KVERT staff. KVERT interprets MODIS and MTSAT images and processes AVHRR data to look for evidence of volcanic ash and thermal anomalies. KVERT obtains visual volcanic information from volcanologist's field trips, web-cameras that monitor Klyuchevskoy (established in 2000), Sheveluch (2002), Bezymianny (2003), Koryaksky (2009), Avachinsky (2009), Kizimen (2011), and Gorely (2011) volcanoes, and pilots. KVERT staff work closely with staff of AVO, AMC (Airport Meteorological Center) at Yelizovo Airport and the Tokyo Volcanic Ash Advisory Center (VAAC), the

  2. Influence of temperature histories during reactor startup periods on microstructural evolution and mechanical properties of austenitic stainless steel irradiated with neutrons

    Science.gov (United States)

    Kasahara, Shigeki; Kitsunai, Yuji; Chimi, Yasuhiro; Chatani, Kazuhiro; Koshiishi, Masato; Nishiyama, Yutaka

    2016-11-01

    This paper addresses influence of two different temperature profiles during startup periods in the Japan Materials Testing Reactor and a boiling water reactor upon microstructural evolution and mechanical properties of austenitic stainless steel irradiated with neutrons to about 1 dpa and 3 dpa. One of the temperature profiles was that the specimens experienced neutron irradiation in both reactors, under which the irradiation temperature transiently increased to 290 °C from room temperature with increasing reactor power during reactor startup periods. Another was that the specimens were pre-heated to about 150 °C prior to the irradiation to suppress the transient temperature increase. Tensile tests at 290 °C and Vickers hardness tests at room temperature were carried out, and their microstructures were observed by FEG-TEM. Difference of the temperature profiles was observed obviously in interstitial cluster formation, in particular, growth of Frank loops. Although influence of neutron irradiation involving transient temperature increase to 290 °C from room temperature on the yield strength and the Vickers hardness is buried in the trend curves of existing data, the influence was also found certainly in increment of in yield strength, existence of modest yield drop, and loss of strain hardening capacity and ductility. As a result, Frank loops, which were observed in austenitic stainless steel irradiated at doses of 1 dpa or more, seemed to have important implications regarding the interpretation of not irradiation hardening, but deformation of the austenitic stainless steel.

  3. Morphometric characterization of monogenetic volcanic cones of the Chichinautzin and Michoacán-Guanajuato monogenetic volcanic fields in Mexico

    Science.gov (United States)

    Zarazua-Carbajal, Maria Cristina; De la Cruz-Reyna, Servando; Mendoza-Rosas, Ana Teresa

    2014-05-01

    Morphometric characterization of volcanic edifices is one of the main approaches providing information about a volcano eruptive history, whether it has one or more eruptive vents or if it had any sector collapses. It also provides essential information about the physical processes that modify their shapes during periods of quietness, and quite significantly, about the volcanoes' ages. In the case of monogenetic activity, a volcanic field can be characterized by the size and slope distributions, and other cone's morphometric parameter distributions that may provide valuable information about the temporal evolution of the volcanic field. The increasingly available high-resolution digital elevation models and the continuously developing computer tools have allowed a faster development and more detailed morphometric characterization techniques. We present here a methodology to readily obtain diverse volcanic cone shape parameters from the contour curves such as mean slope, slope distribution, dimensions of the cone and crater, crater location within the cone, orientation of the cone's principal axis, eccentricity, and other morphological features using an analysis algorithm that we developed, programmed in Python and ArcPy. Preliminary results from the implementation of this methodology to the Chichinautzin and Michoacán-Guanajuato monogenetic volcanic fields in Mexico have permitted a preliminary estimation of the age distribution of some of the cones with an acceptable correlation with the available radiometric ages. A large part of the Chichinautzin region DEM was obtained from a LIDAR survey by the Mexican National Institute of Statistics and Geography (INEGI).

  4. Recurrence models of volcanic events: Applications to volcanic risk assessment

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, B.M. [Los Alamos National Lab., Las Vegas, NV (United States); Picard, R.; Valentine, G. [Los Alamos National Lab., NM (United States); Perry, F.V. [New Mexico Univ., Albuquerque, NM (United States)

    1992-03-01

    An assessment of the risk of future volcanism has been conducted for isolation of high-level radioactive waste at the potential Yucca Mountain site in southern Nevada. Risk used in this context refers to a combined assessment of the probability and consequences of future volcanic activity. Past studies established bounds on the probability of magmatic disruption of a repository. These bounds were revised as additional data were gathered from site characterization studies. The probability of direct intersection of a potential repository located in an eight km{sup 2} area of Yucca Mountain by ascending basalt magma was bounded by the range of 10{sup {minus}8} to 10{sup {minus}10} yr{sup {minus}1 2}. The consequences of magmatic disruption of a repository were estimated in previous studies to be limited. The exact releases from such an event are dependent on the strike of an intruding basalt dike relative to the repository geometry, the timing of the basaltic event relative to the age of the radioactive waste and the mechanisms of release and dispersal of the waste radionuclides in the accessible environment. The combined low probability of repository disruption and the limited releases associated with this event established the basis for the judgement that the risk of future volcanism was relatively low. It was reasoned that that risk of future volcanism was not likely to result in disqualification of the potential Yucca Mountain site.

  5. Field-trip guide to mafic volcanism of the Cascade Range in Central Oregon—A volcanic, tectonic, hydrologic, and geomorphic journey

    Science.gov (United States)

    Deligne, Natalia I.; Mckay, Daniele; Conrey, Richard M.; Grant, Gordon E.; Johnson, Emily R.; O'Connor, Jim; Sweeney, Kristin

    2017-08-16

    The Cascade Range in central Oregon has been shaped by tectonics, volcanism, and hydrology, as well as geomorphic forces that include glaciations. As a result of the rich interplay between these forces, mafic volcanism here can have surprising manifestations, which include relatively large tephra footprints and extensive lava flows, as well as water shortages, transportation and agricultural disruption, and forest fires. Although the focus of this multidisciplinary field trip will be on mafic volcanism, we will also look at the hydrology, geomorphology, and ecology of the area, and we will examine how these elements both influence and are influenced by mafic volcanism. We will see mafic volcanic rocks at the Sand Mountain volcanic field and in the Santiam Pass area, at McKenzie Pass, and in the southern Bend region. In addition, this field trip will occur during a total solar eclipse, the first one visible in the United States in more than 25 years (and the first seen in the conterminous United States in more than 37 years).The Cascade Range is the result of subduction of the Juan de Fuca plate underneath the North American plate. This north-south-trending volcanic mountain range is immediately downwind of the Pacific Ocean, a huge source of moisture. As moisture is blown eastward from the Pacific on prevailing winds, it encounters the Cascade Range in Oregon, and the resulting orographic lift and corresponding rain shadow is one of the strongest precipitation gradients in the conterminous United States. We will see how the products of the volcanoes in the central Oregon Cascades have had a profound influence on groundwater flow and, thus, on the distribution of Pacific moisture. We will also see the influence that mafic volcanism has had on landscape evolution, vegetation development, and general hydrology.

  6. RESISTANT STARCH AND BIOACTIVE CONTENTS OF UNRIPE BANANA FLOUR AS INFLUENCED BY HARVESTING PERIODS AND ITS APPLICATION

    Directory of Open Access Journals (Sweden)

    Anuchita Moongngarm

    2014-01-01

    Full Text Available Recently, various innovative products from unripe banana flour have been reported as it is high in resistant starch and other important compounds. The harvesting period of the unripe banana fruit is one of the key factors affecting the quality of the unripe banana flour in terms of resistant starch and bioactive compound content. The study aimed to investigate the effect of the harvesting stages of unripe banana fruit on Resistant Starch (RS content, carotenoid content, antioxidant activity and the application of unripe banana flour to prepare high RS rice noodle. Four different harvesting stages of banana fruits of Musa sapientum Linn including 75, 90, 105 and 120 days after bloom, were processed for banana flours. The results indicated that the maturation stages affected RS, some bioactive contents, antioxidant activities. The highest RS content (48.88% of banana flour was obtained from the 105 day banana fruits. The total phenolic and carotenoid contents were high in the banana flours harvested between 75 and 105 days. The unripe banana flour could be substituted for rice flour as high as 80% and contained RS content as high as 18.64% whereas the commercial rice noodle had 4.21% of RS content. Therefore, the preparation of unripe banana flour from banana fruit harvested at 105 days and applying it in the preparation of functional food is promising.

  7. Vector competence of Culicoides for arboviruses: three major periods of research, their influence on current studies and future directions.

    Science.gov (United States)

    Carpenter, S; Veronesi, E; Mullens, B; Venter, G

    2015-04-01

    The spectacular and unprecedented outbreaks of bluetongue virus (BTV) that have occurred in Europe since 1998 have led to increased interest in those factors that determine competence of Culicoides biting midges (Diptera: Ceratopogonidae) for arboviruses. In this review the authors critically examine three major periods of research into the biological transmission by Culicoides of two economically important arboviruses ofthefamily Reoviridae: African horse sicknessvirus (AHSV) and BTV. First they examine early studies, largely conducted in southern Africa, that played a key role in initially implicating Culicoides as agents of AHSV and BTV transmission. Then they examine advances in understanding made following the establishment of colonies of the BTV vector species Culicoides sonorensis, which have largely shaped our current understanding of BTV and AHSV transmission. They then consider attempts in recent years to implicate vectors of BTV in the European Union during what has become the most economically damaging series of outbreaks in recorded history. In some cases the origin of these outbreaks was uncertain and unexpected, particularly in northern Europe, where BTV had not previously occurred. Limitations imposed on studies of vector competence by the biology of Culicoides are then discussed, along with advances in the technologies now available and the logistics of working upon agents requiring biosecure containment outside their endemic range. Finally, the authors suggest areas that have either been poorly addressed to date or entirely ignored and ways in which studies could be conducted to provide standardised data for comparison worldwide.

  8. Influence of the interlayer on coupling of surface plasmons in a sandwiched structure with periodic array of nanoapertures.

    Science.gov (United States)

    Sun, Liu-Yang; Qin, Ling; Zhu, Li-Hao; Fan, Ren-Hao; Li, De; Peng, Ru-Wen

    2013-02-01

    In this work, we investigate the optical properties of a multilayer structure, where a SiO2 film is sandwiched by silver films with periodic array of sub-wavelength apertures. Due to the coupling of surface plasmons (SPs) between different layers, electric and magnetic resonances have been observed. By varying the thickness of the interlayer SiO2, we can modify relative phase of the SPs resonance and control the shifts of transmission peaks. Experimentally the multilayers are fabricated by magnetron sputtering and the array of apertures is milled by focused-ion-beam facility. The measured optical transmission spectra reasonably agree with our numerical calculation, which bases on three-dimensional finite-difference time-domain method. To understand the shifts of the peaks, we present a phenomenological explanation, considering the transmission peaks as energy levels, and the coupling of localized surface plasmons as perturbation. These results may have potential applications in designing plasmonic devices and tuning electromagnetic wave in nanophotonics.

  9. Influence of bilayer period on the characteristics of nanometre-scale ZrN/TiAIN multilayers.

    Science.gov (United States)

    Vladescu, A; Kiss, A; Popescu, A; Braic, M; Balaceanu, M; Braic, V; Tudor, I; Logofatu, C; Negrila, C C; Rapeanu, R

    2008-02-01

    In the last decade, considerable research effort was directed to the deposition of multilayer films with layer thicknesses in the nanometer range (superlattice coatings), in order to increase the performance of various cutting tools and machine parts. The goal of the present work was to investigate the main microstructural, mechanical and wear resistance characteristics of a superlattice coating, consisting of alternate multilayer ZrN/TiAIN films, with various bilayer periods (5 / 20 nm). The coatings were deposited by the cathodic arc method on Si, plain carbon steel and high speed steel substrates to be used as wear resistance surfaces. The multilayer structures were prepared by using shutters placed in front of each cathode (Zr and Ti+Al). The characteristics of multilayer structures (elemental and phase composition, texture, Vickers microhardness, thickness, adhesion, and wear resistance) were determined by using various techniques (AES, XPS, XRD, microhardness measurements, scratch, and tribological tests). A comparison with the properties of ZrN and TiAIN single-layer coatings was carried out.

  10. THE INFLUENCE OF CRITICAL PNENOMENA ON THE EDUCATIONAL PROCESS OF CHILDREN AND YOUNG PEOPLE. PART III. "GENERAL SOCIAL FACTORS SHAPING THE EDUCATIONAL PROCESSES OF THE TRANSFORMATION PERIOD"

    Directory of Open Access Journals (Sweden)

    Golbik Ewa

    2010-01-01

    Full Text Available At present, the generation of people born in the eighties, entered the period of their adulthood. The time of their childhood and development was raddled with the time of the highest social tensions, the end of the socialism age, the nascency of the new constitutional transformation, and the changes in almost every aspect of social, economic and political life. The new order was born among conflicts and adversities, which did not come without the influence on the kelter of an average family. All the threats influence the shape of Polish families, and what was noticed by Z. Kwieciński, the educational reactions undertaken in the families are incoherent. If we add often negative, or outright aggressive impact of school and out of school (television, literature etc. factors, it is difficult to be surprised with the miserable educational effects appearing in the form of pathological behaviours touching children and young people.

  11. Influence of Rural Land Institutional Reform on Urbanization During the 13th Five-Year Plan Period:A Case Study of Jiangsu Province

    Institute of Scientific and Technical Information of China (English)

    Chen; Xiaohui; Qian; Fang

    2016-01-01

    The rural land institutions have confined the process of China’s urbanization for a long time. During the 13 th Five-Year Plan period, the Chinese government will push forward a new round of rural land institutional reform, so as to promote the restructuring of current rural land use pattern, change related elements concerning urbanization, and realize the transformation of the urbanization mode. Taking Jiangsu Province, a comprehensive pilot site of new urbanization at the provincial level in China, as an example, the paper summarizes the practical experience of rural land institutional reform in Jiangsu during recent years. Further, through analyzing the influence of rural land institutional reform on the urbanization process of Jiangsu Province during the 13 th Five-Year Plan period, the paper puts forward some policy measures, with the hope of providing a lasting impetus for the new urbanization in Jiangsu Province as well as a reference for other provinces in China.

  12. A 780-year record of explosive volcanism from DT263 ice core in east Antarctica

    Institute of Scientific and Technical Information of China (English)

    ZHOU Liya; LI Yuansheng; Jihong Cole-da; TAN Dejun; SUN BO; REN Jiawen; WEI Lijia; WANG Henian

    2006-01-01

    Ice cores recovered from polar ice sheet Received and preserved sulfuric acid fallout from explosive volcanic eruptions. DT263 ice core was retrieved from an east Antarctic location. The ice core is dated using a combination of annual layer counting and volcanic time stratigraphic horizon as 780 years (1215-1996 A.D.). The ice core record demonstrates that during the period of approximately 1460-1800 A.D., the accumulation is sharply lower than the levels prior to and after this period. This period coincides with the most recent neoglacial climatic episode, the "Little Ice Age (LIA)", that has been found in numerous Northern Hemisphere proxy and historic records.The non-sea-salt SO2-4 concentrations indicate seventeen volcanic events in DT263 ice core. Compared with those from previous Antarctic ice cores, significant discrepancies are found between these records in relative volcanic flux of several well-known events. The discrepancies among these records may be explained by the differences in surface topography, accumulation rate, snow drift and distribution which highlight the potential impact of local glaciology on ice core volcanic records, analytical techniques used for sulfate measurement, etc. Volcanic eruptions in middle and high southern latitudes affect volcanic records in Antarctic snow more intensively than those in the Iow latitudes.

  13. Analysis of The Influence of Liquidity, Credit and Operational Risk, in Indonesian Islamic Bank’s Financing for The Period 2007-2013

    OpenAIRE

    Diallo, Ousmane; Fitrijanti, Tettet; Tanzil, Nanny Nanny

    2015-01-01

    The purpose of this paper is to analyze the influence of credit, liquidity and operational risks in six Indonesian’s islamic banking financing products namely mudharabah, musyarakah, murabahah, istishna, ijarah and qardh, in order to try to discover whether or not Indonesian islamic banking is based on the “risk-sharing” system. This paper relies on a fixed effect model test based on the panel data analysis method, focusing on the period from 2007 to 2013. The research is an exploratory and d...

  14. The influence of Greenland melt water on climate during past and future warm periods: a model study

    Science.gov (United States)

    Blaschek, Michael; Bakker, Pepijn; Renssen, Hans

    2013-04-01

    "Can past climates teach us something about the future?" Under this general question of interest to most palaeoclimate-modeller we specified it more to "Can past changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) related to melt water from the Greenland Ice Sheet (GIS) teach us something about future changes in the AMOC forced by predicted partial melting of the GIS?" To address this question, we developed a series of sensitivity experiments with the global atmosphere-ocean-sea-ice model LOVECLIM to better understand the relationship between the strength of the Atlantic Meridional Overturning Circulation (AMOC) and Greenland Ice Sheet (GIS) melt over the last and present interglacials (the Eemian and the Holocene, respectively) and put these into perspective of future greenhouse gas emission scenarios. In terms of radiative forcing, future emission scenarios are different from past orbitally-forced warm periods, as past insolation varied per season and per latitude, whereas radiative forcing due to future greenhouse gas emissions has no seasonal component (i.e. it is an annual forcing) and shows little variation per latitude. However, the two can be compared when we consider the radiative forcing regimes of the different considered warm climates, by focusing on the energy that is potentially available from radiative forcing to melt the GIS. In a similar approach, Swingedouw et al. (2009) have shown in simulations with an AOGCM that the AMOC sensitivity relates non-linear to freshwater input and that under Last Glacial Maximum (LGM) conditions the climate is more sensitive compared to warmer climates. They conclude that different climatic conditions share similar patterns in response and that past climates are useful for models to evaluate their abilities in reproducing past events. The authors encourage further model sensitivity testing to gain a better understanding of this highly important question. In order to test this approach we

  15. Geochemical Characteristics of Danfeng Meta-Volcanic Rocks in Shangzhou Area,Shaanxi Province

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    The Danfeng meta-volcanics in the Shangzhou area, Shaanxi Province are characterized by oceanic island arc volcanic geochemistry. They are a suite of low-K tholeiitic series and calc-alkaline series meta-volcanic rocks derived from different sources respectively.These meta-volcanics have high Th/Ta ratios and low contents of Ni,Ta,Ti,Y and Yb, suggesting that they were influenced by the subduction zone components.Many lines of evidence show that the Danfeng meta-volcanics were produced in an oceanic island are setting of the supra-subduction zone at the southern margin of the North China Block during the Early Paleozoic.

  16. Two types of alkaline volcanics in the southwestern Iberian margin: The causes of their diversity

    Science.gov (United States)

    Chernysheva, E. A.; Matveenkov, V. V.; Medvedev, A. Ya.

    2012-09-01

    The diverse geodynamic conditions of the parental magma's melting are responsible for the compositional diversity of the alkaline volcanics near the southwestern margin of Iberia. The petrological-geochemical data show that the volcanics of the Gorringe Bank originated within the continental plate. The parental melilitite melts depleted in silica and anomalously enriched with trace elements could have been generated only in deep settings with a low degree of metasomatically enriched mantle matter melting. The volcanic melilitite-nephelinite-phonolite series is widespread in alkaline provinces of the Eurasian, African, and other continental plates. The Ampere, Josephine, and other seamounts and islands of the region are largely composed of volcanic rocks belonging to the picrobasalt-hawaiite-mugearite association. Their parental magmas were generated within the oceanic plate at shallower depths under a higher degree of moderately enriched oceanic lithospheric mantle melting. Both series of volcanics were formed under the influence of mantle plumes.

  17. Water quality observations of ice-covered, stagnant, eutrophic water bodies and analysis of influence of ice-covered period on water quality

    Science.gov (United States)

    sugihara, K.; Nakatsugawa, M.

    2013-12-01

    The water quality characteristics of ice-covered, stagnant, eutrophic water bodies have not been clarified because of insufficient observations. It has been pointed out that climate change has been shortening the duration of ice-cover; however, the influence of climate change on water quality has not been clarified. This study clarifies the water quality characteristics of stagnant, eutrophic water bodies that freeze in winter, based on our surveys and simulations, and examines how climate change may influence those characteristics. We made fixed-point observation using self-registering equipment and vertical water sampling. Self-registering equipment measured water temperature and dissolved oxygen(DO).vertical water sampling analyzed biological oxygen demand(BOD), total nitrogen(T-N), nitrate nitrogen(NO3-N), nitrite nitrogen(NO2-N), ammonium nitrogen(NH4-N), total phosphorus(TP), orthophosphoric phosphorus(PO4-P) and chlorophyll-a(Chl-a). The survey found that climate-change-related increases in water temperature were suppressed by ice covering the water area, which also blocked oxygen supply. It was also clarified that the bottom sediment consumed oxygen and turned the water layers anaerobic beginning from the bottom layer, and that nutrient salts eluted from the bottom sediment. The eluted nutrient salts were stored in the water body until the ice melted. The ice-covered period of water bodies has been shortening, a finding based on the analysis of weather and water quality data from 1998 to 2008. Climate change was surveyed as having caused decreases in nutrient salts concentration because of the shortened ice-covered period. However, BOD in spring showed a tendency to increase because of the proliferation of phytoplankton that was promoted by the climate-change-related increase in water temperature. To forecast the water quality by using these findings, particularly the influence of climate change, we constructed a water quality simulation model that

  18. A pulse of mid-Pleistocene rift volcanism in Ethiopia at the dawn of modern humans

    Science.gov (United States)

    Hutchison, William; Fusillo, Raffaella; Pyle, David M.; Mather, Tamsin A.; Blundy, Jon D.; Biggs, Juliet; Yirgu, Gezahegn; Cohen, Benjamin E.; Brooker, Richard A.; Barfod, Dan N.; Calvert, Andrew T.

    2016-10-01

    The Ethiopian Rift Valley hosts the longest record of human co-existence with volcanoes on Earth, however, current understanding of the magnitude and timing of large explosive eruptions in this region is poor. Detailed records of volcanism are essential for interpreting the palaeoenvironments occupied by our hominin ancestors; and also for evaluating the volcanic hazards posed to the 10 million people currently living within this active rift zone. Here we use new geochronological evidence to suggest that a 200 km-long segment of rift experienced a major pulse of explosive volcanic activity between 320 and 170 ka. During this period, at least four distinct volcanic centres underwent large-volume (>10 km3) caldera-forming eruptions, and eruptive fluxes were elevated five times above the average eruption rate for the past 700 ka. We propose that such pulses of episodic silicic volcanism would have drastically remodelled landscapes and ecosystems occupied by early hominin populations.

  19. Hazardous indoor CO2 concentrations in volcanic environments.

    Science.gov (United States)

    Viveiros, Fátima; Gaspar, João L; Ferreira, Teresa; Silva, Catarina

    2016-07-01

    Carbon dioxide is one of the main soil gases released silently and permanently in diffuse degassing areas, both in volcanic and non-volcanic zones. In the volcanic islands of the Azores (Portugal) several villages are located over diffuse degassing areas. Lethal indoor CO2 concentrations (higher than 10 vol %) were measured in a shelter located at Furnas village, inside the caldera of the quiescent Furnas Volcano (S. Miguel Island). Hazardous CO2 concentrations were detected not only underground, but also at the ground floor level. Multivariate regression analysis was applied to the CO2 and environmental time series recorded between April 2008 and March 2010 at Furnas village. The results show that about 30% of the indoor CO2 variation is explained by environmental variables, namely barometric pressure, soil water content and wind speed. The highest indoor CO2 concentrations were recorded during bad weather conditions, characterized by low barometric pressure together with rainfall periods and high wind speed. In addition to the spike-like changes observed on the CO2 time series, long-term oscillations were also identified and appeared to represent seasonal variations. In fact, indoor CO2 concentrations were higher during winter period when compared to the dry summer months. Considering the permanent emission of CO2 in various volcanic regions of the world, CO2 hazard maps are crucial and need to be accounted by the land-use planners and authorities.

  20. Periodicity in stem growth and litterfall in tidal freshwater forested wetlands: influence of salinity and drought on nitrogen recycling

    Science.gov (United States)

    Cormier, Nicole; Krauss, Ken W.; Conner, William H.

    2013-01-01

    Many tidally influenced freshwater forested wetlands (tidal swamps) along the south Atlantic coast of the USA are currently undergoing dieback and decline. Salinity often drives conversion of tidal swamps to marsh, especially under conditions of regional drought. During this change, alterations in nitrogen (N) uptake from dominant vegetation or timing of N recycling from the canopy during annual litter senescence may help to facilitate marsh encroachment by providing for greater bioavailable N with small increases in salinity. To monitor these changes along with shifts in stand productivity, we established sites along two tidal swamp landscape transects on the lower reaches of the Waccamaw River (South Carolina) and Savannah River (Georgia) representing freshwater (≤0.1 psu), low oligohaline (1.1–1.6 psu), and high oligohaline (2.6–4.1 psu) stands; the latter stands have active marsh encroachment. Aboveground tree productivity was monitored on all sites through monthly litterfall collection and dendrometer band measurements from 2005 to 2009. Litterfall samples were pooled by season and analyzed for total N and carbon (C). On average between the two rivers, freshwater, low oligohaline, and high oligohaline tidal swamps returned 8,126, 3,831, and 1,471 mg N m−2 year−1, respectively, to the forest floor through litterfall, with differences related to total litterfall volume rather than foliar N concentrations. High oligohaline sites were most inconsistent in patterns of foliar N concentrations and N loading from the canopy. Leaf N content generally decreased and foliar C/N generally increased with salinization (excepting one site), with all sites being fairly inefficient in resorbing N from leaves prior to senescence. Stands with higher salinity also had greater flood frequency and duration, lower basal area increments, lower tree densities, higher numbers of dead or dying trees, and much reduced leaf litter fall (103 vs. 624 g m−2 year−1) over the

  1. Volcanic forcing in decadal forecasts

    Science.gov (United States)

    Ménégoz, Martin; Doblas-Reyes, Francisco; Guemas, Virginie; Asif, Muhammad; Prodhomme, chloe

    2016-04-01

    Volcanic eruptions can significantly impact the climate system, by injecting large amounts of particles into the stratosphere. By reflecting backward the solar radiation, these particles cool the troposphere, and by absorbing the longwave radiation, they warm the stratosphere. As a consequence of this radiative forcing, the global mean surface temperature can decrease by several tenths of degrees. However, large eruptions are also associated to a complex dynamical response of the climate system that is particularly tricky do understand regarding the low number of available observations. Observations seem to show an increase of the positive phases of the Northern Atlantic Oscillation (NAO) the two winters following large eruptions, associated to positive temperature anomalies over the Eurasian continent. The summers following large eruptions are generally particularly cold, especially over the continents of the Northern Hemisphere. Overall, it is really challenging to forecast the climate response to large eruptions, as it is both modulated by, and superimposed to the climate background conditions, largely driven themselves by internal variability at seasonal to decadal scales. This work describes the additional skill of a forecast system used for seasonal and decadal predictions when it includes observed volcanic forcing over the last decades. An idealized volcanic forcing that could be used for real-time forecasts is also evaluated. This work consists in a base for forecasts that will be performed in the context of the next large volcanic eruption.

  2. Volcanic ash supports a diverse bacterial community in a marine mesocosm

    Science.gov (United States)

    Verena Witt,; Paul M Ayris,; Damby, David; Corrado Cimarelli,; Ulrich Kueppers,; Donald B Dingwell,; Gert Wörheide,

    2017-01-01

    Shallow-water coral reef ecosystems, particularly those already impaired by anthropogenic pressures, may be highly sensitive to disturbances from natural catastrophic events, such as volcanic eruptions. Explosive volcanic eruptions expel large quantities of silicate ash particles into the atmosphere, which can disperse across millions of square kilometres and deposit into coral reef ecosystems. Following heavy ash deposition, mass mortality of reef biota is expected, but little is known about the recovery of post-burial reef ecosystems. Reef regeneration depends partly upon the capacity of the ash deposit to be colonised by waterborne bacterial communities and may be influenced to an unknown extent by the physiochemical properties of the ash substrate itself. To determine the potential for volcanic ash to support pioneer bacterial colonisation, we exposed five well-characterised volcanic and coral reef substrates to a marine aquarium under low light conditions for 3 months: volcanic ash, synthetic volcanic glass, carbonate reef sand, calcite sand and quartz sand. Multivariate statistical analysis of Automated Ribosomal Intergenic Spacer Analysis (ARISA) fingerprinting data demonstrates clear segregation of volcanic substrates from the quartz and coral reef substrates over 3 months of bacterial colonisation. Overall bacterial diversity showed shared and substrate-specific bacterial communities; however, the volcanic ash substrate supported the most diverse bacterial community. These data suggest a significant influence of substrate properties (composition, granulometry and colour) on bacterial settlement. Our findings provide first insights into physicochemical controls on pioneer bacterial colonisation of volcanic ash and highlight the potential for volcanic ash deposits to support bacterial diversity in the aftermath of reef burial, on timescales that could permit cascading effects on larval settlement.

  3. A Volcanic Hydrogen Habitable Zone

    Science.gov (United States)

    Ramirez, Ramses M.; Kaltenegger, Lisa

    2017-03-01

    The classical habitable zone (HZ) is the circular region around a star in which liquid water could exist on the surface of a rocky planet. The outer edge of the traditional N2–CO2–H2O HZ extends out to nearly ∼1.7 au in our solar system, beyond which condensation and scattering by CO2 outstrips its greenhouse capacity. Here, we show that volcanic outgassing of atmospheric H2 can extend the outer edge of the HZ to ∼2.4 au in our solar system. This wider volcanic-hydrogen HZ (N2–CO2–H2O–H2) can be sustained as long as volcanic H2 output offsets its escape from the top of the atmosphere. We use a single-column radiative-convective climate model to compute the HZ limits of this volcanic hydrogen HZ for hydrogen concentrations between 1% and 50%, assuming diffusion-limited atmospheric escape. At a hydrogen concentration of 50%, the effective stellar flux required to support the outer edge decreases by ∼35%–60% for M–A stars. The corresponding orbital distances increase by ∼30%–60%. The inner edge of this HZ only moves out ∼0.1%–4% relative to the classical HZ because H2 warming is reduced in dense H2O atmospheres. The atmospheric scale heights of such volcanic H2 atmospheres near the outer edge of the HZ also increase, facilitating remote detection of atmospheric signatures.

  4. Evidence for volcanism in NW Ishtar Terra, Venus

    Science.gov (United States)

    Gaddis, L.; Greeley, Ronald

    Venera 15/16 radar data for an area in NW Ishtar Terra, Venus, show an area with moderate radar return and a smooth textured surface which embays low lying areas of the surrounding mountainous terrain. Although this unit may be an extension of the lava plains of Lakshmi Planum to the southeast, detailed study suggests a separate volcanic center in NW Ishtar Terra. Lakshmi Planum, on the Ishtar Terra highland, exhibits major volcanic and tectonic features. On the Venera radar image radar brightness is influenced by slope and roughness; radar-facing slopes (east-facing) and rough surfaces (approx. 8 cm average relief) are bright, while west-facing slopes and smooth surfaces are dark. A series of semi-circular features, apparently topographic depressions, do not conform in orientation to major structural trends in this region of NW Ishtar Terra. The large depression in NW Ishtar Terra is similar to the calderas of Colette and Sacajawea Paterae, as all three structures are large irregular depressions. NW Ishtar Terra appears to be the site of a volcanic center with a complex caldera structure, possibly more than one eruptive vent, and associated lobed flows at lower elevations. The morphologic similarity between this volcanic center and those of Colette and Sacajawea suggests that centralized eruptions have been the dominant form of volcanism in Ishtar. The location of this volcanic center at the intersection of two major compressional mountain belts and the large size of the calders (with an inferred large/deep magma source) support a crustal thickening/melting rather than a hot-spot origin for these magmas.

  5. Tree Rings and Volcanic Eruptions: Reviewing the Potential of Dendrochemistry for the Absolute Dating of Past Volcanism

    Science.gov (United States)

    Pearson, C.; Manning, S. W.; Coleman, M.; Jarvis, K.

    2003-12-01

    Investigations of volcanic impact on human society and the environment are presently restrained by a lack of secure absolute dates for eruptions prior to the last few hundred years. The degree of impact and recovery, and the scope of any sociological repercussions, can only be fully explored if working from a precise, known, starting point and against a secure absolute timescale. A potential means to high resolution dating for the majority of the Holocene lies with globally available, absolutely dated tree ring chronologies. Many of these have been shown to record short term climatic alterations in periods following volcanic eruptions of known or approximate date. This argument however, has been based on an apparent correlation between the dates of specific tree ring growth anomalies and the dates of a number of eruptions in the recent historical period. The statistical correlation is less than decisive and the exact volcano-climate-tree growth linkage is by no means universally agreed. It has been suggested that a potential means to solve this problem and to attach absolute dates to volcanic eruptions via tree rings may lie in the chemistry of the annual woody increment. This paper assesses the potential of conventional Inductively Coupled Plasma Mass Spectrometry (ICP-MS) versus laser ablation ICP-MS (LA-ICP-MS) in terms of exploring this research objective. It also reviews the prospects for a dendrochemical resolution to the problem of attributing an absolute date to the volcanic eruptions of prehistory.

  6. The Role of Authigenic Volcanic Ash in Marine Sediment

    Science.gov (United States)

    Scudder, R.; McKinley, C. C.; Thomas, D. J.; Murray, R. W.

    2016-12-01

    Marine sediments are a fundamental archive of the history of weathering and erosion, biological productivity, volcanic activity, patterns of deep-water formation and circulation, and a multitude of other earth, ocean, and atmosphere processes. In particular, the record and consequences of volcanic eruptions have long fascinated humanity. Volcanic ash layers are often visually stunning, and can have thicknesses of 10s of cm or more. While the ash layer records are of great importance by themselves, we are missing a key piece of information-that of the very fined grained size fractions. Dispersed ash is the very fine grained-component that has either been mixed into the bulk sediment by bioturbation, or is deposited from subaqueous eruptions, erosion of terrestrial deposits, general input during time periods of elevated global volcanism, or other mechanisms, plays an important role in the marine sediment. The presence of dispersed ash in the marine record has previously been relatively over-looked as it is difficult to identify petrographically due to its commonly extremely fine grain size and/or alteration to authigenic clay. The dispersed ash, either altered or unaltered, is extremely difficult to differentiate from detrital/terrigenous/authigenic clay, as they are all "aluminosilicates". Here we apply a combined geochemical, isotopic, and statistical technique that enables us to resolve volcanic from detrital terrigenous inputs at DSDP/ODP/IODP sites from both the Brazil Margin and the Northwest Pacific Oceans. Incorporating the combined geochemical/statistical techniques with radiogenic isotope records allows us to address paleoceanographic questions in addition to studies of the effect of sediment fluxes on carbon cycling, the relationship between volcanic ash and biological productivity of the open ocean and nutrient availability for subseafloor microbial life.

  7. Influence of modulation period and modulation ratio on structure and mechanical properties of TiBN/CrN coatings deposited by multi-arc ion plating

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, S.Y.; Yan, S.J.; Han, B. [Key Laboratory of Artificial Micro- and Nano-Materials of Ministry of Education and School of Physics and Technology, Wuhan University, 430072 Wuhan (China); Yang, B. [School of Power and Mechanical Engineering, Wuhan University, 430072 Wuhan (China); Lin, B.Z.; Zhang, Z.D.; Ai, Z.W. [Key Laboratory of Artificial Micro- and Nano-Materials of Ministry of Education and School of Physics and Technology, Wuhan University, 430072 Wuhan (China); Pelenovich, V.O. [Key Laboratory of Artificial Micro- and Nano-Materials of Ministry of Education and School of Physics and Technology, Wuhan University, 430072 Wuhan (China); Institute of Ion-Plasma and Laser Technologies, Academy of Sciences of Uzbekistan, 700135 Tashkent (Uzbekistan); Fu, D.J., E-mail: djfu@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-Materials of Ministry of Education and School of Physics and Technology, Wuhan University, 430072 Wuhan (China)

    2015-10-01

    Highlights: • TiBN/CrN multilayers were synthesized with varied modulation period and ratio. • The maximum hardness of 38.6 GPa is observed at Λ = 11.7 nm and R = 5:1. • The lowest multilayer COF of 0.32 is lower than that of CrN (0.56). • The wear rate of the coatings is improved and related to H/E and H{sup 3}/E{sup *2} ratios. - Abstract: TiBN/CrN multilayered superlattice coatings with modulation periods Λ (bilayer thickness) ranging from 22.5 to 4.2 nm and modulation ratio R (the thickness ratio of CrN and TiBN layers) ranging from 6:1 to 3:1 were synthesized using an industrial-scale cathodic arc ion plating system in an Ar–N{sub 2} gas mixture. X-ray diffraction (XRD), transmission electron microscopy (TEM) and nanoindention were employed to investigate the influence of modulation period and ratio on microstructure and mechanical properties of the multilayers. The sharp interfaces and nanoscale multilayered modulation were confirmed by TEM. TiBN/CrN multilayer coatings were crystallized with orientations at the (1 1 1), (2 0 0) and (2 2 0) crystallographic planes and the microstructure was strengthened at (2 0 0) preferred orientation. The maximum hardness of 38.6 GPa and elastic modulus of 477 GPa were obtained at Λ = 11.7 nm and R = 5:1. The lowest value of the friction coefficient at 0.32 sliding against a WC-Co ball was obtained at a bilayer period of 11.7 nm, compared to those of the coatings with other modulation periods and monolithic coatings. The wear rate of the multilayered coatings was also lower than those of the monolithic CrN and TiBN coatings.

  8. Observation on the influence of ulinastatin for the cerebral protection and inflammatory reaction of patients with craniocerebral injury surgery during the perioperative period

    Institute of Scientific and Technical Information of China (English)

    Chun-Yu Cai; Dong-Yan Zi; Yi Zheng; Ling-Ling Wang; Xiao-Bin Li; Han Lu

    2016-01-01

    Objective:To observe the influence situation of ulinastatin for the cerebral protection and inflammatory reaction of patients with craniocerebral injury surgery during the perioperative period, in order to understand the application value of ulinastatin in the patients with craniocerebral injury surgery.Methods:A total of 54 patients with craniocerebral injury surgery in our hospital from July 2014 to May 2015 were selected as the study object, and 54 patients were randomly divided into two groups, 27 patients in control group were treated with conventional perioperative treatment, 27 patients in observation group were treated with ulinastatin on the conventional perioperative treatment, then the cerebral blood flow parameters, serum nerve function related indexes, pro-inflammatory cytokines and anti-inflammatory cytokines of two groups before the treatment and at 1st, 3rd and 5th day after the treatment were analyzed and compared.Results:The cerebral blood flow parameters, serum nerve function related indexes, pro-inflammatory cytokines and anti-inflammatory cytokines of two groups before the treatment were compared, while those statistical indexes of observation group at 1st, 3rd and 5th day after the treatment were all better than those of control group, the differences were all significant.Conclusion:The influence role of ulinastatin for the cerebral protection and inflammatory reaction of patients with craniocerebral injury surgery during the perioperative period is better, and its application value for the patients with craniocerebral injury surgery is relatively higher.

  9. Bromo volcano area as human-environment system: interaction of volcanic eruption, local knowledge, risk perception and adaptation strategy

    Science.gov (United States)

    Bachri, Syamsul; Stötter, Johann; Sartohadi, Junun

    2013-04-01

    People in the Bromo area (located within Tengger Caldera) have learn to live with the threat of volcanic hazard since this volcano is categorized as an active volcano in Indonesia. During 2010, the eruption intensity increased yielding heavy ash fall and glowing rock fragments. A significant risk is also presented by mass movement which reaches areas up to 25 km from the crater. As a result of the 2010 eruption, 12 houses were destroyed, 25 houses collapsed and there were severe also effects on agriculture and the livestock sector. This paper focuses on understanding the interaction of Bromo volcanic eruption processes and their social responses. The specific aims are to 1) identify the 2010 eruption of Bromo 2) examine the human-volcano relationship within Bromo area in general, and 3) investigate the local knowledge related to hazard, risk perception and their adaptation strategies in specific. In-depth interviews with 33 informants from four districts nearest to the crater included local people and authorities were carried out. The survey focused on farmers, key persons (dukun), students and teachers in order to understand how people respond to Bromo eruption. The results show that the eruption in 2010 was unusual as it took continued for nine months, the longest period in Bromo history. The type of eruption was phreatomagmatic producing material dominated by ash to fine sand. This kind of sediment typically belongs to Tengger mountain eruptions which had produced vast explosions in the past. Furthermore, two years after the eruption, the interviewed people explained that local knowledge and their experiences with volcanic activity do not influence their risk perception. Dealing with this eruption, people in the Bromo area applied 'lumbung desa' (traditional saving systems) and mutual aid activity for surviving the volcanic eruption. Keywords: Human-environment system, local knowledge, risk perception, adaptation strategies, Bromo Volcano Indonesia

  10. Paleoarchean trace fossils in altered volcanic glass

    Science.gov (United States)

    Staudigel, Hubert; Furnes, Harald; DeWit, Maarten

    2015-01-01

    Microbial corrosion textures in volcanic glass from Cenozoic seafloor basalts and the corresponding titanite replacement microtextures in metamorphosed Paleoarchean pillow lavas have been interpreted as evidence for a deep biosphere dating back in time through the earliest periods of preserved life on earth. This interpretation has been recently challenged for Paleoarchean titanite replacement textures based on textural and geochronological data from pillow lavas in the Hooggenoeg Complex of the Barberton Greenstone Belt in South Africa. We use this controversy to explore the strengths and weaknesses of arguments made in support or rejection of the biogenicity interpretation of bioalteration trace fossils in Cenozoic basalt glasses and their putative equivalents in Paleoarchean greenstones. Our analysis suggests that biogenicity cannot be taken for granted for all titanite-based textures in metamorphosed basalt glass, but a cautious and critical evaluation of evidence suggests that biogenicity remains the most likely interpretation for previously described titanite microtextures in Paleoarchean pillow lavas. PMID:26038543

  11. Paleoarchean trace fossils in altered volcanic glass.

    Science.gov (United States)

    Staudigel, Hubert; Furnes, Harald; DeWit, Maarten

    2015-06-02

    Microbial corrosion textures in volcanic glass from Cenozoic seafloor basalts and the corresponding titanite replacement microtextures in metamorphosed Paleoarchean pillow lavas have been interpreted as evidence for a deep biosphere dating back in time through the earliest periods of preserved life on earth. This interpretation has been recently challenged for Paleoarchean titanite replacement textures based on textural and geochronological data from pillow lavas in the Hooggenoeg Complex of the Barberton Greenstone Belt in South Africa. We use this controversy to explore the strengths and weaknesses of arguments made in support or rejection of the biogenicity interpretation of bioalteration trace fossils in Cenozoic basalt glasses and their putative equivalents in Paleoarchean greenstones. Our analysis suggests that biogenicity cannot be taken for granted for all titanite-based textures in metamorphosed basalt glass, but a cautious and critical evaluation of evidence suggests that biogenicity remains the most likely interpretation for previously described titanite microtextures in Paleoarchean pillow lavas.

  12. The influence of the professional’s gender in the periodicity of Pap Test - doi:10.5020/18061230.2010.p181

    Directory of Open Access Journals (Sweden)

    Luis Rafael Leite Sampaio

    2012-01-01

    Full Text Available Methods: A descriptive study, with a qualitative approach, held in the period of September to November, 2008 with 83 users of the Family Health Strategy of Caio Prado, Itapiúna-Ceará, who had Pap test in delay. The data were collected through a semi-structured interview and organized according to the Content Analysis: (1 Professional gender and the periodicity of Pap test and (2 Test that causes pain and fear. Results: It was observed that 67 (80.72% were between 25 and 59 years, 52 (62.62% were married, 65 (78.31% had primary education, 45 (54.22% were farmers and 49 (59.04% earned less than minimum wage. Most users reported feelings of shame by male examiners as a reason for irregularity in the frequency of Pap test. On a smaller scale, the reason pointed out was to consider this a test that causes pain and fear. Final Considerations: The users reported that the presence of a male professional was a strong influence to irregularity in the frequency of Pap test in this health unit. Albeit to a lesser extent, prior negative experience with this exam and not the professional’s gender issue has been implicated as a reason not to perform periodic cytology.

  13. Phosphorylation of the transcription activator CLOCK regulates progression through a ∼ 24-h feedback loop to influence the circadian period in Drosophila.

    Science.gov (United States)

    Mahesh, Guruswamy; Jeong, EunHee; Ng, Fanny S; Liu, Yixiao; Gunawardhana, Kushan; Houl, Jerry H; Yildirim, Evrim; Amunugama, Ravi; Jones, Richard; Allen, David L; Edery, Isaac; Kim, Eun Young; Hardin, Paul E

    2014-07-11

    Circadian (≅ 24 h) clocks control daily rhythms in metabolism, physiology, and behavior in animals, plants, and microbes. In Drosophila, these clocks keep circadian time via transcriptional feedback loops in which clock-cycle (CLK-CYC) initiates transcription of period (per) and timeless (tim), accumulating levels of PER and TIM proteins feed back to inhibit CLK-CYC, and degradation of PER and TIM allows CLK-CYC to initiate the next cycle of transcription. The timing of key events in this feedback loop are controlled by, or coincide with, rhythms in PER and CLK phosphorylation, where PER and CLK phosphorylation is high during transcriptional repression. PER phosphorylation at specific sites controls its subcellular localization, activity, and stability, but comparatively little is known about the identity and function of CLK phosphorylation sites. Here we identify eight CLK phosphorylation sites via mass spectrometry and determine how phosphorylation at these sites impacts behavioral and molecular rhythms by transgenic rescue of a new Clk null mutant. Eliminating phosphorylation at four of these sites accelerates the feedback loop to shorten the circadian period, whereas loss of CLK phosphorylation at serine 859 increases CLK activity, thereby increasing PER levels and accelerating transcriptional repression. These results demonstrate that CLK phosphorylation influences the circadian period by regulating CLK activity and progression through the feedback loop. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. Volcanic degassing at Somma-Vesuvio (Italy) inferred by chemical and isotopic signatures of groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Caliro, S. [Osservatorio Vesuviano sezione di Napoli dell' Istituto, Nazionale Geofisica Vulcanologia, Via Diocleziano 328, 80124 Naples (Italy)]. E-mail: caliro@ov.ingv.it; Chiodini, G. [Osservatorio Vesuviano sezione di Napoli dell' Istituto, Nazionale Geofisica Vulcanologia, Via Diocleziano 328, 80124 Naples (Italy); Avino, R. [Osservatorio Vesuviano sezione di Napoli dell' Istituto, Nazionale Geofisica Vulcanologia, Via Diocleziano 328, 80124 Naples (Italy); Cardellini, C. [Dipartimento di Scienze della Terra, Universita di Perugia (Italy); Frondini, F. [Dipartimento di Scienze della Terra, Universita di Perugia (Italy)

    2005-06-15

    A geochemical model is proposed for water evolution at Somma-Vesuvio, based on the chemical and isotopic composition of groundwaters, submarine gas emission and chemical composition of the dissolved gases. The active degassing processes, present in the highest part of the volcano edifice, strongly influence the groundwater evolution. The geological-volcanological setting of the volcano forces the waters infiltrating at Somma-Vesuvio caldera, enriched in volcanic gases, to flow towards the southern sector to an area of high pCO{sub 2} groundwaters. Reaction path modelling applied to this conceptual model, involving gas-water-rock interaction, highlights an intense degassing process in the aquifer controlling the chemical and isotopic composition of dissolved gases, total dissolved inorganic C (TDIC) and submarine gas emission. Mapping of TDIC shows a unique area of high values situated SSE of Vesuvio volcano with an average TDIC value of 0.039 mol/L, i.e., one order of magnitude higher than groundwaters from other sectors of the volcano. On the basis of TDIC values, the amount of CO{sub 2} transported by Vesuvio groundwaters was estimated at about 150 t/d. This estimate does not take into account the fraction of gas loss by degassing, however, it represents a relevant part of the CO{sub 2} emitted in this quiescent period by the Vesuvio volcanic system, being of the same order of magnitude as the CO{sub 2} diffusely degassed from the crater area.

  15. The influence of tectonic and volcanic processes on the morphology of the Iberian continental margins; Influencia de los procesos tectonicos y volcanicos en la morfologia de los margenes continentales ibericos

    Energy Technology Data Exchange (ETDEWEB)

    Maestro, A.; Bohoyo, F.; Lopez-Martinez, J.; Acosta, J.; Gomez-Ballesteros, M.; Llaave, E.; Munoz, A.; Terrinha, P. G.; Dominguez, M.; Fernandez-Saez, F.

    2015-07-01

    The Iberian continental margins are mainly passive margins. Nevertheless, the northern sector of the margin was active during some stages of its geological evolution. The southern sector is considered as a transformed margin, which defines the boundary between the Iberian and African plates. This margin was also an active margin in the past. The different types, origins and intensities of the endogenic processes that have affected he Iberian continental margins have led to the development of various tectonic and volcanic morphologies. The North Atlantic rifting allowed the development of large marginal platforms in the Cantabrian and Galician margins the North-Atlantic Ocean spreading. The reactivation of Variscan faults during the Mesozoic and Cenozoic controlled the strike of some of the largest canyons in the Iberian margins. The Gulf of Cadiz margin is characterized by the development of morphologies related to salt tectonic, fluid seepage, thrust fronts and strike-slip fault lineaments hundreds of kilometres long. The Alboran basin and the Betic margin show morphologies connected with the Miocene rift phase, which generated volcanic edifices and various structural reliefs, and with the subsequent compressive phase, when folds and strike-slip, reverse faults, diapirs and mud volcanoes were developed. Finally, the Catalan-Valencian margin and the Balearic promontory are characterized by the presence of horst and graben structures related to the development of the Valencia trough during the Paleogene. The morphological features of endogenic origin have largely controlled the location and extent of the sedimentary processes and morphological products along the Iberian margins. (Author)

  16. Recent seismicity detection increase at Santorini' s volcanic islands

    Science.gov (United States)

    Chouliaras, G.; Drakatos, G.; Makropoulos, K.; Melis, N. S.

    2012-04-01

    Santorini is the most active volcano in the southern Aegean volcanic arc. To improve the seismological network detectability of the Santorini seismicity, the Institute of Geodynamics of the National Observatory of Athens (NOA) installed 6 new seismological stations. The addition of these stations which begun in the year 2010 has significantly improved the detectability and reporting of the local seismic activity in NOA's instrumental seismicity catalog. Anomalous spatial and temporal changes in the b-value of the frequency-magnitude relationship and changes in the seismicity rate have been reported for many active volcanoes and have been used for the mapping of active magma chambers. In this study we present the results from a quantitative analysis of the seismicity in the Santorini volcanic complex using the seismicity catalog of NOA. From these results we observe a significant detection increase after the year 2010 mainly for events of small magnitudes and an increase in the seismicity rate by more than 100%. The statistical significance of this rate change is determined and mapped with the z-value method and it is found that the seismicity rate increases significantly within the two main active fault zones of the volcanic complex, in a zone perpendicular to the extensive tectonic regime that characterizes this region. Temporal variations in the b-value for different time periods indicate a rather homogeneous behaviour of the frequency-magnitude curves. The spatial distribution of the b-value is shown to vary around the volcanic complex exhibiting low b-values in the two main regions of seismic activity. A b-value cross section of the volcanic complex indicates relatively high b-values under the caldera and a significant b-value decrease with depth. The results from this study are found to be in general agreement with the results from other volcanic regions and they encourage further investigations concerning the seismic and volcanic hazard and risk estimates for

  17. How natural is the supernatural? Synthesis of the qualitative literature from low and middle income countries on cultural practices and traditional beliefs influencing the perinatal period.

    Science.gov (United States)

    Raman, Shanti; Nicholls, Rachel; Ritchie, Jan; Razee, Husna; Shafiee, Samaneh

    2016-08-01

    to review qualitative research studies conducted in low resource settings around the perinatal continuum over the past two decades, with particular focus on the cultural realm; to identify common themes in the research-base, in order to provide policy direction for culturally appropriate perinatal interventions. systematic literature search of electronic databases from 1990 to 2014, including Medline, Embase, CINAHL and PsycINFO, using relevant search terms such as traditional beliefs, practices, pregnancy, childbirth; established criteria used to determine quality of studies; and thematic synthesis of the literature enabled by NVivo 10 software. low and middle income countries using the World Bank classification. religious and spiritual beliefs strongly influenced behaviour over the perinatal period. Beliefs in supernatural influences, particularly malevolent forces were widespread, such that pregnancy was concealed in many parts of Africa and Asia. In most low resource settings, pregnancy and childbirth were seen as normal phenomena. Rituals played an important part for women and their infants, reinforced by inter-generational support. Cross-cutting themes that emerged were: (1) the role of women as mothers, demonstrating their'goodness' by bearing pain and suffering; (2) the idea of the 'natural' incorporating the supernatural; and (3) negotiating change across generations. a diverse repertoire of cultural practices influences perinatal well-being across low resource settings. Health practitioners and policy-makers need to acknowledge the primacy of women's reproductive roles, the cultural constructions of motherhood; that supernatural forces are believed to exert powerful influences on the health of mother and infant; that inter-generational tensions result in resisting or embracing change. Public health planners and practitioners need to take culture seriously, not ignore the contribution of culture in shaping women's behaviours and choices throughout the

  18. GIS methods applied to the degradation of monogenetic volcanic fields: A case study of the Holocene volcanism of Gran Canaria (Canary Islands, Spain)

    Science.gov (United States)

    Rodriguez-Gonzalez, A.; Fernandez-Turiel, J. L.; Perez-Torrado, F. J.; Aulinas, M.; Carracedo, J. C.; Gimeno, D.; Guillou, H.; Paris, R.

    2011-11-01

    Modeling of volcanic morphometry provides reliable measurements of parameters that assist in the determination of volcanic landform degradation. Variations of the original morphology enable the understanding of patterns affecting erosion and their development, facilitating the assessment of associated hazards. A total of 24 volcanic Holocene eruptions were identified in the island of Gran Canaria (Canary Islands, Spain). 87% of these eruptions occurred in a wet environment while the rest happened in a dry environment. 45% of Holocene eruptions are located along short barrancos (S-type, less than 10 km in length), 20% along large barrancos (L-type, 10-17 km in length) and 35% along extra-large barrancos (XL-type, more than 17 km in length). The erosional history of Holocene volcanic edifices is in the first stage of degradation, with a geomorphic signature characterized by a fresh, young cone with a sharp profile and a pristine lava flow. After intensive field work, a careful palaeo-geomorphological reconstruction of the 24 Holocene eruptions of Gran Canaria was conducted in order to obtain the Digital Terrain Models (DTMs) of the pre- and post-eruption terrains. From the difference between these DTMs, the degradation volume and the incision rate were obtained. The denudation of volcanic cones and lava flows is relatively independent both their geographical location and the climatic environment. However, local factors, such as pre-eruption topography and ravine type, have the greatest influence on the erosion of Holocene volcanic materials in Gran Canaria. Although age is a key factor to help understand the morphological evolution of monogenetic volcanic fields, the Gran Canaria Holocene volcanism presented in this paper demonstrates that local and regional factors may determine the lack of correlation between morphometric parameters and age. Consequently, the degree of transformation of the volcanic edifices evolves, in many cases, independently of their age.

  19. Anomalous diffusion of volcanic earthquakes

    CERN Document Server

    Abe, Sumiyoshi

    2015-01-01

    Volcanic seismicity at Mt. Etna is studied. It is found that the associated stochastic process exhibits a subdiffusive phenomenon. The jump probability distribution well obeys an exponential law, whereas the waiting-time distribution follows a power law in a wide range. Although these results would seem to suggest that the phenomenon could be described by temporally-fractional kinetic theory based on the viewpoint of continuous-time random walks, the exponent of the power-law waiting-time distribution actually lies outside of the range allowed in the theory. In addition, there exists the aging phenomenon in the event-time averaged mean squared displacement, in contrast to the picture of fractional Brownian motion. Comments are also made on possible relevances of random walks on fractals as well as nonlinear kinetics. Thus, problems of volcanic seismicity are highly challenging for science of complex systems.

  20. Global Volcanism on Mercury at About 3.8 Ga

    Science.gov (United States)

    Byrne, P. K.; Ostrach, L. R.; Denevi, B. W.; Head, J. W., III; Hauck, S. A., II; Murchie, S. L.; Solomon, S. C.

    2014-12-01

    Smooth plains occupy c. 27% of the surface of Mercury. Embayment relations, spectral contrast with surroundings, and morphologic characteristics indicate that the majority of these plains are volcanic. The largest deposits are located in Mercury's northern hemisphere and include the extensive northern plains (NP) and the Caloris interior and exterior plains (with the latter likely including basin material). Both the NP and Caloris deposits are, within statistical error, the same age (~3.8-3.9 Ga). To test whether this age reflects a period of global volcanism on Mercury, we determined crater size-frequency distributions for four smooth plains units in the planet's southern hemisphere interpreted to be volcanic. Two deposits are situated within the Beethoven and Tolstoj impact basins; two are located close to the Debussy and the Alver and Disney basins, respectively. Each deposit hosts two populations of craters, one that postdates plains emplacement and one that consists of partially to nearly filled craters that predate the plains. This latter population indicates that some time elapsed between formation of the underlying basement and plains volcanism, though we cannot statistically resolve this interval at any of the four sites. Nonetheless, we find that the age given by the superposed crater population in each case is ~3.8 Ga, and crater density values are consistent with those for the NP and Caloris plains. This finding supports a global phase of volcanism near the end of the late heavy bombardment of Mercury and may indicate a period of widespread partial melting of Mercury's mantle. Notably, superposition relations between smooth plains, degraded impact structures, and contractional landforms suggest that by this time interior cooling had already placed Mercury's lithosphere in horizontal compression, tending to inhibit voluminous dike-fed volcanism such as that inferred responsible for the NP. Most smooth plains units, including the Caloris plains and our

  1. Satellite Observations of Atmospheric SO2 from Volcanic Eruptions

    Science.gov (United States)

    Khokhar, M. F.; Platt, U.; Wagner, T.

    Volcanoes are an important source of various atmospheric trace gases. Volcanic eruptions and their emissions are sporadic and intermittent and often occur in uninhabited regions. Therefore assessing the amount and size of the gaseous and particulate emission from volcanoes is difficult. Satellite remote sensing measurements provide one well suited opportunity to overcome this difficulty. Onboard ERS-2, GOME's moderate spectral resolution enables us to apply the Differential Optical Absorption Spectroscopy (DOAS) algorithm to retrieve SO2 column densities from radiance/irradiance measurements in UV spectral region. Volcanic emissions can cause significant variations of climate on a variety of time scales; just one very large eruption can cause a measurable change in the Earth's climate with a time scale of a few years. Stratospheric aerosols produced by volcanic eruptions can influence stratospheric chemistry both through chemical reactions that take place on the surface of the aerosols and through temperature changes induced by their presence in the stratosphere. In this work we give a comprehensive overview on several volcanoes and the retrieval of SO2 column densities from GOME data for the years 1996 - 2002. The focus is on both eruption and out gassing scenarios from different volcanic eruptions in Italy, Iceland, Congo/ Zaire, Ecuador and Mexico.

  2. Seismicity at Lusi and the adjacent volcanic complex, Java, Indonesia

    Science.gov (United States)

    Obermann, Anne; Karyono, Karyono; Diehl, Tobias; Lupi, Matteo; Mazzini, Adriano

    2017-04-01

    We study the local seismicity around the spectacular Lusi eruption site, a sedimentary- hosted hydrothermal system in East Java. Lusi is located 10 km NE of the Arjuno-Welirang volcanic complex and is fed by both mantellic and hydrothermal fluids rising and mixing with those present in the sedimentary formations. During a period of 17 months, we observed 289 micro-seismic earthquakes with local magnitudes ranging from ML0.5 to ML1.7. The events predominantly nucleate at depths of 8-13 km below the Arjuno-Welirang volcanic complex. Despite the geological evidence of active tectonic deformation and faulting observed at the surface, little to no seismicity is observed in the sedimentary basin hosting Lusi. Although we cannot entirely rule out artifacts due to a significantly increased detection threshold in the sedimentary basin, the deficit in seismicity suggests aseismic deformation beneath Lusi due to the large amount of fluids that may lubricate the fault system. An analysis of focal mechanisms of seven selected events around the Arjuno-Welirang volcanic complex indicate predominantly strike-slip faulting activity in the region SW of Lusi. This type of activity is consistent the orientation and the movements observed for the Watukosek fault system that extends from the volcanic complex towards the NE of Java. Our results suggest that the tectonic deformation of the region is characterized by scattered faulting, rather than localized along a distinct fault plane.

  3. Pore Structure of Cement Pastes Blended with Volcanic Rock

    Institute of Scientific and Technical Information of China (English)

    YU Lehua; ZHOU Shuangxi; LI Liling

    2016-01-01

    The pore parameters of cement pastes blended with volcanic rock at the curing age of 1, 28 and 90 d were de-termined by a mercury intrusion porosimetry. The pore structure of the pastes was characterized through the analysis of porosity, average pore diameter, the most probable pore aperture, pore size distribution, as well as total pore volume. For the improvement of mechanical property and durability of cement-based material, the correlation of the formed pore structure with hydration time and replacement level of volcanic rock for cement was revealed. The results indicate that volcanic rock can diminish porosity and reduce pore size in cement paste when curing time prolongs, which is particu-larly prominent with replacement level of less than 20% in late period. The more harmful pores (i.e., capillary pore) are gradually transformed into harmless pore (i.e., gel pores or micropore), even fully filled and disappeared when hydration products increase. The pore structure of the cement paste is thus refined. The beneficial effect of volcanic rock on the pore structure of cement paste could enhance the mechanical property and durability of cement-based material.

  4. An independently dated 2000-yr volcanic record from Law Dome, East Antarctica, including a new perspective on the dating of the c. 1450s eruption of Kuwae, Vanuatu

    Directory of Open Access Journals (Sweden)

    C. T. Plummer

    2012-05-01

    Full Text Available Volcanic eruptions are an important cause of natural climate variability. In order to improve the accuracy of climate models, precise dating and magnitude of the climatic effects of past volcanism are necessary. Here we present a 2000-yr record of Southern Hemisphere volcanism recorded in ice cores from the high accumulation Law Dome site, East Antarctica. The ice cores were analyzed for a suite of chemistry signals and are independently dated via annual layer counting, with 11 ambiguous years by the end of the record. Independently dated records are important to avoid circular dating where volcanic signatures are assigned a date from some external information rather than using the date it is found in the ice core. Forty-five volcanic events have been identified using the sulfate chemistry of the Law Dome record. Comparisons between Law Dome and NGRIP (Greenland volcanic records suggest Law Dome is the most accurately dated Antarctic volcanic dataset and allows for the records to be synchronized with NGRIP, leading to an improved global volcanic forcing dataset. Volcanic sulfate deposition estimates are important for modeling the climatic response to eruptions. The largest volcanic sulfate events in our record are dated at 1458 CE (Kuwae, Vanuatu, 1257 and 423 CE (unidentified. Using our record we refine the dating of previously known volcanic events and present evidence for two separate eruptions during the period 1450–1460 CE, potentially causing confusion in the assignment of the Kuwae (Vanuatu eruption to volcanic signatures during this time interval.

  5. Volcanic mercury in Pinus canariensis

    Science.gov (United States)

    Rodríguez Martín, José Antonio; Nanos, Nikos; Miranda, José Carlos; Carbonell, Gregoria; Gil, Luis

    2013-08-01

    Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. Volcanic emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to volcanic activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 μg kg-1) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 μg kg-1). Thus, mercury emissions originating from the eruption remained only as a mark—in pyroclastic wounds—and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 μg kg-1) and bark (6.0 μg kg-1) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in volcanism-adapted species.

  6. 'Failed' eruptions revealed by integrated analysis of gas emission and volcanic tremor data at Mt. Etna, Italy

    Science.gov (United States)

    Salerno, G. G.; Falsaperla, S. M.; Behncke, B.; Langer, H. K.; Neri, M.; Giammanco, S.; Pecora, E.; Biale, E.

    2013-12-01

    Mt Etna in Sicily is among the most intensely monitored and studied volcanoes on Earth due to its very frequent activity, and its location in a densely populated area. Through a sophisticated monitoring system run by the Istituto Nazionale di Geofisica e Vulcanologia - Osservatorio Etneo (INGV-OE), scientists are gaining every day and in real time a picture of the state of volcanic activity of Etna. During the spring of 2007, various episodes of paroxysmal activity occurred at the South-East Crater, one of the four summit craters of Mt Etna. These episodes were always associated with a sharp increase in the amplitude of the volcanic tremor as well as changes in the spectral characteristics of this signal. Eruptive activity ranged from strong Strombolian explosions to lava fountains coupled with copious emission of lava flows and tephra. During inter-eruptive periods, recurrent seismic unrest episodes were observed in form of both temporary enhancements of the volcanic tremor amplitude as well as changes of spectral characteristics. These changes often triggered the automatic alert systems in the operation room of the INGV-OE, even though not being followed by manifest eruptive activity at the surface. The influence of man-made or meteorologically induced noise could be ruled out as a cause for the alarms. We therefore performed a multi-parametric analysis of these inter-eruptive periods by integrating seismic volcanic tremor, in-soil radon, plume SO2 flux and thermal data, discussing the potential volcano-dependent source of these episodes. Short-term changes were investigated applying pattern classification, in particular Kohonen Maps and fuzzy clustering, simultaneously on volcanic tremor, radon and ambient parameters (pressure and temperature). The well established SO2 flux and thermal radiation data were used as the 'smoking gun', for certifying that the observed changes in seismic and in radon data can be considered as volcanogenic. Our results unveil ';failed

  7. THE MEANING OF VOLCANIC ASH CHARACTERISTICS FOUND IN THE ARCHAEOLOGICAL POTTERY OF CHICHEN ITZA, YUCATAN, MEXICO

    OpenAIRE

    Chung, Heajoo; Song, Youngsun

    2014-01-01

    The Yucatan peninsula is a limestone based karst region. However, most of the pottery fragments from the Mayan Postclassic period of Chichen Itza, Yucatan, Mexico, contain volcanic materials as temper. Petrographic thin section analysis of pottery from Chichen Itza and related Yucatan archaeological sites shows that volcanic materials in the paste composition have two distinguishing characteristics. The glass shards and pumice frag-ments found in the pottery are fresh in form, mineralogically...

  8. Alkali Basalts From the Galatia Volcanic Complex, NW Central Anatolia, Turkey

    OpenAIRE

    Tankut, Ayla; GÜLEÇ, Nilgün

    2014-01-01

    Alkali basalts occur as small lava flows associated with the andesitic lava flows and pyroclastics of Early to Middle Miocene age which are the main constituents of the Galatia volcanic complex. The northern margin of the complex is bordered by the North Anatolian Fault wher eas the southern margin is surrounded by a continental sedimentary sequence which interfingers with the volcanics. New K-Ar age determinations of the basalts reveal that alkali basalts erupted at two differ ent periods ...

  9. The impact of stratospheric volcanic aerosol on decadal-scale climate predictions

    Science.gov (United States)

    Timmreck, Claudia; Pohlmann, Holger; Illing, Sebastian; Kadow, Christopher

    2016-04-01

    The possibility of a large future volcanic eruption provides arguably the largest uncertainty concerning the evolution of the climate system on the time scale of a few years; but also the greatest opportunity to learn about the behavior of the climate system, and our models thereof. So the question emerges how large will the uncertainty be for future decadal climate predictions if no volcanic aerosol is taken into account? And how strong has volcanic aerosol affected decadal prediction skill on annual and multi-year seasonal scales over the CMIP5 hindcast period? To understand the impact of volcanic aerosol on multi-year seasonal and decadal climate predictions we performed CMIP5-type hindcasts without volcanic aerosol using the German MiKlip prediction system system baseline 1 from 1961 to 1991 and compared them to the corresponding simulations including aerosols. Our results show that volcanic aerosol significantly affects the prediction skill for global mean surface air temperature in the first five years after strong volcanic eruptions. Also on the regional scale a volcanic imprint on decadal-scale variability is detectable. Neglecting volcanic aerosol leads to a reduced prediction skill over the tropical and subtropical Atlantic, Indic and West Pacific but to an improvement over the tropical East-Pacific, where the model has in general no skill. Multi-seasonal differences in the skill for seasonal-mean temperatures are evident over Continental Europe with significant skill loss due to neglection of volcanic aerosol in boreal winter over central Europe, Scandinavia and over south-eastern Europe and the East-Mediterranean in boreal summer.

  10. Submarine volcanoes along the Aegean volcanic arc

    Science.gov (United States)

    Nomikou, Paraskevi; Papanikolaou, Dimitrios; Alexandri, Matina; Sakellariou, Dimitris; Rousakis, Grigoris

    2013-06-01

    The Aegean volcanic arc has been investigated along its offshore areas and several submarine volcanic outcrops have been discovered in the last 25 years of research. The basic data including swath bathymetric maps, air-gun profiles, underwater photos and samples analysis have been presented along the four main volcanic groups of the arc. The description concerns: (i) Paphsanias submarine volcano in the Methana group, (ii) three volcanic domes to the east of Antimilos Volcano and hydrothermal activity in southeast Milos in the Milos group, (iii) three volcanic domes east of Christiana and a chain of about twenty volcanic domes and craters in the Kolumbo zone northeast of Santorini in the Santorini group and (iv) several volcanic domes and a volcanic caldera together with very deep slopes of several volcanic islands in the Nisyros group. The tectonic structure of the volcanic centers is described and related to the geometry of the arc and the neotectonic graben structures that usually host them. The NE-SW direction is dominant in the Santorini and Nisyros volcanic groups, located at the eastern part of the arc, where strike-slip is also present, whereas NW-SE direction dominates in Milos and Methana at the western part, where co-existence of E-W disrupting normal faults is observed. The volcanic relief reaches 1100-1200 m in most cases. This is produced from the outcrops of the volcanic centers emerging usually at 400-600 m depth and ending either below sea level or at high altitudes of 600-700 m on the islands. Hydrothermal activity at relatively high temperatures observed in Kolumbo is remarkable whereas low temperature phenomena have been detected in the Santorini caldera around Kameni islands and in the area southeast of Milos. In Methana and Nisyros, hydrothermal activity seems to be limited in the coastal areas without other offshore manifestations.

  11. Ultrashort pulse laser dicing of thin Si wafers: the influence of laser-induced periodic surface structures on the backside breaking strength

    Science.gov (United States)

    Domke, Matthias; Egle, Bernadette; Piredda, Giovanni; Stroj, Sandra; Fasching, Gernot; Bodea, Marius; Schwarz, Elisabeth

    2016-11-01

    High power electronic chips are usually fabricated on about 50 µm thin Si wafers to improve heat dissipation. At these chip thicknesses mechanical dicing becomes challenging. Chippings may occur at the cutting edges, which reduce the mechanical stability of the die. Thermal load changes could then lead to sudden chip failure. Ultrashort pulsed lasers are a promising tool to improve the cutting quality, because thermal side effects can be reduced to a minimum. However, laser-induced periodic surface structures occur at the sidewalls and at the trench bottom during scribing. The goal of this study was to investigate the influence of these periodic structures on the backside breaking strength of the die. An ultrafast laser with a pulse duration of 380 fs and a wavelength of 1040 nm was used to cut a wafer into single chips. The pulse energy and the number of scans was varied. The cuts in the wafer were investigated using transmitted light microscopy, the sidewalls of the cut chips were investigated using scanning electron and confocal microscopy, and the breaking strength was evaluated using the 3-point bending test. The results indicated that periodic holes with a distance of about 20–30 µm were formed at the bottom of the trench, if the number of scans was set too low to completely cut the wafer; the wafer was only perforated. Mechanical breaking of the bridges caused 5 µm deep kerfs in the sidewall. These kerfs reduced the breaking strength at the backside of the chip to about 300 MPa. As the number of scans was increased, the bridges were ablated and the wafer was cut completely. Periodic structures were observed on the sidewall; the roughness was below 1 µm. The surface roughness remained on a constant level even when the number of scans was doubled. However, the periodic structures on the sidewall seemed to vanish and the probability to remove local flaws increases with the number of scans. As a consequence, the breaking strength was increased to about

  12. Reprint of “Moisture content behaviour in extensive green roofs during dry periods: The influence of vegetation and substrate characteristics”

    Science.gov (United States)

    Berretta, Christian; Poë, Simon; Stovin, Virginia

    2014-08-01

    Evapotranspiration (ET) is a key parameter that influences the stormwater retention capacity, and thus the hydrological performance, of green roofs. This paper investigates how the moisture content in extensive green roofs varies during dry periods due to evapotranspiration. The study is supported by 29 months continuous field monitoring of the moisture content within four green roof test beds. The beds incorporated three different substrates, with three being vegetated with sedum and one left unvegetated. Water content reflectometers were located at three different soil depths to measure the soil moisture profile and to record temporal changes in moisture content at a five-minute resolution. The moisture content vertical profiles varied consistently, with slightly elevated moisture content levels being recorded at the deepest substrate layer in the vegetated systems. Daily moisture loss rates were influenced by both temperature and moisture content, with reduced moisture loss/evapotranspiration when the soil moisture was restricted. The presence of vegetation resulted in higher daily moisture loss. Finally, it is demonstrated that the observed moisture content data can be accurately simulated using a hydrologic model based on water balance and two conventional Potential ET models (Hargreaves and FAO56 Penman-Monteith) combined with a soil moisture extraction function. Configuration-specific correction factors have been proposed to account for differences between green roof systems and standard reference crops.

  13. Does fish reproduction and metabolic activity influence metal levels in fish intestinal parasites, acanthocephalans, during fish spawning and post-spawning period?

    Science.gov (United States)

    Filipović Marijić, Vlatka; Vardić Smrzlić, Irena; Raspor, Biserka

    2014-10-01

    Application of fish intestinal parasites, acanthocephalans, as bioindicators in metal exposure assessment usually involves estimation of their metal levels and bioconcentration factors. Metal levels in parasite final host, fishes, are influenced by fish physiology but there is no data for acanthocephalan metal levels. Gastrointestinal Zn, Fe, Mn, Cd, Ag levels in European chub (Squalius cephalus L.) from the Sava River were significantly higher during chub spawning (April/May) compared to the post-spawning period (September). In acanthocephalans (Pomphorhynchus laevis and Acanthocephalus anguillae) significantly higher metal levels during chub spawning were observed only for Zn in P. laevis. Bioconcentration factors were twice as high for Fe, Mn, Ag, Pb in the post-spawning period, probably as a consequence of lower gastrointestinal metal levels in fish rather than metal exposure. Therefore, bioconcentration factors should be interpreted with caution, due to their possible variability in relation to fish physiology. In addition, gastrointestinal Cu, Cd and Pb levels were lower in infected than uninfected chub, indicating that metal variability in fishes might be affected by the presence of acanthocephalans.

  14. Mutual touch during mother-infant face-to-face still-face interactions: influences of interaction period and infant birth status.

    Science.gov (United States)

    Mantis, Irene; Stack, Dale M; Ng, Laura; Serbin, Lisa A; Schwartzman, Alex E

    2014-08-01

    Contact behaviours such as touch, have been shown to be influential channels of nonverbal communication between mothers and infants. While existing research has examined the communicative roles of maternal or infant touch in isolation, mutual touch, whereby touching behaviours occur simultaneously between mothers and their infants, has yet to be examined. The present study was designed to investigate mutual touch during face-to-face interactions between mothers and their 5½-month-old fullterm (n=40), very low birth weight/preterm (VLBW/preterm; n=40) infants, and infants at psychosocial risk (n=41). Objectives were to examine: (1) how the quantitative and qualitative aspects of touch employed by mothers and their infants varied across the normal periods of the still-face (SF) procedure, and (2) how these were associated with risk status. Mutual touch was systematically coded using the mother-infant touch scale. Interactions were found to largely consist of mutual touch and one-sided touch plus movement, highlighting that active touching is pervasive during mother-infant interactions. Consistent with the literature, while the SF period did not negatively affect the amount of mutual touch engaged in for mothers and their fullterm infants and mothers and their infants at psychosocial risk, it did for mothers and their VLBW/preterm infants. Together, results illuminate how both mothers and infants participate in shaping and co-regulating their interactions through the use of touch and underscore the contribution of examining the influence of birth status on mutual touch.

  15. The influences of surface plasmons and thermal effects on femtosecond laser-induced subwavelength periodic ripples on Au film by pump-probe imaging

    Science.gov (United States)

    Zhou, Kan; Jia, Xin; Jia, Tianqing; Cheng, Ke; Cao, Kaiqiang; Zhang, Shian; Feng, Donghai; Sun, Zhenrong

    2017-03-01

    In this paper, the influences of surface plasmons and thermal effects on the formation of subwavelength periodic ripples on Au films irradiated by 800 nm femtosecond laser pulses were studied by collinear pump-probe imaging. The spatial and temporal resolutions of the experiment were 300 nm and 1 ps, respectively. No periodic ripples were observed on the Au film during ablation by the first pump pulse, but during ablation by the second pump pulse the appearance of transient ripples was evident from a delay time of hundreds of picoseconds to several nanoseconds. These ripples, however, were not retained after solidification. When the sample was immersed in water during ablation, however, the ripples were retained. It is proposed that, during the second laser pulse irradiation, the surface defects produced by the first pulse induced surface plasmon polaritons on the Au film, which caused a modulated energy deposition and the formation of transient ripples. The weak electron-phonon coupling and significant residual heat erase these ripples after the molten surface was solidified.

  16. Influence of the water quality improvement on fish population in the Seine River (Paris, France) over the 1990-2013 period.

    Science.gov (United States)

    Azimi, Sam; Rocher, Vincent

    2016-01-15

    Over the past 20 years, rules concerning wastewater treatment and quality of water discharged into the environment have changed considerably. Huge investments have been made in Paris conurbation to improve waste water treatment processes in accordance with the European Water Framework Directive. The interdepartmental association for sewage disposal in Paris conurbation (SIAAP) carried out a monitoring of both fish assemblages and water quality in the Seine River around the Paris conurbation (France) since the early 90's. The main goal of this study was to estimate the influence of the water quality improvement on fish. On one hand, the study confirmed the improvement of the water quality (dissolved oxygen, ammonia nitrogen, organic matter) in the Seine River, mostly focused downstream of Paris conurbation. On the other hand, an increase of the number of species occurred from 1990 (14) to 2013 (21). Moreover, changes in the river Seine assemblages happened over that 23-year period with emergence of sensitive species (ruffe, scalpin and pike-perch). The improvement of the water quality was also reported with respect to the Index of Biotic Integrity (IBI). However, no variation of pollutant concentrations in roach, eel and chub muscles has been observed. An exceedance of the environmental quality standards have even been reported all over this period as regards mercury and organochlorine.

  17. Paleomagnetic data from the Trans-Mexican Volcanic Belt: implications for tectonics and volcanic stratigraphy

    Science.gov (United States)

    Alva-Valdivia, L. M.; Goguitchaichvili, A.; Ferrari, L.; Rosas-Elguera, J.; Urrutia-Fucugauchi, J.; Zamorano-Orozco, J. J.

    2000-07-01

    We report a paleomagnetic and rock-magnetic study of Miocene volcanic rocks from the Trans-Mexican Volcanic Belt. A total of 32 sites (238 oriented samples) were collected from three localities: Queretaro, Guadalajara and Los Altos de Jalisco basaltic plateaux, which span from 11 to 7.5 Ma. Several rock-magnetic experiments were carried out in order to identify the magnetic carriers and to obtain information about their paleomagnetic stability. Microscopic observation of polished sections shows that the main magnetic mineral is Ti-poor titanomagnetite associated with exsolved ilmenite. Continuous susceptibility measurements with temperature yield in most cases reasonably reversible curves with Curie points close to that of magnetite. Judging from the ratios of hysteresis parameters, it seems that all samples fall in the pseudo-single domain (PSD) grain size region, probably indicating a mixture of multidomain (MD) and a significant amount of single domain (SD) grains. Based on our paleomagnetic and available radiometric data, it seems that the volcanic units have been emplaced during a relatively short time span of 1 to 2 My at each locality. The mean paleomagnetic directions obtained from each locality differ significantly from that expected for the Middle Miocene. The mean paleomagnetic direction calculated from 28 sites discarding those of intermediate polarity is I= 32.46°, D= 341.2°, k= 7.2 and a95= 11.6°. Comparison with the expected direction indicates some 20° anticlockwise tectonic rotations for the studied area, in accordance with the proposed left-lateral transtensional tectonic regime already proposed for this period.

  18. Analysis of The Influence of Liquidity, Credit and Operational Risk, in Indonesian Islamic Bank’s Financing for The Period 2007-2013

    Directory of Open Access Journals (Sweden)

    Ousmane Diallo

    2015-12-01

    Full Text Available The purpose of this paper is to analyze the influence of credit, liquidity and operational risks in six Indonesian’s islamic banking financing products namely mudharabah, musyarakah, murabahah, istishna, ijarah and qardh, in order to try to discover whether or not Indonesian islamic banking is based on the “risk-sharing” system. This paper relies on a fixed effect model test based on the panel data analysis method, focusing on the period from 2007 to 2013. The research is an exploratory and descriptive study of all the Indonesian islamic banks that were operating in 2013. The results of this study show that the Islamic banking system in Indonesia truly has banking products based on “risk-sharing.” We found out that credit, operational and liquidity risks as a whole, have significant influence on mudarabah, musyarakah, murabahah, istishna, ijarah and qardh based financing. There is a correlation between the credit risk and mudarabah based financing, and no causal relationship between the credit risk and musharaka, murabahah, ijarah, istishna and qardh based financing. There is also correlation between the operational risk and mudarabah and murabahah based financing, and no causal relationship between the operational risk and musharaka, istishna, ijarah and qardh based financing. There is correlation between the liquidity risk and istishna based financing, and no causal relationship between the liquidity risk and musharaka, mudarabah, murabahah, ijarah and qardh based financing. A major implication of this study is the fact that there is no causal relationship between the credit risk and musharakah based financing, which is the mode of financing where the islamic bank shares the risk with its clients, but there is an influence of credit risk toward mudarabah mode financing, a financing mode where the Islamic bank bears all the risk. These findings can lead us to conclude that the Indonesian Islamic banking sector is based on the

  19. Precursory volcanic CO2 signals from space

    Science.gov (United States)

    Schwandner, Florian M.; Carn, Simon A.; Kataoka, Fumie; Kuze, Akihiko; Shiomi, Kei; Goto, Naoki

    2016-04-01

    Identification of earliest signals heralding volcanic unrest benefits from the unambiguous detection of precursors that reflect deviation of magmatic systems from metastable background activity. Ascent and emplacement of new basaltic magma at depth may precede eruptions by weeks to months. Transient localized carbon dioxide (CO2) emissions stemming from exsolution from depressurized magma are expected, and have been observed weeks to months ahead of magmatic surface activity. Detecting such CO2 precursors by continuous ground-based monitoring operations is unfortunately not a widely implemented method yet, save a handful of volcanoes. Detecting CO2 emissions from space offers obvious advantages - however it is technologically challenging, not the least due to the increasing atmospheric burden of CO2, against which a surface emission signal is hard to discern. In a multi-year project, we have investigated the feasibility of space-borne detection of pre-eruptive volcanic CO2 passive degassing signals using observations from the Greenhouse Gas Observing SATellite (GOSAT). Since 2010, we have observed over 40 active volcanoes from space using GOSAT's special target mode. Over 72% of targets experienced at least one eruption over that time period, demonstrating the potential utility of space-borne CO2 observations in non-imaging target-mode (point source monitoring mode). While many eruption precursors don't produce large enough CO2 signals to exceed space-borne detection thresholds of current satellite sensors, some of our observations have nevertheless already shown significant positive anomalies preceding eruptions at basaltic volcanoes. In 2014, NASA launched its first satellite dedicated to atmospheric CO2 observation, the Orbiting Carbon Observatory (OCO-2). Its observation strategy differs from the single-shot GOSAT instrument. At the expense of GOSAT's fast time series capability (3-day repeat cycle, vs. 16 for OCO-2), its 8-footprint continuous swath can slice

  20. Influences of volcano eruptions on Asian Summer Monsoon over the last 110 years

    Science.gov (United States)

    Ning, Liang; Liu, Jian; Sun, Weiyi

    2017-02-01

    Asian summer monsoon (ASM) precipitation is the primary water resource for agriculture in many Asian countries that have experienced rapid economic growth in recent decades, thus implying the necessity for further investigations on both the internal variability of the ASM and the influence of external factors on the ASM. Using long-term high-resolution (0.5° × 0.5°) observed precipitation data, contrary to previous studies on inter-annual timescale, we showed that over the last 110 years, volcanic eruptions have influenced ASM variations on an inter-decadal timescale via teleconnections with the Atlantic Multi-decadal Oscillation (AMO). This relationship was also confirmed by Coupled Model Intercomparison Program Phase 5 (CMIP5) model simulations. During the active volcanic eruption periods (1901–1935 and 1963–1993), significantly lower ASM precipitation was observed compared with that during the inactive volcanic eruption period (1936–1962). We found that during active volcanic eruption periods, which correspond to a negative AMO state, there is an anomalously weakened Walker circulation over the tropical Pacific that transports less moisture to the ASM region and subsequently reduces ASM precipitation. This new finding may help improve decadal predictions of future changes in the ASM.

  1. Influences of volcano eruptions on Asian Summer Monsoon over the last 110 years.

    Science.gov (United States)

    Ning, Liang; Liu, Jian; Sun, Weiyi

    2017-02-16

    Asian summer monsoon (ASM) precipitation is the primary water resource for agriculture in many Asian countries that have experienced rapid economic growth in recent decades, thus implying the necessity for further investigations on both the internal variability of the ASM and the influence of external factors on the ASM. Using long-term high-resolution (0.5° × 0.5°) observed precipitation data, contrary to previous studies on inter-annual timescale, we showed that over the last 110 years, volcanic eruptions have influenced ASM variations on an inter-decadal timescale via teleconnections with the Atlantic Multi-decadal Oscillation (AMO). This relationship was also confirmed by Coupled Model Intercomparison Program Phase 5 (CMIP5) model simulations. During the active volcanic eruption periods (1901-1935 and 1963-1993), significantly lower ASM precipitation was observed compared with that during the inactive volcanic eruption period (1936-1962). We found that during active volcanic eruption periods, which correspond to a negative AMO state, there is an anomalously weakened Walker circulation over the tropical Pacific that transports less moisture to the ASM region and subsequently reduces ASM precipitation. This new finding may help improve decadal predictions of future changes in the ASM.

  2. Volcanic risk perception of young people in the urban areas of Vesuvius: Comparisons with other volcanic areas and implications for emergency management

    Science.gov (United States)

    Carlino, S.; Somma, R.; Mayberry, G.C.

    2008-01-01

    More than 600 000 people are exposed to volcanic risk in the urban areas near the volcano, Vesuvius, and may need to be evacuated if there is renewed volcanic activity. The success of a future evacuation will strongly depend on the level of risk perception and preparedness of the at-risk communities during the current period of quiescence. The volcanic risk perception and preparedness of young people is of particular importance because hazard education programs in schools have been shown to increase the clarity of risk perception and students often share their knowledge with their parents. In order to evaluate young people's risk perception and preparedness for a volcanic crisis, a multiple choice questionnaire was distributed to 400 high-school students in three municipalities located close to the volcano. The overall results suggest that despite a 60-year period of quiescence at Vesuvius, the interviewed students have an accurate perception of the level of volcanic risk. On the other hand, the respondents demonstrate a clear lack of understanding of volcanic processes and their related hazards. Also, the interviewed students show high levels of fear, poor perceived ability to protect themselves from the effects of a future eruption, and insufficient knowledge of the National Emergency Plan for Vesuvian Area (NEPVA). The latter result suggests that in comparison with volcanic crises in other regions, during a future eruption of Vesuvius, there may not be enough time to educate the large number of people living near the volcano about how to appropriately respond. The inadequate risk education and preparedness of respondents implies that a strong effort is needed to improve communication strategies in order to facilitate successful evacuations. Therefore, it is important to take advantage of the present period of quiescence at Vesuvius to improve the accuracy of risk perception of youth in local communities. ?? 2008.

  3. Volcanic hazards at Atitlan volcano, Guatemala

    Science.gov (United States)

    Haapala, J.M.; Escobar Wolf, R.; Vallance, James W.; Rose, William I.; Griswold, J.P.; Schilling, S.P.; Ewert, J.W.; Mota, M.

    2006-01-01

    Atitlan Volcano is in the Guatemalan Highlands, along a west-northwest trending chain of volcanoes parallel to the mid-American trench. The volcano perches on the southern rim of the Atitlan caldera, which contains Lake Atitlan. Since the major caldera-forming eruption 85 thousand years ago (ka), three stratovolcanoes--San Pedro, Toliman, and Atitlan--have formed in and around the caldera. Atitlan is the youngest and most active of the three volcanoes. Atitlan Volcano is a composite volcano, with a steep-sided, symmetrical cone comprising alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs. Eruptions of Atitlan began more than 10 ka [1] and, since the arrival of the Spanish in the mid-1400's, eruptions have occurred in six eruptive clusters (1469, 1505, 1579, 1663, 1717, 1826-1856). Owing to its distance from population centers and the limited written record from 200 to 500 years ago, only an incomplete sample of the volcano's behavior is documented prior to the 1800's. The geologic record provides a more complete sample of the volcano's behavior since the 19th century. Geologic and historical data suggest that the intensity and pattern of activity at Atitlan Volcano is similar to that of Fuego Volcano, 44 km to the east, where active eruptions have been observed throughout the historical period. Because of Atitlan's moderately explosive nature and frequency of eruptions, there is a need for local and regional hazard planning and mitigation efforts. Tourism has flourished in the area; economic pressure has pushed agricultural activity higher up the slopes of Atitlan and closer to the source of possible future volcanic activity. This report summarizes the hazards posed by Atitlan Volcano in the event of renewed activity but does not imply that an eruption is imminent. However, the recognition of potential activity will facilitate hazard and emergency preparedness.

  4. Period Cramps

    Science.gov (United States)

    ... Too Tall or Too Short All About Puberty Period Cramps KidsHealth > For Kids > Period Cramps Print A ... re a girl who gets them. What Are Period Cramps? Lots of girls experience cramps before or ...

  5. The effect of volcanic eruptions on the hydrological cycle

    Science.gov (United States)

    Iles, Carley; Hegerl, Gabriele

    2015-04-01

    Large explosive volcanic eruptions inject sulphur dioxide into the stratosphere where it is oxidised to sulphate aerosols which reflect sunlight. This causes a reduction in global temperature and precipitation lasting a few years. We investigate the robust features of this precipitation response, comparing climate model simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) archive to three observational datasets, including one with ocean coverage. Global precipitation decreases significantly following eruptions in CMIP5 models, with the largest decrease in wet tropical regions. This also occurs in observational land data, and ocean data in the boreal cold season. In contrast, the dry tropical ocean regions show an increase in precipitation in CMIP5 models. Monsoon regions dry following eruptions in both models and observations, whilst in response to individual eruptions, the ITCZ shifts away from the hemisphere with the greater concentration of aerosols in CMIP5. The ocean response in CMIP5 is longer lasting than that over land, but observational results are too noisy to confirm this. We detect the influence of volcanism on precipitation in the boreal cold season, although the models underestimate the size of the response, whilst in the warm season the volcanic influence is marginally detectable. We then examine whether the influence of volcanoes can be seen in streamflow records for 50 major world rivers. Significant reductions in flow are found for the Amazon, Congo, Nile, Orange, Ob, Yenisey and Kolyma amongst others. When neighbouring rivers are combined into regions, informed by climate model predictions of the precipitation response to eruptions, decreases in streamflow can be detected in northern South American, central African and high-latitude Asian rivers and increases in southern South American and SW North American rivers. An improved understanding of how the hydrological cycle responds to volcanic eruptions is valuable in

  6. The Global Water Cycle Drives Volcanism on Seasonal to Millennial Timescales

    Science.gov (United States)

    Pyle, D. M.; Mason, B. G.; Jupp, T. E.; Dade, W. B.

    2005-05-01

    Global rates of occurrence of volcanic eruptions show periodic behaviour on timescales ranging from 106 years. At long timescales (>106 to 107 years), rates of eruption are controlled by plate tectonics. At shorter timescales, the periodic nature of volcanism is forced by the global water cycle. Historical records of the rates of onset of eruption for the past 300 years are dominated by small-scale activity at a number of persistently, or repeatedly, active volcanoes around the world. This record shows statistically significant evidence for `seasonality': globally, rates of eruption are about 18% higher during northern hemisphere winter than northern hemisphere summer. This pattern of seasonality is strong for volcanoes at high northern latitudes; but also exists for volcanic regions in the southern hemisphere (e.g. Chile) and at specific volcanoes (e.g. Sakurajima, Japan). Seasonality is weak at certain ocean-island volcanoes (e.g. Hawaii), and certain volcanic regions (e.g. Mediterranean). The only external parameters that account for the periodic nature of small-scale volcanism (i.e. the observation that eruption rates peak between November and March in both hemispheres) are those related to the global water cycle. Movement of water (including atmospheric vapour; soil moisture; snow and ice) between the northern-hemisphere continents and the world's oceans is responsible for an annual deformation of Earth's surface that is weakly defined in equatorial regions, and stronger at higher latitudes. This external modulation of the Earth's surface has an amplitude of the order of centimetres, and an associated (vertical) strain rate of ~ 10-16 s-1. This deformation is slow enough to be felt by the Earth's interior, and is of the same order of magnitude as the (horizontal) strain rates experienced in tectonically active continental regions. This modulation effectively applies a time-dependence to the `threshold' point at which a volcano will begin to erupt. In this way

  7. Late Holocene volcanism at Medicine Lake Volcano, northern California Cascades

    Science.gov (United States)

    Donnelly-Nolan, Julie M.; Champion, Duane E.; Grove, Timothy L.

    2016-05-23

    accessibility and good exposure of lavas, combined with physical and petrologic evidence for multiple and varied mafic inputs, has created an unusual opportunity to understand the workings of this large magmatic system. A combined total of more than 25 intrusive and extrusive events are indicated for late Holocene time. Plutonic inclusions, some with ages as young as Holocene, were also brought to the surface in five of the eruptions. All eruptions took place along northwest- to northeast-trending alignments of vents, reflecting the overall east-west extensional tectonic environment. The interaction of tectonism and volcanism is a dominant influence at this subduction-related volcano, located where the west edge of the extensional Basin and Range Province impinges on the Cascades arc. Ongoing subsidence focused at the central caldera has been documented along with geophysical evidence for a small magma body. This evidence, combined with the frequency of eruptive and intrusive activity in late Holocene time, an active geothermal system, and intermittent long-period seismic events indicate that the volcano is likely to erupt again.

  8. Deccan volcanism, the KT mass extinction and dinosaurs

    Indian Academy of Sciences (India)

    G Keller; A Sahni; S Bajpai

    2009-11-01

    Recent advances in Deccan volcanic studies indicate three volcanic phases with the phase-1 at 67.5 Ma followed by a 2 m.y. period of quiescence. Phase-2 marks the main Deccan volcanic eruptions in Chron 29r near the end of the Maastrichtian and accounts for ∼80% of the entire 3500 m thick Deccan lava pile. At least four of the world’s longest lava flows spanning 1000 km across India and out into the Gulf of Bengal mark phase-2. The final phase-3 was smaller, coincided with the early Danian Chron 29n and also witnessed several of the longest lava flows. The KT boundary and mass extinction was first discovered based on planktic foraminifera from shallow marine intertrappean sediments exposed in Rajahmundry quarries between the longest lava flows of the main volcanic phase-2 and smaller phase-3. At this locality early Danian (zone P1a) planktic foraminiferal assemblages directly overlie the top of phase-2 eruptions and indicate that the masse extinction coincided with the end of this volcanic phase. Planktic foraminiferal assemblages also mark the KT boundary in intertrappean sediments at Jhilmili, Chhindwara, where freshwater to estuarine conditions prevailed during the early Danian and indicate the presence of a marine seaway across India at KT time. Dinosaur bones, nesting sites with complete eggs and abundant eggshells are known from central India surrounding the hypothesized seaway through the Narmada-Tapti rift zone. A Maastrichtian age is generally assigned to these dinosaur remains. Age control may now be improved based on marine microfossils from sequences deposited in the seaway and correlating these strata to nearby terrestrial sequences with dinosaur remains.

  9. Deccan volcanism, the KT mass extinction and dinosaurs

    Indian Academy of Sciences (India)

    G Keller; A Sahni; S Bajpai

    2010-03-01

    Recent advances in Deccan volcanic studies indicate three volcanic phases with the phase-1 at 67.5 Ma followed by a 2 m.y. period of quiescence. Phase-2 marks the main Deccan volcanic eruptions in Chron 29r near the end of the Maastrichtian and accounts for ∼80% of the entire 3500 m thick Deccan lava pile. At least four of the world’s longest lava flows spanning 1000 km across India and out into the Gulf of Bengal mark phase-2. The final phase-3 was smaller, coincided with the early Danian Chron 29n and also witnessed several of the longest lava flows. The KT boundary and mass extinction was first discovered based on planktic foraminifera from shallow marine intertrappean sediments exposed in Rajahmundry quarries between the longest lava flows of the main volcanic phase-2 and smaller phase-3. At this locality early Danian (zone P1a) planktic foraminiferal assemblages directly overlie the top of phase-2 eruptions and indicate that the masse extinction coincided with the end of this volcanic phase. Planktic foraminiferal assemblages also mark the KT boundary in intertrappean sediments at Jhilmili, Chhindwara, where freshwater to estuarine conditions prevailed during the early Danian and indicate the presence of a marine seaway across India at KT time. Dinosaur bones, nesting sites with complete eggs and abundant eggshells are known from central India surrounding the hypothesized seaway through the Narmada-Tapti rift zone. A Maastrichtian age is generally assigned to these dinosaur remains. Age control may now be improved based on marine microfossils from sequences deposited in the seaway and correlating these strata to nearby terrestrial sequences with dinosaur remains.

  10. K—Ar Geochronology and Evolution of Cenozoic Volcanic Rocks in Eastrn China

    Institute of Scientific and Technical Information of China (English)

    王慧芬; 杨学昌; 等

    1989-01-01

    Cenozoic volcanic rocks widespread in eastern China constitute an important part of the circum-Pacific volcanic belt.This paper presents more than 150K-Ar dates and a great deal of petrochemical analysis data from the Cenozoic volcanic rocks distributed in Tengchong,China's southeast coast,Shandong,Hebei,Nei Monggol and Northeast China.An integrated study shows that ubiquitous but uneven volcanic activities prevailed from the Eogene to the Holocene,characterized as being multi-eqisodic and multicycled.For example,in the Paleocene(67-58Ma),Eocene(57-37.5Ma),Miocene(22-18,16-19Ma),Pliocene(8-3Ma),and Early Pleistocene-Middle Pleistocene(1.2-0.5Ma) there were upsurges of volcanism,while in the Oligocene there was a repose period.In space,the older Eogene volcanic rocks are distributed within the region or in the central part of the NE-NNE-striking fault depression,while the younger Neogene and Quaternary volcanic rocks are distributed in the eastern and western parts.Petrologically,they belong essentially to tholeiite-series and alkali-series basalts,with alkalinity in the rocks increasing from old to youg.The above regularities are controlled by both global plate movement and regional inherent tectonic pattern.

  11. Influence of timing of sea ice retreat on phytoplankton size during marginal ice zone bloom period on the Chukchi and Bering shelves

    Science.gov (United States)

    Fujiwara, A.; Hirawake, T.; Suzuki, K.; Eisner, L.; Imai, I.; Nishino, S.; Kikuchi, T.; Saitoh, S.-I.

    2016-01-01

    The size structure and biomass of a phytoplankton community during the spring bloom period can affect the energy use of higher-trophic-level organisms through the predator-prey body size relationships. The timing of the sea ice retreat (TSR) also plays a crucial role in the seasonally ice-covered marine ecosystem, because it is tightly coupled with the timing of the spring bloom. Thus, it is important to monitor the temporal and spatial distributions of a phytoplankton community size structure. Prior to this study, an ocean colour algorithm was developed to derive phytoplankton size index FL, which is defined as the ratio of chlorophyll a (chl a) derived from cells larger than 5 µm to the total chl a, using satellite remote sensing for the Chukchi and Bering shelves. Using this method, we analysed the pixel-by-pixel relationships between FL during the marginal ice zone (MIZ) bloom period and TSR over the period of 1998-2013. The influences of the TSR on the sea surface temperature (SST) and changes in ocean heat content (ΔOHC) during the MIZ bloom period were also investigated. A significant negative relationship between FL and the TSR was widely found in the shelf region during the MIZ bloom season. However, we found a significant positive (negative) relationship between the SST (ΔOHC) and TSR. Specifically, an earlier sea ice retreat was associated with the dominance of larger phytoplankton during a colder and weakly stratified MIZ bloom season, suggesting that the duration of the nitrate supply, which is important for the growth of large-sized phytoplankton in this region (i.e. diatoms), can change according to the TSR. In addition, under-ice phytoplankton blooms are likely to occur in years with late ice retreat, because sufficient light for phytoplankton growth can pass through the ice and penetrate into the water columns as a result of an increase in solar radiation toward the summer solstice. Moreover, we found that both the length of the ice-free season

  12. Pliocene Basaltic Volcanism in The East Anatolia Region (EAR), Turkey

    Science.gov (United States)

    Oyan, Vural; Özdemir, Yavuz; Keskin, Mehmet

    2016-04-01

    East Anatolia Region (EAR) is one of the high Plateau which is occurred with north-south compressional regime formed depending on continent-continent collision between Eurasia and Arabia plates (Şengör and Kidd, 1979). Recent studies have revealed that last oceanic lithosphere in the EAR have completely depleted to 20 million years ago based on fission track ages (Okay et al. 2010). Our initial studies suggest that extensively volcanic activity in the EAR peaked in the Pliocene and continued in the same productivity throughout Quaternary. Voluminous basaltic lava plateaus and basaltic lavas from local eruption centers occurred as a result of high production level of volcanism during the Pliocene time interval. In order to better understand the spatial and temporal variations in Pliocene basaltic volcanism and to reveal isotopic composition, age and petrologic evolution of the basaltic volcanism, we have started to study basaltic volcanism in the East Anatolia within the framework of a TUBITAK project (project number:113Y406). Petrologic and geochemical studies carried out on the Pliocene basaltic lavas indicate the presence of subduction component in the mantle source, changing the character of basaltic volcanism from alkaline to subalkaline and increasing the amount of spinel peridotitic melts (contributions of lithospheric mantle?) in the mantle source between 5.5-3.5 Ma. FC, AFC and EC-AFC modelings reveal that the while basaltic lavas were no or slightly influenced by crustal contamination and fractional crystallization, to more evolved lavas such as bazaltictrachyandesite, basalticandesite, trachybasalt might have been important processes. Results of our melting models and isotopic analysis data (Sr, Nd, Pb, Hf, 18O) indicate that the Pliocene basaltic rocks were derived from both shallow and deep mantle sources with different melting degrees ranging between 0.1 - 4 %. The percentage of spinel seems to have increased in the mantle source of the basaltic

  13. Agricultural Fragility Estimates Subjected to Volcanic Ash Fall Hazards

    Science.gov (United States)

    Ham, H. J.; Lee, S.; Choi, S. H.; Yun, W. S.

    2015-12-01

    Agricultural Fragility Estimates Subjected to Volcanic Ash Fall Hazards Hee Jung Ham1, Seung-Hun Choi1, Woo-Seok Yun1, Sungsu Lee2 1Department of Architectural Engineering, Kangwon National University, Korea 2Division of Civil Engineering, Chungbuk National University, Korea ABSTRACT In this study, fragility functions are developed to estimate expected volcanic ash damages of the agricultural sector in Korea. The fragility functions are derived from two approaches: 1) empirical approach based on field observations of impacts to agriculture from the 2006 eruption of Merapi volcano in Indonesia and 2) the FOSM (first-order second-moment) analytical approach based on distribution and thickness of volcanic ash observed from the 1980 eruption of Mt. Saint Helens and agricultural facility specifications in Korea. Fragility function to each agricultural commodity class is presented by a cumulative distribution function of the generalized extreme value distribution. Different functions are developed to estimate production losses from outdoor and greenhouse farming. Seasonal climate influences vulnerability of each agricultural crop and is found to be a crucial component in determining fragility of agricultural commodities to an ash fall. In the study, the seasonality coefficient is established as a multiplier of fragility function to consider the seasonal vulnerability. Yields of the different agricultural commodities are obtained from Korean Statistical Information Service to create a baseline for future agricultural volcanic loss estimation. Numerically simulated examples of scenario ash fall events at Mt. Baekdu volcano are utilized to illustrate the application of the developed fragility functions. Acknowledgements This research was supported by a grant 'Development of Advanced Volcanic Disaster Response System considering Potential Volcanic Risk around Korea' [MPSS-NH-2015-81] from the Natural Hazard Mitigation Research Group, Ministry of Public Safety and Security of

  14. Catastrophic volcanic collapse: relation to hydrothermal processes.

    Science.gov (United States)

    López, D L; Williams, S N

    1993-06-18

    Catastrophic volcanic collapse, without precursory magmatic activity, is characteristic of many volcanic disasters. The extent and locations of hydrothermal discharges at Nevado del Ruiz volcano, Colombia, suggest that at many volcanoes collapse may result from the interactions between hydrothermal fluids and the volcanic edifice. Rock dissolution and hydrothermal mineral alteration, combined with physical triggers such as earth-quakes, can produce volcanic collapse. Hot spring water compositions, residence times, and flow paths through faults were used to model potential collapse at Ruiz. Caldera dimensions, deposits, and alteration mineral volumes are consistent with parameters observed at other volcanoes.

  15. Nephelometric Dropsonde for Volcanic Ash Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced dropsondes that could effectively be guided through atmospheric regions of interest such as volcanic plumes could enable unprecedented observations of...

  16. Planetary Aspects of Volcanism: Insights Into the Volcano - Tectonic Relationship on Earth

    Science.gov (United States)

    Cañón-Tapia, E.

    2009-12-01

    There are many alternative definitions of a volcanic system, each focusing on different aspects of volcanic and/or magmatic activity. Although all of these definitions contribute to increase our understanding of volcanic phenomena, each was conceived with a specific aspect of volcanism in mind, therefore reducing its utility when problems beyond its own limits are considered, and perhaps more importantly, introducing subtle biases in the form in which we approach the study of this type of phenomena. In particular, the volcano-tectonic relationship most commonly used in volcanology textbooks seems to be biased towards volcanic activity on Earth, disregarding the presence of this type of phenomena in other planets, moons and even asteroids of our solar system. As a cursory examination of volcanism in the solar system reveals, the causes of volcanic activity deserve to be examined independently of any tectonic influence. Any model of volcanism of this type, however, needs to be flexible enough to accommodate tectonic variables if so required. In this work, such a flexible model of volcanism is outlined. This model is constructed by first exploring the form in which the Tectonic and the Volcanic systems are related to each other in different planets by using a mechanical analogy. Second, the analogy is used to identify key components of the volcanic system that need to be quantified first, therefore leading to the introduction of fundamental physical principles in the conceptual model of volcanism that is independent of the tectonic scenario. Third, the predictive capabilities of this model are compared to specific cases on Earth where the type of required information has been gathered previously. The results suggest that the physical constraints of the model are reasonable, therefore paving the road for further studies aiming to identify the tectonic contribution of volcanism on a case by case basis. Two corollaries of this study are that we need to learn to formulate

  17. Thermal vesiculation during volcanic eruptions

    Science.gov (United States)

    Lavallée, Yan; Dingwell, Donald B.; Johnson, Jeffrey B.; Cimarelli, Corrado; Hornby, Adrian J.; Kendrick, Jackie E.; von Aulock, Felix W.; Kennedy, Ben M.; Andrews, Benjamin J.; Wadsworth, Fabian B.; Rhodes, Emma; Chigna, Gustavo

    2015-12-01

    Terrestrial volcanic eruptions are the consequence of magmas ascending to the surface of the Earth. This ascent is driven by buoyancy forces, which are enhanced by bubble nucleation and growth (vesiculation) that reduce the density of magma. The development of vesicularity also greatly reduces the ‘strength’ of magma, a material parameter controlling fragmentation and thus the explosive potential of the liquid rock. The development of vesicularity in magmas has until now been viewed (both thermodynamically and kinetically) in terms of the pressure dependence of the solubility of water in the magma, and its role in driving gas saturation, exsolution and expansion during decompression. In contrast, the possible effects of the well documented negative temperature dependence of solubility of water in magma has largely been ignored. Recently, petrological constraints have demonstrated that considerable heating of magma may indeed be a common result of the latent heat of crystallization as well as viscous and frictional heating in areas of strain localization. Here we present field and experimental observations of magma vesiculation and fragmentation resulting from heating (rather than decompression). Textural analysis of volcanic ash from Santiaguito volcano in Guatemala reveals the presence of chemically heterogeneous filaments hosting micrometre-scale vesicles. The textures mirror those developed by disequilibrium melting induced via rapid heating during fault friction experiments, demonstrating that friction can generate sufficient heat to induce melting and vesiculation of hydrated silicic magma. Consideration of the experimentally determined temperature and pressure dependence of water solubility in magma reveals that, for many ascent paths, exsolution may be more efficiently achieved by heating than by decompression. We conclude that the thermal path experienced by magma during ascent strongly controls degassing, vesiculation, magma strength and the effusive

  18. Water in volcanic glass: From volcanic degassing to secondary hydration

    Science.gov (United States)

    Seligman, Angela N.; Bindeman, Ilya N.; Watkins, James M.; Ross, Abigail M.

    2016-10-01

    Volcanic glass is deposited with trace amounts (0.1-0.6 wt.%) of undegassed magmatic water dissolved in the glass. After deposition, meteoric water penetrates into the glass structure mostly as molecular H2O. Due to the lower δD (‰) values of non-tropical meteoric waters and the ∼30‰ offset between volcanic glass and environmental water during hydration, secondary water imparts lighter hydrogen isotopic values during secondary hydration up to a saturation concentration of 3-4 wt.% H2O. We analyzed compositionally and globally diverse volcanic glass from 0 to 10 ka for their δD and H2Ot across different climatic zones, and thus different δD of precipitation, on a thermal conversion elemental analyzer (TCEA) furnace attached to a mass spectrometer. We find that tephrachronologically coeval rhyolite glass is hydrated faster than basaltic glass, and in the majority of glasses an increase in age and total water content leads to a decrease in δD (‰), while a few equatorial glasses have little change in δD (‰). We compute a magmatic water correction based on our non-hydrated glasses, and calculate an average 103lnαglass-water for our hydrated felsic glasses of -33‰, which is similar to the 103lnαglass-water determined by Friedman et al. (1993a) of -34‰. We also determine a smaller average 103lnαglass-water for all our mafic glasses of -23‰. We compare the δD values of water extracted from our glasses to local meteoric waters following the inclusion of a -33‰ 103lnαglass-water. We find that, following a correction for residual magmatic water based on an average δD and wt.% H2Ot of recently erupted ashes from our study, the δD value of water extracted from hydrated volcanic glass is, on average, within 4‰ of local meteoric water. To better understand the difference in hydration rates of mafic and felsic glasses, we imaged 6 tephra clasts ranging in age and chemical composition with BSE (by FEI SEM) down to a submicron resolution. Mafic tephra

  19. Geochemical Characteristics and Metallogenesis of Volcanic Rocks as Exemplified by Volcanic Rocks in Ertix,Xinjiang

    Institute of Scientific and Technical Information of China (English)

    刘铁庚; 叶霖

    1997-01-01

    Volcanic rocks in Ertix,Xinjiang,occurring in the collision zone between the Siberia Plate and the Junggar Plate,are distributed along the Eritix River Valley in northern Xinjiang.The volcanic rocks were dated at Late Paleozoic and can be divided into the spilite-keratophyre series and the basalt-andesite series.The spilite-keratophyre series volcanic rocks occur in the Altay orogenic belt at the southwest margin of the Siberia Plate.In addition to sodic volcanic rocks.There are also associated potassic-sodic volcanic rocks and potassic volcanic rocks.The potassic-sodic volcanic rocks occur at the bottom of the eruption cycle and control the distribution of Pb and Zn deposits.The potassic volcanic rocks occur at the top of the eruption cycle and are associated with Au and Cu mineralizations.The sodic volcanic rocks occur in the middle stage of eruption cycle and control the occurrence of Cu(Zn) deposits.The basalt-andesite series volcanic rocks distributed in the North Junggar orogenic belt at the north margin of the Junggar-Kazakstan Plate belong to the potassic sodic volcain rocks.The volcanic rocks distributed along the Ulungur fault are relatively rich in sodium and poor in potassium and are predominated by Cu mineralization and associated with Au mineralization.Those volcanic rocks distributed along the Ertix fault are relatively rich in K and poor in Na,with Au mineralization being dominant.

  20. Volcanic aerosols: Chemistry, evolution, and effects

    Science.gov (United States)

    Turco, Richard

    1991-01-01

    Stratospheric aerosols have been the subject of scientific speculation since the 1880s, when the powerful eruption of Krakatoa attracted worldwide attention to the upper atmosphere through spectacular optical displays. The presence of a permanent tenuous dust layer in the lower stratosphere was postulated in the 1920s following studies of the twilight glow. Junge collected the first samples of these 'dust' particles and demonstrated that they were actually composed of sulfates, most likely concentrated sulfuric acid (Junge and Manson, 1961; Junge, 1963). Subsequent research has been spurred by the realization that stratospheric particles can influence the surface climate of earth through their effects on atmospheric radiation. Such aerosols can also influence, through chemical and physical effects, the trace composition of the atmosphere, ozone concentrations, and atmospheric electrical properties. The properties of stratospheric aerosols (both the background particles and those enhanced by volcanic eruptions) were measured in situ by balloon ascents and high altitude aircraft sorties. The aerosols were also observed remotely from the ground and from satellites using both active (lidar) and passive (solar occultation) techniques (remote sensing instruments were carried on aircraft and balloon platforms as well). In connection with the experimental work, models were developed to test theories of particle formation and evolution, to guide measurement strategies, to provide a means of connecting laboratory and field data, and to apply the knowledge gained to answer practical questions about global changes in climate, depletion of the ozone layer, and related environmental problems.

  1. Influence of arbuscular mycorrhizal fungi and treated wastewater on water relations and leaf structure alterations of Viburnum tinus L. plants during both saline and recovery periods.

    Science.gov (United States)

    Gómez-Bellot, María José; Nortes, Pedro Antonio; Ortuño, María Fernanda; Romero, Cristina; Fernández-García, Nieves; Sánchez-Blanco, María Jesús

    2015-09-01

    Nowadays, irrigation with low quality water is becoming an alternative to satisfy the needs of crops. However, some plant species have to deal with high salinity of reclaimed water, by adapting their physiological behaviour during both saline and recovery periods and developing morphological changes in their leaves. The application of arbuscular mycorrhizal fungi (AMF) could also be a suitable option to mitigate the negative effects of this kind of water, although the effectiveness of plant-AMF association is influenced by many factors. In this work, during forty weeks, the combined effect of Glomus iranicum var. tenuihypharum and two types of water: control, C, EC<0.9 dS m(-1) and reclaimed water, RW (with EC: 4 dS m(-1) during a first saline period and EC: 6 dS m(-1) during a second saline period) was evaluated for laurustinus plants (Viburnum tinus L.) transplanted in soil. This was followed by a recovery period of eight weeks, when all the plants were irrigated in the control irrigation conditions. Seasonal and daily changes in stem water potential (Ψstem), stomatal conductance (gs), photosynthesis (Pn) and leaf internal CO2 concentration (Ci) of laurustinus plants were evaluated. Leaf structure alterations, nutrient imbalance, height and leaf hydraulic conductivity (Kleaf) were also determined. Due to the high difficulty of absorbing water from the soil, RW plants showed a high volumetric water content (θv) in soil. The stem water potential and the stomatal conductance (gs) values were reduced in RW plants throughout the second saline period. These decreases were also found during the day. Leaf Ca(2+)/Na(+) and K(+)/Na(+) ratios diminished in RW plants respect to the C plants due to the Na(+) accumulation, although height and chlorophyll content values did not show statistical differences. Leaves from RW plants showed a significantly thicker mesophyll than Control leaves as a consequence of high EC. The area of palisade parenchyma (PP) increased while the

  2. Stochastic Modelling of Past Volcanic Crises

    Science.gov (United States)

    Woo, Gordon

    2017-04-01

    It is customary to have continuous monitoring of volcanoes showing signs of unrest that might lead to an eruption threatening local populations. Despite scientific progress in estimating the probability of an eruption occurring, the concept of continuously tracking eruption probability remains a future aspiration for volcano risk analysts. During some recent major volcanic crises, attempts have been made to estimate the eruption probability in real time to support government decision-making. These include the possibility of an eruption of Katla linked with the eruption of Eyjafjallajökull in 2010, and the Santorini crisis of 2011-2012. However, once a crisis fades, interest in analyzing the probability that there might have been an eruption tends to wane. There is an inherent outcome bias well known to psychologists: if disaster was avoided, there is perceived to be little purpose in exploring scenarios where a disaster might have happened. Yet the better that previous periods of unrest are understood and modelled, the better that the risk associated with future periods of unrest will be quantified. Scenarios are counterfactual histories of the future. The task of quantifying the probability of an eruption for a past period of unrest should not be merely a statistical calculation, but should serve to elucidate and refine geophysical models of the eruptive processes. This is achieved by using a Bayesian Belief Network approach, in which monitoring observations are used to draw inferences on the underlying causal factors. Specifically, risk analysts are interested in identifying what dynamical perturbations might have tipped an unrest period in history over towards an eruption, and assessing what was the likelihood of such perturbations. Furthermore, in what ways might a historical volcano crisis have turned for the worse? Such important counterfactual questions are addressed in this paper.

  3. The strength of heterogeneous volcanic rocks: A 2D approximation

    Science.gov (United States)

    Heap, Michael J.; Wadsworth, Fabian B.; Xu, Tao; Chen, Chong-feng; Tang, Chun'an

    2016-06-01

    Volcanic rocks typically contain heterogeneities in the form of crystals and pores. We investigate here the influence of such heterogeneity on the strength of volcanic rocks using an elastic damage mechanics model in which we numerically deform two-dimensional samples comprising low-strength elements representing crystals and zero-strength elements representing pores. These circular elements are stochastically generated so that there is no overlap in a medium representing the groundmass. Our modelling indicates that increasing the fraction of pores and/or crystals reduces the strength of volcanic rocks, and that increasing the pore fraction results in larger strength reductions than increasing the crystal fraction. The model also highlights an important weakening role for pore diameter, but finds that crystal diameter has a less significant influence for strength. To account for heterogeneity (pores and crystals), we propose an effective medium approach where we define an effective pore fraction ϕp‧ = Vp/(Vp + Vg) where Vp and Vg are the pore and groundmass fractions, respectively. Highly heterogeneous samples (containing high pore and/or crystal fractions) will therefore have high values of ϕp‧, and vice-versa. When we express our numerical samples (more than 200 simulations spanning a wide range of crystal and pore fractions) in terms of ϕp‧, we find that their strengths can be described by a single curve for a given pore diameter. To provide a predictive tool for the strength of heterogeneous volcanic rocks, we propose a modified version of 2D solution for the Sammis and Ashby (1986) pore-emanating crack model, a micromechanical model designed to estimate strength using microstructural attributes such as porosity, pore radius, and fracture toughness. The model, reformulated to include ϕp‧ (and therefore crystal fraction), captures the strength curves for our numerical simulations over a sample heterogeneity range relevant to volcanic systems. We find

  4. Lidar Observations of Stratospheric Aerosol Layer After the Mt. Pinatubo Volcanic Eruption

    Science.gov (United States)

    Nagai, Tomohiro; Uchino, Osamu; Fujimoto, Toshifumi

    1992-01-01

    The volcano Mt. Pinatubo located on the Luzon Island, Philippines, had explosively erupted on June 15, 1991. The volcanic eruptions such as volcanic ash, SO2 and H2O reached into the stratosphere over 30 km altitude by the NOAA-11 satellite observation and this is considered one of the biggest volcanic eruptions in this century. A grandiose volcanic eruption influences the atmosphere seriously and causes many climatic effects globally. There had been many impacts on radiation, atmospheric temperature and stratospheric ozone after some past volcanic eruptions. The main cause of volcanic influence depends on stratospheric aerosol, that stay long enough to change climate and other meteorological conditions. Therefore it is very important to watch stratospheric aerosol layers carefully and continuously. Standing on this respect, we do not only continue stratospheric aerosol observation at Tsukuba but also have urgently developed another lidar observational point at Naha in Okinawa Island. This observational station could be thought valuable since there is no lidar observational station in this latitudinal zone and it is much nearer to Mt. Pinatubo. Especially, there is advantage to link up these two stations on studying the transportation mechanism in the stratosphere. In this paper, we present the results of lidar observations at Tsukuba and Naha by lidar systems with Nd:YAG laser.

  5. Volcanic hazards and their mitigation: Progress and problems

    Science.gov (United States)

    Tilling, Robert I.

    1989-05-01

    At the beginning of the twentieth century, volcanology began to emerge as a modern science as a result of increased interest in eruptive phenomena following some of the worst volcanic disasters in recorded history: Krakatau (Indonesia) in 1883 and Mont Pelée (Martinique), Soufrière (St. Vincent), and Santa María (Guatemala) in 1902. Volcanology is again experiencing a period of heightened public awareness and scientific growth in the 1980s, the worst period since 1902 in terms of volcanic disasters and crises. A review of hazards mitigation approaches and techniques indicates that significant advances have been made in hazards assessment, volcano monitoring, and eruption forecasting. For example, the remarkable accuracy of the predictions of dome-building events at Mount St. Helens since June 1980 is unprecedented. Yet a predictive capability for more voluminous and explosive eruptions still has not been achieved. Studies of magma-induced seismicity and ground deformation continue to provide the most systematic and reliable data for early detection of precursors to eruptions and shallow intrusions. In addition, some other geophysical monitoring techniques and geochemical methods have been refined and are being more widely applied and tested. Comparison of the four major volcanic disasters of the 1980s (Mount St. Helens, U.S.A. (1980), El Chichón, Mexico (1982); Galunggung, Indonesia (1982); and Nevado del Ruíz, Colombia (1985) illustrates the importance of predisaster geoscience studies, volcanic hazards assessments, volcano monitoring, contingency planning, and effective communications between scientists and authorities. The death toll (>22,000) from the Ruíz catastrophe probably could have been greatly reduced; the reasons for the tragically ineffective implementation of evacuation measures are still unclear and puzzling in view of the fact that sufficient warnings were given. The most pressing problem in the mitigation of volcanic and associated hazards on

  6. Influence of different periods of the year and age on the parameters of antioxidative status and oxidative stress in the blood serum of breeding bulls.

    Science.gov (United States)

    Žaja, Ivona Žura; Samardžija, Marko; Vince, Silvijo; Majić-Balić, Ivanka; Đuričić, Dražen; Milinković-Tur, Suzana

    2016-06-01

    The sources of variations that may cause physiological differences between blood serum biochemistry parameters of bulls have not been investigated in detail. Aim of the present study was to establish influence of different periods of the year and the age of breeding bulls on parameters of antioxidative status and oxidative stress in their serum and to correlate these monitored variables. Research was performed on two groups, each comprising 9 Simmental bulls: a younger group (YB) (aged 2-4 years) and older one (OB) (aged 5-10 years). Blood samples for biochemical analyses were collected from jugular vein in cold (CP) and warm periods (WP) of the year. Reduced glutathione (GSH), uric acid (UA), total protein (TP), albumin (ALB), thiobarbituric acid reactive substance (TBARS), and protein carbonyl content (PCC) serum concentration were determined, as well as activities of selenium-dependent glutathione peroxidase (Se-GSH-Px), total superoxide dismutase (TSOD), manganese superoxide dismutase (MnSOD), copper-zinc superoxide dismutase (CuZnSOD) and catalase (CAT). Serum values of SeGSH-Px, MnSOD, UA and TP in OB were significantly higher compared to those in YB during CP of the year. Significantly higher PCC concentration in serum of YB and OB were established in CP of the year than in WP. TBARS serum concentration in YB was significantly higher in comparison to that in OB during CP of the year. It can be concluded that both OB and YB show a great sensitivity to climate condition alterations during CP in comparison to WP of the year and that YB show even greater sensitivity.

  7. Factors influencing uptake of contraceptive implants in the immediate postpartum period among HIV infected and uninfected women at two Kenyan District Hospitals.

    Science.gov (United States)

    Shabiby, Mufida M; Karanja, Joseph G; Odawa, Francis; Kosgei, Rose; Kibore, Minnie W; Kiarie, James N; Kinuthia, John

    2015-08-19

    Family planning is a cost effective strategy for prevention of mother to child transmission of HIV and reduction of maternal/infant morbidity and mortality. Contraceptive implants are a safe, effective, long term and reversible family planning method whose use remains low in Kenya. We therefore set out to determine and compare the uptake, and factors influencing uptake of immediate postpartum contraceptive implants among HIV infected and uninfected women at two hospitals in Kenya. This cross sectional study targeted postpartum mothers at two Kenyan district hospitals (one urban and one rural). All participants received general family planning and method specific (Implant) counseling followed by immediate insertion of contraceptive implants to those who consented. The data was analyzed by descriptive analysis, T-test, Chi square tests and logistic regression. One hundred eighty-five participants were enrolled (91 HIV positive and 94 HIV negative) with a mean age of 26 years. HIV positive mothers were significantly older (27.5 years) than their HIV negative counterparts (24.5 years), P = 0.001. The two groups were comparable in education, employment, marital status and religious affiliation. Overall, the uptake of contraceptive implants in the immediate postpartum period was 50.3% and higher among HIV negative than HIV positive participants (57% vs. 43%, P = 0.046). Multivariate analysis revealed that a negative HIV status (P = 0.017) and prior knowledge of contraceptive implants (P = 0.001) were independently associated with increased uptake of contraceptive implants. There was a high uptake of immediate postpartum contraceptive implants among both HIV infected and un-infected women; efforts therefore need to be made in promoting this method of family planning in Kenya and providing this method to women in the immediate postpartum period so as to utilize this critical opportunity to increase uptake and reduce the high unmet need for family planning.

  8. Observational evidence for volcanic impact on sea level and the global water cycle.

    Science.gov (United States)

    Grinsted, A; Moore, J C; Jevrejeva, S

    2007-12-11

    It has previously been noted that there are drops in global sea level (GSL) after some major volcanic eruptions. However, observational evidence has not been convincing because there is substantial variability in the global sea level record over periods similar to those at which we expect volcanoes to have an impact. To quantify the impact of volcanic eruptions we average monthly GSL data from 830 tide gauge records around five major volcanic eruptions. Surprisingly, we find that the initial response to a volcanic eruption is a significant rise in sea level of 9 +/- 3 mm in the first year after the eruption. This rise is followed by a drop of 7 +/- 3 mm in the period 2-3 years after the eruption relative to preeruption sea level. These results are statistically robust and no particular volcanic eruption or ocean region dominates the signature we find. Neither the drop nor especially the rise in GSL can be explained by models of lower oceanic heat content. We suggest that the mechanism is a transient disturbance of the water cycle with a delayed response of land river runoff relative to ocean evaporation and global precipitation that affects global sea level. The volcanic impact on the water cycle and sea levels is comparable in magnitude to that of a large El Niño-La Niña cycle, amounting to approximately 5% of global land precipitation.

  9. Disentangling High Frequency Climate Oscillations In A Volcanic Setting Laguna Lejia, Chile

    Science.gov (United States)

    Saltzman, S. H.; Ukstins Peate, I.; Giralt, S.; Peate, D. W.; van Alderwerelt, B. M.

    2015-12-01

    Our understanding of the tropics response to periods of rapid climate change such as CAPE I and the Younger Dryas is limited. Laguna Lejia (23°30'0" S 67°42'0" E ~4,300m asl), Chile is a small alkaline paleolake located in the central Altiplano. The volcanoes Lascar, Chiliques, Aguas Calientes and Acamarachi surround it. 1-3 mm laminations in calcareous clay sediments deposited on the southern terrace of Lejia record high-resolution chemical variability in the lake. Preliminary U-Th ages range from 19,567 +739/- 734 yr to 4208 +431/-429 yr, indicating that the Lejia terrace deposits span both CAPE I and the Younger Dryas, periods of rapid global climate change. Changes in the major and trace element composition, δ18O and δ13 C isotopic ratios, and the amount of Li, Mg, Ca, and Sr that can be readily leached from high magnesium smectite clays provide a direct proxy for hydrologic fluctuations. A climate signal can be detected through reoccurring trends in the chemical variability of these sediments; however, the detection of this signal is complicated by interaction with surrounding volcanic edifices. Statistical methods such as PCA analyses using R have been implemented to separate groupings of volcanic controlled elemental fluctuations (Fe, Zr, Nd, Ti, and Al) from ones under the influence of climate. Spectral analyses have been applied to high-resolution major element data collected on Lejia's paleoshores tufa deposits. Data was collected on Ca, Mg and As at .5 um intervals using a Jeol JXA- 8230 Electron Microprobe at the University of Iowa, Earth and Environmental Sciences. These analyses provided statistical evidence for cyclisity at intervals of 5-15 um and 75-150 um in the banding of the tufas. While previous literature attributes the larger bands to annual chemical cycles the origin of the smaller bands is currently under investigation.

  10. Mode switching in volcanic seismicity: El Hierro 2011-2013

    Science.gov (United States)

    Roberts, Nick S.; Bell, Andrew F.; Main, Ian G.

    2016-05-01

    The Gutenberg-Richter b value is commonly used in volcanic eruption forecasting to infer material or mechanical properties from earthquake distributions. Such studies typically analyze discrete time windows or phases, but the choice of such windows is subjective and can introduce significant bias. Here we minimize this sample bias by iteratively sampling catalogs with randomly chosen windows and then stack the resulting probability density functions for the estimated b>˜ value to determine a net probability density function. We examine data from the El Hierro seismic catalog during a period of unrest in 2011-2013 and demonstrate clear multimodal behavior. Individual modes are relatively stable in time, but the most probable b>˜ value intermittently switches between modes, one of which is similar to that of tectonic seismicity. Multimodality is primarily associated with intermittent activation and cessation of activity in different parts of the volcanic system rather than with respect to any systematic inferred underlying process.

  11. Formation of volcanic edifices in response to changes in magma budget at intermediate spreading rate ridges

    Science.gov (United States)

    Howell, J.; White, S. M.; Bohnenstiehl, D. R.; Bizimis, M.

    2010-12-01

    The spatial and abundance distributions of volcanic edifices along mid-ocean ridges have a well known correlation with spreading rate. Along slow spreading centers, volcanic edifices are normally distributed about the segment center. Volcanic edifices along fast spreading centers have the opposing trend, i.e. edifices form primarily at the ends of segments. However, in ridges affected by plumes and at back arc basins, the spatial and abundance distributions of volcanic edifices differ from that observed at normal ridges of the same spreading rate. This suggests that magma supply rate may control the spatial and abundance distribution of volcanic edifices. Recent geophysical and geochemical studies along the Galapagos Spreading Centers (GSC), Juan de Fuca Ridge (JdFR), Southeast Indian Ridge (SEIR) and the Valu Fa (VF) and Eastern Lau Spreading Centers (ELSC) put tight constraints on crustal thickness, making it possible investigate the effect of magma budget and axial morphology on the formation of volcanic edifices. Volcanic edifices are described according to their volume, shape (their height to basal radius ratio) and their location relative to the end or center of a segment (abundance distribution). For the GSC, the shape and distribution of volcanic edifices correlate with changes in crustal thickness and axial morphology, consistent with a magma supply control on their formation in this region. This relationship is not apparent along the SEIR or JdFR, where edifices show little variation with changes in axial morphology at relatively constant spreading rates. Results for VF and ELSC are what we expect for changes in spreading rate, not axial morphology. Our study suggests that the formation of volcanic edifices at intermediate spreading rate ridges are influenced by magma budget but only when it is above a certain threshold.

  12. Volcanic ash layers illuminate the resilience of Neanderthals and early modern humans to natural hazards.

    Science.gov (United States)

    Lowe, John; Barton, Nick; Blockley, Simon; Ramsey, Christopher Bronk; Cullen, Victoria L; Davies, William; Gamble, Clive; Grant, Katharine; Hardiman, Mark; Housley, Rupert; Lane, Christine S; Lee, Sharen; Lewis, Mark; MacLeod, Alison; Menzies, Martin; Müller, Wolfgang; Pollard, Mark; Price, Catherine; Roberts, Andrew P; Rohling, Eelco J; Satow, Chris; Smith, Victoria C; Stringer, Chris B; Tomlinson, Emma L; White, Dustin; Albert, Paul; Arienzo, Ilenia; Barker, Graeme; Boric, Dusan; Carandente, Antonio; Civetta, Lucia; Ferrier, Catherine; Guadelli, Jean-Luc; Karkanas, Panagiotis; Koumouzelis, Margarita; Müller, Ulrich C; Orsi, Giovanni; Pross, Jörg; Rosi, Mauro; Shalamanov-Korobar, Ljiljiana; Sirakov, Nikolay; Tzedakis, Polychronis C

    2012-08-21

    Marked changes in human dispersal and development during the Middle to Upper Paleolithic transition have been attributed to massive volcanic eruption and/or severe climatic deterioration. We test this concept using records of volcanic ash layers of the Campanian Ignimbrite eruption dated to ca. 40,000 y ago (40 ka B.P.). The distribution of the Campanian Ignimbrite has been enhanced by the discovery of cryptotephra deposits (volcanic ash layers that are not visible to the naked eye) in archaeological cave sequences. They enable us to synchronize archaeological and paleoclimatic records through the period of transition from Neanderthal to the earliest anatomically modern human populations in Europe. Our results confirm that the combined effects of a major volcanic eruption and severe climatic cooling failed to have lasting impacts on Neanderthals or early modern humans in Europe. We infer that modern humans proved a greater competitive threat to indigenous populations than natural disasters.

  13. Volcanic ash layers illuminate the resilience of Neanderthals and early modern humans to natural hazards

    Science.gov (United States)

    Lowe, John; Barton, Nick; Blockley, Simon; Ramsey, Christopher Bronk; Cullen, Victoria L.; Davies, William; Gamble, Clive; Grant, Katharine; Hardiman, Mark; Housley, Rupert; Lane, Christine S.; Lee, Sharen; Lewis, Mark; MacLeod, Alison; Menzies, Martin; Müller, Wolfgang; Pollard, Mark; Price, Catherine; Roberts, Andrew P.; Rohling, Eelco J.; Satow, Chris; Smith, Victoria C.; Stringer, Chris B.; Tomlinson, Emma L.; White, Dustin; Albert, Paul; Arienzo, Ilenia; Barker, Graeme; Borić, Dušan; Carandente, Antonio; Civetta, Lucia; Ferrier, Catherine; Guadelli, Jean-Luc; Karkanas, Panagiotis; Koumouzelis, Margarita; Müller, Ulrich C.; Orsi, Giovanni; Pross, Jörg; Rosi, Mauro; Shalamanov-Korobar, Ljiljiana; Sirakov, Nikolay; Tzedakis, Polychronis C.

    2012-01-01

    Marked changes in human dispersal and development during the Middle to Upper Paleolithic transition have been attributed to massive volcanic eruption and/or severe climatic deterioration. We test this concept using records of volcanic ash layers of the Campanian Ignimbrite eruption dated to ca. 40,000 y ago (40 ka B.P.). The distribution of the Campanian Ignimbrite has been enhanced by the discovery of cryptotephra deposits (volcanic ash layers that are not visible to the naked eye) in archaeological cave sequences. They enable us to synchronize archaeological and paleoclimatic records through the period of transition from Neanderthal to the earliest anatomically modern human populations in Europe. Our results confirm that the combined effects of a major volcanic eruption and severe climatic cooling failed to have lasting impacts on Neanderthals or early modern humans in Europe. We infer that modern humans proved a greater competitive threat to indigenous populations than natural disasters. PMID:22826222

  14. Center for Volcanic and Tectonic Studies: 1992--1993 annual report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    The annual report of the Center for Volcanic Studies (CVTS) contains a series of papers, reprints and a Master of Science thesis that review the progress made by the CVTS between October 1, 1992 and February 1, 1994. During this period CVTS staff focused on several topics that have direct relevance to volcanic hazards related to the proposed high-level nuclear waste repository at Yucca Mountain, Nevada. These topics include: (1) polygenetic/polycyclic volcanism in Crater Flat, Nevada; (2) the role of the mantle during crustal extension; (3) the detailed geology of Crater Flat, Nevada; (4) Pliocene volcanoes in the Reveille Range, south-central Nevada; (5) estimating the probability of disruption of the proposed repository by volcanic eruptions. This topic is being studied by Dr. C.H. Ho at UNLV. The report contains copies of these individual papers as they were presented in various conference proceedings.

  15. 2012 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    Science.gov (United States)

    Herrick, Julie A.; Neal, Christina A.; Cameron, Cheryl E.; Dixon, James P.; McGimsey, Robert G.

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, or suspected unrest at 11 volcanic centers in Alaska during 2012. Of the two verified eruptions, one (Cleveland) was clearly magmatic and the other (Kanaga) was most likely a single phreatic explosion. Two other volcanoes had notable seismic swarms that probably were caused by magmatic intrusions (Iliamna and Little Sitkin). For each period of clear volcanic unrest, AVO staff increased monitoring vigilance as needed, reviewed eruptive histories of the volcanoes in question to help evaluate likely outcomes, and shared observations and interpretations with the public. 2012 also was the 100th anniversary of Alaska’s Katmai-Novarupta eruption of 1912, the largest eruption on Earth in the 20th century and one of the most important volcanic eruptions in modern times. AVO marked this occasion with several public events.

  16. Volcanic processes on early-forming asteroids.

    Science.gov (United States)

    Wilson, L.; Keil, K.

    2011-12-01

    A variety of meteorite groups represent samples of asteroids that formed while 26Al was still the dominant heat source in Solar System materials. These bodies differentiated to varying degrees beyond the temperature of FeNi-FeS melting, with sufficient silicate melting to allow metal core formation. The silicate melts segregated upward from the interiors to suffer various fates: intrusion at shallow levels, eruption onto the surface, or ejection into space in explosive eruptions in which the eruption speed exceeded the escape speed. These three styles of plutonic/volcanic activity were not mutually exclusive; their relative importance was a function of asteroid size and composition, with the major compositional factor being the total available volatile inventory. Much research has been concerned with whether silicate melts were extracted from the mantle during the period of mantle heating or while the mantle was cooling after reaching its peak temperature and degree of partial melting (a "magma ocean" stage). Traditionally, the relevant arguments have been based on the petrology and geochemistry of the meteorites sampling these bodies. Instead, we focus on the fluid dynamic aspects of eruption and intrusion processes and show how these impose additional limitations on various aspects of the igneous activity. For example, 40% melting of bodies the size of 4 Vesta (~250 km radius) and the Ureilite Parent Body (UPB, ~100 km radius) over the course of a 0.5 Ma heating period represent melt volume production rates of ~350 and 20 cubic meters per second, respectively, in each of what we demonstrate should have been ~4 volcanic provinces on each body. All differentiated asteroids must of necessity have had a surface layer ~10 km thick at sub-solidus temperatures controlled by conductive cooling. To erupt magma at the surface (or intrude magma at very shallow depth) through such a crust would have required the propagation of dikes within which the combination of dike width

  17. Assessing the Altitude and Dispersion of Volcanic Plumes Using MISR Multi-angle Imaging from Space: Sixteen Years of Volcanic Activity in the Kamchatka Peninsula, Russia

    Science.gov (United States)

    Flower, Verity J. B.; Kahn, Ralph A.

    2017-01-01

    Volcanic eruptions represent a significant source of atmospheric aerosols and can display local, regional and global effects, impacting earth systems and human populations. In order to assess the relative impacts of these events, accurate plume injection altitude measurements are needed. In this work, volcanic plumes generated from seven Kamchatka Peninsula volcanoes (Shiveluch, Kliuchevskoi, Bezymianny, Tolbachik, Kizimen, Karymsky and Zhupanovsky), were identified using over 16 years of Multi-angle Imaging SpectroRadimeter (MISR) measurements. Eighty-eight volcanic plumes were observed by MISR, capturing 3-25% of reported events at individual volcanoes. Retrievals were most successful where high intensity events persisted over a period of weeks to months. Compared with existing ground and airborne observations, and alternative satellite-based reports compiled by the Global Volcanism Program (GVP), MISR plume height retrievals showed general consistency; the comparison reports appear to be skewed towards the region of highest concentration observed in MISR-constrained vertical plume extent. The report observations display less discrepancy with MISR toward the end of the analysis period, with improvements in the suborbital data likely the result of the deployment of new instrumentation. Conversely, the general consistency of MISR plume heights with conventionally reported observations supports the use of MISR in the ongoing assessment of volcanic activity globally, especially where other types of volcanic plume observations are unavailable. Differences between the northern (Shiveluch, Kliuchevskoi, Bezymianny and Tolbachik) and southern (Kizimen, Karymsky and Zhupanovsky) volcanoes broadly correspond to the Central Kamchatka Depression (CKD) and Eastern Volcanic Front (EVF), respectively, geological sub-regions of Kamchatka distinguished by varying magma composition. For example, by comparison with reanalysis-model simulations of local meteorological conditions

  18. Influence of timing of sea ice retreat on phytoplankton size during marginal ice zone bloom period in the Chukchi and Bering shelves

    Directory of Open Access Journals (Sweden)

    A. Fujiwara

    2015-08-01

    Full Text Available Timing of sea ice retreat (TSR as well as cell size of primary producers (i.e., phytoplankton plays crucial roles in seasonally ice-covered marine ecosystem. Thus, it is important to monitor the temporal and spatial distribution of phytoplankton community size structure. Prior to this study, an ocean color algorithm has been developed to derive phytoplankton size index FL, which is defined as the ratio of chlorophyll a derived from the cells larger than 5 μm to the total chl a using satellite remote sensing for the Chukchi and Bering shelves. Using this method, we analyzed pixel-by-pixel relationships between FL during marginal ice zone (MIZ bloom period and TSR over a period of 1998–2013. The influence of TSR on sea surface temperature (SST and changes in ocean heat content (ΔOHC during the MIZ bloom period were also investigated. A significant negative relationship between FL and TSR was widely found in the shelf region during MIZ bloom season. On the other hand, we found a significant positive (negative relationship between SST (ΔOHC and TSR. That is, earlier sea-ice retreat was associated with a dominance of larger phytoplankton during a colder and weakly stratified MIZ bloom season, suggesting that duration of nitrate supply, which is important for large-sized phytoplankton growth in this region (i.e., diatoms, can change according to TSR. In addition, under-ice phytoplankton blooms are likely to occur in years with late ice retreat, because sufficient light for phytoplankton growth can pass through the ice and penetrate into the water columns due to an increase in solar radiation toward the summer solstice. Moreover, we found not only the length of ice-free season but also annual median of FL positively correlated with annual net primary production (APP. Thus, both phytoplankton community composition and growing season are important for APP in the study area. Our findings showed quantitative relationship between the inter

  19. Influence of close-up dry period protein supplementation on productive and reproductive performance of Holstein cows in their subsequent lactation.

    Science.gov (United States)

    Robinson, P H; Moorby, J M; Arana, M; Hinders, R; Graham, T; Castelanelli, L; Barney, N

    2001-10-01

    Holstein cows on a commercial dairy were assigned to close-up dry groups and offered an 11.7% crude protein (CP) ration based on corn silage, alfalfa cubes, oat hay, corn, and barley grain without (Control; C) or with (Supplemented; S) 0.8 kg/d per cow of a high CP supplement of SoyPass, distillers dried grains, ring dried blood meal, feather meal, and corn gluten meal. Heifers (C: 37, S: 44) and mature cows (C: 96, S: 81) were allocated to one of four groups based upon their time in the close-up groups (i.e., 1 to 4, 5 to 8, 9 to 12, and 13 to 19 d) within parity (i.e., heifers or mature) for statistical analysis. Full lactation means of all response parameters for cows confirmed to be pregnant that completed a lactation (i.e., lactating at 305 d in milk or dried off before 305 d in milk but not culled; C: 28, S: 23 for heifers and C: 48, S: 43 for mature cows) were analyzed by ANOVA. Lactation curves were evaluated by parallel curve analysis to assess differences in lactation curve shape, and curve separation, due to treatments. Protein supplementation had no impact on full-lactation milk or milk component yields of heifers, determined by ANOVA, although parallel curve analysis showed higher milk and milk protein yield with protein supplementation. As the number of days cows spent consuming their assigned close-up dry rations increased, heifers produced more milk, milk fat and milk protein, although the maximum yield for milk and milk protein occurred for those fed close-up rations for 9 to 12 d. For mature cows, neither time close up or close-up period protein supplementation influenced any mean response parameter, by ANOVA, although parallel curve analysis showed higher milk and protein yield for supplemented cows as time close up increased. Overall, results suggest the optimum close-up period length was 9 to 12 d, with a protein content intermediate between 11.7 and 14.4% of DM, for heifers. In contrast, results do not support any substantive benefit of a

  20. Particle sedimentation and diffusive convection in volcanic ash-clouds

    Science.gov (United States)

    Carazzo, G.; Jellinek, A. M.

    2013-04-01

    Understanding the longevity of volcanic ash-clouds generated by powerful explosive eruptions is a long standing problem for assessing volcanic hazards and the nature and time scale of volcanic forcings on climate change. It is well known that the lateral spreading and longevity of these clouds is influenced by stratospheric winds, particle settling and turbulent diffusion. Observations of the recent 2010 Eyjafjallajökull and 2011 Grimsvötn umbrella clouds, as well as the structure of atmospheric aerosol clouds from the 1991 Mt Pinatubo event, suggest that an additional key process governing the cloud dynamics is the production of internal layering. Here, we use analog experiments on turbulent particle-laden umbrella clouds to show that this layering occurs where natural convection driven by particle sedimentation and the differential diffusion of primarily heat and fine particles give rise to a large scale instability. Where umbrella clouds are particularly enriched in fine ash, this "particle diffusive convection" strongly influences the cloud longevity. More generally, cloud residence time will depend on fluxes due to both individual settling and diffusive convection. We develop a new sedimentation model that includes both sedimentation processes, and which is found to capture real-time measurements of the rate of change of particle concentration in the 1982 El Chichon, 1991 Mt Pinatubo and 1992 Mt Spurr ash-clouds. A key result is that these combined sedimentation processes enhance the fallout of fine particles relative to expectations from individual settling suggesting that particle aggregation is not the only mechanism required to explain volcanic umbrella longevity.

  1. Influence of viscosity on the reflection and transmission of an acoustic wave by a periodic array of screens. The general 3-D problem.

    Science.gov (United States)

    Homentcovschi, Dorel; Miles, Ronald N

    2008-01-01

    An analysis is presented of the diffraction of a pressure wave by a periodic grating including the influence of the air viscosity. The direction of the incoming pressure wave is arbitrary. As opposed to the classical nonviscous case, the problem cannot be reduced to a plane problem having a definite 3-D character. The system of partial differential equations used for solving the problem consists of the compressible Navier-Stokes equations associated with no-slip boundary conditions on solid surfaces. The problem is reduced to a system of two hypersingular integral equations for determining the velocity components in the slits' plane and a hypersingular integral equation for the normal component of velocity. These equations are solved by using Galerkin's method with some special trial functions. The results can be applied in designing protective screens for miniature microphones realized in MEMS technology. In this case, the physical dimensions of the device are on the order of the viscous boundary layer so that the viscosity cannot be neglected. The analysis indicates that the openings in the screen should be on the order of 10 microns in order to avoid excessive attenuation of the signal. This paper also provides the variation of the transmission coefficient with frequency in the acoustical domain.

  2. Influence of viscosity on the reflection and transmission of an acoustic wave by a periodic array of screens. The general 3-D problem

    Science.gov (United States)

    Homentcovschi, Dorel; Miles, Ronald N.

    2008-01-01

    An analysis is presented of the diffraction of a pressure wave by a periodic grating including the influence of the air viscosity. The direction of the incoming pressure wave is arbitrary. As opposed to the classical nonviscous case, the problem cannot be reduced to a plane problem having a definite 3-D character. The system of partial differential equations used for solving the problem consists of the compressible Navier-Stokes equations associated with no-slip boundary conditions on solid surfaces. The problem is reduced to a system of two hypersingular integral equations for determining the velocity components in the slits’ plane and a hypersingular integral equation for the normal component of velocity. These equations are solved by using Galerkin’s method with some special trial functions. The results can be applied in designing protective screens for miniature microphones realized in MEMS technology. In this case, the physical dimensions of the device are on the order of the viscous boundary layer so that the viscosity cannot be neglected. The analysis indicates that the openings in the screen should be on the order of 10 microns in order to avoid excessive attenuation of the signal. This paper also provides the variation of the transmission coefficient with frequency in the acoustical domain. PMID:19122753

  3. Does Pain in the Neonatal Period Influence Motor and Sensory Functions in a Similar Way for Males and Females During Post-Natal Development in Rats?

    Science.gov (United States)

    Carmo, Elisabete de Cássia do; Sanada, Luciana Sayuri; Machado, Nathalia Leilane Berto; Fazan, Valéria Paula Sassoli

    2016-08-01

    OBJECTIVE : Early pain experiences can lead to disruption in the long-term responses to pain and in abnormal development and behavior in rodents. We evaluated the sensory and motor development of Wistar rats after exposure to painful stimulation (repetitive needle prickling) immediately after birth. METHODS : Male and female rats were followed up to 6 months of life, and sensory and motor functions were investigated by testing paw withdrawal with von Frey filaments, calibrated forceps (CF), and grip strength (GS) tests. RESULTS : Body weight increased with age and tended to be smaller in pain groups compared with their controls of the same sex. GS values also increased with age in controls but were stable and even decreased in pain groups from 120 up to 180 days. The von Frey filaments test showed higher values on the nonstimulated paws in male and female pain groups, with no differences between sides on the controls. The CF test showed smaller values on the stimulated paws in the pain group, with no differences between sides on the controls. CONCLUSIONS : Pain in the neonatal period influences sensory and motor functions negatively during development in male and female rats, even long term after the painful stimulus is ceased. The neonatal injury-induced hypersensitivity is persistent, and male and female rats respond similarly to the stimulus.

  4. Reservoir characteristics and control factors of Carboniferous volcanic gas reservoirs in the Dixi area of Junggar Basin, China

    Directory of Open Access Journals (Sweden)

    Ji'an Shi

    2017-02-01

    volcanic breccia reservoir more easily leached by fresh water or groundwater, leading to secondary erosion pores. Volcanic rock weathering obviously has control on reservoir properties, and while the thickness of the weathering crust is 200–300 m, the properties of volcanic rock reservoir are the best. This is attributed mainly to the period during and after the volcano eruption, in which tectonism made the brittle volcanic rock develop a large number of fractures and micro cracks. This has led to the increased permeability of volcanic rock reservoir, the weathering and leaching effect of volcanic rock diagenetic late phase (which also formed lots of secondary pores, and greatly improved reservoir conditions. The overlying Permian Wutonggou formation mudstone provided high-quality cap rock for oil and gas accumulation.

  5. Cenozoic volcanic rocks of Saudi Arabia

    Science.gov (United States)

    Coleman, R.G.; Gregory, R.T.; Brown, G.F.

    2016-01-01

    The Cenozoic volcanic rocks of Saudi Arabia cover about 90,000 km2, one of the largest areas of alkali olivine basalt in the world. These volcanic rocks are in 13 separate fields near the eastern coast of the Red Sea and in the western Arabian Peninsula highlands from Syria southward to the Yemen Arab Republic.

  6. Relationship between earthquake and volcanic eruption inferred from historical records

    Institute of Scientific and Technical Information of China (English)

    陈洪洲; 高峰; 吴雪娟; 孟宪森

    2004-01-01

    A large number of seismic records are discovered for the first time in the historical materials about Wudalianchi volcanic group eruption in 1720~1721, which provides us with abundant volcanic earthquake information. Based on the written records, the relationship between earthquake and volcanic eruption is discussed in the paper. Furthermore it is pointed that earthquake swarm is an important indication of volcanic eruption. Therefore, monitoring volcanic earthquakes is of great significance for forecasting volcanic eruption.

  7. Lakshmi Planum: A distinctive highland volcanic province

    Science.gov (United States)

    Roberts, Kari M.; Head, James W.

    Lakshmi Planum, a broad smooth plain located in western Ishtar Terra and containing two large oval depressions (Colette and Sacajawea), has been interpreted as a highland plain of volcanic origin. Lakshmi is situated 3 to 5 km above the mean planetary radius and is surrounded on all sides by bands of mountains interpreted to be of compressional tectonic origin. Four primary characteristics distinguish Lakshmi from other volcanic regions known on the planet, such as Beta Regio: (1) high altitude, (2) plateau-like nature, (3) the presence of very large, low volcanic constructs with distinctive central calderas, and (4) its compressional tectonic surroundings. Building on the previous work of Pronin, the objective is to establish the detailed nature of the volcanic deposits on Lakshmi, interpret eruption styles and conditions, sketch out an eruption history, and determine the relationship between volcanism and the tectonic environment of the region.

  8. Controls on chemical weathering on a mountainous volcanic tropical island: Guadeloupe (French West Indies)

    Science.gov (United States)

    Dessert, C.; Lajeunesse, E.; Lloret, E.; Clergue, C.; Crispi, O.; Gorge, C.; Quidelleur, X.

    2015-12-01

    Guadeloupe Island is a natural laboratory, ideally suited to the study of biogeochemical processes in tropical and mountainous volcanic environments. The island's east-west rainfall gradient (1200-8000 mm/yr) is superimposed on a north-south age gradient (2.7 Ma to present), providing a unique opportunity to investigate the influence of rainfall and rock age on the chemical weathering of volcanic terrains. Taking advantage of this configuration, we present the first temporal survey (2007-2013) of the geochemical composition of the dissolved load of rain and river waters in Guadeloupe. Our data demonstrate that the chemical composition of river water is influenced by rainfall abundance, hydrothermal alteration (from active or fossilized volcanic systems) and interactions between water and minerals during chemical weathering processes. The contribution of rain to the overall chemical balance is especially significant in the older northern part of the island, where the ferralitic soils are base-cation-depleted. Between 15% and 65% of the Ca or Mg riverine budgets comes from atmospheric deposits, highlighting the major role of rainfall in the geochemical budgets of small tropical and mountainous watersheds. The river water dataset indicates that different chemical weathering processes dominate the budget depending on the age of the local bedrock. In the younger, southern part of the island, a pool of easily-weatherable andesitic minerals from the bedrock dominates. The contribution from this pool decreases significantly (to 5-15 wt.% of the bulk soil) towards the older terrains in the north. The northern rivers are characterized by low Ca/Mg ratios (0.5-1.0), intermediate between those of fresh rocks (1.7-3.3) and soil (0.1). Weathering in the northern part of the island is therefore dominated by the dissolution of depleted secondary minerals into soils. The Ca/Mg ratio of the river water increases from north to south, eventually reaching values similar to those of the

  9. Geomorphological Approach for Regional Zoning In The Merapi Volcanic Area

    Directory of Open Access Journals (Sweden)

    Langgeng Wahyu Santosa

    2013-07-01

    Full Text Available Geomorphologial approach can be used as the basic for identifying and analyzing the natural resources potentials, especially in volcanic landscape. Based on its geomorphology, Merapi volcanic landscape can be divided into 5 morphological units, i.e.: volcanic cone, volcanic slope, volcanic foot, volcanic foot plain, and fluvio-volcanic plain. Each of these morphological units has specific characteristic and natural resources potential. Based on the condition of geomorphology, the regional zoning can be compiled to support the land use planning and to maintain the conservation of environmental function in the Merapi Volcanic area.

  10. Volcanism and associated hazards: the Andean perspective

    Science.gov (United States)

    Tilling, R. I.

    2009-12-01

    Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene. The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent hazardous eruptions in Chile, Colombia, Ecuador, and Peru has spurred significant improvements in reducing volcano risk in the Andean region. But much remains to be done.

  11. Volcanism and associated hazards: The Andean perspective

    Science.gov (United States)

    Tilling, R.I.

    2009-01-01

    Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene. The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent hazardous eruptions in Chile, Colombia, Ecuador, and Peru has spurred significant improvements in reducing volcano risk in the Andean region. But much remains to be done.

  12. Engineering a robotic approach to mapping exposed volcanic fissures

    Science.gov (United States)

    Parcheta, C. E.; Parness, A.; Mitchell, K. L.

    2014-12-01

    Field geology provides a framework for advanced computer models and theoretical calculations of volcanic systems. Some field terrains, though, are poorly preserved or accessible, making documentation, quantification, and investigation impossible. Over 200 volcanologists at the 2012 Kona Chapman Conference on volcanology agreed that and important step forward in the field over the next 100 years should address the realistic size and shape of volcanic conduits. The 1969 Mauna Ulu eruption of Kīlauea provides a unique opportunity to document volcanic fissure conduits, thus, we have an ideal location to begin addressing this topic and provide data on these geometries. Exposed fissures can be mapped with robotics using machine vision. In order to test the hypothesis that fissures have irregularities with depth that will influence their fluid dynamical behavior, we must first map the fissure vents and shallow conduit to deci- or centimeter scale. We have designed, constructed, and field-tested the first version of a robotic device that will image an exposed volcanic fissure in three dimensions. The design phase included three steps: 1) create the payload harness and protective shell to prevent damage to the electronics and robot, 2) construct a circuit board to have the electronics communicate with a surface-based computer, and 3) prototype wheel shapes that can handle a variety of volcanic rock textures. The robot's mechanical parts were built using 3d printing, milling, casting and laser cutting techniques, and the electronics were assembled from off the shelf components. The testing phase took place at Mauna Ulu, Kīlauea, Hawai'i, from May 5 - 9, 2014. Many valuable design lessons were learned during the week, and the first ever 3D map from inside a volcanic fissure were successfully collected. Three vents had between 25% and 95% of their internal surfaces imaged. A fourth location, a non-eruptive crack (possibly a fault line) had two transects imaging the textures

  13. Volcanic Activities of Hakkoda Volcano after the 2011 Tohoku Earthquake

    Science.gov (United States)

    Yamamoto, M.; Miura, S.

    2014-12-01

    The 2011 Tohoku Earthquake of 11 March 2011 generated large deformation in and around the Japanese islands, and the large crustal deformation raises fear of further disasters including triggered volcanic activities. In this presentation, as an example of such potential triggered volcanic activities, we report the recent seismic activities of Hakkoda volcano, and discuss the relation to the movement of volcanic fluids. Hakkoda volcano is a group of stratovolcanoes at the northern end of Honshu Island, Japan. There are fumaroles and hot springs around the volcano, and phreatic eruptions from Jigoku-numa on the southwestern flank of Odake volcano, which is the highest peak of the volcanic group, were documented in its history. Since just after the occurrence of the Tohokui Earthquake, the seismicity around the volcano became higher, and the migration of hypocenters of volcano-tectonic (VT) earthquakes was observed.In addition to these VT earthquakes, long-period (LP) events started occurring beneath Odake at a depth of about 2-3 km since February, 2013, and subtle crustal deformation caused by deep inflation source was also detected by the GEONET GNSS network around the same time. The spectra of LP events are common between events irrespective of the magnitude of events, and they have several spectral peaks at 6-7 sec, 2-3 sec, 1 sec, and so on. These LP events sometimes occur like a swarm with an interval of several minutes. The characteristics of observed LP events at Hakkoda volcano are similar to those of LP events at other active volcanoes and hydrothermal area in the world, where abundant fluids exist. Our further analysis using far-field Rayleigh radiation pattern observed by NIED Hi-net stations reveals that the source of LP events is most likely to be a nearly vertical tensile crack whose strike is NE-SW direction. The strike is almost perpendicular to the direction of maximum extensional strain estimated from the geodetic analysis, and is almost parallel to

  14. Influences of land use and antecedent dry-weather period on pollution level and ecological risk of heavy metals in road-deposited sediment.

    Science.gov (United States)

    Zhang, Jin; Hua, Pei; Krebs, Peter

    2017-09-01

    Road-deposited sediment and its adsorbed pollutants have been regarded as significant sources of urban diffuse pollution. In this study, the solid-phase concentrations (mg/g), surface load (mg/m(2)) and chemical fractionation of zinc (Zn), copper (Cu) and cadmium (Cd) were determined. Geo-accumulation (Igeo) and ecological risk (RI) indexes were employed for metal risk assessment. Results show that the highest solid-phase concentrations of Zn and Cu were usually found at an industrial area. However, Cd had the highest solid-phase concentrations at a rural area, followed by a commercial area. The surface loads of Zn and Cu decreased along the city centre to city border gradient. However, Cd was distributed irregularly. In terms of chemical fractionation, the predominant components of Zn and Cd were identified in the unstable exchangeable fractions, indicating high potential ecological risks to the aquatic environments. Cu posed a comparably low risk due to the high proportions of the stable components of residual and oxidisable fractions. According to a two-dimensional hierarchical cluster analysis, Zn and Cu surface loads were dominantly influenced by the antecedent dry-weather period; Cd contents were strongly land-use type dependent. In addition, the enrichment capability was ranked as Zn > Cu > Cd determined by Igeo index. The sampling site dependent potential ecological risk was determined as rural area (R) > commercial city centre (W) > federal highway (B) > industrial area (I) > main road (S) > secondary road (A) by the RI index. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Influence of winds on temporally varying short and long period gravity waves in the near shore regions of Eastern Arabian Sea

    Directory of Open Access Journals (Sweden)

    J. Glejin

    2012-09-01

    Full Text Available Wave data collected off Ratnagiri, west coast of India during 1 May 2010 to 30 April 2012 is used in the study. Seasonal and annual variation in wave data controlled by the local wind system such as sea breeze and land breeze, and remote wind generated long period waves observed along the west coast of India, is studied. Sea breeze plays an important role in determining the sea state during pre and post monsoon seasons and the maximum wave height is observed during peak hours of sea breeze at 15:00 UTC. Long period waves (peak period over 13 s are observed mainly during the pre and the post monsoon season. Maximum peak period observed during the study is 22 s and is in the month of October. Long period waves observed during the south west monsoon period of 2011 are identified as swell propagated from the Southern Ocean with an estimated travelling time of 5–6 days. The swells reaching the Arabian Sea from the South Indian Ocean and Southern Ocean, due to storms during the pre and post monsoon periods will modify the near surface winds, due to the dominant wave induced wind regime. Energy spectrum of observed waves indicates onset and decline of strong south west monsoon winds. Convergence of energy-containing frequency bands corresponding to short period waves (Tp < 8 s and long period waves (Tp > 13 s to intermediate period waves (8 < Tp < 13 s are observed at the end of the pre monsoon season; divergence is observed during the start of the post monsoon period from intermediate period waves to short period waves and long period waves. South west monsoon period is characterized by the energy corresponding to the frequency band of intermediate period waves along the west coast of India.

  16. Spatial evaluation of volcanic ash forecasts using satellite observations

    Science.gov (United States)

    Harvey, N. J.; Dacre, H. F.

    2016-01-01

    The decision to close airspace in the event of a volcanic eruption is based on hazard maps of predicted ash extent. These are produced using output from volcanic ash transport and dispersion (VATD) models. In this paper the fractions skill score has been used for the first time to evaluate the spatial accuracy of VATD simulations relative to satellite retrievals of volcanic ash. This objective measure of skill provides more information than traditional point-by-point metrics, such as success index and Pearson correlation coefficient, as it takes into the account spatial scale over which skill is being assessed. The FSS determines the scale over which a simulation has skill and can differentiate between a "near miss" and a forecast that is badly misplaced. The idealized scenarios presented show that even simulations with considerable displacement errors have useful skill when evaluated over neighbourhood scales of 200-700 (km)2. This method could be used to compare forecasts produced by different VATDs or using different model parameters, assess the impact of assimilating satellite-retrieved ash data and evaluate VATD forecasts over a long time period.

  17. Spatial evaluation of volcanic ash forecasts using satellite observations

    Directory of Open Access Journals (Sweden)

    N. J. Harvey

    2015-09-01

    Full Text Available The decision to close airspace in the event of a volcanic eruption is based on hazard maps of predicted ash extent. These are produced using output from volcanic ash transport and dispersion (VATD models. In this paper an objective metric to evaluate the spatial accuracy of VATD simulations relative to satellite retrievals of volcanic ash is presented. The metric is based on the fractions skill score (FSS. This measure of skill provides more information than traditional point-by-point metrics, such as success index and Pearson correlation coefficient, as it takes into the account spatial scale over which skill is being assessed. The FSS determines the scale over which a simulation has skill and can differentiate between a "near miss" and a forecast that is badly misplaced. The idealised scenarios presented show that even simulations with considerable displacement errors have useful skill when evaluated over neighbourhood scales of 200–700 km2. This method could be used to compare forecasts produced by different VATDs or using different model parameters, assess the impact of assimilating satellite retrieved ash data and evaluate VATD forecasts over a long time period.

  18. Impact of volcanic eruptions on the climate of the 1st millennium AD in a comprehensive climate simulation

    Science.gov (United States)

    Wagner, Sebastian; Zorita, Eduardo

    2015-04-01

    The climate of the 1st millennium AD shows some remarkable differences compared to the last millennium concerning variation in external forcings. Together with an orbitally induced increased solar insolation during the northern hemisphere summer season and a general lack of strong solar minima, the frequency and intensity of large tropical and extratropical eruptions is decreased. Here we present results of a new climate simulation carried out with the comprehensive Earth System Model MPI-ESM-P forced with variations in orbital, solar, volcanic and greenhouse gas variations and land use changes for the last 2,100 years. The atmospheric model has a horizontal resolution of T63 (approx. 125x125 km) and therefore also allows investigations of regional-to-continental scale climatic phenomena. The volcanic forcing was reconstructed based on a publication by Sigl et al. (2013) using the sulfate records of the NEEM and WAIS ice cores. To obtain information on the aerosol optical depth (AOD) these sulfate records were scaled to an established reconstruction from Crowley and Unterman (2010), which is also a standard forcing in the framework of CMIP5/PMIP3. A comparison between the newly created data set with the Crowley and Unterman dataset reveals that the new reconstruction shows in general weaker intensities, especially of the large tropical outbreaks and fewer northern hemispheric small-to-medium scale eruptions. However, the general pattern in the overlapping period is similar. A hypothesis that can be tested with the simulation is whether the reduced volcanic intensity of the 1st millennium AD contributed to the elevated temperature levels over Europe, evident within a new proxy-based reconstruction. On the other hand, the few but large volcanic eruptions, e.g. the 528 AD event, also induced negative decadal-scale temperature anomalies. Another interesting result of the simulation relates to the 79 AD eruption of the Vesuvius, which caused the collapse of the city of

  19. Observations of volcanic earthquakes and tremor at Deception Island - Antarctica

    Directory of Open Access Journals (Sweden)

    J. Morales

    1999-06-01

    Full Text Available Deception Island - South Shetlands, Antarctica is site of active volcanism. Since 1988 field surveys have been carried out with the aim of seismic monitoring, and in 1994 a seismic array was set up near the site of the Spanish summer base in order to better constrain the source location and spectral properties of the seismic events related to the volcanic activity. The array was maintained during the Antarctic summer of 1995 and the last field survey was carried out in 1996. Data show the existence of three different groups (or families of seismic events: 1 long period events, with a quasi-monochromatic spectral content (1-3 Hz peak frequency and a duration of more than 50 s, often occurring in small swarms lasting from several minutes to some day; 2 volcanic tremor, with a spectral shape similar to the long period events but with a duration of several minutes (2-10; 3 hybrid events, with a waveform characterised by the presence of a high frequency initial phase, followed by a low frequency phase with characteristics similar to those of the long period events. The high frequency phase of the hybrid events was analysed using polarisation techniques, showing the presence of P waves. This phase is presumably located at short epicentral distances and shallow source depth. All the analysed seismic events show back-azimuths between 120 and 330 degrees from north (corresponding to zones of volcanic activity showing no seismic activity in the middle of the caldera. Particle motion, Fourier spectral and spectrogram analysis show that the low frequency part of the three groups of the seismic signals have similar patterns. Moreover careful observations show that the high frequency phase which characterises the hybrid events is present in the long period and in the tremor events, even with lower signal to noise ratios. This evidence suggests that long period events are events in which the high frequency part is simply difficult to observe, due to a very

  20. The Western Arabian intracontinental volcanic fields as a potential UNESCO World Heritage site

    Science.gov (United States)

    Németh, Károly; Moufti, Mohammed R.

    2017-04-01

    UNESCO promotes conservation of the geological and geomoprhological heritage through promotion of protection of these sites and development of educational programs under the umbrella of geoparks among the most globally significant ones labelled as UNESCO Global Geoparks. UNESCO also maintains a call to list those natural sites that provide universal outstanding values to demonstrate geological features or their relevance to our understanding the evolution of Earth. Volcanoes currently got a surge in nomination to be UNESCO World Heritage sites. Volcanic fields in the contrary fell in a grey area of nominations as they represents the most common manifestation of volcanism on Earth hence they are difficult to view as having outstanding universal values. A nearly 2500-km long 300-km wide region of dispersed volcanoes located in the Western Arabian Penninsula mostly in the Kingdom of Saudi Arabia form a near-continuous location that carries universal outstanding value as one of the most representative manifestation of dispersed intracontinental volcanism on Earth to be nominated as an UNESCO World Heritage site. The volcanic fields formed in the last 20 Ma along the Red Sea as group of simple basaltic to more mature and long-lived basalt to trachyte-to-rhyolite volcanic fields each carries high geoheritage values. While these volcanic fields are dominated by scoria and spatter cones and transitional lava fields, there are phreatomagmatic volcanoes among them such as maars and tuff rings. Phreatomagmatism is more evident in association with small volcanic edifices that were fed by primitive magmas, while phreatomagmatic influences during the course of a larger volume eruption are also known in association with the silicic eruptive centres in the harrats of Rahat, Kishb and Khaybar. Three of the volcanic fields are clearly bimodal and host small-volume relatively short-lived lava domes and associated block-and-ash fans providing a unique volcanic landscape commonly not

  1. The Dras arc: two successive volcanic events on eroded oceanic crust

    Science.gov (United States)

    Reuber, Ingrid

    1989-04-01

    The Dras arc is recognized as a volcanic arc system in the western part of the Indus suture zone and it constitutes the link between the Ladakh batholith and the Kohistan arc. This study is based on detailed mapping of the area between Dras, Kargil and Sanku which revealed the following: (1) The ultramafics of Dras and Thasgam can be followed across the Suru Dras ridge and are not intrusive into the arc volcanics, but instead constitute the most probably oceanic substratum of these volcanics. (2) Successive volcanic events are distinguished: (a) Dras I is a variable volcaniclastic series rich in slates and carbonates, which can probably be assigned to the Albo-Cenomanian, as dated by orbitolines. This series is intruded by gabbro, diorite and granite and is deformed, essentially in the northern part. It is unconformably overlain by (b) the Dras II pyroclastics which grade southward into volcanic breccia and thus enable the location of the centres of volcanic activity during this younger period.

  2. Climatic Impacts of a Volcanic Double Event: 536/540 CE

    Science.gov (United States)

    Toohey, M.; Krüger, K.; Sigl, M.; Stordal, F.; Svensen, H.

    2015-12-01

    Volcanic activity in and around the year 536 CE led to the coldest decade of the Common Era, and has been speculatively linked to large-scale societal crises around the world. Using a coupled aerosol-climate model, with eruption parameters constrained by recently re-dated ice core records and historical observations of the aerosol cloud, we reconstruct the radiative forcing resulting from a sequence of two major volcanic eruptions in 536 and 540 CE. Comparing with a reconstruction of volcanic forcing over the past 1200 years, we estimate that the decadal-scale Northern Hemisphere (NH) extra-tropical radiative forcing from this volcanic "double event" was larger than that of any known period. Earth system model simulations including the volcanic forcing are used to explore the temperature and precipitation anomalies associated with the eruptions, and compared to available proxy records, including maximum latewood density (MXD) temperature reconstructions. Special attention is placed on the decadal persistence of the cooling signal in tree rings, and whether the climate model simulations reproduce such long-term climate anomalies. Finally, the climate model results will be used to explore the probability of socioeconomic crisis resulting directly from the volcanic radiative forcing in different regions of the world.

  3. Developing a NASA strategy for sampling a major Pinatubo-like volcanic eruption

    Science.gov (United States)

    Newman, P. A.; Jucks, K. W.; Maring, H. B.

    2016-12-01

    Based on history, it is reasonable to expect a major volcanic eruption in the foreseeable future. By "major volcanic eruption", we mean an eruption that injects a substantial amount of material, gases and particles, into the stratosphere as a result of one eruption event. Such a volcanic eruption can impact weather, climate, and atmospheric chemistry on regional, hemispheric and global scales over significant time periods. Further, such an eruption can be an unintended analog for a number of geo-engineering schemes for mitigating greenhouse warming of the Earth. In order to understand and project the consequences of a major eruption, it is necessary to make a number of observations from a variety of perspectives. Such an eruption will occur, in the immediate sense, unexpectedly. Therefore, it is wise to have a thoughtfully developed plan for executing a rapid response that makes useful observations. A workshop was held on 17-18 May 2016 at NASA GSFC to develop a NASA observation strategy that could be quickly implemented in response to a major volcanic eruption, and would characterize the changes to atmospheric (especially stratospheric) composition following a large volcanic eruption. In this presentation we will provide an overview of the elements of this strategy with respect to satellite, balloon, ground, and aircraft observations. In addition, models simulations and forecasts will play a key role in any response strategy. Results will also be shown from a spectrum of simulations of volcanic eruptions that support this NASA strategy.

  4. Dating of the late Quaternary volcanic events using Uranium-series technique on travertine deposit: A case study in Ihlara, Central Anatolia Volcanic Province

    Science.gov (United States)

    Karabacak, Volkan; Tonguç Uysal, İ.; Ünal-İmer, Ezgi

    2016-04-01

    Dating of late Quaternary volcanism is crucial to understanding of the recent mechanism of crustal deformation and future volcanic explosivity risk of the region. However, radiometric dating of volcanic products has been a major challenge because of high methodological error rate. In most cases, there are difficulties on discrimination of the volcanic lava flow relations in the field. Furthermore, there would be unrecorded and unpreserved volcanoclastic layers by depositional and erosional processes. We present a new method that allows precise dating of late Quaternary volcanic events (in the time range of 0-500,000 years before present) using the Uranium-series technique on travertine mass, which is thought to be controlled by the young volcanism. Since the high pressure CO2 in the spring waters are mobilized during crustal strain cycles and the carbonates are precipitated in the fissures act as conduit for hot springs, thus, travertine deposits provide important information about crustal deformation. In this study we studied Ihlara fissure ridge travertines in the Central Anatolia Volcanic Province. This region is surrounded by many eruption centers (i.e. Hasandaǧı, Acıgöl and Göllüdaǧı) known as the late Quaternary and their widespread volcanoclastic products. Recent studies have suggested at least 11 events at around Acıgöl Caldera for the last 180 ka and 2 events at Hasandaǧı Stratovolcano for the last 30 ka. Active travertine masses around Ihlara deposited from hotwaters, which rise up through deep-penetrated fissures in volcanoclastic products of surrounding volcanoes. Analyses of the joint systems indicate that these vein structures are controlled by the crustal deformation due to young volcanism in the vicinity. Thus, the geological history of Ihlara travertine mass is regarded as a record of surrounding young volcanism. We dated 9 samples from 5 ridge-type travertine masses around Ihlara region. The age distribution indicates that the crustal

  5. Volcanism on the Red Planet: Mars. Chapter 4

    Science.gov (United States)

    Greeley, Ronald; Bridges, Nathan T.; Crown, David A.; Crumpler, Larry S.; Fagents, Sarah A.; Mouginis-Mark, Peter J.; Zimbelman, James R.

    2000-01-01

    Of all the planets in the Solar System, Mars is the most Earthlike in its geological characteristics. Like Earth, it has been subjected to exogenic processes, such as impact cratesing and erosion by wind and water, as well as endogenic processes, including tectonic deformation of the crust and volcanism. The effects of these processes are amply demonstrated by the great variety of surface features, including impact craters, landslides, former river channels, sand dunes, and the largest volcanoes in the Solar System. Some of these features suggest substantial changes in Mars' environment during its history. For example, as reviewed by Carr, today Mars is a cold, dry desert with an average atmospheric pressure of only 5.6 mbar which does not allow liquid water to exist on the surface. To some planetary scientists, the presence of the channels bespeaks a time when Mars was warmer and wetter. However, others have argued that these features might have formed under current conditions and that there might not have been a shift in climate. Could the morphology of volcanoes and related features provide clues to past Martian environments? What role is played by atmospheric density in the styles of eruptions on Mars and resulting landforms? If these and related questions can be answered, then we may have a means for assessing the conditions on Mars' surface in the past and comparing the results with models of Martian evolution. In this chapter, we outline the sources of information available for volcanism on Mars, explore the influence of the Martian environment on volcanic processes, and describe the principal volcanic features and their implications for understanding the general evolution of the Martian surface.

  6. Revisiting the observed surface climate response to large volcanic eruptions

    Science.gov (United States)

    Wunderlich, Fabian; Mitchell, Daniel M.

    2017-01-01

    In light of the range in presently available observational, reanalysis and model data, we revisit the surface climate response to large tropical volcanic eruptions from the end of the 19th century until present. We focus on the dynamically driven response of the North Atlantic Oscillation (NAO) and the radiative-driven tropical temperature response. Using 10 different reanalysis products and the Hadley Centre Sea Level Pressure observational dataset (HadSLP2) we confirm a positive tendency in the phase of the NAO during boreal winters following large volcanic eruptions, although we conclude that it is not as clear cut as the current literature suggests. While different reanalyses agree well on the sign of the surface volcanic NAO response for individual volcanoes, the spread in the response is often large (˜ 1/2 standard deviation). This inter-reanalysis spread is actually larger for the more recent volcanic eruptions, and in one case does not encompass observations (El Chichón). These are all in the satellite era and therefore assimilate more atmospheric data that may lead to a more complex interaction for the surface response. The phase of the NAO leads to a dynamically driven warm anomaly over northern Europe in winter, which is present in all datasets considered. The general cooling of the surface temperature due to reduced incoming shortwave radiation is therefore disturbed by dynamical impacts. In the tropics, where less dynamically driven influences are present, we confirm a predominant cooling after most but not all eruptions. All datasets agree well on the strength of the tropical response, with the observed and reanalysis response being statistically significant but the modelled response not being significant due to the high variability across models.

  7. Volcanism on the Red Planet: Mars. Chapter 4

    Science.gov (United States)

    Greeley, Ronald; Bridges, Nathan T.; Crown, David A.; Crumpler, Larry S.; Fagents, Sarah A.; Mouginis-Mark, Peter J.; Zimbelman, James R.

    2000-01-01

    Of all the planets in the Solar System, Mars is the most Earthlike in its geological characteristics. Like Earth, it has been subjected to exogenic processes, such as impact cratesing and erosion by wind and water, as well as endogenic processes, including tectonic deformation of the crust and volcanism. The effects of these processes are amply demonstrated by the great variety of surface features, including impact craters, landslides, former river channels, sand dunes, and the largest volcanoes in the Solar System. Some of these features suggest substantial changes in Mars' environment during its history. For example, as reviewed by Carr, today Mars is a cold, dry desert with an average atmospheric pressure of only 5.6 mbar which does not allow liquid water to exist on the surface. To some planetary scientists, the presence of the channels bespeaks a time when Mars was warmer and wetter. However, others have argued that these features might have formed under current conditions and that there might not have been a shift in climate. Could the morphology of volcanoes and related features provide clues to past Martian environments? What role is played by atmospheric density in the styles of eruptions on Mars and resulting landforms? If these and related questions can be answered, then we may have a means for assessing the conditions on Mars' surface in the past and comparing the results with models of Martian evolution. In this chapter, we outline the sources of information available for volcanism on Mars, explore the influence of the Martian environment on volcanic processes, and describe the principal volcanic features and their implications for understanding the general evolution of the Martian surface.

  8. Volcano seismicity and ground deformation unveil the gravity-driven magma discharge dynamics of a volcanic eruption.

    Science.gov (United States)

    Ripepe, Maurizio; Donne, Dario Delle; Genco, Riccardo; Maggio, Giuseppe; Pistolesi, Marco; Marchetti, Emanuele; Lacanna, Giorgio; Ulivieri, Giacomo; Poggi, Pasquale

    2015-05-18

    Effusive eruptions are explained as the mechanism by which volcanoes restore the equilibrium perturbed by magma rising in a chamber deep in the crust. Seismic, ground deformation and topographic measurements are compared with effusion rate during the 2007 Stromboli eruption, drawing an eruptive scenario that shifts our attention from the interior of the crust to the surface. The eruption is modelled as a gravity-driven drainage of magma stored in the volcanic edifice with a minor contribution of magma supplied at a steady rate from a deep reservoir. Here we show that the discharge rate can be predicted by the contraction of the volcano edifice and that the very-long-period seismicity migrates downwards, tracking the residual volume of magma in the shallow reservoir. Gravity-driven magma discharge dynamics explain the initially high discharge rates observed during eruptive crises and greatly influence our ability to predict the evolution of effusive eruptions.

  9. Periodic paralysis.

    Science.gov (United States)

    Fontaine, Bertrand

    2008-01-01

    Periodic paralyses are rare diseases characterized by severe episodes of muscle weakness concomitant to variations in blood potassium levels. It is thus usual to differentiate hypokalemic, normokalemic, and hyperkalemic periodic paralysis. Except for thyrotoxic hypokalemic periodic paralysis and periodic paralyses secondary to permanent changes of blood potassium levels, all of these diseases are of genetic origin, transmitted with an autosomal-dominant mode of inheritance. Periodic paralyses are channelopathies, that is, diseases caused by mutations in genes encoding ion channels. The culprit genes encode for potassium, calcium, and sodium channels. Mutations of the potassium and calcium channel genes cause periodic paralysis of the same type (Andersen-Tawil syndrome or hypokalemic periodic paralysis). In contrast, distinct mutations in the muscle sodium channel gene are responsible for all different types of periodic paralyses (hyper-, normo-, and hypokalemic). The physiological consequences of the mutations have been studied by patch-clamp techniques and electromyography (EMG). Globally speaking, ion channel mutations modify the cycle of muscle membrane excitability which results in a loss of function (paralysis). Clinical physiological studies using EMG have shown a good correlation between symptoms and EMG parameters, enabling the description of patterns that greatly enhance molecular diagnosis accuracy. The understanding of the genetics and pathophysiology of periodic paralysis has contributed to refine and rationalize therapeutic intervention and will be without doubts the basis of further advances.

  10. Characteristics of Mineralized Volcanic Centers in Javanese Sunda Island Arc, Indonesia

    Science.gov (United States)

    Setijadji, L. D.; Imai, A.; Watanabe, K.

    2007-05-01

    The subduction-related arc magmatism in Java island, Sunda Arc, Indonesia might have started in earliest Tertiary period, but the distinctively recognizable volcanic belts related with Java trench subduction occurred since the Oligocene. We compiled geoinformation on volcanic centers of different epochs, distribution of metallic mineral deposits, petrochemistry of volcanic rocks, geologic structures, and regional gravity image in order to elucidate characteristics of the known mineralized volcanic centers. Metallic deposits are present in various styles from porphyry-related, high-sulfidation, and low-sulfidation epithermal systems; all related with subaerial volcanism and subvolcanic plutonism. Only few and small occurrences of volcanigenic massive sulfides deposits suggest that some mineralization also occurred in a submarine environment. Most locations of mineral deposits can be related with location of Tertiary volcanic centers along the volcanic arcs (i.e. volcanoes whose genetic link with subduction is clear). On the other side there is no mineralization has been identified to occur associated with backarc magmatism whose genetic link with subduction is under debate. There is strong evidence that major metallic deposit districts are located within compressive tectonic regime and bound by coupling major, deep, and old crustal structures (strike-slip faults) that are recognizable from regional gravity anomaly map. So far the most economical deposits and the only existing mines at major industry scale are high-grade epithermal gold deposits which are young (Upper Miocene to Upper Pliocene), concentrated in Bayah dome complex in west Java, and are associated with alkalic magmatism-volcanism. On the other hand, known porphyry Cu-Au deposits are associated with old (Oligocene to Upper Miocene) stocks, and except for one case, all deposits are located in east Java. Petrochemical data suggest a genetic relationship between porphyry mineralization with low- to

  11. Variation of Accumulation Rates Over the Last Eight Centuries on the East Antarctic Plateau Derived from Volcanic Signals in Ice Cores

    Science.gov (United States)

    Anschuetz, H.; Sinisalo, A.; Isaksson, E.; McConnell, J. R.; Hamran, S.-E.; Bisiaux, M. M.; Pasteris, D.; Neumann, T. A.; Winther, J.-G.

    2011-01-01

    Volcanic signatures in ice-core records provide an excellent means to date the cores and obtain information about accumulation rates. From several ice cores it is thus possible to extract a spatio-temporal accumulation pattern. We show records of electrical conductivity and sulfur from firn cores from the Norwegian-USA scientific traverse during the International Polar Year 2007-2009 (IPY) through East Antarctica. Major volcanic eruptions are identified and used to assess century-scale accumulation changes. The largest changes seem to occur in the most recent decades with accumulation over the period 1963- 2007/08 being up to 25 % different from the long-term record. There is no clear overall trend, some sites show an increase in accumulation over the period 1963 to present while others show a decrease. Almost all of the sites above 3200 m above sea level (asl) suggest a decrease. These sites also show a significantly lower accumulation value than large-scale assessments both for the period 1963 to present and for the long-term mean at the respective drill sites. The spatial accumulation distribution is influenced mainly by elevation and distance to the ocean (continentality), as expected. Ground-penetrating radar data around the drill sites show a spatial variability within 10-20 % over several tens of kilometers, indicating that our drill sites are well representative for the area around them. Our results are important for large-scale assessments of Antarctic mass balance and model validation.

  12. The volcanic response to deglaciation: Evidence from glaciated arcs and a reassessment of global eruption records

    Science.gov (United States)

    Watt, Sebastian F. L.; Pyle, David M.; Mather, Tamsin A.

    Several lines of evidence have previously been used to suggest that ice retreat after the last glacial maximum (LGM) resulted in regionally-increased levels of volcanic activity. It has been proposed that this increase in volcanism was globally significant, forming a substantial component of the post-glacial rise in atmospheric CO2, and thereby contributing to climatic warming. However, as yet there has been no detailed investigation of activity in glaciated volcanic arcs following the LGM. Arc volcanism accounts for 90% of present-day subaerial volcanic eruptions. It is therefore important to constrain the impact of deglaciation on arc volcanoes, to understand fully the nature and magnitude of global-scale relationships between volcanism and glaciation. The first part of this paper examines the post-glacial explosive eruption history of the Andean southern volcanic zone (SVZ), a typical arc system, with additional data from the Kamchatka and Cascade arcs. In all cases, eruption rates in the early post-glacial period do not exceed those at later times at a statistically significant level. In part, the recognition and quantification of what may be small (i.e. less than a factor of two) increases in eruption rate is hindered by the size of our datasets. These datasets are limited to eruptions larger than 0.1 km3, because deviations from power-law magnitude-frequency relationships indicate strong relative under-sampling at smaller eruption volumes. In the southern SVZ, where ice unloading was greatest, eruption frequency in the early post-glacial period is approximately twice that of the mid post-glacial period (although frequency increases again in the late post-glacial). A comparable pattern occurs in Kamchatka, but is not observed in the Cascade arc. The early post-glacial period also coincides with a small number of very large explosive eruptions from the most active volcanoes in the southern and central SVZ, consistent with enhanced ponding of magma during

  13. Volcanic Seismicity - The Power of the b-value

    Science.gov (United States)

    Main, I. G.; Roberts, N.; Bell, A. F.

    2016-12-01

    The Gutenberg-Richter `b-value' is commonly used in volcanic eruption forecasting to infer material or mechanical properties from earthquake distributions. It is `well known' that the b-value tends to be high or very high for volcanic earthquake populations relative to b = 1 for those of tectonic earthquakes, and that b varies significantly with time during periods of unrest. Subject to suitable calibration the b-value also allows us to quantify and characterise earthquake distributions of both ancient and currently-active populations, as a measure of the frequency-size distribution of source rupture area or length. Using a new iterative sampling method (Roberts et al. 2016), we examine data from the El Hierro seismic catalogue during a period of unrest in 2011-2013, and quantify the resulting uncertainties. The results demonstrate commonly-applied methods of assessing uncertainty in b-value significantly underestimate the total uncertainty, particularly when b is high. They also show clear multi-modal behaviour in the evolution of the b-value. Individual modes are relatively stable in time, but the most probable b-value intermittently switches between modes, one of which is similar to that of tectonic seismicity, and some are genuinely higher within the total error. A key benefit of this approach is that it is able to resolve different b-values associated with contemporaneous processes, even in the case where some generate high rates of events for short durations and others low rates for longer durations. These characteristics that are typical for many volcanic processes. Secondly, we use a range field observations from the exhumed extinct magma chamber on the Isle of Rum, NW Scotland, to infer an equivalent a b-value for the `frozen' fracture system that would have been active at the time of volcanism 65Ma ago. Using measurements from millimetre-scale fractures to lineation's on satellite imagery over 100m in length, we estimate b=1.8, significantly greater than

  14. Sediment transport dynamics in steep, tropical volcanic catchments

    Science.gov (United States)

    Birkel, Christian; Solano Rivera, Vanessa; Granados Bolaños, Sebastian; Brenes Cambronero, Liz; Sánchez Murillo, Ricardo; Geris, Josie

    2017-04-01

    How volcanic landforms in tropical mountainous regions are eroded, and how eroded materials move through these mostly steep landscapes from the headwaters to affect sediment fluxes are critical to water resources management in their downstream rivers. Volcanic landscapes are of particular importance because of the short timescales (Central Volcanic Cordillera of Costa Rica (Figure 1A). Typical for tropical volcanic and montane regions, deeply incised V-form headwaters (Figure 1B) deliver the majority of water (>70%) and sediments to downstream rivers. At the catchment outlet (Figure 1C) of the San Lorencito stream, we established high temporal resolution (5min) water quantity and sediment monitoring (turbidity). We also surveyed the river network on various occasions to characterize fluvial geomorphology including material properties. We could show that the rainfall-runoff-sediment relationships and their characteristic hysteresis patterns are directly linked to variations in the climatic input (storm intensity and duration) and the size, form and mineralogy of the transported material. Such a relationship allowed us to gain the following insights: (i) periodic landslides contribute significant volumes of material (> 100m3 per year) to the stream network, (ii) rainfall events that exceed a threshold of around 30mm/h rain intensity activate superficial flow pathways with associated mobilization of sediments (laminar erosion). However, the erosion processes are spatially very heterogeneous and mostly linked to finer material properties of the soils that mostly developed on more highly weathered bedrock. (iii) extreme events (return period > 50 years) mainly erode the streambed and banks cutting deeper into the bedrock and re-distribute massive amounts of material in the form of removed old alluvial deposits and new deposits created elsewhere, (iv) recovery after such extreme events in the form of fine material transport even during low intensity rainfall towards pre

  15. SHRIMP zircon U-Pb dating for volcanic rocks of the Dasi Formation in southeast Hubei Province, middle-lower reaches of the Yangtze River and its implications

    Institute of Scientific and Technical Information of China (English)

    XIE Guiqing; MAO Jingwen; LI Ruiling; ZHOU Shaodong; YE Huishou; YAN Quanren; ZHANG Zusong

    2006-01-01

    The Jinniu Basin in southeast Hubei,located at the westernmost part of middle-lower valley of the Yangtze River, is one of the important volcanic basins in East China. Volcanic rocks in the Jinniu Basin are distributed mainly in the Majiashan Formation, the Lingxiang Formation and the Dasi Formation, consisting of rhyolite, basalt and basaltic andesite, (trachy)-basalt and basaltic trachy-andesite and (trachy)-andesite and (trachy)-dacite and rhyolite respectively, in which the Dasi volcanism is volumetrically dominant and widespread. The Dasi volcanic rocks were selected for SHRIMP zircon U-Pb dating to confirm the timing of volcanism. The results indicate that there exist a large amount of magmatic zircons characterized by high U and Th contents in the volcanic rocks. The concordia ages for 13 points are 128±1Ma (MSWD = 3.0). On account of the shape of zircons and Th/U ratios, this age is considered to represent the crystallization time of the Dasi volcanism. The volcanic rocks in the Dasi, Majiashan and Lingxiang Formations share similar trace element and REE partition patterns as well as Sr-Nd isotopic compositions. In combination with the regional geology, it is proposed that the southeast Hubei volcanic rocks were formed mainly during the Early Cretaceous, just like other volcanic basins in middle-lower Yangtze valley. A lithospheric extension is also suggested for tectonic regime in this region in the Cretaceous Period.

  16. Volcanic caves of East Africa - an overview

    Directory of Open Access Journals (Sweden)

    Jim W. Simons

    1998-01-01

    Full Text Available Numerous Tertiary to recent volcanoes are located in East Africa. Thus, much of the region is made up volcanic rock, which hosts the largest and greatest variety of East Africas caves. Exploration of volcanic caves has preoccupied members of Cave Exploration Group of East Africa (CEGEA for the past 30 years. The various publications edited by CEGEA are in this respect a treasure troves of speleological information. In the present paper an overview on the most important volcanic caves and areas are shortly reported.

  17. Volcanic Plume Measurements with UAV (Invited)

    Science.gov (United States)

    Shinohara, H.; Kaneko, T.; Ohminato, T.

    2013-12-01

    Volatiles in magmas are the driving force of volcanic eruptions and quantification of volcanic gas flux and composition is important for the volcano monitoring. Recently we developed a portable gas sensor system (Multi-GAS) to quantify the volcanic gas composition by measuring volcanic plumes and obtained volcanic gas compositions of actively degassing volcanoes. As the Multi-GAS measures variation of volcanic gas component concentrations in the pumped air (volcanic plume), we need to bring the apparatus into the volcanic plume. Commonly the observer brings the apparatus to the summit crater by himself but such measurements are not possible under conditions of high risk of volcanic eruption or difficulty to approach the summit due to topography etc. In order to overcome these difficulties, volcanic plume measurements were performed by using manned and unmanned aerial vehicles. The volcanic plume measurements by manned aerial vehicles, however, are also not possible under high risk of eruption. The strict regulation against the modification of the aircraft, such as installing sampling pipes, also causes difficulty due to the high cost. Application of the UAVs for the volcanic plume measurements has a big advantage to avoid these problems. The Multi-GAS consists of IR-CO2 and H2O gas analyzer, SO2-H2O chemical sensors and H2 semiconductor sensor and the total weight ranges 3-6 kg including batteries. The necessary conditions of the UAV for the volcanic plumes measurements with the Multi-GAS are the payloads larger than 3 kg, maximum altitude larger than the plume height and installation of the sampling pipe without contamination of the exhaust gases, as the exhaust gases contain high concentrations of H2, SO2 and CO2. Up to now, three different types of UAVs were applied for the measurements; Kite-plane (Sky Remote) at Miyakejima operated by JMA, Unmanned airplane (Air Photo Service) at Shinomoedake, Kirishima volcano, and Unmanned helicopter (Yamaha) at Sakurajima

  18. Volcanic tremors: Good indicators of change in plumbing systems during volcanic eruptions

    Science.gov (United States)

    Tárraga, Marta; Martí, Joan; Abella, Rafael; Carniel, Roberto; López, Carmen

    2014-03-01

    Geophysical and geochemical signals recorded during episodes of unrest preceding volcanic eruptions provide information on movements of magma inside the lithosphere and on how magma prepares to reach the surface. When the eruption ensues continuous volcanic monitoring can reveal the nature of changes occurring in the volcano's plumbing system, which may be correlated with changes in both eruption behaviour and products. During the 2011-2012 submarine eruption of El Hierro (Canary Islands), the seismic signal, surface deformation, a broad stain on the sea surface of the eruption site, and the occasional appearance of floating lava balloons and pyroclastic fragments were the main observable signs. A strong continuous tremor in the vent accompanied the eruption and varied significantly in amplitude, frequency and dynamical parameters. We analysed these variations and correlated them with changes in the distribution of earthquakes and in the petrology of the erupting magma. This enabled us to relate variations in tremors to changes in the (i) stress conditions of the plumbing system, (ii) dimensions of the conduit and vent, (iii) intensity of the explosive episodes, and (iv) rheological changes in the erupting magma. The results obtained show how the tremor signal was strongly influenced by stress changes in the host rock and in the rheological variations in the erupting magma. We conclude that the tracking of real-time syn-eruptive tremor signals via the observation of variations in plumbing systems and magma physics is a potentially effective tool for interpreting eruption dynamics, and suggest that similar variations observed in pre-eruptive tremors will have a similar origin.

  19. Paleoproterozoic andesitic volcanism in the southern Amazonian craton (northern Brazil); lithofacies analysis and geodynamic setting

    Science.gov (United States)

    Roverato, Matteo; Juliani, Caetano; Capra, Lucia; Dias Fernandes, Carlos Marcelo

    2016-04-01

    Precambrian volcanism played an important role in geological evolution and formation of new crust. Most of the literature on Precambrian volcanic rocks describes settings belonging to subaqueous volcanic systems. This is likely because subaerial volcanic rocks in Proterozoic and Archean volcano-sedimentary succession are poorly preserved due to erosive/weathering processes. The late Paleoproterozoic Sobreiro Formation (SF) here described, seems to be one of the rare exceptions to the rule and deserves particular attention. SF represents the subaerial expression of an andesitic magmatism that, linked with the upper felsic Santa Rosa F., composes the Uatumã Group. Uatumã Group is an extensive magmatic event located in the Xingú region, southwestern of Pará state, Amazonian Craton (northern Brazil). The Sobreiro volcanism is thought to be related to an ocean-continent convergent margin. It is characterized by ~1880 Ma well-preserved calc-alkaline basaltic/andesitic to andesitic lava flows, pyroclastic rocks and associated reworked successions. The superb preservation of its rock-textures allowed us to describe in detail a large variety of volcaniclastic deposits. We divided them into primary and secondary, depending if they result from a direct volcanic activity (pyroclastic) or reworked processes. Our study reinforces the importance of ancient volcanic arcs and rocks contribution to the terrestrial volcaniclastic sedimentation and evolution of plate tectonics. The volcanic activity that produced pyroclastic rocks influenced the amount of detritus shed into sedimentary basins and played a major role in the control of sedimentary dispersal patterns. This study aims to provide, for the first time, an analysis of the physical volcanic processes for the subaerial SF, based in field observation, lithofacies analysis, thin section petrography and less geochemical data. The modern volcanological approach here used can serve as a model about the evolution of Precambrian

  20. Evolution of the East African rift: Drip magmatism, lithospheric thinning and mafic volcanism

    Science.gov (United States)

    Furman, Tanya; Nelson, Wendy R.; Elkins-Tanton, Linda T.

    2016-07-01

    The origin of the Ethiopian-Yemeni Oligocene flood basalt province is widely interpreted as representing mafic volcanism associated with the Afar mantle plume head, with minor contributions from the lithospheric mantle. We reinterpret the geochemical compositions of primitive Oligocene basalts and picrites as requiring a far more significant contribution from the metasomatized subcontinental lithospheric mantle than has been recognized previously. This region displays the fingerprints of mantle plume and lithospheric drip magmatism as predicted from numerical models. Metasomatized mantle lithosphere is not dynamically stable, and heating above the upwelling Afar plume caused metasomatized lithosphere with a significant pyroxenite component to drip into the asthenosphere and melt. This process generated the HT2 lavas observed today in restricted portions of Ethiopia and Yemen now separated by the Red Sea, suggesting a fundamental link between drip magmatism and the onset of rifting. Coeval HT1 and LT lavas, in contrast, were not generated by drip melting but instead originated from shallower, dominantly anhydrous peridotite. Looking more broadly across the East African Rift System in time and space, geochemical data support small volume volcanic events in Turkana (N. Kenya), Chyulu Hills (S. Kenya) and the Virunga province (Western Rift) to be derived ultimately from drip melting. The removal of the gravitationally unstable, metasomatized portion of the subcontinental lithospheric mantle via dripping is correlated in each case with periods of rapid uplift. The combined influence of thermo-mechanically thinned lithosphere and the Afar plume together thus controlled the locus of continental rift initiation between Africa and Arabia and provide dynamic support for the Ethiopian plateau.

  1. Environmental hazards of fluoride in volcanic ash: a case study from Ruapehu volcano, New Zealand

    Science.gov (United States)

    Cronin, Shane J.; Neall, V. E.; Lecointre, J. A.; Hedley, M. J.; Loganathan, P.

    2003-03-01

    The vent-hosted hydrothermal system of Ruapehu volcano is normally covered by a c. 10 million m 3 acidic crater lake where volcanic gases accumulate. Through analysis of eruption observations, granulometry, mineralogy and chemistry of volcanic ash from the 1995-1996 Ruapehu eruptions we report on the varying influences on environmental hazards associated with the deposits. All measured parameters are more dependent on the eruptive style than on distance from the vent. Early phreatic and phreatomagmatic eruption phases from crater lakes similar to that on Ruapehu are likely to contain the greatest concentrations of environmentally significant elements, especially sulphur and fluoride. These elements are contained within altered xenolithic material extracted from the hydrothermal system by steam explosions, as well as in residue hydrothermal fluids adsorbed on to particle surfaces. In particular, total F in the ash may be enriched by a factor of 6 relative to original magmatic contents, although immediately soluble F does not show such dramatic increases. Highly soluble NaF and CaSiF 6 phases, demonstrated to be the carriers of 'available' F in purely magmatic eruptive systems, are probably not dominant in the products of phreatomagmatic eruptions through hydrothermal systems. Instead, slowly soluble compounds such as CaF 2, AlF 3 and Ca 5(PO 4) 3F dominate. Fluoride in these phases is released over longer periods, where only one third is leached in a single 24-h water extraction. This implies that estimation of soluble F in such ashes based on a single leach leads to underestimation of the F impact, especially of a potential longer-term environmental hazard. In addition, a large proportion of the total F in the ash is apparently soluble in the digestive system of grazing animals. In the Ruapehu case this led to several thousand sheep deaths from fluorosis.

  2. Paleosubmarine Volcanism and Mineralization from North Qilian Mountains

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    This paper summarizes the history of tectono-magmatic evolution, the types and backgrounds of mineralization prior to the orogenic period of North Qilian Mountains. It points out that: during the process of Paleozoic ocean basin opening and closing, the large scale marine volcanism and massive sulfide deposits controlled by sea floor hydrothermal circulation systems are the two sharpest features in the geological developing history of the orogenic belt, which are also the most two important aspects related to each other and should be given a special attention in the geological studies in the region.

  3. People's behaviour in the face of volcanic hazards: Perspectives from Javanese communities, Indonesia

    Science.gov (United States)

    Lavigne, Franck; De Coster, Benjamin; Juvin, Nancy; Flohic, François; Gaillard, Jean-Christophe; Texier, Pauline; Morin, Julie; Sartohadi, Junun

    2008-05-01

    This paper is concerned with the way in which the Indonesian people living on the slopes or near active volcanoes behave in the face of volcanic threats. It explores the role of three factors in the shaping of this behaviour, e.g. risk perception, cultural beliefs and socio-economic constraints. The paper is mainly based on field data collected during the last 5 years on four volcanoes in Central Java, namely Sumbing, Sindoro, Dieng, and Merapi. The common assumption that hazard knowledge, risk perception and people's behaviour are closely related and conditional on volcanic activity is debatable in the Indonesian context. Factors that play a role in hazard knowledge—e.g. basic knowledge of volcanic processes, personal experience of volcanic crisis, time lapsed since the last volcanic eruption, etc.—differ from those that influence risk perception. Indeed, local people often underestimate the scientifically or statistically estimated risk. This poor risk perception is characterized by an approximate personal representation of the volcanic processes, an excess of trust in concrete countermeasures, the presence of a physical-visual obstructions, or cultural beliefs related to former eruptions. In addition, the commonly-acknowledged factors that influence hazard knowledge and/or risk perception may be at odds with the non hazard-related factors that prompt or force people to live in or to exploit areas at risk. These factors may be either socio-cultural—e.g., attachment to place, cultural beliefs, etc.—or social and socio-economical —e.g., standard of living, strength of people's livelihoods, well-being. These factors are fundamental in explaining the short-term behaviour in the face of a developing threat during a volcanic crisis.

  4. Effects of deglaciation on the petrology and eruptive history of the Western Volcanic Zone, Iceland

    Science.gov (United States)

    Eason, Deborah E.; Sinton, John M.; Grönvold, Karl; Kurz, Mark D.

    2015-06-01

    New observations and geochemical analyses of volcanic features in the 170-km-long Western Volcanic Zone (WVZ) of Iceland constrain spatial and temporal variations in volcanic production and composition associated with the last major deglaciation. Subglacial eruptions represent a significant portion of the late Quaternary volcanic budget in Iceland. Individual features can have volumes up to ˜48 km3 and appear to be monogenetic. Subaqueous to subaerial transition zones provide minimum estimates of ice sheet thickness at the time of eruption, although water-magma interactions and fluctuating lake levels during eruption can lead to complex lithological sequences. New major and trace element data for 36 glacial and postglacial eruptive units, combined with observations of lava surface quality, passage zone heights, and 3He exposure ages of some glacial units, indicate a maximum in volcanic production in the WVZ during the last major ice retreat. Anomalously high volcanic production rates continue into the early postglacial period and coincide with significant incompatible element depletions and slightly higher CaO and SiO2 and lower FeO content at a given MgO. Subglacial units with strong incompatible element depletions also have lava surfaces that lack evidence of subsequent glaciation. These units likely formed after the onset of deglaciation, when rapidly melting ice sheets increased decompression rates in the underlying mantle, leading to anomalously high melting rates in the depleted upper mantle. This process also can explain the eruption of extremely depleted picritic lavas during the early postglacial period. These new observations indicate that the increased volcanic activity associated with glacial unloading peaked earlier than previously thought, before Iceland was completely ice free.

  5. Time trend analysis of basaltic volcanism for the Yucca Mountain site

    Science.gov (United States)

    Ho, Chih-Hsiang

    1991-05-01

    The possible recurrence of volcanic activity near the proposed nuclear waste repository at Yucca Mountain, Nevada, U.S.A. is evaluated by estimating the instantaneous recurrence rate using a nonhomogeneous Poisson process with Weibull intensity and by using a homogeneous Poisson process to predict future eruptions. Analysis on the post-6-Ma volcanism near the Yucca Mountain region indicates a moderate developing time trend ( p-value = 0.01) of volcanic activity. A similar time trend is obtained by trimming the observation period to 3.7 Ma and younger (period of the youngest episode). Data from the Quaternary basaltic volcanism also show a slight developing time trend, although the developing volcanic activity is not significant at the 0.05 level. Thus, it would oversimplify the assessment of the volcanic risk to the proposed Yucca Mountain repository site if a simple Poisson model were used to model the volcanism. Based on the Quaternary data, the estimated instantaneous recurrence rate is about 5.5 × 10 -6/yr. An estimate of the mean time to the next eruption is about 1.8 × 10 5 years from now, if it is assumed that the